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  • 1. Christensen, XP.W
    et al.
    Klarbring, A
    Pang, J.S.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Formulation and comparison of algorithms for frictional contact problems1998Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 42, nr 1, s. 145-173Artikkel i tidsskrift (Fagfellevurdert)
  • 2. Gustafsson, E
    et al.
    Hofwing, Magnus
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Simulation and Measurement of Residual Stresses in a Stress Lattice2007Inngår i: Proceedings of the the 2nd International Conference of Simulation and Modelling of Metallurgical Processes in Steelmaking, September 12-14, Austria, 2007, Leoben: ASMET , 2007, s. 285-290Konferansepaper (Fagfellevurdert)
  • 3. Gustafsson, E
    et al.
    Hofwing, Magnus
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Simulering och mätning av restspänningar i spänningsharpor2007Inngår i: Luleå tekniska universitet, Svenska Mekanikdagar, 13-15 juni, 2007, 2007Konferansepaper (Annet vitenskapelig)
  • 4. Gustafsson, E
    et al.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Shape optimization of castings by using successive response surface methodology2008Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 35, nr 1, s. 11-28Artikkel i tidsskrift (Fagfellevurdert)
  • 5. Gustafsson, E
    et al.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Structural optimization of castings by using ABAQUS and Matlab2005Inngår i: Proceedings of the Seminar on Competent Design by Castings (GJUTDESIGN -2005), June 13-14, Espoo, FINLAND,, 2005Konferansepaper (Fagfellevurdert)
  • 6. Gustafsson, E.
    et al.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Structural optimization of castings by using Abaqus and Matlab2005Inngår i: Proceedings of the Abaqus World Users' Conference, May 18-20, Stockholm, Sweden, 2005., 2005Konferansepaper (Fagfellevurdert)
  • 7.
    Gustafsson, E
    et al.
    Högskolan i Jönköping.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strukturoptimering av gjutgods med hänsyn tagen till gjutspänningar2007Inngår i: Luleå tekniska universitet, Svenska Mekanikdagar, 13-15 juni, 2007, 2007Konferansepaper (Annet vitenskapelig)
  • 8. Gustafsson, E
    et al.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Successive Response Surface Methodology by using Neural Networks2007Inngår i: Proceedings of the 7th World Congress on Structural and Multidisciplinary Optimization, May 21-25, Seoul, Korea, 2007Konferansepaper (Fagfellevurdert)
  • 9.
    Gustafsson, Erik
    et al.
    Väderstad-Verken AB.
    Hofwing, Magnus
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Residual stresses in a stress lattice - experiments and finite element simulations2009Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 209, nr 9, s. 4320-4328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work residual stresses in a stress lattice are studied. The residual stresses are both measured and simulated. The stress lattice is casted of low alloyed grey cast iron. In fact, nine similar lattices are casted and measured. The geometry of the lattice consists of three sections in parallel. The diameter of the two outer sections are thinner than the section in the middle. When the stress lattice cools down, this difference in geometry yields that the outer sections start to solidify and contract before the section in the middle. Finally, an equilibrium state, with tensile stresses in the middle and compressive stresses in the outer sections, is reached. The thermo-mechanical simulation of the experiments is performed by using Abaqus. The thermo-mechanical solidification is assumed to be uncoupled. First a thermal analysis, where the lattice is cooled down to room temperature, is performed. Latent heat is included in the analysis by letting the fraction of solid be a linear function of the temperature in the mushy zone. After the thermal analysis a quasi-static mechanical analysis is performed where the temperature history is considered to be the external force. A rate independent J2-plasticity model with isotropic hardening is considered, where the material data depend on the temperature. Tensile tests are performed at room temperature, 200°C, 400°C, 600°C and 800°C in order to evaluate the Young´s modulus, the yield strength and the hardening accurate. In addition, the thermal expansion coefficient is evaluated for temperatures between room temperature and 1000°C. The state of residual stresses is measured by cutting the mid section or the outer section. The corresponding elastic spring-back reveals the state of residual stresses. The measured stresses are compared to the numerical simulations. The simulations show good agreement with the results from the experiments.

