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  • 51.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Influence of limiting shear strength of oils on breakdown ofalubricating oil fil1992In: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 11, no 4, p. 106-114Article in journal (Refereed)
  • 52.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Influence of surface roughness on normal-sliding lubrication1995In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 28, no 5, p. 317-322Article in journal (Refereed)
    Abstract [en]

    Contact between machine components can involve normal, sliding and rolling motion, either singly or in combination. Combined normal and sliding motion, which occur for example in the meshing of gear teeth and in heavily-loaded rolling elements, can present problems for lubrication. The purpose of the present experimental study was to investigate how surface roughness affects the lubricant film characteristics under conditions of combined normal and sliding motion. The experimental arrangement consisted of a rotating roller which impacted a stationary ball in the presence of a lubricant. Under the same conditions of normal surface approach, increasing the surface roughness significantly decreased the level of roller sliding that could occur without breakdown of the lubricating film. This behaviour was similar to a step function. Of the several surface roughness parameters investigated, only those which involved the maximum peak-to-valley height correlated well with experimental results. In general, surface roughness had a greater effect on oil film breakdown than did either viscosity or load.

  • 53.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lubrication of a rotating ball in normal approach1989In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 130, no 1, p. 203-212Article in journal (Refereed)
    Abstract [en]

    An experimental study has been made of the degree of lubrication, which is defined as the number of interacting asperities, when a rotating spherical body approaches a plane during rotation. The normal velocity was varied between 0.1 and 0.5 m s-1 and the sliding velocity between 0 and 9.2 m s-1. The experiments show that the oil viscosity is the most important lubricant parameter. The degree of lubrication is not affected by either the normal velocity, the pressure viscosity coefficient or the shear strength proportionality constant. An increase in the sliding velocity gives a decrease in lubrication of between 25% and 65% depending on the surface roughness and type of lubricant. The surface roughness is also a most important factor impeding good lubrication. To avoid wear one has to increase the viscosity from 8 to 145 mm2 s-1 if the mean surface roughness Ra is increased from 0.01 to 0.14.

  • 54.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lubrication of machine elements during combined squeeze and sliding motion1993In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 169, no 2, p. 161-166Article in journal (Refereed)
    Abstract [en]

    The motion when two parts in a machine come into contact can be a normal, sliding or rolling approach, or a combination of the three. The case of combined normal and sliding motion can be very unfavourable from the point of view of lubrication. Nevertheless, this situation does occur, for example in a gear mesh and in heavily loaded rolling-element bearings.The following factors in the case of lubrication of machine elements during combined normal and sliding motion were studied experimentally: oil viscosity, surface texture, shear strength of oil and maximum pressure. The pressure also involves the parameters normal force, Young's modulus, Poisson's ratio and surface curvature.Based on the experimental results, an equation has been deduced which describes how the above-mentioned factors influence the permissible limiting sliding velocity Vsl without oil film breakdown: Vsl=0.127×10-6(v0.1-1.575)(ψ-13.1-1.707)(3840-pmax)This equation agrees well with results from experiments carried out by other authors, and is valid if combined sliding and impact between the machine elements, resulting in a limited contact time, are present.

  • 55.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Methodologies for prediction of bearing wear with application in arctic railway maintenance2010In: The Seventh International Conference on Condition Monitoring and Machinery Failure Prevention Technologies: 22 - 24 June 2010, Ettington Chase, Stratford-upon-Avon, England ; CM 2010/MFPT 2010, Northampton: Coxmoor Publishing Co. , 2010, p. 528-539Conference paper (Refereed)
    Abstract [en]

    A three years field test has been carried out to investigate suitable parameters for wear prediction of spherical roller bearings in railway wagon wheels. New un-destroyed greases of the same composition as in the field test were examined in laboratory conditions using 19 different test methodologies, mainly conventional ones, but also some newly developed. By correlating the results from the laboratory tests with the field test, a specification of testing methodologies for prediction of bearing wear were set up and the connection between the tested parameters were investigated. It was found that a combination of the roll stability test and the limiting shear stress coefficient enables a prediction of bearing wear. One example of another finding is that the bearing temperature could be predicted by utilization of the base oil viscosity

  • 56.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Migration of almost neutrally buoyant spheres in a rectangular channel with special reference to oil in water emulsions1986Report (Other academic)
  • 57.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Mineraloljors obliteration1984Report (Other academic)
  • 58.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Provning av bakaxeloljors förmåga att motstå kombinerad glid- och normalrörelse1991Report (Other academic)
  • 59.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Provning av smörjfett med rullstötapparat1990Report (Other academic)
  • 60.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rheological model of a dilute emulsion1988In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 31, no 1, p. 83-90Article in journal (Refereed)
    Abstract [en]

    The viscosity of an emulsion, consisting of oil droplets and surrounding water, is highly dependent on the position of the droplets during fluid transport. To better understand this rheological phenomenon, the migration of nylon spheres of various densities, flowing through a vertical, rectangular channel was studied. The results from the present experiments show that spheres which have lower density than the fluid always migrate to the center of the channel, almost independent of density difference and sphere size. If on the other hand, the spheres are only slightly more dense than the fluid, they will reach an equilibrium position near, or at one of the channel walls. If the spheres are still denser than the fluid they will reach an equilibrium position somewhere between the wall and the center of the channel. This position depends on the sphere size.

