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  • 1.
    Amouzgar, Kaveh
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Cenanovic, Mirza
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Multi-objective optimization of material model parameters of an adhesive layer by using SPEA22015Inngår i: Advances in structural and multidisciplinary optimization: Proceedings of the 11th World Congress of Structural and Multidisciplinary Optimization (WCSMO-11) / [ed] Qing Li, Grant P Steven, Zhongpu (Leo) Zhang, The International Society for Structural and Multidisciplinary Optimization (ISSMO) , 2015, s. 249-254Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The usage of multi material structures in industry, especially in the automotive industry are increasing. To overcome the difficulties in joining these structures, adhesives have several benefits over traditional joining methods. Therefore, accurate simulations of the entire process of fracture including the adhesive layer is crucial. In this paper, material parameters of a previously developed meso mechanical finite element (FE) model of a thin adhesive layer are optimized using the Strength Pareto Evolutionary Algorithm (SPEA2). Objective functions are defined as the error between experimental data and simulation data. The experimental data is provided by previously performed experiments where an adhesive layer was loaded in monotonically increasing peel and shear. Two objective functions are dependent on 9 model parameters (decision variables) in total and are evaluated by running two FEsimulations, one is loading the adhesive layer in peel and the other in shear. The original study converted the two objective functions into one function that resulted in one optimal solution. In this study, however, a Pareto frontis obtained by employing the SPEA2 algorithm. Thus, more insight into the material model, objective functions, optimal solutions and decision space is acquired using the Pareto front. We compare the results and show good agreement with the experimental data.

  • 2. Andersson, Tobias
    et al.
    Salomonsson, Kent
    Meso-Mechanical Modelling Of Thin Adhesive Layers2004Inngår i: ECF15, Stockolm 2004 / [ed] T Svensson, P Johannesson, J de Maré, 2004Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A meso-mechanical finite element model for a thin adhesive layer is developed. The model is calibrated to experimental results where the adhesive layer is loaded in monotonically increasing peel or shear, cf. Andersson and Stigh [1] and Alfredsson et al. [2], and to an in situ SEM study of the fracture process. The purpose of the meso-mechanical finite element model is to facilitate the development of constitutive laws for adhesive layers. Ideas developed by Needleman [3], where structural continuum elements are bonded by cohesive elements are used as a basis for the finite element mesh. This thus enables micro cracks to propagate along the finite element boundaries. The simulations are found to be in good agreement with the experiments. The model is also capable of reproducing realistically the deformation observed in both peel [1] and shear [2] experiments.

  • 3.
    Belov, Ilja
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Nordh, Andreas
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Leisner, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Fin‐Tube and Plate Heat Exchangers: Evaluation of Transient Performance2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A methodology for evaluation of transient performance of, and comparison between plate heat exchanger and plate-fin-and-tube heat exchanger was developed and realized, including experiment and 3-D simulation. Heat transfer from water to a gas medium was addressed. The heated gas volume was the same for both heat exchanger designs. This was achieved by placing the plate-fin-and-tube heat exchanger into enclosure. The volume average temperature of the gas as function of time was computed. Estimated material cost for the studied designs was at least seven times lower than for the stainless steel plate heat exchanger. The performance of the selected plate-fin-and-tube heat exchanger design was found comparable to the plate heat exchanger, when both fin and tube materials were set to Al, and the enclosure was a light-weight thermal insulator. Transient behavior of the studied heat exchangers should be of interest for micro-grid applications, but also for thermal management in electronic cabinets and data centers.

  • 4.
    Ghasemi, Rohollah
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Elmquist, Lennart
    Swerea SWECAST, Jönköping, Sweden.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Abrasion resistance of lamellar graphite iron: Interaction between microstructure and abrasive particles2018Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 120, s. 465-475Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study focuses on abrasion resistance of Lamellar Graphite Iron (LGI) using microscratch test under constant and progressive load conditions. The interactions between a semi-spherical abrasive particle, cast iron matrix and graphite lamellas were physically simulated using a sphero-conical indenter. The produced scratches were analysed using LOM and SEM to scrutinise the effect of normal load on resulting scratch depth, width, frictional force, friction coefficient and deformation mechanism of matrix during scratching. Results showed a significant matrix deformation, and change both in frictional force and friction coefficient by increase of scratch load. Furthermore, it was shown how abrasive particles might produce deep scratches with severe matrix deformation which could result in graphite lamella's coverage and thereby deteriorate LGI's abrasion resistance.