  • 10.
    Hofwing, Magnus
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    D-optimality of non-regular design spaces by using a Bayesian modification and a hybrid method2010Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 42, nr 1, s. 73-88Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work a hybrid method of a genetic algorithm  and sequential linear programming is suggested to obtain a D-optimal design of experiments. Regular as well as non-regular design spaces are considered. A D-optimal design of experiments maximizes the determinant of the information matrix, which appears in the normal equation. It is known that D-optimal design of experiments sometimes include duplicate design points. This is, of course, not preferable since duplicates do not add any new information to the response surface approximation and the computational effort is therefore wasted. In this work a Bayesian modification, where higher order terms are added to the response surface approximation, is used in case of duplicates in the design of experiments. In such manner, the draw-back with duplicates might be eliminated. The D-optimal problem, which is obtained by using the Bayesian modification, is then solved by a hybrid method. A hybrid method of a genetic algorithm that generates a starting point for sequential linear programming is developed. The genetic algorithm performs genetic operators such as cross-over and mutation on a binary version of the design of experiments, while the real valued version is used to evaluate the fitness. Next, by taking the gradient of the objective, a LP-problem is formulated which is solved by an interior point method that is available in Matlab. This is repeated in a sequence until convergence is reached. The hybrid method is tested for four numerical examples. Results from the numerical examples show a very robust convergence to a global optimum. Furthermore, the results show that the problem with duplicates is eliminated by using the Bayesian modification.

  • 11.
    Hofwing, Magnus
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    D-optimality of non-regular design spaces by using a Genetic Algorithm2009Inngår i: proceedings of the 8th World Congress on Structural and Multidisciplinary Optimization, June 1-5, Lisbon, Portugal, 2009, 2009Konferansepaper (Fagfellevurdert)
  • 12.
    Hofwing, Magnus
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Robustness of residual stresses in castings and an improved process window2009Inngår i: proceedings of the 35th Design Automation Conference, August 30-September 2, San Diego, USA 2009., 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work the robustness of residual stresses in finite element simulations with respect to deviations in mechanical parameters in castings is evaluated. Young's modulus, the thermal expansion coefficient and the hardening are the studied parameters. A 2D finite element model of a stress lattice is used. The robustness is evaluated by comparing purely finite element based Monte Carlo simulations and Monte Carlo simulations based on linear and quadratic response surfaces. Young's modulus, the thermal expansion coefficient and the hardening are assumed to be normal distributed with a standard deviation that is 10% of their nominal value at different temperatures. In this work an improved process window is also suggested to show the robustness graphically. By using this window it is concluded that least robustness is obtained for high hardening values in combination to deviations in Young's modulus and the thermal expansion coefficient. It is also concluded that quadratic response surface based Monte Carlo simulations substitute finite element based Monte Carlo simulations satisfactory. Furthermore, the standard deviation of the responses are evaluated analytically by using the Gauss formula, and are compared to results from Monte Carlo simulations. The analytical solutions are accurate as long as the Gauss formula is not utilized close to a stationary point.

  • 13.
    Hofwing, Magnus
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Simulation of residual stresses in stamping dies2008Inngår i: Proceedings of the IDDRG 2008 Conference: Best in class stamping, 16-18 June 2008, Olofström, Sweden / [ed] Nader Asnafi, Olofström: Industriellt utvecklingscentrum i Olofström AB , 2008, s. 765-776Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the past stamping dies have in principle been designed by rules of thumb and intuition. As the sheet metals in the vehicle industry have got increased mechanical properties in recent years the demands on the stamping dies have increased. For instance increase in stiffness is desirable in order to better control spring-back. The most simple way to satisfy this new demand would be to make the stamping dies even more heavy in order to be able to handle the new sheet metals. Since there are restrictions of the weight of the stamping dies in the stamping machines and since the overhead cranes usually have reached the limit of what they can handle, this is not a desirable solution. Another approach, in order to increase the stiffness without increasing the weight is to use topology optimization. Recently in a master thesis at Volvo Car Corporation a conceptual design of a stamping die has been done by topology optimization. In that work no consideration is taken to the fact that the stamping die is casted. Casting implies that residual stresses possibly are produced during the solidification and cooling process. The residual stresses might affect the fatigue life and the risk of failure of the stamping die.