  • 61. Lundberg, Jan
    Rheological properties of lubricating fluids1987Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Obliteration (gobbing) caused by water based lubricating fluids is studied experimentally by analyzing the flow through a small channel. Flow measurements, energy dispersive X-ray microscopy and photos show, that the rate of gobbing depends on which type of fluid that is being used. The explanation of the obliteration is chemical reactions between the fluids and surrounding material or dust in the fluids. In order to get a better understanding of the rheology of emulsions, the migration of visible spheres, with varying density, flowing downstreams through a vertical, rectangular channel, is studied. The results from the experiments show, that the equilibrium position of a sphere is a function of the density difference between the sphere and surrounding fluid. A density difference of 0.5 per mille is enough to give stable positions. A theory is presented, which gives good agreement with the experimental results. Experiments have also been carried out in order to measure the effective viscosity of emulsions, flowing through a small horizontal channel. The viscosity is lower than the value obtained in a rotational viscosimeter. A theoretical explanation is proposed. An interesting example of two-phase flow is studied by means of a new prototype of a nozzle which lubricates a water jet with air. With this experimental nozzle, the dynamic pressure of the water jet increases 37 per cent. The explanation of this improvement is that some of the air forms a layer between the tube wall and the water, thus reducing friction between wall and water, giving a higher velocity of the water jet. With the results from the experimental nozzle in mind, five different full scale water cannon nozzles are designed, each with a certain method of air injection. The casting length, water flow and power consumption are measured and compared to a conventional nozzle. The performance is strongly dependent on the rate of water flow. For water flows of order 7 dm3/s, an increase in casting length of 12 per cent was achieved compared to a conventional nozzle. To achieve the same casting length, a conventional nozzle needs 39 per cent more power. Unfortunately the water flow with the new nozzle decreased with up to 48 per cent. For water flows of order 3 dm3/s, an increase in casting length of 93 per cent was achieved. To achieve the same casting length, a conventional nozzle needs 90 per cent more power. The water flow with the new nozzle decreased with 36 per cent. The final paper is an investigation of the lubrication between a plate and a rotating ball in normal approach. The normal velocity was varied between 0.1 and 0.5 m/s and the sliding velocity between 0 and 9.2 m/s. The experiments show, that the viscosity is the most important lubricant parameter. The normal velocity, the pressure viscosity coefficient, and the shear strength proportionality constant do not affect the degree of lubrication. An increase of the sliding velocity gave a decrease of the degree of lubrication between 25 and 65 per cent depending on surface roughness and type of lubricant. The surface roughness is also of great importance in getting good lubrication. To avoid wear, one has to increase the viscosity from 8 to 145 mm2/S if the mean surface roughness, Ra, is increased from 0.01 to 0.14.

  • 62.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Studium av obliteration och viskositet: obliteration av vattenbaserade hydraulvätskor och mineraloljor samt viskositet för emulsioner vid plan Poiseuille strömning1984Licentiate thesis, comprehensive summary (Other academic)
  • 63.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Vattenbaserade hydraulvätskors obliteration1984In: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 3, no 4, p. 1-24Article in journal (Refereed)
  • 64.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Vattenbaserade hydraulvätskors obliteration1984Report (Other academic)
  • 65.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Velocity measurement in a squeeze/sliding contact1991In: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 10, no 4Article in journal (Refereed)
  • 66.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Viscosity dependence of squeeze/sliding lubrication1992In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 155, no 1, p. 31-36Article in journal (Refereed)
    Abstract [en]

    It has been found experimentally that increased lubricant viscosity will increase the permissible sliding speed without leading to breakdown of the lubricant film while the normal velocity is held at a constant level. The dependence approaches a square root function. It is also apparent that with a squeeze velocity present, increased sliding velocity will decrease the oil-film thickness. An initial attempt at an explanation is given in terms of a combination of Reynolds' equation and further experimental results.

  • 67.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Viskositetsoberoende smörjförmåga hos bakaxeloljor vid kombinerad glid- och normalrörelse1991Report (Other academic)
  • 68. Lundberg, Jan
    et al.
    Berg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Grease-lubrication of roller bearings in railway waggons. Part 2: Laboratory tests and selection of proper test methods2000In: Industrial Lubrication and Tribology, ISSN 0036-8792, E-ISSN 1758-5775, Vol. 52, no 2, p. 76-86Article in journal (Refereed)
    Abstract [en]

    New, undestroyed greases of the same brands as those used in a field test, described in Part 1, were examined using conventional methods, such as the SKF V2F test, the roll stability test (ASTM D-1831), the Grease Worker (ASTM D-217), the torque test (ASTM 1478-91), bleeding measurements ( IP 121), yield stress measurements, the 4-ball test (ASTM D 2266-86), base oil viscosity measurements, thickener content and the cone penetration test (ASTM D217-88). The greases have also been tested with several new test methods developed at the University. A specification for relevant testing methods was drawn up and the connections between the tested parameters were investigated. It was found that the mechanical stability could be predicted with a combination of ASTM D-1831 and the limiting shear stress coefficient ?. This coefficient is capable of predicting wear. It was found that the bearing temperature could be predicted by using the base oil viscosity.

