Change search
Refine search result
12 1 - 50 of 70
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Anandika, Rayendra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Phased array ultrasonic inspection of near-surface cracks in a railhead and its verification with rail slicing2020In: Insight: Non-Destructive Testing & Condition Monitoring, ISSN 1354-2575, E-ISSN 1754-4904, Vol. 62, no 7, p. 387-395Article in journal (Refereed)
    Abstract [en]

    In this study, near-surface cracks in a railhead are inspected thoroughly using phased array ultrasonic testing (PAUT). This research finds an alternative technique to inspect for near-surface cracks because the conventional non-destructive testing method for rail inspection lacks the capacity to inspect the near-surface crack profile. This study shows that PAUT can determine not only the crack depth but also the near-surface crack profile, so that the inspector can estimate the stage of crack growth and how the crack propagates. This information is valuable to the rail maintainer as one of the considerations for deciding the thickness of metal to remove when grinding the rail. In this study, after the measurement, the inspected region of the cracked railhead is sliced into thin pieces so that crack network information can be extracted. A 3D image reconstruction of the surface cracks based on the crack marks from all of the sliced rail pieces is performed. This image is then used as a reference to confirm the PAUT results. The results show that PAUT can clearly deliver crack profile estimation and provide an accurate estimation of a 3.51 mm crack-tip depth with an absolute error range of 8%-18%. The results also suggest that PAUT is a potential method for installation in a measurement train for near-surface crack inspection.

  • 2.
    Anandika, Rayendra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ultrasonic phased array measurement of near-surface cracks in the railhead.2019In: World Congress on Railway Research (WCRR) 2019, Tokyo, Japan, Railway Technical Research Institute (RTRI, Japan) , 2019, article id PB027753Conference paper (Refereed)
    Abstract [en]

    Ultrasonic measurement is one of the non-destructive techniques used to inspect defects in the rail body. Ultrasonic measurement is known inappropriate to inspect near-surface defects because of a challenge, called dead-zone. It is signal noise or ringing phenomenon located at near-field in front of the transducer when measuring a material. Due to this, there is difficulty in analysing any measurement signal at this zone, including signals from near-surface defects. In this study, the dead zone was eliminated by attaching wedge to shift the location of noise signals relative to the near-surface defect locations. First, a known-depth defect was measured by using phased array ultrasonic testing (PAUT) to calibrate the ultrasonic equipment and found the best signal gain to eliminate diffuse scattering from defects. Second, a cracked spot on railhead was inspected at the right and left direction of the spot. After the measurement, the inspected spot was sliced into 0.65 mm-thick pieces. From those pieces, the actual crack depth could be observed directly. Based on those sliced pieces, the ultrasonic measurement results were verified. From this study, PAUT delivered accurate measurement result of 3.51-mm crack tip depth with an absolute error of 0.8% - 18%. This accurate result indicates that PAUT can be an alternative to inspect the near-surface crack in railhead. 

    Download full text (pdf)
    Ultrasonic phased array measurement of near-surface cracks in the railhead
  • 3.
    Anandika, Rayendra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Non-destructive measurement of artificial near-surface cracks for railhead inspection2019In: Insight: Non-Destructive Testing & Condition Monitoring, ISSN 1354-2575, E-ISSN 1754-4904, Vol. 61, no 7, p. 373-379Article in journal (Refereed)
    Abstract [en]

    This paper delivers a study involving the inspection of artificial surface cracks with depths ranging from 0.25-2.5 mm from the surface and with a crack angle of 30°, which is a typical angle for surface cracks in railheads. The inspections were conducted using three different techniques: phased array ultrasonics, single-element ultrasonics and alternating current potential drop (ACPD). For the ultrasonic techniques, the study focused on employing either longitudinal or shear wave signals. In the railway industry, shallow surface cracks in railheads are caused by rolling contact fatigue (RCF). In this study, artificial defects were made, allowing the authors to explore the extent to which the ultrasonic measurement techniques can detect such defects. The negative effect of a dead zone near to the surface in the ultrasonic tests was reduced by using a wedge attachment. A discussion on the extent to which the techniques can be used in field tests was also provided. The most important result is that shallow cracks ranging from 0.25-2.5 mm were successfully characterised with acceptable accuracy. The 2.5 mm-deep crack can be measured with an accuracy of 0.8% using a 20 MHz single-element probe and with an accuracy of 3.5% using a 5 MHz phased array (64 elements, 0.6 mm pitch). The characterisations were performed using a filtering method that was developed in this study.

    1675605

  • 4.
    Berges, Luis
    et al.
    Department of Design Engineering and Manufacturing, University of Zaragoza.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Qualitative and quantitative aspects of maintenance performance measurement: a data fusion approach2013In: International Journal of Strategic Engineering Asset Management (IJSEAM), ISSN 1759-9733, E-ISSN 1759-9741, Vol. 1, no 3, p. 238-252Article in journal (Refereed)
    Abstract [en]

    The measurement of maintenance performance is often faced with a lack in knowledge about the real function of the maintenance department within organisations, and consequently appropriate targets from the global mission and vision are absence. Measurement metrics are not adapted to real needs, which have a strong human factor; nor is there a roadmap of the amount of data to be collected, their processing or how they are used in decision making. This article proposes a model where qualitative and quantitative methods are combined to complement the advantages of both.

  • 5.
    Eriksson, Kjell
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Homogenization of the 1D Peri-static/dynamic Bar with Constant Micromodulus2020In: Journal of Peridynamics and Nonlocal Modeling, ISSN 2522-896X, Vol. 2, no 2, p. 205-228Article in journal (Refereed)
    Abstract [en]

    Because of the nonlocal interparticle forces inherent in peridynamics, surface, boundary, and end effects appear in 3D, 2D and 1D body problems, respectively. In certain situations, the effect is seen as a disturbance, and various efforts, mostly centering on 2D and 1D problems, have been made to reduce it. A simple method has been derived to remove the end effects in a 1D body by homogenizing the body. When a certain body type, common in practice, is homogenized, its linear elastic behavior, independent of the interparticle force range and with a finite number of material points, in the limit infinite, is identical to that of a corresponding classical continuum mechanics body.

  • 6.
    Eriksson, Kjell
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Stenström, Christer
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. Luossavaara-Kiirunavaara Aktiebolag (LKAB), Luleå, Sweden.
    Homogenization of the 1D Peri-static/dynamic Bar with Triangular Micromodulus2021In: Journal of Peridynamics and Nonlocal Modeling, ISSN 2522-896X, Vol. 3, no 2, p. 85-112Article in journal (Refereed)
    Abstract [en]

    In peridynamics, boundary effects generally appear due to nonlocality of interparticle forces; in particular, end effects are found in 1D bars. In a previous work by Eriksson and Stenström (J Peridyn Nonlocal Model 2(2):205–228, 2020), a simple method to remove end effects in certain types of 1D bars, or to homogenize such bars, was presented for bars with constant micromodulus. In this work, which is a continuation of Eriksson and Stenström (J Peridyn Nonlocal Model 2(2):205–228, 2020), the homogenizing procedure is applied to bars with a linear, or “triangular,” micromodulus. For the examples studied, common in practice, the linear elastic behavior of a homogenized bar, is identical to that of a corresponding classical continuum mechanics bar, independently of the interparticle force range and total number of material points of the bar.

  • 7.
    Famurewa, Stephen Mayowa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asplund, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Composite indicator for railway infrastructure management2014In: Journal of Modern Transportation, ISSN 2095-087X, E-ISSN 2196-0577, Vol. 22, no 4, p. 214-224Article in journal (Refereed)
    Abstract [en]

    The assessment and analysis of railway infrastructure capacity is an essential task in railway infrastructure management carried out to meet the required quality and capacity demand of railway transport. For sustainable and dependable infrastructure management, it is important to assess railway capacity limitation from the point of view of infrastructure performance. However, the existence of numerous performance indicators often leads to diffused information that is not in a format suitable to support decision making. In this paper, we demonstrated the use of fuzzy inference system for aggregating selected railway infrastructure performance indicators to relate maintenance function to capacity situation. The selected indicators consider the safety, comfort, punctuality and reliability aspects of railway infrastructure performance. The resulting composite indicator gives a reliable quantification of the health condition or integrity of railway lines. A case study of the assessment of overall infrastructure performance which is an indication of capacity limitation is presented using indicator data between 2010 and 2012 for five lines on the network of Trafikverket (Swedish Transport Administration). The results are presented using customised performance dashboard for enhanced visualisation, quick understanding and relevant comparison of infrastructure conditions for strategic management. This gives additional information on capacity status and limitation from maintenance management perspective.

