TR73

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C2 - Material Model



Development of a Material Model for Metal Sheets at Finite Deformation

Project Status: Active

Last Update: 14.02.2019



Members


One task of subproject C2 in periode 3 is to predict the fatigue lifetime taking both damage evolution and cyclical loading into account. Fatigue lifetime prediction is one of significant issues among engineering design and manufacture. The most applied S-N curves (Stress-cycles) can be obtained either by numerous experiment on testing machines or running simulations on computers. By the way of experiments, a metal specimen is placed into the testing machine and subjected to thousands of cyclic loading until a crack or failure occurs in the specimen. In general, the cycle numbers is up to 10^7 in a high-cycle fatigue testing. This process is expensive and time-consuming because one single test can run for months. Therefore, a fast and accurate numerical method for fatigue lifetime prediction is demanding.

The fracture and failure on macro-scale are an acculumative result due to the crack formation on the micro-scale. The damage model should be capable to evaluate the damage accumulative under the cyclical loading condition. In order to capture the accurate material response with dynamic loading cycles, both Extended Finite Element(XFEM) method and a gradient enhanced damage model are investigated for the numerical simulation. Based on the work of period 2 of the SFB/TR73, a time stepping method is introduced by define the time as fine time scale and coarse time scale. This new time stepping method can accelerate the computational time for high cycles fatigue prediction, and at the same time, track the evolution of local state variables adequately in both elastic region and plastic region.


Working Groups


Publications

    2019

    • Zeller, S.; Baldrich, M.; Gerstein, G.; Nürnberger, F.; Löhnert, S.; Maier, H.; Wriggers, P.: Material models for the thermoplastic material behaviour of a dual-phase steel on a microscopic and a macroscopic length scale. In: Journal of the Mechanics and Physics of Solids https://doi.org/10.1016/j.jmps.2019.04.012, (2019), in print

    2018

    • Löhnert, S.: A mixed extended finite element formulation for the simulation of cracks in nearly incompressible materials.. In: Proc. Appl. Math. Mech. DOI: 10.1002/pamm.201800452, (2018), in print
    • Zeller, S.: Material models for the thermoplastic material behaviour of a dual-phase steel DP600 on a microscopic and a macroscopic length scale. In: Dissertation, Institut für Kontinuumsmechanik, Fakultät für Maschinenbau, Leibniz Universität Hannover (Edt.): (2018), published