  • 69. Lundberg, Jan
    et al.
    Berg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Handbook for grease applications2000In: Industrial Lubrication and Tribology, ISSN 0036-8792, E-ISSN 1758-5775, Vol. 52, no 5, p. 221-232Article in journal (Refereed)
    Abstract [en]

    The process of finding the ultimate grease is described in this report using an example from railway applications. This example includes steps such as a requirement list, field tests, laboratory tests and an evaluation method. The example deals with the problems discovered in a field test performed to determine the best grease for tapered roller bearings in railway wagon wheels and to increase the knowledge of grease lubrication. Seven different fully formulated commercial greases were examined in the wheel bearings of one ore wagon, used for transporting ore commercially by railway from the Kiruna Mine in northern Sweden to Narvik in northern Norway for shipping to foreign markets. The steps performed in this study are recommended in all problems associated.

  • 70.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Bohlin, Alf
    Andreasen AB.
    Syk, Malin
    Trafikverket, Luleå.
    Blindfold tests on manganese crossing in railway application2011In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 2, no 2, p. 169-182Article in journal (Refereed)
    Abstract [en]

    Manganese crossings are widely used in the railway sector because of their self-hardening properties, but one major disadvantage is that maintenance actions using condition monitoring of internal flaws are problematic to perform. The reason is that manganese material is coarse-grained with internal reflections. In the present study, measurements on internal flaws with a spectrum of ultrasonic equipment were performed on a real manganese crossing. After the measurements, the crossing was cut up and inspected. Correlations with the measurements and the real flaws indicate that, independent of the equipment used, false echoes were common, as well as a low capacity to indicate real flaws.

  • 71.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Bohlin, Alf
    Syk, Malin
    Trafikverket, Luleå.
    Capacity test of ultrasonic equipment used for crack detection in railway application2011In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 2, no 2, p. 163-168Article in journal (Refereed)
    Abstract [en]

    Manganese crossings are widely used in the railway sector because of their self-hardening properties, but one major disadvantage is that maintenance actions using condition monitoring of internal flaws are problematic to perform since manganese material is coarse-grained with internal reflections. In the present study, spike- and square-pulsed ultrasonic apparatus, as well as phased aperture and time-corrected gain, together with suitable probes, was tested on manganese material in order to increase the understanding of the signal-noise ratio and the capacity to detect deeply placed internal flaws. Some of the most important results indicate that square pulses and timecorrected gain will increase the signal-noise ratio and also increase the capacity to find deeply placed flaws

  • 72. Lundberg, Jan
    et al.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A new method for determining the mechanical stability of lubricating greases2000In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 33, no 3-4, p. 217-223Article in journal (Refereed)
    Abstract [en]

    Mechanical stability is of central importance when dealing with the long-term service-length of grease-lubricated roller bearings. Poor stability will lead to consistency degradation of the grease, because of mechanical forces between the rolling parts of the bearing. The result can be leakage of grease through seals, or at worst a total failure of the bearing. The present investigation was initiated because present-day methods for prediction of mechanical stability show weak correlation with real service-length. The aim of the project was to develop a useful alternative. In order to fulfil this, both field tests and laboratory tests were carried out. In the field tests, nine different commercial greases were examined in the wheel bearings of five ore waggons, used for transporting ore by railroad from the Kiruna Mine in northern Sweden to Narvik in northern Norway for shipping to foreign markets. The test ore waggons travelled a distance of about 300,000 km during a period of 3 years. Small samples of greases were taken, on eight different occasions, for consistency testing. After the end of the test period, the damage on the bearings was also studied. In the laboratory tests, new undestroyed greases of the same brand as in the field tests were examined using conventional methods, such as the V2F, the Roll Stability Test and the Grease Worker. Comparisons between the field tests and these laboratory tests indicate poor correlation. In addition to these conventional methods, the relevance of the shear strength of the greases to the prediction of the mechanical stability was also tested. The shear stress τL depends on the applied pressure p, thus τL=τO+γ·p where τO is the shear stress at atmospheric pressure, γ is a property of the lubricant in the same way as viscosity or density. It was found that γ correlates well with the mechanical stability in service. Increased γ values lead to a decrease in the mechanical stability. One reasonable explanation is that high γ values correspond to high shear stresses in the grease, and thus severe conditions for the thickener.