  • 8.
    Famurewa, Stephen Mayowa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asplund, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Composite indicator for railway infrastructure management2013Conference paper (Refereed)
    Abstract [en]

    The assessment of efficiency and effectiveness of past maintenance decisions and actions is an essential element in maintenance process. The significance of this is not only limited to communicating the value contribution of maintenance to overall business objectives but also to drive maintenance for improvement and towards excellence. However the existence of numerous maintenance result areas and many operational level indicators often lead to distributed information that is not in a suitable format required to support decision making. This paper motivates the use of fuzzy logic approach to aggregate selected indicators to appreciate the information bit distributed in each indicator. The selected indicators include measures related to safety, comfort, punctuality, availability and reliability aspects of maintenance. Linguistic description and fuzzy sets are developed for each of the indicators which are regarded as input parameters. Also domain experts are employed to develop inference rules for the aggregation process. The methodology of using fuzzy inference system for aggregating maintenance performance indicators is demonstrated with selected line sections of Trafikverket (Swedish Transport Administration). The resulting composite indicator gives a reliable quantification of the health condition of the asset and performance of maintenance within the period under consideration. This can be easily communicated and benchmarked within the organization of the infrastructure manager.

  • 9.
    Fecarotti, Claudia
    et al.
    University of Nottingham.
    Heubach, Justin
    Strukton Rail Bv.
    Kirwan, Andy
    Network Rail Infrastructure Ltd.
    Samson, Henk
    Strukton Rail Bv.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Requirements and Initial Concept for an Asset Management Framework2017Report (Other academic)
    Abstract [en]

    This document constitutes the first issue of Deliverable D6.2 ‘Requirements and initial concept for an asset management framework’ in the framework of the project titled ‘Innovative Intelligent Rail’ (Project Acronym: In2Rail; Grant Agreement No 635900).

    This document has been prepared to provide the requirements and initial concept of a comprehensive framework for performance prediction, modelling and decision support for railway asset management, taking into account UIC asset management (AM) guidelines, rail infrastructure performance and constraints on resources and the supply chain. Two objectives guide the work: developing a key performance indicator (KPI) decision framework and defining a framework for performance prediction, modelling and decision support.

    Based on interviews and a study of previous work, including In2Rail D6.1, a KPI decision framework has been constructed, fully compliant with UIC AM guidelines, and an adapted KPI definition guide has been applied to two case studies. Specifically, the KPI definition guide has been used to exemplarily define availability KPI and risk matrix KPI in the context of rail transportation, using 36 questions to define the indicators and 10 questions to verify them. The KPIs are demonstrated using infrastructure managers’ (IMs) records of operation and maintenance.

    The developed framework constitutes a comprehensive modelling structure for describing, analysing, and optimising asset management decisions on a whole-life, whole-system basis. It defines a systematic approach to analysing the effects of any intervention plan and produces performance, risk and cost profiles that can be used as decision support. The framework will facilitate the assessment and development of intervention plans in three planning stages: strategic, tactical and operational. In this sense, the framework is fully compliant with ISO 55001, complementary to the UIC AM framework, and aligned with the Intelligent Asset Management System (IAMS) developed in In2Smart leverabel D2.1.

  • 10.
    Galar, Diego
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berges, Luis
    Manufacturing Engineering and Advanced Metrology Group, Aragon Institute of Engineering Research (13A), University of Zaragoza.
    Maintenance metrics: a hierarchical model of balanced scorecard2011In: 2011 IEEE International Conference on Quality and Reliability: ICQR 2011 : Bangkok, 14 September 2011-17 September 2011, Piscataway, NJ: IEEE Communications Society, 2011, p. 67-74Conference paper (Refereed)
    Abstract [en]

    The system of performance measurement of maintenance function should cover all processes related to it within the organization. There must be an interconnection between the different indicators, so the numbers can be interpreted in order to reach a good conclusion for decision making. This premise implies a hierarchy of indicators needed in a dual way. First, it will require maintenance indicators to be segmented according to the areas of influence for the rest of the organization, posed by interactions with finance department, human resources, purchasing, and, of course, with production in the seeking of compliance with corporate objectives. Simultaneously, these indicators correspond to different levels in the organization and therefore they will be segmented according to the hierarchical position of end users.

  • 11.
    Galar, Diego
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Peters, Ralph
    Maintenance Excellence Institute.
    Berges, Luis
    Manufacturing Engineering and Advanced Metrology Group, Aragon Institute of Engineering Research (13A), University of Zaragoza.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Composite indicators in asset management2012Conference paper (Refereed)
    Abstract [en]

    Composite indicators are formed when individual indicators are compiled into a single index. A composite indicator should ideally measure multidimensional concepts which cannot be captured by a single index. Since asset management is multidisciplinary, composite indicators would be helpful. The paper describes a method of monitoring a complex entity in a processing plant. In this scenario, a plurality of use indices and weighting values are used to create a composite use index from a combination of lower level use indices and weighting values. Each use index contains status information on one aspect of the lower level entities, and each weighting value corresponds to one lower level entity. The resulting composite indicator can be a decision-making tool for asset managers.Keywords – Indicator, aggregation, KPI, performance, hierarchy, DSS

  • 12.
    Galar, Diego
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Auditoria de Manutenção Baseada em Elementos Quantitativos e Qualitativos em Sistemas de Saúde: [Maintenance Audit Based on Quantitative and Qualitative Elements for Health Care Systems]2011In: Tecno Hospital, ISSN 1645-9431, no 47, p. 24-29Article in journal (Other academic)
    Abstract [en]

    The dependability of hospital facilities and equipments is a critical element in the performance of health care systems. The availability needs to be near one hundred percent, especially equipment related to the emergency department. Faults in equipments have to be rectified as fast as possible, i.e. the organizational readiness and the maintainability of the equipments need to be excellent. This paper introduces a maintenance audit model, based on quantitative and qualitative elements, together with a maturity model for facilities and equipments of health care systems. Qualitative and quantitative methods are combined in order to complement advantages and disadvantages of them both.

    Download full text (pdf)
    fulltext
    Download full text (pdf)
    English translation
  • 13.
    Galar, Diego
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Rupesh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berges, Luis
    University of Zaragoza.
    Human factor in maintenance performance measurement2011In: IEEE International Conference on Industrial Engineering and Engineering Management (IEEM), Piscataway, NJ: IEEE Communications Society, 2011, p. 1569-1576Conference paper (Refereed)
    Abstract [en]

    The maintenance performance measurement is often faced with a lack in knowledge about the real function of the maintenance department within organizations, and consequently the absence of appropriate targets emanating from the global mission and vision. These facts bring about metrics not adapted to the real needs, which has a strong load of human factor and without a roadmap of the amount of data to be collected, their processing and use in decision making. This article proposes a model where qualitative and quantitative methods are combined in order to complement advantages and disadvantages of them both.

