ECCOMAS 2024

Computational analysis of non-proportional biaxial shear reverse experiments superimposed by different cyclic loads

  • Wei, Zhichao (Institut f¨ur Mechanik und Statik, Universit¨)
  • Gerke, Steffen (Institut f¨ur Mechanik und Statik, Universit¨)
  • Brünig, Michael (Institut f¨ur Mechanik und Statik, Universit¨)

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Currently, the numerical analysis of ductile damage and fracture behavior under biaxial non-proportional reverse loading is an attractive research topic with a notable gap in the literature. Most researchers are focusing on the uniaxial reverse loading tests with dog-bone or cylindrical specimens. However, a recent study by Wei et al. [1-2] has made strides in this field by conducting a series of biaxial non-proportional reverse loading tests with 4 mm metal sheets superimposing by different constant preloads without unloading. The corresponding experimental and numerical results indicated that the reverse loading histories and different degrees of preloads significantly influence the ductile damage and fracture behaviors. In the present work, three different cyclic loading patterns, including unloading conditions, are superimposed with the shear reverse experiments compared to the constant preload carried out in the previous work [1]. It is important to emphasize that biaxial loading can either occur simultaneously in the same direction or counteractively in the opposite direction. Concerning the numerical aspects, an anisotropic stress-state-dependent cyclic elastic-plastic-damage continuum model is used to predict the material response at both macro- and micro-levels. The proposed continuum model is implemented as a user-defined subroutine in ANSYS. The details of the numerical approach can be found in [2]. Moreover, the numerically predicted macroscopic force-displacement curves and local strain fields are compared with the experimental ones obtained from the digital image correlation technique (DIC). In addition, the predicted damage strains are used to verify the different damage mechanisms at the micro-level in terms of the scanning electron microscopy images taken from the fractured surfaces. [1] Z. Wei, S. Gerke, M. Brünig, Damage and fracture behavior under non-proportional biaxial reverse loading in ductile metals: Experiments and material modeling, Int. J. Plast. 171 (2023) 103774. [2]Z. Wei, S. Gerke, M. Brünig, Numerical analysis of non-proportional biaxial reverse experiments with a two-surface anisotropic cyclic plasticity-damage approach (accepted), Comput. Methods Appl. Mech. Eng. 2023 116630