  • 73.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Influence of limiting shear strength of oils on breakdown of a lubricating oil film1992In: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 11, no 4, p. 106-114Article in journal (Refereed)
  • 74.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Velocity measurements in a squeeze/sliding lubricated contact1991In: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 10, no 4, p. 32-47Article in journal (Refereed)
  • 75.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    McFadden, Terry
    Creep transport of grease subjected to low frequency vibrations1996In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 9, no 1, p. 71-83Article in journal (Refereed)
    Abstract [en]

    Creep transport is defined as the velocity of a mass of grease when it is subjected to vibrational and gravitational forces. The method developed to assess this, measured the time taken for the grease submitted to low frequency vibrations to creep, under the influence of gravity, a specified distance down a cylindrical tube. The vibrations were characteristic in frequency and amplitude to those commonly experienced by commercial rotating machinery. Vibrational excitation was found to have a widely varying effect on creep transport of grease, suggesting that this parameter may be important in the selection of greases for specific applications where vibration is present; in contrast, the NLGI number gave almost no indication as to the effect of vibration on a particular grease. A vibration number related to the creep rate is suggested for grease selection. The vibration number correlates to the yield stress of the grease, with higher yield stress correlating to higher creep rate. However, no correlations between creep rate and base oil viscosity or bleed rate were found.

  • 76.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    McFadden, Terry
    Low temperature performance rating criteria for lubrication greases1996In: Cold regions engineering : the cold regions infrastructure--an international imperative for the 21st century: proceedings of the Eighth International Conference on Cold Regions Engineering, University of Alaska Fairbanks, Fairbanks, Alaska, August 12-16, 1996 / [ed] Robert F. Carlson, New York: American Society of Civil Engineers (ASCE), 1996, p. 153-172Conference paper (Refereed)
    Abstract [en]

    The development of a rational evaluation method that can be applied to greases subject to low temperature service is attempted using a two level approach. The greases are evaluated as to their expected performance based on criteria that are currently believed to be important. The actual performance of the greases is then assessed in service on a railway hauling iron ore in northern Sweden and Norway under severe conditions of low temperatures and heavy duty demands. The relevance of the expected criteria in predicting actual performance will be used to establish a weighting system for each criteria to develop an overall performance number that can be used for rational selection of greases for low temperature service. Several methods of evaluating the performance criteria are discussed along with their advantages and drawbacks. The overall plan for developing the performance number is presented. Present progress is reported along with an estimate of future developments and their expected availability and impact on the overall plan.

  • 77. Lundberg, Jan
    et al.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Söderholm, Peter
    Running temperature and mechanical stability of grease as maintenance parameters of railway bearings2010In: International Journal of Automation and Computing, ISSN 1476-8186, E-ISSN 1751-8520, Vol. 7, no 2, p. 160-166Article in journal (Refereed)
    Abstract [en]

    Spherical roller bearings in railway car wheels are critical components whose failure may have catastrophic consequences. The present study aims to analyse the mechanical stability of greases and temperature of bearings as indicators for condition-based bearing maintenance. The performed case study includes nine fully-formulated commercial greases examined in the wheel bearings of five ore cars operated in northern Scandinavia. The studied ore cars travelled a distance of about 300 000 km during a period of three years. Small samples of the greases were taken on eight occasions to test their mechanical stability. In addition, the temperatures of the bearings were continuously recorded. After the test period, the wear, electrical damage, and corrosion of the bearings were examined. One of the findings is that the shear stress of the grease at a certain shear velocity (the certain yieldstress (CEY) value) is a good maintenance indicator and is highly dependent on the grease type. The bearing's wear, electrical damage and corrosion also depend on the grease type. However, no oxidation of the greases was identified. The paper also outlines a systematic methodology to determine an overall maintenance indicator for railway roller bearings which is based on the field measurements

  • 78.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Division of Operation and Maintenance, Luleå University of Technology.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Division of Operation and Maintenance, Luleå University of Technology.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Division of Geosciences and Environmental Engineering, Luleå University of Technology.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics. Division of Fluid and Experimental Mechanics, Luleå University of Technology.
    Measurements of friction coefficients between rails lubricated with a friction modifier and the wheels of an IORE locomotive during real working conditions2015In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 324-325, p. 109-117Article in journal (Refereed)
    Abstract [en]

    The real friction coefficients between the rails and the wheels on a 360. t and 10,800. kW IORE locomotive were measured using the locomotive[U+05F3]s in-built traction force measurement system. The locomotive consisted of two pair-connected locomotives had a CoCo+CoCo bogie configuration, and hauled a fully loaded set of 68 ore wagons (120. t/wagon). The measurements were performed both on rails in a dry condition and on rails lubricated with a water-based top-of-rail (ToR) friction modifier on the Iron Ore Line between the cities of Kiruna and Narvik in Northern Sweden and Norway, respectively. Since full-scale measurements like these are costly, the friction coefficients were also measured at the same time and place using a conventional hand-operated tribometer, with and without the ToR friction modifier. The most important results are that the real friction coefficient is definitely not constant and is surprisingly low (0.10-0.25) when the ToR friction modifier is used, and that it is also significantly dependent on the amount of ToR friction modifier. A large amount will reduce the friction coefficient. Furthermore, it is concluded that the real friction coefficients are in general lower than the friction coefficients measured with the hand-operated tribometer. A final remark is thus that the use of a water-based ToR friction modifier can give excessively low friction, which can result in unacceptably long braking distances.