  • 14.
    Juntti, Ulla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asplund, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ripke, Burchard
    Lundwall, Björn
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kent, Stephen
    Glebe, Filip
    Nissen, Arne
    AUTOMAIN: D4.1 Improvement analysis for high performance maintenance and modular infrastructure2013Report (Other academic)
    Download full text (pdf)
    FULLTEXT01
  • 15.
    Juntti, Ulla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asplund, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nissen, Arne
    Ripke, Burchard
    Lundwall, Björn
    AUTOMAIN: D4.2 Optimised maintenance activities like, grinding, tamping and other maintenance processes2013Report (Other academic)
  • 16.
    Juntti, Ulla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Eriksson, Kristina
    Trafikverket.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Increasing market credibility through continuous vulnerability reduction: A3.5, WP32013Report (Other academic)
    Download full text (pdf)
    FULLTEXT01
  • 17.
    Khan, Saad Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Carry distance of top-of-rail friction modifiers2018In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 232, no 10, p. 2418-2430Article in journal (Refereed)
    Abstract [en]

    Rail issues such as corrugation, rolling contact fatigue, noise and wear have been increasing with the increase in railway traffic. The application of top-of-rail friction modifiers (TOR-FMs) is claimed by their manufacturers in the railway industry to be a well-established technique for resolving the above-mentioned issues. There are various methods for applying friction modifiers at the wheel–rail interface, among which stationary wayside systems are recommended by TOR-FM manufacturers when a distance of a few kilometres is to be covered. TOR-FM manufacturers also claim that by using wayside equipment, the TOR-FM can be spread over a minimum distance of 3 km, over which it maintains a coefficient of friction of µ = 0.35 ± 0.05. To determine the carry distance of TOR-FMs, some researchers use tribometers to measure the coefficients of friction. However, moisture and deposits from the environment and trains can alter the top-of-rail friction and give a misleading indication of the presence of a friction modifier. Therefore, the coefficient of friction itself is not a clear indicator of the presence of TOR-FMs. In the present study, cotton swabs dipped in a mixture of alcohol and ester were used to collect surface deposits (a third body) from both the wheel and rail at various distances from the point of application. Subsequently, the third body collected on the cotton swab was analysed using an energy dispersive X-ray analysis. The results have shown that the maximum carry distance of TOR-FMs on the top of the rail is limited to 70 m when using a TOR-FM from one manufacturer and to 450 m when using a TOR-FM from another manufacturer. The carry distance on the contact band of the wheel is limited to 100 m and 340 m. The friction modifier on the edges of the contact band was detected over a distance of up to 3 km; however, this will not minimise the damage or friction at the wheel–rail interface.

  • 18.
    Khan, Saad Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Life cycle cost analysis for the top-of-rail friction-modifier application: A case study from the Swedish iron ore line2021In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 235, no 1, p. 83-93Article in journal (Refereed)
    Abstract [en]

    The application of top-of-rail friction modifiers (TOR-FMs) is claimed by their manufacturers as a well-established technique for minimising the damages in the wheel–rail interface. There are various methods for applying friction modifiers at the wheel–rail interface, among which stationary wayside systems are recommended by TOR-FM manufacturers when a distance of a few kilometres is to be covered. An on-board system is recommended when an area of many kilometres has to be covered and focus is more on particular trains. Trafikverket in Sweden is considering the implementation of the TOR-FM technology on the iron ore line. Directly implementing such technology can be inappropriate and expensive, because the life cycle cost of a TOR-FM system has never been assessed for the conditions of the iron ore line. In the present study, the life cycle cost is calculated for wayside and on-board application systems, by taking inputs from the research performed on iron ore line. The present research has taken the iron ore line as a case study, but the results will be applicable to other infrastructure with similar conditions. The results have shown that the wayside equipment is economically unfeasible for the iron ore line. In this case, the life cycle cost increases by 4% when the friction modifier is applied on all curves with a radius smaller than 550 m and by 19% when the friction modifier is applied on all curves with a radius smaller than 850 m. The on-board system used in this study is shown to be economically feasible, as it has a significantly lower operation and maintenance cost than the wayside equipment. The reduction in the maintenance (grinding and rail replacement) cost when the cost of the friction modifier application is added is 27% when the friction modifier is applied on curves with a radius smaller than 550 m and 23% when the friction modifier is applied on curves with a radius smaller than 850 m.

  • 19.
    Khan, Saad Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    The effect of third bodies on wear and friction at the wheel-rail interface2022In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 236, no 6, p. 662-671Article in journal (Refereed)
    Abstract [en]

    The friction forces between the wheel and rail depend on a number of variables including the third body layer at the wheel–rail interface, the wheel and rail profiles, and the train dynamics. The third body layer significantly influences the damage mechanisms at the wheel-rail interface, especially wear, rolling contact fatigue (RCF), corrugations and other surface defects that then require maintenance. The introduction of additional constituents at the wheel–rail interface in the form of an additive with anti-wear and anti-crack properties can reduce the wear and RCF. In general, such an additive also reduces the friction. However, it is important to avoid the friction coefficient between the wheel tread and the top of the rail falling below 0.3 because the result would be wheel slip and long braking distances. Measuring friction coefficients accurately is still a challenge, as most existing tribometers are unable to replicate the wheel-rail contact conditions, specifically the contact pressure and sliding speed. The present study used a newly designed handheld tribometer that is able to match the typical contact pressure. Results obtained with the handheld tribometer have been compared with values extracted from the traction-force measurement system of a locomotive. The tribometer field measurements have shown that by using a top-of-rail friction modifier (TOR-FM), both the wear and the friction coefficients can be reduced, but also that heavy TOR-FM films may cause unacceptably low friction. Comparing the results of field and laboratory tests confirms that weather and realistic third bodies present on the track have a significant effect on friction and wear. © IMechE 2021.

  • 20.
    Khan, Saad Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Persson, Ingemar
    AB DEsolver, Östersund, Sweden.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Prediction of the effects of friction control on top-of-rail cracks2018In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 232, no 2, p. 484-494Article in journal (Refereed)
    Abstract [en]

    Rolling contact fatigue is a major problem connected with railway tracks, especially in curves, since it leads to highermaintenance costs. By optimising the top-of-rail friction, the wear and cracks on the top of the rail can eventually bereduced without causing very long braking distances. There are several research articles available on crack prediction,but most of the research is focused either on rail without a friction modifier or on wheels with and without frictioncontrol. In the present study, in order to predict the formation of surface-initiated rolling contact fatigue, a range offriction coefficients with different Kalker’s reduction factors has been assumed. Kalker’s reduction factor takes care ofthe basic tendency of creepage as a function of the traction forces at lower creepage. The assumed range covers possiblefriction values from those for non-lubricated rail to those for rail with a minimum measured friction control on the top ofthe rail using a friction modifier. A fatigue index model based on the shakedown theory was used to predict thegeneration of surface-initiated rolling contact fatigue. Simulations were performed using multi-body simulation, forwhich inputs were taken from the Iron Ore line in the north of Sweden. The effect of friction control was studiedfor different curve radii, ranging from 200 m to 3000 m, and for different axle loads from 30 to 40 tonnes at a constanttrain speed of 60 km/h. One example of a result is that a maximum friction coefficient (m) of 0.2 with a Kalker’s reductionfactor of 15% is needed in the case of trains with a heavy axle load to avoid crack formation.

    Download full text (pdf)
    fulltext
  • 21.
    Khan, Saad Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Persson, Ingemar
    AB DEsolver, Östersund.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Prediction of top-of-rail friction control effects on rail RCF suppressed by wear2017In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 380-381, p. 106-114Article in journal (Refereed)
    Abstract [en]

    Rolling contact fatigue (RCF) and wear, two major deterioration processes, limit the lifetime of rails. These deterioration processes are even more severe on the curves of tracks used by heavy haul trains. Because wear is a material removing process, it can suppress the formation of RCF (also known as surface initiated cracks). In railways, cracks have a higher risk of instigating a catastrophic failure than wear; hence, it is comparatively better to have wear than to have cracks. By controlling the top-of-rail friction, both of these deteriorating processes can be reduced to enhance the lifetime of rails. In order to achieve these possible advantages, the infrastructure manager of the Swedish railway is planning to implement a top-of-rail friction control technology on the iron ore line in northern Sweden wherein RCF is a major problem on the curves. The present study uses a damage index model in a multi-body simulation software and predicts the probability of RCF formation with suppressing effect of wear for different friction control values. The effect of friction control is simulated on curve radii ranging from 200 to 3,000 m and axle loads ranging from 30 to 40 t at a constant train speed of 60 km/h. Findings show that on a very sharp circular curve, radius < 300 m, RCF can be eliminated without friction control due to the high wear rate. On moderate curves, 300 < radius < 1,000 m, a friction coefficient (µ) of, at most, 0.3 with a Kalker's coefficient of, at most, 30% is required to avoid RCF

  • 22.
    Kumar, Uday
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Maintenance audits using balanced scorecard and maturity model2011In: Maintworld, ISSN 1798-7024, E-ISSN 1799-8670, no 3, p. 34-40Article in journal (Other academic)
    Abstract [en]

    There is increasing interest in the use of maintenance performance measurement (MPM) and the possibility of using the maintenance audits for benchmarking metrics. This article proposes a methodology for simple measurement, one that accepts the indicators used on a scorecard with four perspectives and is hierarchized according to organizational level. The maintenance audit will evaluate the degree of fulfillment of objectives and the degree of satisfaction obtained from each of those perspectives. It will provide a clear picture of the current status of maintenance organization and the success of implemented policies taking into account the maintenance maturity model, i.e, the logical evolution of the maintenance function in the company.