    In this work the residual stress state after casting is analyzed for the original stamping die as well as the optimized stamping die from the master thesis discussed above. The analyses are performed using an uncoupled approach, where one thermal analysis is followed by a quasi-static elasto-plastic analysis. The thermal analysis simulates the solidification and cooling during the casting process, while the quasi-static elasto-plastic analysis uses the temperature history, obtained from the thermal analysis, in order to build up residual stresses. The thermal analysis includes the release of latent heat. Furthermore, the material properties included in the heat equation (density, conductivity, specific heat) are given as temperature dependent properties for the mould as well as the casting. In the quasi-static elasto-plastic analysis the plasticity is described by the von Mises yield surface in combination with isotropic hardening and the mechanical properties (thermal expansion coefficient, Young's modulus, yield stress, hardening parameter, Poisson's ratio) are given as temperature dependent properties. The simulations show high levels of residual stresses.

     

  • 14.
    Hofwing, Magnus
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Tapankov, Martin
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Optimal Polynomial Regression Models by using a Genetic Algorithm2011Inngår i: Proceedings of the second International Conference on Soft Computing Technology in Civil, Structural and Environmental Engineering / [ed] Yiannis Tsompanakis; B H V Topping, 2011Konferansepaper (Fagfellevurdert)
  • 15. Ireman, P
    et al.
    Klarbring, A
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A model of damage coupled to wear2003Inngår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 40, nr 12, s. 2957-2974Artikkel i tidsskrift (Fagfellevurdert)
  • 16. Ireman, P
    et al.
    Klarbring, A
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Algorithms for thermoelastic wear problems2002Inngår i: Contact mechanics: proceedings of the 3rd Contact Mechanics International Symposiuum, Praia da Consolação, Peniche, Portugal, 17-21 June 2001, Dordrecht: Kluwer Academic , 2002, s. 363-370Konferansepaper (Fagfellevurdert)
  • 17. Ireman, P
    et al.
    Klarbring, A
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Algoritmer för termoelastiska nötningsproblem2001Inngår i: Svenska Mekanikdagar, Linköpings universitet, 11-13 juni,2001, 2001Konferansepaper (Annet vitenskapelig)
  • 18. Ireman, P
    et al.
    Klarbring, A
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Finite element algorithms for thermoelastic wear problems2002Inngår i: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 21, nr 3, s. 423-440Artikkel i tidsskrift (Fagfellevurdert)
  • 19. Ireman, P
    et al.
    Klarbring, A
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Gradient Theory of Damage Coupled to Frictional Contact and Wear, and Its Numerical Treatment2009Inngår i: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 52, nr 2, s. 125-158Artikkel i tidsskrift (Fagfellevurdert)
  • 20. Klarbring, A
    et al.
    Lundvall, O
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A flexible multi-body approach for frictional contact in spur gears2004Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 278, nr 3, s. 479-499Artikkel i tidsskrift (Fagfellevurdert)
  • 21.
    Klarbring, Anders
    et al.
    Linköping university.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    A Note on the Min-Max Formulation of Stiffness Optimization including Non-Zero Prescribed Displacements2012Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 45, nr 1, s. 147-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present theoretical note shows how a naturalobjective function in stiffness optimization, including bothprescribed forces and non-zero prescribed displacements,is the equilibrium potential energy. It also shows how theresulting problem has a saddle point character that may beutilized when calculating sensitivities.

  • 22.
    Klarbring, Anders
    et al.
    Linköping university.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Topology optimization of hyperelastic bodies including non-zero prescribed displacements2013Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 47, nr 1, s. 37-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stiffness topology optimization is usually based on a state problem of linear elasticity, and there seems to be little discussion on what is the limit for such a small rotation-displacement assumption. We show that even for gross rotations that are in all practical aspects small (<3 deg), topology optimization based on a large deformation theory might generate different design concepts compared to what is obtained when small displacement linear elasticity is used. Furthermore, in large rotations, the choice of stiffness objective (potential energy or compliance), can be crucial for the optimal design concept. The paper considers topology optimization of hyperelastic bodies subjected simultaneously to external forces and prescribed non-zero displacements. In that respect it generalizes a recent contribution of ours to large deformations, but we note that the objectives of potential energy and compliance are no longer equivalent in the non-linear case. We use seven different hyperelastic strain energy functions and find that the numerical performance of the Kirchhoff–St.Venant model is in general significantly worse than the performance of the other six models, which are all modifications of this classical law that are equivalent in the limit of infinitesimal strains, but do not contain the well-known collapse in compression. Numerical results are presented for two different problem settings.