  • 79.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Shen, Hayley H.
    Clarkson University, Potsdam, NY.
    Collisional restitution dependence on viscosity1992In: Journal of engineering mechanics, ISSN 0733-9399, E-ISSN 1943-7889, Vol. 118, no 5, p. 979-989Article in journal (Refereed)
    Abstract [en]

    Dense two-phase flows occur in many material processing situations. In these flows, particle collision presents a mechanism for internal resistance. In the literature, restitution coefficients are given for collisions between dry objects. Little is known about two colliding objects placed in a fluid. Thus, although two-phase flow models exist for dense mixtures, realistic values of the required restitution coefficient are not available. Recent theoretical and experimental analyses of colliding spheres in a viscous fluid show that collisional rebound depends greatly on the interstitial fluid. At very high viscosity, contact may not occur. This paper presents an experimental study of collisional restitution between steel and nylon, and a range of Newtonian viscous fluids. The fluids have a viscosity range from 27 mm2/s to 2,600 mm2/s. The normal impact velocity ranges from 0.015 m/s to 0.75 m/s. Preliminary results show that the behaviour of the impact and the resulting restitution coefficient depend on the interstitial fluid. These results will be useful to the mathematical modeling of dense two-phase flows.

  • 80.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Söderholm, Peter
    Mechanical stability of grease and running temperature as indicators of railway roller bearing temperature2008In: ICOMS Conference Proceedings, Surrey Hills, VIC: Asset Management Council , 2008Conference paper (Refereed)
    Abstract [sv]

    En systematisk metod för pediktering av underhållsbehov av hjullager till malmvagnar har utvecklats. Metoden bygger på merittalsberäkning och fältprov.

  • 81.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Åström, H.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grease lubrication of an elliptical EHD: contact in combined squeezing and sliding1990In: Putting tribology to work: reliability and maintainability through lubrication and wear technology ; preprints of papers ; Brisbane, 2 - 5 December 1990 / International Tribology Conference 1990, Barton: Academia adacta, 1990, p. 151-155Conference paper (Refereed)
    Abstract [en]

    Experimental investigations have been made using an apparatus specially built to study lubrication combined squeezing and sliding. In this investigation nine different lubricating greases and two base oils have been tested. The results are presented as a critical sliding velocity above which asperity contact occurs. The squeeze (normal) velocity was 0.2 m/s and the critical sliding velocity was between 1 and 6 m/s depending on the lubrican Although the greases have the same NLGI grade (2), they show quite different lubricating ability. The experiment showed that the lithium and lithium complex thickeners increased the lubrication ability of the base oil.

  • 82.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Östensen, Jan Ove
    Luleå tekniska universitet.
    Åström, Henrik
    Luleå tekniska universitet.
    High-speed video photographs of lubrication breakdown in squeeze-sliding contact1992In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 157, no 2, p. 427-433Article in journal (Refereed)
    Abstract [en]

    Using photographs from a high-speed video camera it was confirmed that the main part of breakdown of a lubricating film will appear at the end of the contact time for a contact simultaneously subjected to squeeze and sliding motion. This corresponds with earlier findings using totally different equipment for electric detection of the asperity contact. The present investigation used glass and steel as the lubricated surfaces, instead of steel and steel as was the case in the earlier investigation. In combination with far less stiff equipment, the new materials gave longer contact time and larger elastic deformations of the contact bodies. It was also verified that increased surface roughness, increased sliding velocity and decreased viscosity increase the risk of oil film breakdown

  • 83.
    Nordström, Jakob
    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.
    Dandotiya, Rajiv
    Lundberg, Jan
    Crack detection methods and ranking for mining mill machinery2009In: 22nd International Congress on Condition Monitoring and Diagnostic Engineering Management: COMADEM 2009 ; June 9 - 11, 2009, San Sebastian, Spain, Miramar Palace / [ed] Aitor Arnaiz, Eibar: Fundaci n Tekniker , 2009, p. 313-321Conference paper (Refereed)
    Abstract [en]

    The mining industry is severely exposed to various effects of the dynamic global business scenario today. The main issue for the mining industry is to maximize the availability of its machinery. Fatigue cracking in rotating mill machines is one of many critical factors in the context of function, safety, reliability and increased maintenance cost due to related unpredictable mill failures. There are several reasons for the appearance of cracks in mills. Several detection methods and technologies are available today, which are crack specific, depending on size and location. It is essential to select an appropriate crack detection method to fulfil the needs of the industries and the operational conditions, because each method has its own particular advantages and disadvantages. The main aim of this paper is to highlight the scopes and limitations of these methods. In this paper also the Analytical Hierarchical Process (AHP) is applied to determine the rank or unified measure for the selected crack detection methods. The aim of this analysis is to assist maintenance personnel in selecting the appropriate crack detection device.