    Download full text (pdf)
    FULLTEXT01
  • 23.
    Kumar, Uday
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berges, L.
    University of Zaragoza.
    Maintenance performance metrics: a state of the art review2011In: MPMM 2011: Maintenance Performance Measurement & Management: Conference Proceedings / [ed] Diego Galar; Aditya Parida; Håkan Schunnesson; Uday Kumar, Luleå: Luleå tekniska universitet, 2011, p. 3-34Conference paper (Refereed)
    Abstract [en]

    This paper provides an overview of research and developments in the measurement of maintenance performance. It considers the problems of various measuring parameters and comments on the lack of structure in, and references for, the measurement of maintenance performance.The main focus is to determine how value can be created for organizations by measuring maintenance performance, looking at such maintenance strategies as condition based maintenance, reliability centered maintenance, e-maintenance etc. In other words, the objectives are to find frameworks or models that can be used to evaluate different maintenance strategies and determine the value of these frameworks for an organization.The paper asks the following research questions:- What approaches and techniques are used for Maintenance Performance Measurement (MPM) and which MPM techniques are optimal for evaluating maintenance strategies?- In general, how can MPM create value for organizations, and more specifically, which system of measurement is best for which maintenance strategy?The body of knowledge on maintenance performance is both quantitative and qualitative based. Quantitative approaches include economic and technical ratios, value-based and balanced scorecards, system audits, composite formulations, and statistical and partial maintenance productivity indices. Qualitative approaches include human factors, amongst others. Qualitative-based approaches are adopted because of the inherent limitations of effectively measuring a complex function such as maintenance through quantitative models. Maintenance decision makers often come to the best conclusion using heuristics, backed up by qualitative assessment, supported by quantitative measures. Both maintenance performance perspectives are included in this overview.

    Download full text (pdf)
    FULLTEXT01
  • 24.
    Kumar, Uday
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berges, Luis
    University of Zaragoza.
    Maintenance performance metrics: a state-of-the-art review2013In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 19, no 3, p. 233-277Article in journal (Refereed)
    Abstract [en]

    Purpose - This paper provides an overview of research and development in the measurement of maintenance performance. It considers the problems of various measuring parameters and comments on the lack of structure in and references for the measurement of maintenance performance. The main focus is to determine how value can be created for organizations by measuring maintenance performance, examining such maintenance strategies as condition-based maintenance, reliability-centred maintenance, e-maintenance, etc. In other words, the objectives are to find frameworks or models that can be used to evaluate different maintenance strategies and determine the value of these frameworks for an organization.Design/methodology/approach - A state-of-the-art literature review has been carried out to answer the following two research questions. Firstly, what approaches and techniques are used for maintenance performance measurement (MPM) and which MPM techniques are optimal for evaluating maintenance strategies? Secondly, in general, how can MPM create value for organizations and, more specifically, which system of measurement is best for which maintenance strategy?Findings - The body of knowledge on maintenance performance is both quantitatively and qualitatively based. Quantitative approaches include economic and technical ratios, value-based and balanced scorecards, system audits, composite formulations, and statistical and partial maintenance productivity indices. Qualitative approaches include human factors, amongst other aspects. Qualitatively based approaches are adopted because of the inherent limitations of effectively measuring a complex function such as maintenance through quantitative models. Maintenance decision makers often come to the best conclusion using heuristics, backed up by qualitative assessment, supported by quantitative measures. Both maintenance performance perspectives are included in this overview.Originality/value - A comprehensive review of maintenance performance metrics is offered, aiming to give, in a condensed form, an extensive introduction to MPM and a presentation of the state of the art in this field.

  • 25.
    Norrbin, Per
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Sweco Rail.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Tillförlitlighet och underhåll inom järnväg: Terminologi på svenska och engelska2017Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Denna rapport är ett delresultat ifrån FUD-projektet ’Begreppsapparat och kvalitetssäkrad information för bättre effektsamband inom järnvägar’. Syftet är att med hjälp av grundläggande och viktiga begrepp baserat på standarder göra en terminologisk ordlista för att öka samsynen och kunskaperna inom områdena förvaltning av tillgångar, tillförlitlighet och underhållsteknik.

    Download full text (pdf)
    fulltext
  • 26.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Juntti, Ulla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Capacity Enhancement through Optimized Maintenance of Railway Networks2014Conference paper (Refereed)
    Abstract [en]

    Rail traffic has increased manifold during the last decade. This development and the need for shift transportation from road to rail to decrease CO2 emission, creates a challenge for the railway industry to improve capacity in the network. The challenge is to do more effective inspection and maintenance in less time. An EU project ‘AUTOMAIN’ was initiated to optimize and automate maintenance and inspection activities with introduction of new planning and scheduling tools and methodologies. The project looked into reducing the maintenance possession time by around 40%. The project aim was to; adopt best practices from other industries in maintenance optimization, developing novel track inspection approaches for freight routes. The scope was for in-train measuring and self-inspecting switch, researching and assessing innovations that can improve the effectiveness and efficiency of large scale inspection and maintenance processes with a scope on track and switch maintenance, track inspection; developing key technologies that will drive the development of modular infrastructure design, and developing a new maintenance planning and scheduling tool to optimize the maintenance activities, taking account of the benefits brought about by other improvements in this project.The Consortium composition covers the railway maintenance and inspection field like; infrastructure managers, contractors, train operating companies, railway component industry, research organizations, small and medium enterprises (SMEs) and railway industry related organizations. In this paper, the authors have tried to summarize the methodology and results achieved in this project and how it has achieved the reduced maintenance possession time for higher railway traffic movements.

    Download full text (pdf)
    FULLTEXT01
  • 27.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Juntti, Ulla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asplund, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Arasteh Khouy, Iman
    Project: Augmented Usage of Track by Optimisation of Maintenance, Allocation and Inspection of railway Networks2011Other (Other (popular science, discussion, etc.))
  • 28.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Performance measurement and management for maintenance: A literature review2015In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 21, no 1, p. 2-33Article in journal (Refereed)
    Abstract [en]

    Purpose:The purpose of this paper is to provide a literature review of the performance measurement in maintenance. The authors aim to discuss the background and development of the performance measurement for maintenance, besides defining the concept of performance measures for maintenance and the frameworks developed.Design/methodology/approach:A detailed and extensive literature search and study was undertaken by the authors on the concept and definition of performance measurement, performance indicators, maintenance performance indicators and various performance frameworks. The history and theory of performance measurement over different phases of business and technological developments have been critically examined and analysed in this review paper. Findings:This paper reviews and presents the different performance indicators (PIs) and performance measurement (PM) frameworks like; balanced scorecard, performance prism, performance pyramid and performance matrix etc, and identifies their characteristics and shortcomings. After considering related issues and challenges, frameworks and approaches for the maintenance performance measurement (MPM) are also presented, where the emerging techniques like; e-maintenance have also been discussed amongst others. More and more industries are applying the balanced and integrated MPM frameworks for their competitive survivability and sustainability.Practical implications:The concept, issues and approaches considered for the MPM frameworks can be adapted by the practicing managers, while trying to define and develop an MPM framework for the operation and maintenance activities. The considerations of the advantages and limitations of different frameworks can provide insights to the managers for implementation. Originality/value:Some literature reviews on MPM and MPM frameworks are available today. This paper makes an attempt to provide a detailed and relevant literature review, besides adding value in this new and emerging area.

