Multiscale modeling of unidirectional composites with interfacial debonding using molecular dynamics and micromechanics

Abstract

In this study, a new multiscale micromechanical model based on the finite-volume direct averaging micromechanics (FVDAM) theory and molecular dynamics (MD) is constructed. It describes the interfacial debonding phenomena of unidirectional composites, whereby a solid fracture interface is incorporated with the FVDAM for the first time. To better elucidate the debonding behavior of the solid interface, a six-degrees-of-freedom (6-DoF) cohesive zone model (CZM) is proposed using MD simulation. The damage matrix Dc(k) in the kth subvolume of the interface is obtained using the 6-DoF CZM, and its explicit form is described herein to facilitate its implementation in commercial software packages. To verify the effectiveness of the model, both experimental data and numerical simulations were adopted for comparison. The experimental data of the unidirectional SiCf/Ti6Al4V composite were compared with the simulation results of FVDAM, and a good agreement was established. A finite element method-based unit cell model is constructed using ABAQUS for numerical validation, and homogenized responses and local fields are compared. The excellent correlations prove the effectiveness of the proposed model. Furthermore, the effects of thermal residual stress and fiber orientations are revealed, which may provide some useful information for the design and manufacture of composites.