Changyu Meng | Searcharxiv

arXiv2021

A Nonlocal Damage-enhanced Lattice Particle Model for Ductile Fracture Analysis

Ductile fracture of metallic materials typically involves the elastoplastic deformation and associated damaging process. The nonlocal lattice particle method (LPM) can be extended to model this complex behavior. Recently, a distortional energy-based model is formulated into LPM to simulate J2 plasticity. However, this model is based on the incremental updating algorithm which needs very small loading steps to get reasonable results. This is time-consuming and unstable for large systems. Therefore, in this paper, a tensor-based return-mapping algorithm is proposed to deal with these deficiencies. The material deterioration process is modelled as a nonlocal damage evolution process. The particle-size/lattice dependency of macroscopic mechanical responses are handled properly by using the proposed model. Numerical examples of predicting the elastoplastic behavior of engineering structures with/without damage and fracture are also provided. A multi-threaded implementation of LPM using C is available on the website: https://github.com/ymlasu/LPM-C.

cond-mat.mtrl-sci↗

arXiv2018

Study on failure mechanism of Cu-Polyethylene-Cu sandwich structure by molecular dynamics simulation

The tensile failure mechanism of Cu-Polyethylene-Cu (CPC) sandwich structure was clarified by molecular dynamics (MD) simulations subjected to a uniaxial tensile loading at microscopic scale. The sensitivity analysis of parameters such as model size, relaxation time for equilibrium and initial velocity distribution was carried out to verify the rationality of modeling. The evolutions of stress-strain relationship and each potential energy component were provided to describe the failure process of the structure. The peak of non-bond energy shows a delay compared to the yield point in stress-strain curve, which coincides with the local maximum point of the trans-fraction curve of dihedral angles. After that, an inflexion appeared in the trans-fraction curve indicates an energy transport process, which corresponds with the slope change of the stress-strain curve. It is assumed that the dihedral distribution plays a crucial role in the damage process of CPC structure. In addition, the temperature field and the density profile were adopted to predict the position of damage initiation, which was confirmed by the microstructure evolution. The intrinsic thickness-dependence of CPC was explored by taking the coupling effect of bridging and entanglement into account, which is in reverse proportion with the yield strength of CPC.

cond-mat.soft↗