  • 29.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Asset performance evaluation: A recipe for success or failure2016In: Proceedings for the COMADEM 2016, 2016Conference paper (Refereed)
    Abstract [en]

    Abstract.The prevailing economicdownturn, looming global recession, vola-tile energy and asset prices with emerging technology for prescriptive analytics and increasing budgetary cuts have compelled the companies to manage its en-gineering assets competitively for survival and growth. As per international standard ISO 55001:2014, performance evaluation is fundamental to asset man-agement system (AMS). Asset maintenance performance measurement and management (AMPM) is a recognized process and best practice for supporting sustainability and return on investment.It is hard for an organization to improve the present level of performance of the engineering assets without measurement. Therefore, all functions including units and processes of the organization need to be built and developed as per as-set management principles, such as; ISO 55000 series standard. The challenges in AMPM are to prepare a strategic road map from top management level to the operational level through a link and effect model for identifying and developing key performance indicators (KPI). These KPIs are broken down to measures which are used for monitoring and controlling the unplanned downtime with in-creased reliability, availability, maintainability and safety. Other challenges are to define and develop methods for right data collection through condition moni-toring and big data analytics, beside management for knowledge management. eMaintenance is required for remote data collection, storage, analysis and deci-sion making. The KPIs and indicators will be used for developingcomposite indicators (CI) for bench marking the performance with the best in the industry, besides verifying the return on investment.The author has discussed the various compulsions and challenges associated with asset performance evaluation (APE) for AMPM for the organization. Once the AMPM fundamentals and recipe is known, its success or failure will depend on finding solutions for the challenges while defining, structuring, developing, and implementing AMPM system.

    Download full text (pdf)
    fulltext
  • 30.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Project: Link and Effect Model for Maintenance of Railway Infrastructure2011Other (Other (popular science, discussion, etc.))
  • 31.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Performance Measurement for Managing Railway Infrastructure2014In: The international Journal of railway technology, ISSN 2049-5358, E-ISSN 2053-602X, Vol. 2, no 4, p. 1-14Article in journal (Refereed)
    Abstract [en]

    An effective and efficient railway infrastructure is essential to assure assetperformance which is often measured in terms of high availability, high level ofsafety and good track quality, besides value addition. Thus, the measurement ofasset maintenance performance has become an essential element of strategicthinking for railway asset owners and managers. The area of asset maintenanceperformance is relatively new and emerging, besides its complexity with regards to the many internal and external stakeholders, all with conflicting interests. Therailway infrastructures’ overall objectives and strategies are required to be broken down through the hierarchical level, converting them into various key performance indicators (KPIs) for measurement, data collection, analysis, and decision making at appropriate levels through aggregation. This paper looks into some of the performance measurement issues of railways, and how these issues can be solved through data aggregation, analysis, simulation,and presentation. Following a discussion of these issues, a case study is carried out to demonstrate how performance can be analysed and presented.

  • 32.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Diffuse Ultrasonic Scattering in Advanced Composites2010Report (Other academic)
    Abstract [en]

    Non destructive testing (NDT) is a noninvasive technique used for characterization and inspection of the integrity of objects. NDT is an important tool for research, manufacturing monitoring and in-service inspections. Ultrasonic testing is the most used NDT technique, which for advanced composites can identify several types of defects, like delamination and interlaminar cracks. Diffuse ultrasonics has shown to be able to extract information at the microscale of metals and therefore it is believed it can be used for advanced composites to extract microstructural information, i.e. at the level of fibers. In this thesis, diffuse ultrasonic methods, together with spatial variance analysis, have been used to quantify the scattering within unidirectional advanced composites that have been loaded to different states of fiber damage. Results show that the spread in data is too large to give a clear trend of how the scattering changes with fiber damage. Further research has to be done in order to lower the spread in the results and increase the reproducibility. This can be done with higher precision in the experimental set-ups and new parametric analysis.

  • 33.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Effektsamband för underhåll av järnväg: Förstudie2015Report (Other academic)
    Abstract [sv]

    Syftet med förstudien är att beskriva hur en formel för effektsamband mellan underhåll och merförsening för järnvägsinfrastruktur kan byggas upp, samt inventera vilka data en sådan formel behöver och vilka av dessa data som finns tillgängliga i Trafikverkets databaser.Ett effektsamband mellan förebyggande underhåll och merförsening har formulerats: När en inspektion utförs är sannolikheten att hitta ett potentiellt fel mellan 0 och 100 %. Det potentiella felet registreras som en inspektionsanmärkning. Risken att ett potentiellt fel inom en viss tid utvecklas till ett funktionsfel är även den mellan 0 och 100 %. Strikt sett är denna tid lika med angiven åtgärdstid, t.ex. veckoanmärkning, men i praktiken längre. Som ett exempel kan man anta 100 inspektioner, med 10 % sannolikhet att hitta potentiellt fel, 75 % risk för funktionsfel om inte åtgärd vidtas inom en snar framtid och 25 % risk för merförsenande funktionsfel. Detta ger 100 • 0,1 • 0,75 • 0,25 = 1,875 avstyrda merförsenande funktionsfel, och därmed 1,875 • medelmerförsening i minskad merförsening.Resultatet visar att avstyrd merförsening per inspektion för olika system inom de studerade 65 bandelarna ligger mellan 0-40 minuter per inspektion. Detta effektsamband beror dock till stor grad på definitionen av inspektion. Effekt-sambandet beror även på typen av inspektion, t.ex. säkerhets- och underhållsinspektioner. Slutligen beror effektsambandet även på kriterierna som används för tilldelning av prioritet avseende inspektionsanmärkningar.En följdfråga till mål 1 i denna studie är vad effekten av förebyggande underhåll blir mätt i kronor. Kostnad-nytta-förhållandet (B/C) blir ≈3,3. Resultaten beror dock på inkluderande/uteslutande av användarkostnader.Trafikverket har ett omfattande system för insamling av data som sträcker sig långt tillbaka i tiden. Tillgänglig data är tillräcklig för att beräkna ovan nämnda effektsamband. Men både data och funktioner i databaserna Bessy och Ofelia behöver studeras vidare för att avgöra kvaliteten och betydelsen avseende effektsambanden beskrivna ovan.

    Download full text (pdf)
    FULLTEXT01
  • 34.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Idégenerering för tillståndsövervakning av järnvägar och fordon: En workshop med 635-metoden2017Report (Other academic)
    Abstract [sv]

    635-metoden har tillämpats i en workshop för att identifiera möjliga praktiska tillämpningar av dataloggers/sensorer i järnvägsinfrastruktur. Workshopen bestod av elva deltagare och varade i tre timmar. Sammanställning resulterade i ca. 40 frågställningar vid införsel eller utökade av sensorer i järnvägar, samt ca. 80 idéer på tillämpningar/fenomen för sensorer i järnvägar. Många frågor och idéer på tillämpningar är väl kända sedan tidigare, men vissa frågor/idéer är mer sällan uttryckta.

    Frågorna/idéerna i denna rapport kan vara behjälpliga vid arbete eller tankeverksamhet kring tillståndsövervakning av järnvägar och rullande materiel. Frågorna/idéerna behandlar både småkalig tillämpning av sensorer och storskaling tillämpning, dvs. sakernas internet eller internet of things.

    För att gå vidare med frågorna/idéerna kan de väljas ut i en workshop i grupp eller genom individuellt arbete. Att utveckla eller diksutera idéerna vidare är dock utom denna rapports räckhåll.