  • 5.
    Hansbo, Peter
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering. Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Rashid, Asim
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Least-squares stabilized augmented Lagrangian multiplier method for elastic contact2016Inngår i: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 116, s. 32-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we propose a stabilized augmented Lagrange multiplier method for the finite element solution of small deformation elastic contact problems. We limit ourselves to friction-free contact with a rigid obstacle, but the formulation is readily extendable to more complex situations.

  • 6.
    Hansbo, Peter
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    A discontinuous Galerkin method for cohesive zone modelling2015Inngår i: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 102-103, s. 1-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a discontinuous finite element method for small strain elasticity allowing for cohesive zone modeling. The method yields a seamless transition between the discontinuous Galerkin method and classical cohesive zone modeling. Some relevant numerical examples are presented. 

  • 7. Högberg, Li
    et al.
    Salomonsson, Kent
    Simulation of an adhesive layer using a novel mixed mode cohesive law2006Inngår i: CDCM 2006-Conference on Damage in Composite Materials 2006 18th-19th of September 2006 in Stuttgart, Germany: Online-Proceedings, 2006Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The purpose of this work is to develop a flexible cohesive law to simulate the constitutive behaviour of an adhesive layer under mixed mode loading. A mixed mode cohesive law that captures the linear elastic and softening behaviour before fracture is presented. This simple model uses a coupled formulation to describe the mixed mode cohesive behaviour. It also allows for different fracture parameters, such as fracture energy, strength and critical separation in different mode mixities. Thus, the fracture process in mode I (peel), in mode II (shear) or in mixed mode (a combination of peel and shear) can be modelled without the usual constraint of a common fracture energy in peel and shear. Examples are given of FE-implementation of the normalised cohesive law, namely for the Unsymmetric Double Cantilever Beam (UDCB) specimen and the Mixed-mode double Cantilever Beam (MCB) specimen. Both specimens are adhesively bonded and loaded in mixed-mode.

  • 8.
    Jansson, Johan
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Gustafsson, T.
    Högskolan i Jönköping, Tekniska Högskolan.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Olofsson, Jakob
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Johansson, Joel
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Appelsved, P.
    Kongsberg Automotive AB, Mullsjö, Sweden.
    Palm, M.
    Husqvarna AB, Huskvarna, Sweden.
    An anisotropic non-linear material model for glass fibre reinforced plastics2018Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 195, s. 93-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper aims to present a methodology to predict the anisotropic and non-linear behaviour of glass fibre reinforced plastics using finite element methods. A material model is implemented in order to remedy the need of multiple material definitions, and to control the local plastic behaviour as a function of the fibre orientation. Injection moulding simulations traditionally provide second order orientation tensors, which are considered together with a homogenization scheme to compute local material properties. However, in the present study, fourth order tensors are used in combination with traditional methods to provide more accurate material properties. The elastic and plastic response of the material model is optimized to fit experimental test data, until simulations and experiments overlap. The proposed material model can support design engineers in making more informed decisions, allowing them to create smarter products without the need of excessive safety factors, leading to reduced component weight and environmental impact. 

  • 9.
    Jansson, Johan
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Olofsson, Jakob
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    On the use of heterogeneous thermomechanical and thermophysical material properties in finite element analyses of cast components2019Inngår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics (IOP), 2019, Vol. 529, nr 1, artikkel-id 012076Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cast components generally show a heterogeneous distribution of material properties, caused by variations in the microstructure that forms during solidification. Variations caused by the casting process are not commonly considered in structural analyses, which might result in manufacturing of sub-optimised components with unexpected in-use behaviour. In this paper, we present a methodology which can be used to consider both thermomechanical and thermophysical variations using finite element analyses in cast components. The methodology is based on process simulations including microstructure modelling and correlations between microstructural features and material properties. Local material data are generated from the process simulation results, which are integrated into subsequent structural analyses. In order to demonstrate the methodology, it is applied to a cast iron cylinder head. The heterogeneous distribution of material properties in this component is investigated using experimental methods, demonstrating local variations in both mechanical and physical behaviour. In addition, the strength-differential effect on tensile and compressive behaviour of cast iron is considered in the modelling. The integrated simulation methodology presented in this work is relevant to both design engineers, production engineers as well as material scientists, in order to study and better understand how local variations in microstructure might influence the performance and behaviour of cast components under in-use conditions. 