  • 23.
    Rashid, Asim
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    An Efficient Sequential Approach for Simulation of Thermal Stresses in Disc Brakes2012Inngår i: Nordtrib 2012, 15th Nordic Symposium on Tribology, 2012, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper an efficient approach to simulate thermal stresses due to frictional heating of disc brakes is presented. Inthe approach thermal and stress analysis are performed sequentially. The frictional heat analysis is based on the Eulerianmethod, which requires significantly low computational time as compared to the Lagrangian approach. Completethree-dimensional geometries of a disc and a pad are considered for the numerical simulations. The contact forcesare computed at each time step taking the thermal deformations of the disc into account. The nodal temperaturehistory is recorded at each time step and is used in sequentially coupled stress analysis, where a temperature dependentelasto-plastic material model is used to compute the stresses in a disc brake. The results show that during hard braking,high compressive stresses are generated on the disc surface in circumferential direction which cause plastic yielding. Butwhen the disc cools down, the compressive stresses transform to tensile stresses. Such thermoplastic stress history maycause cracks on disc surface after a few braking cycles. These results are in agreement with experimental observationsavailable in the literature.

  • 24.
    Rashid, Asim
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Sequential simulation of thermal stresses in disc brakes for repeated braking2013Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 227, nr 8, s. 919-929Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, an efficient sequential approach for simulating thermal stresses in brake discs for repeated braking is presented. First, a frictional heat analysis is performed by using an Eulerian formulation of the disc. Then, by using the temperature history from the first step of the sequence, a plasticity analysis with temperature dependent material data is performed in order to determine the corresponding thermal stresses. Three-dimensional geometries of a disc and a pad to a heavy truck are considered in the numerical simulations. The contact forces are computed at each time step taking the thermal deformations of the disc and pad into account. In such manner, the frictional heat power distribution will also be updated in each time step, which in turn will influence the development of heat bands. The plasticity model is taken to be the von Mises yield criterion with linear kinematic hardening, where both the hardening and the yield limit are temperature dependent. The results show that during hard braking, high compressive stresses are generated on the disc surface in the circumferential direction which cause yielding. But when the disc cools down, these compressive stresses transform to tensile residual stresses. For repeated hard braking when this kind of stress history is repeated, we also show that stress cycles with high amplitudes are developed which might generate low cycle fatigue cracks after a few braking cycles.

  • 25.
    Rashid, Asim
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Thermomechanical Simulation of Wear and Hot Bands in a Disc Brake by Adopting an Eulerian Approach2013Inngår i: Eurobrake 2013, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper frictional heating of a disc brake is simulated while taking wear into account. By performing thermomechanical finite element analysis, it is studied how the wear history will influence the development of hot bands. The frictional heat analysis is based on an Eulerian formulation of the disc, which requires significantly lower computational time as compared to a standard Lagrangian approach. A real disc-pad system to a heavy truck is considered, where complete three-dimensional geometries of the ventilated disc and pad are used in the simulations. A sequential approach is adopted, where the contact forces are computed at each time step taking the wear and thermal deformations of the mating parts into account. After each brake cycle, the wear profile of the pad is updated and used in subsequent analysis. The results show that when wear is considered, different distributions of the temperature on disc are obtained for each new brake cycle. After a few braking cycles two hot bands appear on the disc surface instead of only one. These results are in agreement with experimental observations.