    Download full text (pdf)
    fulltext
  • 35.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Link and Effect Model – Part II: Methods for Measuring Maintenance Performance of Rail Infrastructure2016Report (Other academic)
    Abstract [en]

    Congestion of roads and sky, increasing energy costs and a demand to reduce emissions, have created a need to shift transportation from road and air to rail. Consequently, rail utilisation is increasing, adding stress to the rail infrastructure and time constraints to maintenance. At the same time, the performance and capacity of rail infrastructure are expected to be preserved or even improved. Railway performance and capacity can be enhanced by: expanding infrastructure; introducing better technology; and improving the efficiency and effectiveness of operation and maintenance. Performance measurement has shown to improve the efficiency and effectiveness of organisations, but the development and integration of performance measurements are essential. A key issue in performance measurement is the process of collecting, storing and converting data into information and knowledge, i.e. data analysis and presentation. Organisations use various systems and methods to collect and analyse data, but the analysis of the collected data to extract relevant information is often a challenge. With improved data analysis and performance measurement, rail transportation can meet the requirements of performance and capacity. Specifically, maintenance planning and optimisation of preventive maintenance can be made more effective, which can decrease interruptions of train operation, reduce costs and ensure safety.In this project, methods for measuring maintenance performance of rail infrastructure are developed. The work aims to facilitate decision-making in rail infrastructure maintenance.Keywords: Operation and maintenance, indicators, performance measurement, maintenance cost, rail infrastructure, linear assets, preventive maintenance, corrective maintenance, aggregation, composite indicators, cost-benefit analysis, decision support

    Download full text (pdf)
    fulltext
  • 36.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Link and effect model for performance improvement of railway infrastructure2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Railway traffic has increased over the last decade and it is believed to increase further with transportation shifting from road to rail, due to rising energy costs and the demand to reduce emissions. To manage railway infrastructure assets effectively against agreed-upon and set objectives, performance must be measured and monitored. Different systems are used to collect and store data of traffic, failures, inspections, track quality, etc., for subsequent analysis and data exchange. Performance indicators (PIs), e.g. for RAMS (reliability, availability, maintainability, safety), are continuously developed to support infrastructure managers (IMs) in identifying performance killers in order to make efficient and effective decisions. However, they are often ad hoc and seldom standardised. Moreover, the use of standards and the need for harmonisation of railway operations have grown with interoperability, e.g. building of a trans-European railway network. The~efficiency and effectiveness of railway infrastructure can be improved if an appropriate performance measurement (PM) system is identified and specifically developed. In traditional PM systems, PIs are given threshold values, indicating when an action needs to be taken, i.e. they can to some extent be reactive. Also, PIs are often aggregated measures, which can make them abstract. By this trend in transportation and shortcomings in performance measurement, there is a need to improve the strategic planning and measurement of performance for more proactive decision making and future standardisation.In this research, a link and effect model for performance improvement of railway infrastructure is developed. It provides a continuous methodology for breaking down objectives into operational requirements and linking them to results, using performance indicators, and algorithms for data analysis and simulation, for decision support.Keywords: railway infrastructure, performance, RAMS, maintenance, dependability, indicators, link and effect, decision support

    Download full text (pdf)
    FULLTEXT01
  • 37.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Maintenance performance measurement of railway infrastructure with focus on the Swedish network2012Report (Other academic)
    Abstract [en]

    Railway traffic has increased over the last decade and it is believed to increase further with the movement of transportation from road to rail, due to the increasing energy costs and the demand to reduce emissions. Efficient and effective maintenance is required in order to assure maximum dependability and capacity of the existing railway infrastructure. To manage maintenance successfully within the scope and set objectives, the effect of maintenance activities must be measured and monitored. Performance indicators (PIs) for reliability, capacity, punctuality, etc., are extensively used by infrastructure managers (IMs) in decisions making. However, they are often ad-hoc and seldom standardised. Performance measurements can give large savings and bring business safety by more proactive management, while there are additional costs associated with measuring. It is therefore important to thoroughly analyse what, where, when and how to measure. Thus, there exists a need to study the railway infrastructure PIs used by different IMs, to find out which ones are the most important, which are required and which are not required.In this technical report, a study was undertaken to review the maintenance PIs used by researchers in the field of railway maintenance, as well as reviewing European railway project reports, and also documentations of the Swedish infrastructure manager Trafikverket, like policy documents, handbooks, etc. Interviews were also carried out to get additional inputs. In order to understand the different PIs, a high-level study of the maintenance of railway infrastructure in Sweden was carried out as well.The listed indicators form a basis for constructing a maintenance performance measurement system for railway infrastructure.

    Download full text (pdf)
    FULLTEXT01
  • 38.
    Stenström, Christer
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Modelling of fracture toughness using peridynamics: A Study of J-integral, essential work and homogenisation2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fracture toughness is one of the most important properties of a material. Being able toaccurately estimate the energy that goes into forming new crack surfaces is essential for the development of new materials, quality assurance, structural monitoring and failure analysis. Fracture toughness parameters are routinely determined by mechanical testing and are often used in numerical tools. Furthermore, fracture toughness is a common property in material specification. Numerical simulation of fracture toughness can reduce the need of mechanical testing and is sometimes the only viable alternative when mechanical testing is not an option, for example in component optimisation and in the assessment of operational structural components.  However, complex fracture is a challenge in material modelling, which comes from that a material body is assumed to remain continuous in classical continuum mechanics. Classical continuum mechanics is formulated assuming a continuous body and that spatial derivatives are defined. However, this is not the case at cracks and other dis­ continuities. Complementing continuum mechanics with supplementary procedures for modelling discontinues can also add further challenges. Besides, the assumption of locality, that each material point only interacts with is immediate neighbouring points, becomes invalid for nanoscale geometries. Thus, fracture cannot easily be modelled. An alternative is therefore of interest. Peridynamics is a nonlocal extension of continuum mechanics with the constitutive model formulated as an integro-differential equation. The advantages of using an integral expression are foremost that long-range forces can be handled and that the theory is valid even in the presence of discontinuities, such as cracks, allowing unguided modelling of fracture. Since damage is introduced to the constitutive model of peridynamics, there is no requirement of supplementary procedures that can add further complications. Due to its nonlocal formulation, the method is also capable of capturing nano-effects. However, the use and reporting of fracture toughness parameters in peridynamics is a routine in its infancy as the method is under development.In this thesis, two fracture toughness methods, the classical J-integral and the essential work of fracture (EWF), are studied with peridynamics. Also, as the nonlocality of peri­ dynamics give rise to certain boundary effects, e.g. on crack faces, homogenisation is a part of the study. The thesis consists of two parts; an introductory summary with discussion and conclu­ sions, followed by a series of appended papers. The first paper concerns application of Rice's J-integral on displacement derivatives formulation in peridynamics with comparison to an exact analytical stress-strain-displacement specimen solution. The next two papers concerns homogenisation of a peridynamic bar, to remove the end effects, arisen from the nonlocality of peridynamics, to obtain an elastic behaviour exact to a classical continuum mechanics bar. The fourth paper is an implementation of the J-area integral into peridynamics, with study of various discretisation methods. Thereafter, in the last paper, Rice's J-integral and the nonlocal peridynamic J-integral are compared on various specimens, followed by an extension of the research to study EWF with peridynamics for the first time. The study includes a novel automated calibration at the interparticle bond level to simulate nonlinear elastic behaviour, which subsequently is complemented with softening and used for EWF modelling. As a part of introducing the peridynamic J-integral, the study also includes a proof of path independence.

    Major findings of the study includes:

    • The classical J-integral on a displacement derivative formulation gives accurateestimations of fracture toughness in peridynamics.

    • The peridynamic lD bar can be homogenised to obtain a linear elastic behaviour identical to that of an corresponding continuum mechanics body.

    • The bond calibration method gives a nonlinear elastic peridynamic model that can accurately recover an experimentally obtained stress-strain response. Up to the start of material softening, the nonlinear elastic model recovered the experimentally obtained stress-strain response of two very different materials; a lower-ductility martensitic-bainitic steel and a higher-ductility bainitic steel.

    • The nonlinear elastic model were able to match very well the experimentally measured EWF for the higher-ductility bainitic steel.

    • The J-integral value obtained from the peridynamic model, matched the experimen­tally obtained EWF value for the higher-ductility bainitic steel.