  • 10.
    Kasvayee, Keivan Amiri
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Jarfors, Anders E. W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Microstructural strain distribution in ductile iron; Comparison between finite element simulation and digital image correlation measurements2015Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper presents a study on micro-scale deformation and the effect of microstructure on localised deformation of ductile iron, utilizing in-situ tension testing, digital image correlation (DIC) and finite element analysis (FEA). A tensile stage integrated with an optical microscope was used to acquire a series of micrographs during the tensile test. Applying DIC and an etched speckle pattern, a high resolution local strain field was measured in the microstructure. In addition, a finite element (FE) model was used to predict the strain maps. The materials parameters were optimized based on Ramberg-Osgood model. The DIC and simulation strain maps conformed to a large extent resulting in the verification of the model in micro-scale level. It was found that the Ramberg-Osgood theory can be used to capture the main trends of strain localization. The discrepancies between the simulated and DIC results were explained based on microstructure dimensionality, differences in spatial resolution and uncertainty in the FE-model.

  • 11.
    Kasvayee, Keivan Amiri
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Jarfors, Anders E. W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Microstructural strain localization and crack evolution in ductile iron2015Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper focuses on the deformation and crack evolution in ductile iron under tension, investigated by coupled in-situ tensile test and finite element simulation. Micro-crack initiation and development were tracked at the microstructure level. The local strain around micro-cracks were measured by using Digital Image Correlation (DIC). The results obtained from the experiments were compared to a finite element  model including cohesive elements to enable crack propagation. The resulting local strains were analyzed in connection to the observed micro-crack incidents in both DIC and simulation. The predictions of the finite element model showed good agreement with those obtained from the experiment, in the case of early decohesion, the amplitude of the strain localization and macroscopic stress-strain behavior. The results revealed that decohesion was commonly initiated early around graphite surrounded by ferrite which was identified as high strain regions. By increasing the global deformation, micro-cracks initiated in these areas and propagated but were arrested within the ferrite zone due to strain hardening and stress shielding of pearlite. Both the DIC and the simulation revealed that irregular shaped graphite were more susceptible to strain localization and micro-crack initiation. It could be observed that the cohesive model was able to capture the main trends of localized plastic deformation and crack initiation

  • 12.
    Kasvayee, Keivan Amiri
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Sujakhu, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Castagne, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Strain localization and crack formation effects on stress-strain response of ductile iron2017Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 702, s. 265-271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The strain localization and crack formation in ferritic-pearlitic ductile iron under tension was investigated by in-situ tensile tests. In-situ tensile tests under optical microscope were performed and the onset of the early ferrite-graphite decohesions and micro-cracks inside the matrix were studied. The results revealed that early ferrite-graphite decohesion and micro-cracks inside the ferrite were formed at the stress range of 280–330 MPa, where a kink occurred in the stress-strain response, suggesting the dissipation of energy in both plastic deformation and crack initiation. Some micro-cracks initiated and propagated inside the ferrite but were arrested within the ferrite zone before propagating in the pearlite. Digital Image Correlation (DIC) was used to measure local strains in the deformed micrographs obtained from the in-situ tensile test. Higher strain localization in the microstructure was measured for the areas in which the early ferrite-graphite decohesions occurred or the micro-cracks initiated.

  • 13.
    Kasvayee, Keivan Amiri
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Sujakhu, Surendra
    Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore.
    Castagne, Sylvie
    KU Leuven, Department of Mechanical Engineering, Leuven, Belgium.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Microstructural strain mapping during in-situ cyclic testing of ductile iron2018Inngår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 140, s. 333-339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on local strain distribution in the microstructure of high silicon ductile iron during cyclic loading. In-situ cyclic test was performed on compact-tension (CT) samples inside the scanning electron microscope (SEM) to record the whole deformation and obtain micrographs for microstructural strain measurement by means of digital image correlation (DIC) technique. Focused ion beam (FIB) milling was used to generate speckle patterns necessary for DIC measurement. The equivalent Von Mises strain distribution was measured in the microstructure at the maximum applied load. The results revealed a heterogeneous strain distribution at the microstructural level with higher strain gradients close to the notch of the CT sample and accumulated strain bands between graphite particles. Local strain ahead of the early initiated micro-cracks was quantitatively measured, showing high strain localization, which decreased by moving away from the micro-crack tip. It could be observed that the peak of strain in the field of view was not necessarily located ahead of the micro-cracks tip which could be because of the (i) strain relaxation due to the presence of other micro-cracks and/or (ii) presence of subsurface microstructural features such as graphite particles that influenced the strain concentration on the surface.