  • 84.
    Normark, Carl Jörgen
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Kappfjell, Monica
    Luleå tekniska universitet.
    Tretten, Phillip
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Gärling, Anita
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Evaluation of car instrumentation clusters by using eye-tracking2007In: EAEC 2007 Proceedings: 11th European Automotive Congress, EAEC , 2007Conference paper (Refereed)
    Abstract [en]

    The importance of the ambience presented by instrumentation in the vehicle of today is of great significance for the automotive industry. The rapid technological development of electronic equipment has enabled the large amount of information devices in the drivers' environment. The types of driver information and their appearances are well identified by car manufacturers, but there is a lack of knowledge regarding drivers' perceptions of instrumentation clusters as well as their appearance. To increase this knowledge a study was conducted in order to measure these perceptions. Twenty-three subjects were studied using a method consisting of eye-tracking, assessments and interviews. Each subject was to view eight clusters and to assess each cluster according to six different semantic descriptions. The interviews were based on the subject's individual eye-tracking data. The subject was monitored by an eye-tracking equipment during the assessment task. The results showed that there were some significant correlations between time spent viewing a cluster and its assessment. Moreover, the results also give a view on how clusters are assessed and why they are assessed in particular ways.

  • 85.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    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.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Modelling perceptual dimensions of saxophone sounds2009In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 95, no 3, p. 539-549Article in journal (Refereed)
    Abstract [en]

    In the past, musical instruments were developed over long periods of time by skilled craftsmen. Today, most instruments are mass-produced. Design of musical instruments as mass-produced products requires using strategies which make it easier to identify customer needs and develop exact specifications. To develop useful specifications it is necessary to convert general descriptions into something which can be commonly understood and also be interpretable in terms of acoustic metrics. In this study, methods for analysis and specification of steady state parts of alto saxophone sounds were developed. Saxophonists' use of verbal descriptions of saxophone sounds was investigated. Sound stimuli were binaurally recorded. Judgements upon perceived qualities were made by saxophonists and non-saxophonists using the method of verbal attribute magnitude estimation. Perceptual dimensions were identified using principal component analysis of listening test data. Three prominent dimensions were found and described using the verbal attributes: 1) warm/soft, 2) back vowel analogues and 3) sharp/rough. The perceptual dimensions were modelled as linear functions of acoustic metrics. The results were validated through listening tests with new subjects and new stimuli. Based on the findings, the method was seen as an approach which can enhance the musical instrument design process.

  • 86.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    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.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Perceptual and acoustical dimensions of saxophone sound2005In: Forum Acusticum Budapest 2005, 4th European Congress on Acoustics: 29 August - 2 September 2005, Budapest, Hungary, 2005, p. 519-524Conference paper (Refereed)
    Abstract [en]

    Specifications of product sound qualities may contain both perceptual and acoustical descriptions. The perceptual descriptions are most helpful when they contain adequate detail and utilises understandable wording. To facilitate the product design process the descriptions should also be interpretable as acoustical quantities. The objectives of the study reported upon here were to investigate how musicians use verbal descriptions of sound and to interpret these descriptions in terms of commonly used acoustical quantities. Musicians' use of verbal descriptions of saxophone sound was investigated through interviews. The most frequently used words were evaluated through listening tests. The subjects were asked to judge how well the words described the timbre of test sounds. To find the most significant perceptual dimensions for the test sounds Principal Component Analysis was used. Four significant dimensions were found and described by 9 words. To interpret the perceptual dimensions in terms of physically measurable indices, models for how acoustical quantities relate to the perceptual dimensions were developed. Dimension 1 was described by full-toned/warm/soft. The psycho-acoustical quantity sharpness correlated negatively with this dimension. Dimension 2 was described by the term [o]-like. Sharpness and specific roughness (9-11 Bark) correlated negatively with this dimension. Dimension 3 was described by sharp/keen/rough. Sharpness and roughness correlated with this dimension. Dimension 4 was described by the term [e]-like. No model for prediction of this dimension was found. To validate the models the effect of a changed design of the tone holes of a saxophone was predicted with the model and validated with new listening tests.

  • 87.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nordström, Jakob
    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.
    Dandotiya, Rajiv
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Crack detection methods for mining mill machinery2010In: Asset Management & Maintenance Journal, ISSN 1835-789X, Vol. 23, no 2, p. 44-49Article in journal (Refereed)
  • 88.
    Petersson, Anna Malou
    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.
    Applying action design research (ADR) to develop concept generation and selection methods2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 50, p. 222-227Article in journal (Refereed)
    Abstract [en]

    During conceptual design, concept generation and selection methods can be used to facilitate the generation of new ideas and the selection of the most promising suggestions. The present paper is an effort to understand better how action design research can be utilized to develop such methods. Using action design research, methods were developed through iterative cycles of building, testing and evaluation in the context of a deregulated railway market, through a close collaboration between actors from industry, a government agency and academia. The approach was found to be feasible and to provide generalization of the context-specific findings through the formulation of design principles.