    Download full text (pdf)
    fulltext
  • 39.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Mått för tillgänglighet i järnvägen2015Conference paper (Other academic)
    Abstract [sv]

    Tillgänglighet är ett mått på driftsäkerhet och mäter förmågan hos en enhet att kunna utföra krävd funktion under angivna förutsättningar vid ett givet tillfälle eller tidsintervall. Mått på tillgänglighet kan hittas i många områden, såsom inom elektronik, IT, militär, elnät och industri. Men ett sådan mått har inte integrerats i järnvägar enligt erkända definitioner. Måttet är intressant eftersom det inbegriper både tekniska och organisatoriska faktorer. Vikten av att kunna mäta tillgänglighet i järnvägar har betonats i olika järnvägsprojekt, t.ex. i EU-projektet INNOTRACK. Därmed, som en del i projektet Åtgärds- och effektmodell, i samarbete med Trafikverket, Järnvägstekniskt centrum och Luleå tekniska universitet, har tillgänglighet som mått inom järnvägar studerats.Resultet visar att det föreslagna tillgänglighetmåttet ger en högre korrelation med tågförseningar (R^2 = 0,94) än vad funktionsfel ger med tågförseningar (R^2 = 0,73). Resultatet är rimligt eftersom tillgängligheten beror på funktionssäkerhet, underhållsmässighet och underhållssäkerhet, d.v.s. det innefattar funktionsfel, reparationstid och logistiktid.

    Download full text (pdf)
    FULLTEXT01
  • 40.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nyckeltal för driftsäkerhet inom järnvägstransport2017Report (Other academic)
    Abstract [sv]

    Driftsäkra järnvägar och tåg är avgörande för konkurrenskraftig och ökande andel järnvägstranport. För uppföljning av driftsäkerhet använder infrastrukturförvaltare (Trafikverket), tågoperatörer och entreprenörer olika indikatorer, så som merförsening och antal funktionsfel. Indikatorerna mäter olika aspekter och kan illustreras mer eller mindre intuitivt och tilltalande. Metod för definiering och införsel av indikatorer skiljer sig mellan organisationer. En enkel och vanlig metod är diskussion och beslut inom en sammanträdande grupp. En mer objektiv metod är att följa uppsatta riktlinjer för definiering och utvärdering av indikatorer. Dock är det få allmängiltiga metoder tillgängliga för att definiera indikatorer. Utifrån behov inom järnvägstransport och avsaknaden av metoder för definiering och utvärdering av indikatorer, avses i denna studie en sådan allmänt tillämplig metod presenteras och appliceras inom järnvägstransport. Applicering innebär att i detalj dokumentera två indikatorer som kan användas som branschgemensamma nyckeltal inom järnvägstransport.

    Två indikatorer definierades och utvärderade i denna studie avseende möjlighet att tillämpa dessa som branschgemensamma indikatorer inom järnvägstransport. Val av indikatorer utgick från litteraturstudie av i Sverige gällande standarder avseende driftsäkerhet. Definiering och utvärdering av valda indikatorer utgick från mall av Neely (2002) bestående av 46 frågor.

    De definierade och utvärderade indikatorerna är tillgänglighet och feleffektmatris. Definiering och utvärdering av de två indikatorerna, med utgång från givna 46 frågor, tog i denna rapport fyra arbetsdagar (16 timmar/nyckeltal). Detta ger en fingervisning på arbetsinsatsen som krävs för en organisation som vill införa föreslagen metod för att definiera indikatorer. Förutsatt att data och ett underhållssystem finns tillgängligt, består kostnaderna vid implementering och drift i stora drag av: definiering och utvärdering; implementering av kod i underhållssystem; förbättringsarbete av indikatorer och kod; samt drift av kod i underhållssystem. Det kan därmed vara relevant att utföra en kostnad-nytta-analys avseende indikatorerna. En stor kostnad i sammanhanget är insamling av data. Dock ska denna kostnad eventuellt inte tillskrivas till indikatorerna, eftersom det troligtvis inte är acceptabelt att inte samla in data avseende antal fel, återställelsetider och merförseningar.

    Tre överväganden berörande indikatorn tillgänglighet som bör tas i beaktning är: möjlighet att bryta ner indikatorn för att komma närmare orsakerna till indikatorvärden; tidsrymd för beräkning; samt användande av median, medelvärde och registrerade återställningstider vid beräkning. Valen som görs vid en mjukvaruimplementering kan uppdateras efterhand med erfarenhet från tillämpning.

    En egenskap hos feleffektmatrisen, så som den är tillämpad i denna studie, är att den påverkas av tidtabeller och gångtidstillägg. Tillgänglighet påverkas inte av tidtabeller och gångtidstillägg, men kan istället inte fånga upp skillnaden mellan få långa fel och många korta fel, så som feleffektmatrisen gör. I detta avseende kompletterar tillgänglighet och feleffektmatris varandra.

    Download full text (pdf)
    fulltext
  • 41.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Operation and maintenance performance of rail infrastructure: Model and Methods2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Congestion of roads and sky, increasing energy costs and a demand to reduce emissions, have created a need to shift transportation from road and air to rail. Consequently, rail utilisation is increasing, adding stress to the rail infrastructure and time constraints to maintenance. At the same time, the performance and capacity of rail infrastructure are expected to be preserved or even improved. Railway performance and capacity can be enhanced by: expanding infrastructure; introducing better technology; and improving the efficiency and effectiveness of operation and maintenance. Performance measurement has shown to improve the efficiency and effectiveness of organisations, but the development and integration of performance measurements are essential. A key issue in performance measurement is the process of collecting, storing and converting data into information and knowledge, i.e. data analysis and presentation. Organisations use various systems and methods to collect and analyse data, but the analysis of the collected data to extract relevant information is often a challenge. With improved data analysis and performance measurement, rail transportation can meet the requirements of performance and capacity. Specifically, maintenance planning and optimisation of preventive maintenance can be made more effective, which can decrease interruptions of train operation, reduce costs and ensure safety.In this thesis, a model for monitoring and analysis of operation and maintenance performance of rail infrastructure is developed. The model includes various methods for analysis of operation and maintenance data. The work aims to facilitate improvements and optimisation of decision-making in railways.The thesis consists of two parts. The first part gives an introductory summary of the subject and research, followed by a discussion of the appended papers, an extension of the research and conclusions. The second part consists of five appended papers. The first paper concerns the development of a model for improving performance measurement of rail infrastructure. The second paper is a study of indicators related to rail infrastructure performance. The three subsequent papers are development of data analysis methods for: operational availability of rail infrastructure, composite indicators and maintenance costs.Keywords: operation and maintenance, indicators, performance measurement, maintenance cost, rail infrastructure, linear assets, preventive maintenance, corrective maintenance, aggregation, composite indicators, cost-benefit analysis, decision support

    Download full text (pdf)
    FULLTEXT01
  • 42.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Performance measurement of railway infrastructure2013Conference paper (Other academic)
  • 43.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ultrasonics for Monitoring of Mining Mill Linings: Pilot Experiments2016Report (Other academic)
    Abstract [en]

    Mining mill linings are continuously exposed to wear induced by the charge, and thus, mill operation has to be interrupted on a regular basis for inspections. Stoppages due to inspections and replacement of linings lead to large production and monetary losses; especially in case of unplanned corrective maintenance. Condition monitoring during mill operation can assist in the maintenance planning and decision process to increase the availability and the overall performance of the material processing.In this pilot study, the feasibility of using waterflow ultrasonics for condition monitoring of the lining of mining mills during operation is to be investigated. The proposed waterflow ultrasonic technique uses a water beam to transmit the ultrasound to the mill shell and lining. By measuring the time of flight (TOF), it can be possible to monitor the thickness of mill linings, without the need of interrupting operation. The method can lead to significant energy and monetary savings by reducing inspections and corrective maintenance stoppages, and possibly increase product quality by optimised performance.Since steel has a very high acoustic impedance in comparison to rubber, TOF measurements on aluminium-rubber has been used as an intermediate step towards the goal of measuring steel-rubber combinations. TOF measurements of aluminium-rubber layers have been achieved, and advancement towards the understanding of TOF measurements in steel-rubber laysers have been achieved.The following conclusions have been reached:- Rubber thickness can be measured through aluminium. In practice, aluminium plugs/rivets can be mounted on the steel shell of a mill to measure TOF of rubber shell plates and lifter bars.- Ultrasound signals can be measured through steel-rubber layers in through-transmission and pitch-catch set-ups.- Ultrasound signals measured in pulse-echo or pitch-catch set-up on a solid steel plate connected to rubber, give rise to reverberations (ringing signal) that mask the rubber backwall echoes. For avoiding reverberations of steel plate sides, an experimental set-up requires the steel plate to be at least eight times wider and deeper (x- and y-axis) than the thickness (z-axis) of the rubber under inspection.Keywords: ultrasonic testing, mining mill lining, lined pipes, NDT, condition monitoring, comminution, non-destructive testing, thickness gauge.