    Fulltekst tilgjengelig fra 2020-04-12 00:00
  • 14.
    Kasvayee, Keivan Amiri
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Microstructural strain distribution in ductile iron: Comparison between finite element simulation and digital image correlation measurements2016Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 655, s. 27-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a study on microstructural deformation of a ferritic–pearlitic ductile iron, utilizing in-situ tensile testing, digital image correlation (DIC) and finite element analysis (FEA). For this purpose, the in-situ tensile test and DIC were used to measure local strain fields in the deformed microstructure. Furthermore, a continuum finite element (FE) model was used to predict the strain maps in the microstructure. Ferrite and pearlite parameters for the FE-model were optimized based on the Ramberg–Osgood relation. The DIC and simulation strain maps were compared qualitatively and quantitatively. Similar strain patterns containing shear bands in identical locations were observed in both strain maps. The average and localized strain values of the DIC and simulation conformed to a large extent. It was found that the Ramberg–Osgood model can be used to capture the main trends of strain localization. The discrepancies between the simulated and DIC results were explained based on the; (i) subsurface effect of the microstructure; (ii) differences in the strain spatial resolutions of the DIC and simulation and (iii) abrupt changes in strain prediction of the continuum FE-model in the interface of the phases due to the sudden changes in the elastic modulus.

  • 15.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Cenni, Riccardo
    Imola, Italy.
    Cova, Matteo
    Imola, Italy.
    Bertuzzi, Giacomo
    Imola, Italy.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Johansson, Joel
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Multidisciplinary shape optimization of ductile iron castings by considering local microstructure and material behaviour2018Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 57, nr 5, s. 1889-1903Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the casting process and solidification of ductile iron castings, a heterogeneous microstructure is formed throughout the casting. This distribution is strongly influenced by the item geometry and the process related factors, as chemical composition and local solidification conditions. Geometrical changes to the geometry of the casting thus alters the local mechanical behavior and properties, as well as the distribution of stresses and strains when the casting is subjected to load. In order to find an optimal geometry, e.g. with reduced weight and increased load-bearing capacity, this interdependency between geometry and local material behavior needs to be considered and integrated into the optimization method. In this contribution, recent developments in the multidisciplinary integration of casting process simulation, solidification and microstructure modelling, microstructure-based material characterization, finite element structural analyses with local material behavior and structural optimization techniques are presented and discussed. The effect and relevance of considering the local material behavior in shape optimization of ductile iron castings is discussed and evidenced by an industrial application. It is shown that by adopting a multidisciplinary optimization approach by integration of casting simulation and local material behavior into shape optimization, the potential of the casting process to obtain components with high performance and reliability can be enabled and utilized. 

  • 16.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Cenni, Riccardo
    Università degli Studi di Modena e Reggio Emilia, Italy.
    Cova, Matteo
    Università degli Studi di Modena e Reggio Emilia, Italy.
    Bertuzzi, Giacomo
    Zanardi Fonderie, Italy.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Johansson, Joel
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Datorstödd konstruktion.
    Multidisciplinary shape optimization of ductile iron castings byconsidering local microstructure and material behaviour2017Inngår i: WCSMO12, 12th World Congress of Structural and Multidisciplinary Optimisation: Book of Abstracts / [ed] Kai-Uwe Bletzinger, Sierk Fiebig, Kurt Maute, Axel Schumacher, Thomas Vietor, Technische Universität , 2017, s. 82-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the casting process and solidification of ductile iron castings, a heterogeneous microstructure is formed throughout the casting. This distribution is highly controlled by process related factors, as chemical composition, local solidification conditions, and the geometry of the casting. Geometrical changes to the geometry of the casting thus alters the local mechanical behaviour, as well as the distribution of stresses and strains when the casting is subjected to load. In order to find an optimal geometry, e.g. with reduced weight and increased load-bearing capacity, this interdependency between geometry and local material behaviour needs to be considered and integrated into the optimization method. In this contribution, recent developments in the multidisciplinary integration of casting process simulation, solidification and microstructure modelling, microstructure-based material characterization, Finite Element Analyses (FEA) with local material behaviour and structural optimization techniques are presented and discussed. The effect and relevance of considering the local material behaviour in shape optimization of ductile iron castings is discussed and evidenced by an industrial application. It is shown that by adopting a multidisciplinary optimization approach by integration of casting simulation and local material behaviour into shape optimization, the potential of the casting process to obtain components with high performance and reliability can be enabled and utilized.

  • 17.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Dahle, Arne
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Mathiesen, Ragnvald H.
    Department of Physics, Faculty of Natural Sciences, Norwegian University of Science and Technology, NTNU, Trondheim, Norway.
    Three-dimensional study of nodule clustering and heterogeneous strain localization for tailored material properties in ductile iron2019Inngår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics (IOP), 2019, Vol. 529, nr 1, artikkel-id 012078Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Tailored heterogeneous distributions of microstructural features enable extraordinary material performance in biological and physiological structures such as trees, the aortic arch, human teeth and dinosaur skulls. In ductile iron, a heterogeneous distribution in size and morphology of graphite nodules and variations of the fractions of ferrite and pearlite are created during solidification, and varies as a function of parameters such as local cooling rate, segregation and flow. In the current work, the size distribution as well as the orientation and relation between graphite nodules is obtained by a three-dimensional reconstruction of a ductile iron microstructure from X-ray tomography. The effect of the nodule morphology and clustering on the localization of plastic strains is studied numerically using finite element analysis of the reconstructed microstructure. Real castings have a variation in geometry, solidification conditions and are subjected to variations in loads. A framework for optimized geometry and solidification conditions in order to design and deliver castings with tailored local material performance is proposed.

