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Fransson, Lennart
Publikasjoner (10 av 75) Visa alla publikasjoner
Bonath, V., Edeskär, T., Lintzén, N., Fransson, L. & Cwirzen, A. (2019). Properties of ice from first-year ridges in the Barents Sea and Fram Strait. Cold Regions Science and Technology
Åpne denne publikasjonen i ny fane eller vindu >>Properties of ice from first-year ridges in the Barents Sea and Fram Strait
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2019 (engelsk)Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441Artikkel i tidsskrift (Fagfellevurdert) Epub ahead of print
Abstract [en]

First-year ice ridges are one of the main load scenarios that off-shore structures and vessels operating in ice-covered waters have to be designed for. For simulating such load scenarios, the knowledge gap on ice mechanical properties from the consolidated part of first-year ridges has to be filled. In total 410 small-scale uniaxial compression tests were conducted at different strain rates and ice temperatures on ice from the consolidated layer of 6 different first-year ridges in the sea around Svalbard. For the first time uniaxial tensile tests were performed on ice from first-year ridges using a new testing method. Ice strength was evaluated for different ice type, which are determined for each specimen based on a proposed ice classification system for ice from first-year ridges. 78% of all samples contained mixed ice with various compounds of brecciated columnar and granular ice. Ice strength of mixed ice showed isotropy, except for the samples containing mainly columnar ice crystals. For horizontal loading, mixed ice was stronger than columnar and granular ice. The residual strength of ductile ice depended on the strain rate. At 1.5% strain remained 70% of peak strength at 10−4 s−1 and 50% at 10−3 s−1. Ductile failure dominated for 75% of all mixed ice tests at 10−3 s−1 and − 10 °C. Ductile compressive strength was generally higher than brittle compressive strength for mixed ice. Brine volume was the main parameter influencing the tensile strength of the mixed ice which was between 0.14 MPa and 0.78 MPa measured at constant ice temperature of −10 °C.

sted, utgiver, år, opplag, sider
Elsevier, 2019
Emneord
First-year ice ridges, Ice texture, Uniaxial compression strength, Tensile strength, Mechanical properties
HSV kategori
Forskningsprogram
Byggmaterial; Geoteknik
Identifikatorer
urn:nbn:se:ltu:diva-76074 (URN)10.1016/j.coldregions.2019.102890 (DOI)
Tilgjengelig fra: 2019-09-20 Laget: 2019-09-20 Sist oppdatert: 2019-09-20
Bonath, V., Petrich, C., Sand, B., Fransson, L. & Cwirzen, A. (2018). Morphology, internal structure and formation of ice ridges in the sea around Svalbard. Cold Regions Science and Technology, 155, 263-279
Åpne denne publikasjonen i ny fane eller vindu >>Morphology, internal structure and formation of ice ridges in the sea around Svalbard
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2018 (engelsk)Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 155, s. 263-279Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.

sted, utgiver, år, opplag, sider
Elsevier, 2018
HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-70645 (URN)10.1016/j.coldregions.2018.08.011 (DOI)000444514700024 ()2-s2.0-85052209862 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-08-29 (andbra)

Tilgjengelig fra: 2018-08-29 Laget: 2018-08-29 Sist oppdatert: 2018-10-10bibliografisk kontrollert
Patil, A., Sand, B. & Fransson, L. (2015). Finite element simulation of punch through test using a continuous surface cap model (ed.). In: (Ed.), (Ed.), Proceedings of the 23nd International Conference on Port and Ocean Engineering under Arctic Conditions: POAC 2015, Trondheim, Norway; 14-18 June 2015. Paper presented at International Conference on Port and Ocean Engineering under Arctic Conditions : 14/06/2015 - 18/06/2015.
Åpne denne publikasjonen i ny fane eller vindu >>Finite element simulation of punch through test using a continuous surface cap model
2015 (engelsk)Inngår i: Proceedings of the 23nd International Conference on Port and Ocean Engineering under Arctic Conditions: POAC 2015, Trondheim, Norway; 14-18 June 2015, 2015Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

An attempt has been made to calibrate the material model parameters of the continuous surface cap model with data from punch through tests performed in the Northern Gulf of Bothnia. An axisymmetric finite element model has been used to simulate the field tests. The continuous surface cap model based on a combination of elastic-plastic and continuum damage mechanics formulation is used as constitutive model for ice rubble. Material properties such as internal friction angle, cohesion and Young’s modulus are evaluated in a parametric study and the response is compared to the experimental data for the chosen test. An optimization algorithm is used for determining the parameters used for describing the continuous surface cap model. The material model parameters are chosen to get best fit to test load displacement curve. Conclusion has been drawn based on the application of continuous surface cap model on ice rubble.