  • 89.
    Petersson, Anna Malou
    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.
    Developing an ideation method to be used in cross-functional inter-organizational teams by means of action design research2018In: Research in Engineering Design, ISSN 0934-9839, E-ISSN 1435-6066, Vol. 29, no 3, p. 433-457Article in journal (Refereed)
    Abstract [en]

    Using ideation methods in an optimal way has a great potential to increase the number of ideas which a team can contribute during the conceptual phase of product development in industry. Previous studies on ideation methods have been mainly statistical studies in a laboratory setting. In the present study, however, the aim was to develop tailor-made ideation methods in a specific context, among actors on a deregulated railway market, through close interaction between researchers and engineers in a real-world context. Considering previous relevant research on ideation methods, associative memory models and the findings from tests of established ideation methods performed in the same group, a number of preliminary design principles were formulated and implemented in an ideation method that combines individual phases of rotational and gallery viewing with phases of verbal group interaction. The method was tested and refined in a cross-functional inter-organizational group comprising participants from different actors in the railway sector. Besides its provision of qualitative and quantitative test results, the present study has considered the opinions of the participants in detail, which can give important insights into the factors determining whether such a method will be implemented in industry. The participants found the method to be more useful and to generate more ideas that could be used in practice compared to the established ideation methods which they had tried. The learning derived from the specific case was formalized into a number of design principles for ideation methods to be used in cross-functional inter-organizational groups.

  • 90.
    Petersson, Anna Malou
    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.
    Evaluating an ideation method in a real-life context: A field test from the railway sector2016In: ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, New York: ASME Press, 2016, Vol. 7, article id DETC2016-59992Conference paper (Refereed)
    Abstract [en]

    A great number of ideation methods are available to assist the engineer in the conceptual phase of product development. Previous research on idea generation suggests that, in order to understand how ideation can be successful in reality, the context must be taken into account. Therefore, evaluating promising ideation methods in the intended use setting should be an important complement to other research studies in the field of engineering design. In the present study, an ideation method which had previously been developed by the present authors in close collaboration with industry, a government agency, and academia was evaluated in a typical use setting. Testing the method in a use setting led to unexpected events and to new insights into the method. During the most ideation-intensive stage of the method, one of the groups in the use setting generated suggestions at a rate similar to that of the small representative group in which the development of the method had taken place, whereas the other three groups in the use setting had a lower suggestion generation rate. The findings indicated that the participants' views on the method correlated with those of the group which had developed the method.

  • 91.
    Petersson, Anna Malou
    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.
    The Impact of Competitive Tendering on Railway Maintenance Performance in Sweden2014In: Proceedings of the Second International Conference on Railway Technology: research, development and maintenance ; 8 - 11 April 2014, Ajaccio, Corsica, France / [ed] J. Pombo, Kippen: Civil-Comp Press , 2014, article id 290Conference paper (Refereed)
  • 92.
    Petersson, Anna Malou
    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.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ideation methods applied in a cross-functional inter-organizational group: an exploratory case study from the railway sector2017In: Research in Engineering Design, ISSN 0934-9839, E-ISSN 1435-6066, Vol. 28, no 1, p. 71-97Article in journal (Refereed)
    Abstract [en]

    The conceptual design phase is a critical step, since it influences the subsequent steps during product development with regard to cost, quality and performance. Previous research has focused on cross-functional teams within an organization. However, many product development projects benefit from the participation of members from different organizations, not least during the conceptual design phase of technical products, where it is essential to consider different aspects of the product-to-be. Therefore, we conducted an in-depth case study of a cross-functional inter-organizational group testing ideation methods in a real-life setting within a development project in the railway sector. The group comprised participants from an infrastructure manager, a supplier, a maintenance contractor and research bodies. The tested ideation methods were Method 635, the gallery method and the SIL method. The participants found working in a cross-functional inter-organizational group to be beneficial both during the group-analysis of the topics and during the generation of ideas on how to address the ideation topic. Applying the ideation methods to the ideation topics facilitated the sharing of information between participants, and the diversity of the group manifested itself in several ways during ideation. Overall, the gallery method was most popular, and the SIL method was least popular among the participants. 

  • 93.
    Rantatalo, Matti
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Wijaya, Andj
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Thurley, Matthew
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Fredriksson, Håkan
    Project: HLRC Pre-study: Owner-specific methods for production-increasing improvements of mining machinery2012Other (Other (popular science, discussion, etc.))
  • 94.
    Saari, Juhamatti
    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.
    Odelius, Johan
    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.
    Selection of features for fault diagnosis on rotating machines using random forest and wavelet analysis2018In: Insight (Northampton), ISSN 1354-2575, E-ISSN 1754-4904, Vol. 60, no 8, p. 434-442Article in journal (Refereed)
    Abstract [en]

    Identification of component faults using automated condition monitoring methods has a huge potential to improve the prediction of machine failures. The ongoing development of the Internet of Things (IoT) will support and benefit feature selection and improve preventative maintenance decision making. However, there may be problems with the selection of features that best describe a specific fault and remain valid even when the operation mode is changing (for example different levels of load). In this study, features were extracted from vibration signals using wavelet analysis; a feature subset was selected using the random forest ensemble technique. Three different datasets were created where the load of the system was changing while the rotational speed remained the same. The tests were repeated five times by first recording the nominal condition and then introducing four faults: angular misalignment; offset misalignment; partially broken gear tooth failure; and macro-pitting of the gear. To improve previous feature selection techniques, a method is proposed where, before training a classifier, the most promising features are compared at different degrees of torsional load. The results indicate that the proposed method of using random forests to select top variables can help to choose good features that may not have been considered in manual feature selection or in individual load zones.