  • 18.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Johansson, Joel
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Datorstödd konstruktion.
    Amouzgar, Kaveh
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering. University of Skövde, Sweden.
    A methodology for microstructure-based structural optimization of cast and injection moulded parts using knowledge-based design automation2017Inngår i: Advances in Engineering Software, ISSN 0965-9978, E-ISSN 1873-5339, Vol. 109, s. 44-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The local material behaviour of cast metal and injection moulded parts is highly related to the geometrical design of the part as well as to a large number of process parameters. In order to use structural optimization methods to find the geometry that gives the best possible performance, both the geometry and the effect of the production process on the local material behaviour thus has to be considered.

    In this work, a multidisciplinary methodology to consider local microstructure-based material behaviour in optimizations of the design of engineering structures is presented. By adopting a knowledge-based industrial product realisation perspective combined with a previously presented simulation strategy for microstructure-based material behaviour in Finite Element Analyses (FEA), the methodology integrates Computer Aided Design (CAD), casting and injection moulding simulations, FEA, design automation and a multi-objective optimization scheme into a novel structural optimization method for cast metal and injection moulded polymeric parts. The different concepts and modules in the methodology are described, their implementation into a prototype software is outlined, and the application and relevance of the methodology is discussed.

  • 19.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Svensson, Ingvar L.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Modelling and simulations of ductile iron solidification-induced variations in mechanical behaviour on component and microstructural level2015Inngår i: IOP Conference Series: Materials Science and Engineering, Volume 84: MCWASP XIV: International Conference on Modeling of Casting, Welding and Advanced Solidification Processes / [ed] Hideyuki Yasuda, Kyoto University, Japan, London: Institute of Physics Publishing (IOPP), 2015, Vol. 84, s. 1-8Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

  • 20.
    Olofsson, Jakob
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Svensson, Ingvar L.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    The multi-scale closed chain of simulations – incorporating local variations in microstructure into finite element simulations2015Inngår i: TMS 2015 144th Annual Meeting & Exhibition: Supplemental Proceedings, Springer, 2015, s. 1057-1064Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Numerical simulations of component behavior and performance is critical to develop optimized and robust load-bearing components. The reliability of these simulations depend on the description of the components material behavior, which for e.g. cast and polymeric materials exhibit component specific local variations depending on geometry and manufacturing parameters. Here an extension of a previously presented strategy, the closed chain of simulations for cast components, to predict and incorporate local material data into Finite Element Method (FEM) simulations on multiple scales is shown. Manufacturing process simulation, solidification modelling, material characterization and representative volume elements (RVE) provides the basis for a microstructure-based FEM analysis of component behavior and a simulation of the mechanical behavior of the local microstructure in a critical region. It is discussed that the strategy is applicable not only to cast materials but also to injection molded polymeric materials, and enables a common integrated computational microstructure-based approach to optimized components.

  • 21.
    Pesämaa, Ossi
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Centre for Innovation Systems, Entrepreneurship and Growth. Högskolan i Jönköping, Internationella Handelshögskolan, IHH, EMM (Entreprenörskap, Marknadsföring, Management).
    Abbasian, Saeid
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Centre for Innovation Systems, Entrepreneurship and Growth.
    Rylander, David
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Centre for Innovation Systems, Entrepreneurship and Growth. Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Nationalekonomi.
    Salomonsson, Kent
    Attitudes to change in Gnosjöregion2009Inngår i: Presented at The international Symposium on Entrepreneurship in Tourism, Rovaniemi, Finland, March 17-21, 2009, 2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This study promotes ideas into two main academic areas, that is attitudes towards change processes and regional development.  The implications of the study are written to tourism in the Gnosjöregion and other countryside areas. We specifically ask what attitudes towards change processes in development projects in tourism generate commitments to tourism and to what extent these effects are moderated by perceived involvement. Our objective is to develop more knowledge to the area of attitudes within project management. The results of the study engender from a pre-study from 59 responses of a survey distributed during spring 2008 in the Gnosjöregion. Our major implication is that future study may consider freedom rather than interest towards working in change processes and that these effects are also moderated when individuals perceive an enhanced involvement. Our study is a first attempt to develop these two areas and results should therefore be read and interpreted with the same carefulness as any pre-study is prepared and conducted.