  • 26.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A method for structural dynamic contact problems with friction and wear2003Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 58, nr 15, s. 2371-2385Artikkel i tidsskrift (Fagfellevurdert)
  • 27.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A Newton algorithm for fretting problems1996Inngår i: Euromech Colloquium 351, Systems with Coulomb friction, Vadstena, Sweden, August 5-7, 1996, 1996Konferansepaper (Annet vitenskapelig)
  • 28.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A Newton algorithm for wear problems1997Inngår i: 3rd EUROMECH Solid Mechanics Conference, Stockholm, Sweden, August 18-22, 1997, 1997Konferansepaper (Annet vitenskapelig)
  • 29.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    A Newton method for three-dimensional fretting problems1999Inngår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 36, nr 14, s. 2075-2090Artikkel i tidsskrift (Fagfellevurdert)
  • 30.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    An augmented Lagrangian method for fretting problems1996Inngår i: Euromech Colloquium 346, March 20-22, Oxford, 1996., 1996Konferansepaper (Annet vitenskapelig)
  • 31.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    An augmented Lagrangian method for fretting problems1997Inngår i: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 16, nr 4, s. 573-593Artikkel i tidsskrift (Fagfellevurdert)
  • 32.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    An Efficient Tradeoff Approach for Topology Optimization with Manufacturing Constraints2010Inngår i: 36th Design Automation Conference, ASME proceedings, 2010Konferansepaper (Fagfellevurdert)
  • 33.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    An Eulerian approach for simulating frictional heat bands in rotating discs2012Konferansepaper (Annet vitenskapelig)
  • 34.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    An Eulerian Approach for Simulating Frictional Heating in Disc-Pad Systems2011Inngår i: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 30, nr 5, s. 673-683Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermal stresses as a result from frictional heating must be considered when designing disc brakes, clutches or other rotating machine components with sliding contact conditions. The rotational symmetry of the disc in these kind of applications makes it possible to model these systems using an Eulerian approach instead of a Lagrangian framework. In this paper such an approach is developed and implemented. The disc is formulated in an Eulerian frame where the convective terms are defined by the angular velocity. By utilizing the Eulerian framework, a node-to-node formulation of the contact interface is obtained, producing most accurate frictional heat power solutions. The energy balance of the interface is postulated by introducing an interfacial temperature. Both frictional power and contact conductances are included in this energy balance. The contact problem is solved by a non-smooth Newton method. By adopting the augmented Lagrangian approach, this is done by rewriting Signorini’s contact conditions to an equivalent semi-smooth equation. The heat transfer in the disc is discretized by a Petrov–Galerkin approach, i.e. the numerical difficulties due to the non-symmetric convective matrix appearing in a pure Galerkin discretization is treated by following the streamline-upwind approach. In such manner a stabilization is obtained by adding artificial conduction along the streamlines. For each time step the thermo-elastic contact problem is first solved for the temperature field from the previous time step. Then, the heat transfer problem is solved for the corresponding frictional power. In such manner a temperature history is obtained sequentially via the trapezoidal rule. In particular the parameter is set such that both the Crank–Nicolson and the Galerkin methods are utilized. The method seems very promising. This is demonstrated by solving a two-dimensional benchmark as well as a real disc brake system in three dimensions.

  • 35.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    An Implicit Method for Frictional Contact, Impact and Rolling2005Inngår i: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 24, nr 6, s. 1016-1029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper an implicit method for frictional contact, impact and rolling is suggested. A nonclassical formulation of a two-dimensional hyperelastic body unilaterally constrained to rigid supports is proposed by following the ideas of Moreau and Jean. A total Lagrangian formulation of the system is given. The elastic properties are defined by coupling the second Piola–Kirchhoff stress to the Green–Lagrange strain via the Kirchhoff–St. Venant law. The equation of motion is written in the spirit of Moreau by using the mean value impulses introduced by Jean. The mean value impulses appear explicitly in the equation of motion. In such manner the treatment of nonconstant kinematic transformation matrices becomes straightforward. The rigid supports are described by smooth functions. By utilizing these functions and the mean value impulses, new contact/impact laws of Signorini and Coulomb type are formulated. The governing equations are solved by a nonsmooth Newton method. This is performed by following the augmented Lagrangian approach and deriving the consistent stiffness matrix as well as the contact stiffness matrices. Three two-dimensional examples are solved by the method: a contact problem, an impact problem and a rolling contact problem.