  • 95.
    Saari, Juhamatti
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    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.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Using wavelet transform analysis and the support vector machine to detect angular misalignment of a rubber coupling2015In: Maintenance, Condition Monitoring and DiagnosticsMaintenance Performance Measurement and Management / [ed] Sulo Lahdelma and Kari Palokangas, 2015, p. 117-126Conference paper (Other academic)
    Abstract [en]

    Shaft misalignment is a common problem for many types of rotating systems. It can cause machine breakdowns due to the premature failure of bearings or other components. Common diagnostic approaches rely on detecting increasing vibration response spectra at multiples of the shaft speed. However, in many time-variant systems, such as wind turbines, the speed and load vary considerably, which can make spectrum analysis insufficient. In this paper, a method for detecting shaft misalignment by using wavelet analysis is proposed. The method was experimentally evaluated in a laboratory test rig for four different operating conditions by varying the rotational speed and load. An angular misalignment was introduced between a hydraulic pump (load) and a medium-sized industrial gearbox connected with a rubber coupling. Vibration data were collected by using two accelerometers mounted in an axial and a radial direction directly on the gearbox casing. The features extracted from wavelet representation were classified by using a support vector machine algorithm. The detection of misalignment and the sensitivity of the proposed method are presented using validation data and confusion matrices. The final results of the confusion matrices clearly indicate that this method can detect misalignment even when the speed and load vary. The proposed method can be used for systems which are connected with shafts and there are many similar systems (comprising an electric motor, a gearbox and a centrifugal pump) working under the same circumstances.

  • 96.
    Saari, Juhamatti
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Luleå University of Technology, SKF-LTU University Technology Centre.
    Strömbergsson, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. Luleå University of Technology, SKF-LTU University Technology Centre.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Thomson, A.
    SKF (U.K), Livingston, Scotland, United Kingdom.
    Detection and identification of windmill bearing faults using a one-class support vector machine (SVM)2019In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 137, p. 287-301Article in journal (Refereed)
    Abstract [en]

    The maintenance cost of wind turbines needs to be minimized in order to keep their competitiveness and, therefore, effective maintenance strategies are important. The remote location of wind farms has led to an opportunistic maintenance strategy where maintenance actions are postponed until they can be handled simultaneously, once the optimal opportunity has arrived. For this reason, early fault detection and identification are important, but should not lead to a situation where false alarms occur on a regular basis. The goal of the study presented in this paper was to detect and identify wind turbine bearing faults by using fault-specific features extracted from vibration signals. Automatic identification was achieved by training models by using these features as an input for a one-class support vector machine. Detection models with different sensitivity were trained in parallel by changing the model tuning parameters. Efforts were also made to find a procedure for selecting the model tuning parameters by first defining the criticality of the system and using it when estimating how accurate the detection model should be. Method was able to detect the fault earlier than using traditional methods without any false alarms. Optimal combination of features and model tuning parameters was not achieved, which could identify the fault location without using any additional techniques.

  • 97.
    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.

  • 98.
    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, ISSN 0019-6398, 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.

  • 99.
    Stenström, Christer
    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.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Squirter Ultrasonic Thickness Gauge for Monitoring of Mining Mill Lining During Operation (SV: Mätning av tjocklek på kvarninfodring med ultraljud under drift)2014Other (Other (popular science, discussion, etc.))
  • 100.
    Stenström, Christer
    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.
    Lundberg, Jan
    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.
    Development of an integrity index for benchmarking and monitoring rail infrastructure: application of composite indicators2015In: International Journal of Rail transportation, ISSN 2324-8378, E-ISSN 2324-8386, Vol. 3, no 2, p. 61-80Article in journal (Refereed)
    Abstract [en]

    Railways are large, geographically dispersed assets, consisting of numerous systems, subsystems and components, for which considerable amounts of data and numerous indicators are generated for monitoring their operation and maintenance. Proper assessment of operation and maintenance performance is essential for sustainable and competitive rail transportation. Composite indicators (CIs), or indices, can simplify the performance measurement by summarising the overall performance of a complex asset into a single figure, making it easier to interpret than multiple indicators and plots. In this article, a CI termed ‘rail infrastructure integrity index’ is developed and verified in a case study. The results show that CIs can be used for benchmarking and assessing the overall performance of railway sections in a single figure, indicating which sections need further study. Their implementation should allow data users to do sensitivity analysis and decomposition for traceability.Keywords: rail infrastructure; composite indicator; integrity index; dependability; RAMS; benchmarking

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