Serie
Proceedings - International Conference on Port and Ocean Engineering under Arctic Conditions, ISSN 0376-6756
HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-38461 (URN)84942162926 (Scopus ID)cdeb9450-a89d-48b2-9faf-6340bcf32590 (Lokal ID)cdeb9450-a89d-48b2-9faf-6340bcf32590 (Arkivnummer)cdeb9450-a89d-48b2-9faf-6340bcf32590 (OAI)
Konferanse
International Conference on Port and Ocean Engineering under Arctic Conditions : 14/06/2015 - 18/06/2015
Merknad
Godkänd; 2015; 20150926 (anipat)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Patil, A., Sand, B. & Fransson, L. (2015). Smoothed particle hydrodynamics and continuous surface cap model to simulate ice rubble in punch through test (ed.). In: (Ed.), (Ed.), Proceedings of the 23nd International Conference on Port and Ocean Engineering under Arctic Conditions: POAC 2015, Trondheim, Norway; 14-18 June 2015. Paper presented at International Conference on Port and Ocean Engineering under Arctic Conditions : 14/06/2015 - 18/06/2015.
Åpne denne publikasjonen i ny fane eller vindu >>Smoothed particle hydrodynamics and continuous surface cap model to simulate ice rubble in punch through test
2015 (engelsk)Inngår i: Proceedings of the 23nd International Conference on Port and Ocean Engineering under Arctic Conditions: POAC 2015, Trondheim, Norway; 14-18 June 2015, 2015Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Recent trend in computational mechanics shows considerable development of numerical methods to simulate discrete materials such as ice rubble. Ice rubble has highly nonlinear behavior and to simulate shear properties requires a new numerical method. An attempt has been made to simulate a punch through test using the Lagrangian mesh-free partial based method formulation known as smoothed particle hydrodynamics. A newly implemented material model in LS-Dyna called the continuous surface cap model has been used in this simulation. A continuous surface cap model based on a combination of elastic-plastic and continuum damage mechanics formulation is used as constitutive model for ice rubble. The material model parameters are chosen to get best fit to test load displacement curve. A brief overview of the smoothed particle hydrodynamics is given. Finally, the results from simulations have compared with experimental results.

Serie
Proceedings - International Conference on Port and Ocean Engineering under Arctic Conditions, ISSN 0376-6756
HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-37688 (URN)bc865304-9057-4460-8a31-34135d866105 (Lokal ID)bc865304-9057-4460-8a31-34135d866105 (Arkivnummer)bc865304-9057-4460-8a31-34135d866105 (OAI)
Konferanse
International Conference on Port and Ocean Engineering under Arctic Conditions : 14/06/2015 - 18/06/2015
Merknad
Godkänd; 2015; 20150926 (anipat)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Petrich, C., Sæther, I., Fransson, L., Sand, B. & Arntsen, B. (2015). Time-dependent spatial distribution of thermal stresses in the ice cover of a small reservoir (ed.). Paper presented at . Cold Regions Science and Technology, 120, 35-44
Åpne denne publikasjonen i ny fane eller vindu >>Time-dependent spatial distribution of thermal stresses in the ice cover of a small reservoir
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2015 (engelsk)Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 120, s. 35-44Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Static ice loads (ice actions) are a key design parameter for dams in cold climates. However, their theoretical description is still elusive, introducing uncertainty in design and hindering development of remediation measures. We present and analyze measurements of stresses due to thermal loads in a small reservoir in northern Norway. Several weeks of observations, including both cold and warm spells, were well-described by a simple equation that accounts for thermal expansion and temperature-dependent creep. One model parameter was found to depend systematically on the location of measurements within the reservoir. Biaxial stress measurements showed that the stress field was not homogeneous. Results suggest that the stress field in reservoirs should be predictable from first principles with numerical methods and point toward a promising, simple parameterization.

HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-3218 (URN)10.1016/j.coldregions.2015.09.003 (DOI)000365055400004 ()2-s2.0-84942314058 (Scopus ID)103e1f63-f16c-4960-acb9-ae2da302d379 (Lokal ID)103e1f63-f16c-4960-acb9-ae2da302d379 (Arkivnummer)103e1f63-f16c-4960-acb9-ae2da302d379 (OAI)
Merknad
Validerad; 2015; Nivå 2; 20150914 (andbra)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Casselgren, J., Engström, N., Rosendahl, S. & Fransson, L. (2014). Investigation of ice surface change during vehicle testing (ed.). Paper presented at . International Journal of Vehicle Systems Modelling and Testing, 9(2), 137-150
Åpne denne publikasjonen i ny fane eller vindu >>Investigation of ice surface change during vehicle testing
2014 (engelsk)Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 9, nr 2, s. 137-150Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is that the liquid like layer which appears due to increasing temperature can be reduced by manipulating the ice roughness. This in turn should decrease the temperature dependence of the roadgrip in temperatures around 0°C. In order to investigate this, measurements of temperature, surface roughness and hardness and roadgrip were performed on three outdoor ice surfaces using an IR thermometer, an optical sensor with three IR-diodes, a steel ball drop indentation test and an RT3 curve, respectively. Additional ice roughness measurements were also made on two tempered ice surfaces in an ice hall. Results show a clear connection between ice temperature and roadgrip, unfortunately the created ice roughness was too small to influence the change in roadgrip

HSV kategori
Forskningsprogram
Experimentell mekanik; Maskinelement; Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-7501 (URN)10.1504/IJVSMT.2014.061435 (DOI)2-s2.0-84901634457 (Scopus ID)5e55df2a-1148-4308-bf6f-d8fde27fbe78 (Lokal ID)5e55df2a-1148-4308-bf6f-d8fde27fbe78 (Arkivnummer)5e55df2a-1148-4308-bf6f-d8fde27fbe78 (OAI)
Prosjekter
CASTT - Centre for Automotive Systems Technologies and Testing
Merknad
Validerad; 2014; 20131128 (sarros)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Dempsey, J. P., Jochmann, P., Fransson, L., Mu, Z., Weiss, J. & Palmer, A. (2013). Cleavage fracture of warm brackish ice (ed.). In: (Ed.), (Ed.), Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions: June 9-13, 2013 Espoo, Finland. Paper presented at International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013.
Åpne denne publikasjonen i ny fane eller vindu >>Cleavage fracture of warm brackish ice
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2013 (engelsk)Inngår i: Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions: June 9-13, 2013 Espoo, Finland, 2013Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Two sets of cleavage (cracking parallel to the ice surface) fracture toughness tests were conducted at the Hamburg Ship Model Basin (HSVA) on brackish ice harvested from two separate locations in the Gulf of Bothnia. The ice was split using a pin-loaded compact tension geometry. The fracture tests were accompanied by tensile and compressive tests. This paper discusses the experiments and the results.

HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-30345 (URN)41e28d3d-4148-463c-b8df-e9f7988904c3 (Lokal ID)41e28d3d-4148-463c-b8df-e9f7988904c3 (Arkivnummer)41e28d3d-4148-463c-b8df-e9f7988904c3 (OAI)
Konferanse
International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013
Merknad
Godkänd; 2013; 20140818 (johsod)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Bonath, V. & Fransson, L. (2013). Isförhållanden inom Luleå hamnbassäng (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Åpne denne publikasjonen i ny fane eller vindu >>Isförhållanden inom Luleå hamnbassäng
2013 (svensk)Rapport (Annet vitenskapelig)
Abstract [sv]

Issituationen i Luleå hamn vintern 2012/13 var normalsvår vilket innebar en ökad istillväxt motsvarade 150 cm ren is i områden som bröts kontinuerligt. Detta ska jämföras med det obrutna istäckets tjocklek som var ca 60 cm. Isen i rännan bestod av klotformade isblock (10 – 120 cm) omgivna av issörja. Under mars månad var isblockens storlek mätt vid vattenytan i genomsnitt 45 cm och andelen vatten eller finfördelad issörja var ca 30%. Analyser av isborrkärnor visar att isblocken hade en hållfasthet som ökade med antalet brytningar och var i paritet med det ostörda istäcket i början av mars. Blocken bestod då till 70% av finkrossad is eller frusen snösörja.Isproduktionen i området med bruten is tycks vara linjärt beroende av antalet negativa graddagar där tillväxttakten uppmättes till 0,235 cm per grad och dygn. En numerisk modell för beräkning av istillväxt föreslås där frysning av issörja vid ytan och under isblock ingår. Modellen stämmer bra överens med uppmätta värden från en ränna nära hamnen som bröts kontinuerligt två gånger i veckan. Mer fältstudier av isbildning och uppbrytning är önskvärd för att öka modellens tillförlitlighet under förhållanden som skiljer sig väsentligt från de som rådde i testrännan. Samtliga mätprotokoll från ismätningarna i rännan finns bifogade i rapporten.Tillgänglig statistik visar att antalet negativa graddagar efter isläggningen i Luleå hamn vid en svår isvinter är ca 1000. Våra mätningar tyder på att det under en sådan vinter bildas 2,4 m ren is om ett vändområde används kontinuerligt. Beräkningar med den numeriska modellen resulterade i en möjlig istjocklek på 3 m under en svår vinter om medeltemperaturen är 50% kallare än under den aktuella mätperioden 2012. I nuläget klarar hamnisbrytaren Viscaria att operera och vända fartyg i bruten is motsvarande 1,4 m. Om tjockare is bildas är det väsentligt att ett nytt vändområde med ostörd is kan tas i bruk. Under en svår isvinter krävs därför att minst tre åtskilda vändområden är tillgängliga i Luleå hamn.