  • 22.
    Salomonsson, Kent
    Högskolan i Skövde, Institutionen för teknik och samhälle.
    Meso-Mechanical Modeling and Analysis of Adhesive Layers2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is concerned with the modeling, simulation and analysis of adhesive layers. By use of an in situ scanning electron microscopy study it is found that the adhesive studied in the present thesis has a very complex structure with two different compounds, a mineral and an epoxy/thermoplastic blend. A representative volume element (RVE) model is developed to study the behavior of the adhesive layer at the meso-level. It is a continuum model where interface finite elements are implemented at the boundaries of the continuum elements in order to enable crack initiation and propagation of micro cracks. On a structural level, two deformation modes, modes I and II, dominate the behavior of thin adhesive layers. With the RVE it is possible reproduce experimental stress-deformation relations from both modes. However, in a real structure, mixed mode loading usually occur. A range of mode mixes is studied, using the RVE, from an un-loaded state until fracture of the layer. The results indicate that the behavior of the interface elements dominate for mode mixes close to mode I and plasticity in the continuum elements dominates for mode II dominated mode mixes. Furthermore, effects of large root curvatures of the adherends is analyzed numerically by simulating plastically deforming double cantilever beam specimens using the finite element model. The developed RVE is implemented in the models to simulate the behavior of the adhesive layer. By this methodology, virtual experiments can be analyzed with extreme detail. It is shown that in-plane straining of the adhesive layer significantly influences the strength of adhesive joints at large plastic strain of the adherends. There is a never ending need in industries to minimize computational time. To this end, an interphase finite element for structural analyses is developed. The element considers in-plane straining of the adhesive layer due to large curvatures of surrounding substrates.

  • 23. Salomonsson, Kent
    Mixed mode modeling of a thin adhesive layer using a meso-mechanical model2008Inngår i: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 40, nr 8, s. 665-672Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A representative volume element is modeled using the finite element method. It is used to analyze mixed mode behavior of a thin adhesive layer. Two sources of dissipation is modeled; plasticity and decohesion. Macroscopic traction–separation laws are extracted from the simulations. The results indicate that a boundary of mode mix exists between a region where major plastic dissipation is present and a region where it is not. Without major plastic dissipation, the fracture energy is low and essentially governed by the cohesive properties. This is the case in peel dominated loading cases. In shear dominated loading cases plastic dissipation gives a substantial contribution to the fracture energy. The results show that pure shear loading gives the largest fracture energy.

  • 24. Salomonsson, Kent
    et al.
    Andersson, Tobias
    Högskolan i Skövde.
    Modeling and parameter calibration of an adhesive layer at the meso level2008Inngår i: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 40, nr 1, s. 48-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mesomechanical finite element model of a thin adhesive layer is developed. The model is calibrated to previously performed experiments. In these, the adhesive layer is loaded in monotonically increasing peel or shear. An in situ SEM study is also performed and used to guide the modeling and calibration. The purpose of the mesomechanical finite element model is to facilitate the development of constitutive laws for adhesive layers. The modeling is based on Xu and Needleman’s method where all continuum finite elements are surrounded by interface elements that allow for the development of micro cracks. Thus, this enables the modeling of the entire process of degradation and fracture of the adhesive layer. A genetic algorithm is developed for the calibration. The simulations show good agreement with the experiments.

  • 25. Salomonsson, Kent
    et al.
    Andersson, Tobias
    Simulation of crack initiation and propagation in an adhesive layer using a meso-mechanical model2006Inngår i: Proc. of 27th Risø International Symposium on Materials Science, Polymer Composite Materials for Wind Power Turbines, 2006Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A finite element model of a double cantilever beam specimen is developed. The adherends are modeled using plane strain elastic continuum elements. Furthermore, the adhesive is modeled using a mesomechanical modeling technique which allows for simulation of initiation and propagation of micro-cracks. This enables the modeling of the entire process of degradation and fracture of the adhesive layer. The purpose of the present study is to compare the stress-deformation behavior in an idealized peel loading to the behavior in a double cantilever beam (DCB) specimen where the adhesive layer is deformed wilt a slight gradient along the layer. Previously performed experiments and simulations of the RVE are used as a comparison to the simulated results.

  • 26. Salomonsson, Kent
    et al.
    Andersson, Tobias
    Weighted Potential Methodology for Mixed Mode Cohesive Laws2010Inngår i: Proceedings of the MECOM DEL BICENTENARIO, IX Argentinian Congress on Computational Mechanics / [ed] Asociación Argentina de Mecánica Comptacional, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A  weighted  potential  methodology  is  developed  by  utilizing  pure  mode  I  and mode  II  energy  release  rate  experiments  to  determine  the  traction-separation  relations  for thin  adhesive  layers.  The  experimentally  measured  energy  release  rates  act  as  boundary conditions  for  developing  a  weighted  potential  function.  Thus,  the  tractions  for  any  mixed mode loading can be established.  Changes of mode mix during an experiment can also be captured  by  the  law  since  every  mixed  mode  variation  is  given  by  the  potential  function. Furthermore,  by  use  of  an  inverse  J-integral  approach  and  damage  type  variables,  the traction-separation  relations  for  any  mode  mix  can  be  approximated  by  use  of  pure  mode experiments.  Numerical  simulations  show  the  applicability  of  the  methodology.  The  results indicate  that  the  methodology  is  promising  when  simulating  the  constitutive  behavior  of adhesive layers.

  • 27.
    Salomonsson, Kent
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Three-dimensional microstructural characterization of cast iron alloys for numerical analyses2018Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, s. 427-435Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models.

  • 28.
    Salomonsson, Kent
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Olofsson, Jakob
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Analysis of Localized Plastic Strain in Heterogeneous Cast Iron Microstructures Using 3D Finite Element Simulations2017Inngår i: Proceedings of the 4th World Congress on Integrated Computational Materials Engineering, ICME 2017 / [ed] Paul Mason, Charles R Fisher, Ryan Glamm, Michele V Manuel, Georg J Schmitz, Amarendra K Singh, Alejandro Strachan, Cham: Springer, 2017, s. 217-225Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The design and production of light structures in cast iron with high static and fatigue performance is of major interest in e.g. the automotive area. Since the casting process inevitably leads to heterogeneous solidification conditions and variations in microstructural features and material properties, the effects on multiple scale levels needs to be considered in the determination of the local fatigue performance. In the current work, microstructural features of different cast irons are captured by use of micro X-ray tomography, and 3D finite element models generated. The details of the 3D microstructure differ from the commonly used 2D representations in that the actual geometry is captured and that there is not a need to compensate for 3D-effects. The first objective with the present study is to try and highlight certain aspects at the micro scale that might be the underlying cause of fatigue crack initiation, and ultimately crack propagation, under fatigue loading for cast iron alloys. The second objective is to incorporate the gained knowledge about the microstructural behavior into multi-scale simulations at a structural length scale, including the local damage level obtained in the heterogeneous structure subjected to fatigue load.

  • 29. Salomonsson, Kent
    et al.
    Stigh, Ulf
    An adhesive interphase element for structural analyses2008Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 76, nr 4, s. 482-500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A special purpose finite element is developed for structural simulations of complex adhesively bonded structures. In the interphase element, the adhesive is explicitly regarded as a material phase between two substrates. The element considers large rotations. Furthermore, it considers in-plane straining of the adhesive due to large curvatures of the bonded shells. This feature appears especially important when considering bonding of thin plastically deforming metallic shell structures. Simulations are made on specimens where the adherends deform both elastically and plastically. The results are in good agreement with previously performed experiments. 

  • 30. Salomonsson, Kent
    et al.
    Stigh, Ulf
    Influence of root curvature on the fracture energy of adhesive layers2009Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 76, nr 13, s. 2025-2038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previously performed experiments to study the mode I behavior of an adhesive layer revealed an apparent increase in the fracture toughness when the adherends deformed plastically. Attempts to simulate the experiments are made; both with elastically and plastically deforming adherends. Thus, effects of the size of the process zone and the deformation of the adherends are revealed. The adhesive layer is modeled using finite elements with different approaches; cohesive elements and representative volume elements. The adherends are modeled with solid elements. With a long process zone, all models give good results as compared to the experiments. However, only the model with representative volume elements gives good agreement for large root curvatures and correspondingly short process zones. The results are interpreted by analyzing the deformation and mechanisms of crack propagation in the representative volume elements. It is shown that with large root curvature of the adherends, the in-plane stretching of the adhesive layer gives a substantial contribution to the fracture energy. A simple formula is derived and shown to give an accurate prediction of the effects of the root curvature. This result indicates the limits of conventional cohesive zone modeling of an adhesive layer of finite thickness.

  • 31. Salomonsson, Kent
    et al.
    Stigh, Ulf
    On the apparent influence of the adherends on the fracture toughness of adhesive layers2007Inngår i: Proceedings of the 28th Risø international symposium on materials science, 2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A detailed model of experiments with the double cantilever beam specimen is set up. Analysis of the model shows that an experimentally deduced apparent increase of fracture energy with severely deforming adherends is due to contributions of in-plane straining of the adhesive layer to the fracture energy. An analysis with the J-integral confirms the result.