    Download full text (pdf)
    FULLTEXT01
  • 44.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Al-Jumaili, Mustafa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Computerised Analysis of Text Entry Fields in Maintenance Work Orders Data2014In: Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications / [ed] Uday Kumar; Ramin Karim; Aditya Parida; Phillip Tretten, Luleå: Luleå tekniska universitet, 2014, p. 97-100Conference paper (Refereed)
    Abstract [en]

    Enterprise resource planning systems and computerised maintenance management systems are commonly used by organisations for handling of maintenance work orders through a graphical user interface. A work order consists of a number of data fields, such as drop-down lists, list boxes, check boxes and text entry fields. In contrast to the other data fields, the operator has the freedom to type in any text in the text entry fields, to complement and make the work order description complete. Accordingly, the text entry fields of work orders can contain any words, in any number, as necessary.Data quality is crucial in statistical analysis of work orders data, and therefore manual analysis of work orders’ text entry fields is often necessary before any decision making. However, this may be a very tedious and resource consuming process.In this article, we apply computerised analysis of text entry fields of work orders data, to study if it can bring further value in the assessment of technical assets’ performance.Keywords:Data quality, eMaintenance, maintenance, work orders, failure, decision support, natural language processing

    Download full text (pdf)
    fulltext
    Download full text (pdf)
    fulltext
  • 45.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Al-Jumaili, Mustafa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Natural language processing of maintenance records data2015In: International Journal of COMADEM, ISSN 1363-7681, Vol. 18, no 2, p. 33-37Article in journal (Refereed)
    Abstract [en]

    Enterprise resource planning systems and maintenance management systems are commonly used by organisations for handling of maintenance records, through a graphical user interface. A maintenance record consists of a number of data fields, such as drop-down lists, list boxes, check boxes and text entry fields. In contrast to the other data fields, the operator has the freedom to type in any text in the text entry fields, to complement and make the maintenance record as complete as possible. Accordingly, the text entry fields of maintenance records can contain any words, in any number.Data quality is crucial in statistical analysis of maintenance records, and therefore manual analysis of maintenance records’ text entry fields is often necessary before any decision making. However, this may be a very tedious and resource consuming process.In this article, natural language processing is applied to text entry fields of maintenance records in a case study, to show how it can bring further value in the assessment of technical assets’ performance.

    Download full text (pdf)
    FULLTEXT01
  • 46.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Mining mill condition monitoring using water jet ultrasonics2013In: 2012 IEEE International Ultrasonics Symposium (IUS), Piscataway, NJ: IEEE Communications Society, 2013, p. 1913-1916Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the feasibility of using a water jet ultrasound scanning system for condition monitoring of the shell of a rotating mining mill. The practical requirements of such a system were first analyzed, which shows that it is possible to achieve the spatial resolution of 1±1 mm, using a pulse-echo setup with a pulse repetition frequency of approximately 6 kHz. Experiments were then performed on a lab-scale prototype, where typical defects were introduced. The results show that it is possible to detect and image internal defects down to a size of around than 1 ± 0.4 mm.

    Download full text (pdf)
    FULLTEXT01
  • 47.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Condition monitoring of cracks and wear in mining mills using water squirter ultrasonics2015In: International Journal of Condition Monitoring, E-ISSN 2047-6426, Vol. 5, no 1, p. 2-8Article in journal (Refereed)
    Abstract [en]

    Mining mills are continuously exposed to loads that give rise to wear of the liners, as well as fatigue and crack development in the steel shell. The feasibility of using water squirter ultrasonics for condition monitoring of the shell and the lining of mining mills during operation has been studied in this paper. This method will make it possible to monitor cracks in mining mills without stopping them, which can result in significant monetary savings due to less downtime and increased product quality. The practical requirements of such a system were first analysed, which shows that it is possible to achieve the spatial resolution of 1 × 1 mm, using a pulse-echo set-up with a pulse repetition frequency of approximately 6 kHz. Experiments were then performed on a lab-scale prototype, where typical defects were introduced. The results show that it is possible to detect and image internal defects down to a size of around 1 × 0.4 mm.

  • 48.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Eriksson, Kjell
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    The J-contour integral in peridynamics via displacements2019In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 216, no 2, p. 173-183Article in journal (Refereed)
    Abstract [en]

    Peridynamics is a nonlocal formulation of solid mechanics capable of unguided modelling of crack initiation, propagation and fracture. Peridynamics is based upon integral equations, thereby avoiding spatial derivatives, which are not defined at discontinuities, such as crack surfaces. Rice’s J-contour integral is a firmly established expression in classic continuum solid mechanics, used as a fracture characterizing parameter for both linear and nonlinear elastic materials. A corresponding nonlocal J-integral has previously been derived for peridynamic modelling, which is based on the calculation of a set of displacement derivatives and force interactions associated with the contour of the integral. In this paper, we present an alternative calculation of the classical linear elastic J-integral for use in peridynamics, by writing Rice’s J-integral as a function entirely of displacement derivatives. The accuracy of the proposed J-integral on displacement formulation is investigated by applying it to the exact analytical displacement solution of an infinite specimen with a central crack and comparing the exact analytical expression of its J-integral. Further comparison with a well-known peridynamic crack problem shows very good agreement. The suggested method is computationally efficient and further allows testing of the accuracy of a peridynamic model as such.

    Download full text (pdf)
    fulltext
  • 49.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. Luossavaara-Kiirunavaara Aktiebolag (LKAB), Luleå, Sweden.
    Eriksson, Kjell
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    The J-area integral applied in peridynamics2021In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 228, no 2, p. 127-142Article in journal (Refereed)
    Abstract [en]

    The J-integral is in its original formulation expressed as a contour integral. The contour formulation was, however, found cumbersome early on to apply in the finite element analysis, for which method the more directly applicable J-area integral formulation was later developed. In a previous study, we expressed the J-contour integral as a function of displacements only, to make the integral directly applicable in peridynamics (Stenström and Eriksson in Int J Fract 216:173–183, 2019). In this article we extend the work to include the J-area integral by deriving it as a function of displacements only, to obtain the alternative method of calculating the J-integral in peridynamics as well. The properties of the area formulation are then compared with those of the contour formulation, using an exact analytical solution for an infinite plate with a central crack in Mode I loading. The results show that the J-area integral is less sensitive to local disturbances compared to the contour counterpart. However, peridynamic implementation is straightforward and of similar scope for both formulations. In addition, discretization, effects of boundaries, both crack surfaces and other boundaries, and integration contour corners in peridynamics are considered.

  • 50.
    Stenström, Christer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Luossavaara-Kiirunavaara Aktiebolag (LKAB), Luleå, Sweden.
    Eriksson, Kjell
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Bobaru, Florin
    Mechanical and Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE, USA.
    Golling, Stefan
    Gestamp R&D, Luleå, Sweden.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    The essential work of fracture in peridynamics2023In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 242, no 2, p. 129-152Article in journal (Refereed)
    Abstract [en]

    In this work, the essential work of fracture (EWF) method is introduced for a peridynamic (PD) material model to characterize fracture toughness of ductile materials. First, an analytical derivation for the path-independence of the PD J-integral is provided. Thereafter, the classical J-integral and PD J-integral are computed on a number of analytical crack problems, for subsequent investigation on how it performs under large scale yielding of thin sheets. To represent a highly nonlinear elastic behavior, a new adaptive bond stiffness calibration and a modified bond-damage model with gradual softening are proposed. The model is employed for two different materials: a lower-ductility bainitic-martensitic steel and a higher-ductility bainitic steel. Up to the start of the softening phase, the PD model recovers the experimentally obtained stress-strain response of both materials. Due to the high failure sensitivity on the presence of defects for the lower-ductility material, the PD model could not recover the experimentally obtained EWF values. For the higher-ductility bainitic material, the PD model was able to match very well the experimentally obtained EWF values. Moreover, the J-integral value obtained from the PD model, at the absolute maximum specimen load, matched the corresponding EWF value.

    Download full text (pdf)
    fulltext
12 1 - 50 of 70
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf