Continuous processes in discontinuous phenomena: A novel multiscale model based on MD and DEM to investigate the energy absorption mechanism of SiCf/SiC composites

Abstract

In this paper, a novel multiscale model that integrates molecular dynamics (MD) and the discrete element method (DEM) is introduced to facilitate an in-depth investigation of energy absorption mechanisms. By integrating the damage evolution of the matrix obtained through MD with a Soft-Bond contact model in the DEM, a formula for the softening factor is derived, enabling the transfer of continuous damage behavior from the nanoscale to the microscale. A microscale RVE model that takes into account the discontinuous damage behavior observed at the microscale is then developed to conduct uniaxial tension simulations using the DEM. Results indicate that, compared to experimental data, the stress–strain curve from this model exhibits a root mean square deviation of only 5.7 % in the progressive damage stage, with the final fracture strength differing by just 3 %. While the matrix undergoes an 85 % reduction in elastic modulus at the initial damage saturation state, its cumulative energy absorption prior to complete material failure accounts for 66.4 % of the total energy dissipation. Furthermore, loading–unloading experiments were conducted to further validate the robustness and accuracy of this multi-scale model. The multi-scale model provides a bridge for the transfer of mechanical behavior from the nanoscale to the macroscale and can be used in future investigations of strain rate effects in discontinuous media and its thermodynamic studies.