PERIDYNAMIC MODELING OF WAVE PROPAGATION AND THE EFFECT OF MICROSTRUCTURE IN ANISOTROPIC MATERIALS

The microstructure of metals significantly impacts their macroscopic mechanical properties, and a deep understanding of the mechanical response of metals under dynamic conditions is of great significance. Peridynamics, an emerging nonlocal theory, has a natural theoretical advantage in studying the damage and failure of materials under impact. In this paper, the theory of non-ordinary state-based peridynamics is used as the theoretical framework to simulate the propagation of waves in anisotropic materials and to investigate the interaction between waves and microstructures. To accurately capture shock waves in the nonlocal model of peridynamics, the interface pressure in the nonlocal force state is corrected using an approximate Riemann solution, ensuring the conservation and solution stability of the physical quantities at the shock wave interface. To improve computational efficiency, a non-iterative solver is implemented in the peridynamic framework. Based on the rate dependent crystal plasticity theory and homogenization theory, the finite deformation crystal viscoplastic constitutive model is introduced into the nonlocal theoretical framework of peridynamics. Comparisons with analytical solutions show that the proposed model can effectively eliminate non-physical oscillations behind the wavefront and accurately capture the elastic as well as elastoplastic wave structures. Comparisons with experimental results of annealed oxygen-free high conductivity (OFHC) copper subjected to compression show that the macroscopic mechanical response obtained from the crystal viscoplastic peridynamics simulation is in good agreement, and the explicit computation exhibits high efficiency. On this basis, the effects of different impact velocities and the initial microstructure of the material on the anisotropy of the impact response are discussed. Specifically, the heterogeneity of plastic deformation is captured in the simulations. The crystal orientation determines the Hugoniot elastic limit and also the soft and hard orientations of the material, thereby affecting the evolution of the elastoplastic wave structure. Grain boundaries lead to highly heterogeneous stress distributions and cumulative slip strains in the Hugoniot state.