sted, utgiver, år, opplag, sider
Luleå: Luleå tekniska universitet, 2013. s. 87
Serie
Forskningsrapport / Luleå tekniska universitet, ISSN 1402-1528
HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-21962 (URN)0edacec7-baba-4f82-bd72-c30e8b7292ac (Lokal ID)978-91-7439-815-1 (ISBN)978-91-7439-816-8 (ISBN)0edacec7-baba-4f82-bd72-c30e8b7292ac (Arkivnummer)0edacec7-baba-4f82-bd72-c30e8b7292ac (OAI)
Merknad
Godkänd; 2013; 20131127 (frans)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-05-29bibliografisk kontrollert
Bonath, V., Patil, A., Fransson, L. & Sand, B. (2013). Laboratory testing of compressive and tensile strength on level ice and ridged ice from Svalbard region (ed.). In: (Ed.), (Ed.), Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions: . Paper presented at International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013.
Åpne denne publikasjonen i ny fane eller vindu >>Laboratory testing of compressive and tensile strength on level ice and ridged ice from Svalbard region
2013 (engelsk)Inngår i: Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions, 2013Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Compression and tensile strength properties are important input data for constitutive modelling. Still strength properties of ridged ice are not yet sufficiently investigated. During winter 2011 and 2012 field trips were performed to the Svalbard region with the aim to investigate structure and strength of pressure ridges. Core samples from different ridges and the surrounding level ice were taken and transported to the laboratory at Luleå University of Technology. Studies on thin sections of the ice samples under cross-polarized light delivered information about internal structure of the ice. Uniaxial compressive and tensile strength tests were performed with horizontal and vertical loading directions. The experimental procedure is explained in detail. Salinity and porosity were measured for each sample. In this paper the mechanical properties obtained from the testing are documented by consideration of crystal type, ice depth and total porosity.

HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-29439 (URN)2eb9a1dc-f790-43ca-8acf-d23a5ef7be97 (Lokal ID)2eb9a1dc-f790-43ca-8acf-d23a5ef7be97 (Arkivnummer)2eb9a1dc-f790-43ca-8acf-d23a5ef7be97 (OAI)
Konferanse
International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013
Merknad
Godkänd; 2013; 20131201 (anipat)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2018-05-29bibliografisk kontrollert
Patil, A., Sand, B. & Fransson, L. (2013). Numerical simulations of shear properties of ice rubble: a shear box experiment (ed.). In: (Ed.), (Ed.), Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions: June 9-13, 2013 Espoo, Finland. Paper presented at International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013.
Åpne denne publikasjonen i ny fane eller vindu >>Numerical simulations of shear properties of ice rubble: a shear box experiment
2013 (engelsk)Inngår i: Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions: June 9-13, 2013 Espoo, Finland, 2013Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Ice rubble has highly nonlinear behavior and thus simulate shear properties requires sophisticated constitutive models including a relatively large number of parameters and complicated calibration procedures. An attempt has been made to simulate shear properties of ice rubble. A shear box experiment is chosen from test series performed by Fransson and Sandkvist (1985). In this paper a shear box test is simulated with nonlinear finite element code LS-Dyna. A newly implemented material model in LS-Dyna called continuous surface cap model (CSCM) has been used in this simulation. This model is proposed by Schwer and Murray (1994). For the sake of simplicity, experimental results are compared with Mohr-Coulomb material model. A brief overview of continuous surface cap model is given. Finally, comparisons with experimental results have been made.

HSV kategori
Forskningsprogram
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-28611 (URN)27758cbf-ce21-4167-aec6-51f01195ec33 (Lokal ID)27758cbf-ce21-4167-aec6-51f01195ec33 (Arkivnummer)27758cbf-ce21-4167-aec6-51f01195ec33 (OAI)
Konferanse
International Conference on Port and Ocean Engineering under Arctic Conditions : 09/06/2013 - 13/06/2013
Merknad
Godkänd; 2013; 20131126 (anipat)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Organisasjoner