  • 32.
    Salomonsson, Kent
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering. Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Zhao, Xuefang
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Kallin, Sara
    Högskolan i Jönköping, Hälsohögskolan, HHJ, Avd. för rehabilitering. Högskolan i Jönköping, Tekniska Högskolan, JTH, Produktutveckling.
    Analysis of the Internal Mechanical Conditions in the Lower Limb Due to External Loads2016Inngår i: World Academy of Science, Engineering and Technology, International Science Index, International Journal of Medical, Health, Biomedical, Bioengineering and Pharmaceutical Engineering, London, 2016, s. 288-293Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Human soft tissue is loaded and deformed by any activity, an effect known as a stress-strain relationship, and is often described by a load and tissue elongation curve. Several advances have been made in the fields of biology and mechanics of soft human tissue. However, there is limited information available on in vivo tissue mechanical characteristics and behavior. Confident mechanical properties of human soft tissue cannot be extrapolated from e.g. animal testing. Thus, there is need for non invasive methods to analyze mechanical characteristics of soft human tissue. In the present study, the internal mechanical conditions of the lower limb, which is subject to an external load, is studied by use of the finite element method. A detailed finite element model of the lower limb is made possible by use of MRI scans. Skin, fat, bones, fascia and muscles are represented separately and the material properties for them are obtained from literature. Previous studies have been shown to address macroscopic deformation features, e.g. indentation depth, to a large extent. However, the detail in which the internal anatomical features have been modeled does not reveal the critical internal strains that may induce hypoxia and/or eventual tissue damage. The results of the present study reveals that lumped material models, i.e. averaging of the material properties for the different constituents, does not capture regions of critical strains in contrast to more detailed models.

  • 33.
    Stigh, Ulf
    et al.
    Högskolan i Skövde.
    Alfredsson, Svante
    Högskolan i Skövde.
    Andersson, Tobias
    Högskolan i Skövde.
    Biel, Anders
    Högskolan i Skövde.
    Carlberger, Thomas
    Högskolan i Skövde.
    Salomonsson, Kent
    Högskolan i Skövde.
    Some aspects of cohesive models and modelling with special application to strength of adhesive layers2010Inngår i: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 165, nr 2, s. 149-162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An overview of recent development of cohesive modelling is given. Cohesive models are discussed in general and specifically for the modelling of adhesive layers. It is argued that most cohesive models model a material volume and not a surface. Detailed microscopic and mesomechanical studies of the fracture process of an engineering epoxy are discussed. These studies show how plasticity on the mesomechanical length scale contributes to the fracture energy in shear dominated load cases. Methods to measure cohesive laws are presented in a general setting. Conclusions and conjectures based on experimental and mesomechanical studies are presented. The influence of temperature and strain rate on the peak stress and fracture energy of cohesive laws indicates fundamentally different mechanisms responsible for these properties. Experiments and mesomechanical studies show that in-plane straining of an adhesive layer can give large contributions to the registered fracture energy. Finite element formulations including a method to incorporate this influence are discussed.

  • 34.
    Svensson, Ingvar L.
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Salomonsson, Kent
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Mathematical characterization of the tensile deformation curve of cast iron materials2018Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, s. 444-450Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The manufacturing process gives cast iron castings properties which are dependent on component design, metallurgy and casting method. Factors such as local wall thickness influences the coarseness and type of microstructure and the castings will have local properties depending on the local metallurgical and thermal history. The stress/strain behaviour of cast materials is typically determined by performing a tensile test in a tensile test machine. The deformation behaviour will normally be determined by two mechanisms, namely, elastic and plastic phenomena. The plastic behaviour is based on dislocation movements in the lattice. Commonly, the deformation history of cast iron involves elastic, plastic and crack phases. The cast iron material has a complex microstructure and first order equations cannot be used to predict the deformation during loading. Until methods have been developed, the characterization of complex microstructure materials such as cast iron has to be determined by use of empirical methods. The empirical methods have to couple the internal microstructure and composition of the material with deformation phenomena during loading. The paper will show a method to characterize tensile test curves of cast iron materials which can be used to couple deformation phenomena with for example microstructure. The equations are aimed to make the tensile test curve ready for curve fitting and optimization in two steps. Each stress/strain curve is like a finger print of the material and requires well performed tests and some advices are given. The paper also wants to encourage researchers and people working with tensile testing to get out more of their effort to measure strength of cast iron materials and connect the result to the microstructure of the specimens. 

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