  • 36.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Augmented Lagrangian methods for wear problems1995Inngår i: NSCM VIII: eighth Nordic seminar on computational mechanics : Göteborg November 17-18, 1995 : short papers, Göteborg: Department of Structural Mechanics, Chalmers University of Technology , 1995Konferansepaper (Annet vitenskapelig)
  • 37.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Conceptual design of a hub by using topology optimization and residual stress simulations2007Inngår i: handouts in the proceedings of the 1st European HTC, 23-24 October, Berlin, 2007, 2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 38.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Contact, impact and rolling of a nonlinear elastic body on rigid foundations2005Inngår i: Proceedings of Multibody Dynamics, International Conference on Advances in Computational Multibody Dynamics: June 21-24, Madrid, Spain, 2005, 2005Konferansepaper (Fagfellevurdert)
  • 39.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Contact Modeling in Topology Optimization2010Inngår i: the IV European Conference on Computational Mechanics (Abstracs), 2010Konferansepaper (Fagfellevurdert)
  • 40.
    Strömberg, Niclas
    Linköping University.
    Continuum Thermodynamics of Contact Friction and Wear1995Licentiatavhandling, monografi (Annet vitenskapelig)
  • 41.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Development and Implementation of an Eulerian Approach for Efficient Simulation of Frictional Heating in Sliding Contacts2011Inngår i: Coupled problems 2011 : computational methods for coupled problems in science and engineering IV: proceedings of the IV International Conference on Computational Methods for Coupled Problems in Science and Engineering held in Kos, Greece, 20 - 22 June 2011, 2011Konferansepaper (Fagfellevurdert)
  • 42.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    En implicit metod för kontakt och stötproblem med stora rotationer2007Inngår i: Luleå tekniska universitet, Svenska Mekanikdagar, 13-15 juni, 2007, 2007Konferansepaper (Annet vitenskapelig)
  • 43.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Finite element treatment of thermoelastic wear problems1998Inngår i: Proceedings of the IUTAM-Symposium on Unilateral Multibody Dynamics, 1998Konferansepaper (Fagfellevurdert)
  • 44.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Finite element treatment of tribological problems1998Inngår i: Proceedings of the International Symposium on Impact and Friction of Solids, Structures and Machines, June 27-30, Ottawa, Canada, 1998, 1998Konferansepaper (Fagfellevurdert)
  • 45.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Finite element treatment of two-dimensional thermoelastic wear problems1999Inngår i: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 177, nr 3-4, s. 441-455Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Frictional Contact/Impact between a Hyperelastic Body and Moving Rigid Obstacles2006Inngår i: Proceedings of the 3rd European Conference on Computational Mechanics: June 5-9, Lisbon, Portugal, 2006., 2006Konferansepaper (Fagfellevurdert)
  • 47.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Optimering av styrstavsbladets huvuddimensioner med hjälp av FE-programmet ANSYS, LiTH-IKP-Ex-10171992Licentiatavhandling, monografi (Annet vitenskapelig)
  • 48.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    RBDO with Non-Gaussian Variables by using a LHS- and SORM-based SLP approach and Optimal Regression Models2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A general sequential linear programming (SLP) approach for reliability based design optimization (RBDO) with non-Gaussian random variables is presented. The RBDO problems are formulated by using optimal regression models (ORM) as surrogate models and S-optimal design of experiments (DoE). The S-optimal DoE is obtained by maximizing the average mean of the distances between the nearest neighbors. Finite element simulations are performed for the S-optimal DoE and corresponding ORM are obtained by a genetic algorithm. In such manner not only optimal regression coefficients are generated but also optimal rational base functions. The RBDO problems are solved by introducing intermediate variables defined by the iso-probabilistic transformation at the most probable point. By using these variables in the Taylor expansions, a corresponding deterministic linear programming problem is derived, which is corrected by applying second order reliability methods (SORM) as well as Monte Carlo simulations. For low target values on the reliability crude Monte Carlo simulations are used, but for high targets a Latin hypercube sampling (LHS) approach is utilized. The implementation of the suggested sampling- and SORM-based SLP approach is efficient and robust. This is demonstrated by presenting trade-off curves between the objective function, constraints, variables and the target of reliability.

  • 49.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Simulation of Rotary Draw Bending using Abaqus and a Neural Network2005Inngår i: Proceedings of Nafems Nordic Conference on Component and System Analysis using Numerical Simulation Techniques - FEA, CFD, MBS: November 24-25, Gothenburg, 2005., 2005Konferansepaper (Fagfellevurdert)
  • 50.
    Strömberg, Niclas
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Simulering av bromsvärme i en skivbroms med en Eulerformulering, Svenska Mekanikdagar2011Konferansepaper (Annet vitenskapelig)
12 1 - 50 of 72
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