Three-Dimensional Discrete Element Modeling of the Damage Behaviour of Cross-Ply Laminate under Low-Velocity Impact

Yang, Dongmin and Tan, Y. Q. and Ye, Jianqiao and Sheng, Yong (2009) Three-Dimensional Discrete Element Modeling of the Damage Behaviour of Cross-Ply Laminate under Low-Velocity Impact. Civil-Comp Proceedings, 91. ISSN 1759-3433

Abstract

A three-dimensional discrete element model (DEM) [1,2] was used to simulate the dynamic damage process of a cross-ply fiber reinforced polymer laminate (0°/90°/0°/90°) under a low-velocity impact. Nominal fibers were defined in the longitudinal and transverse directions to describe the anisotropic behavior in 0° ply and 90° ply. Both the matrix and the nominal fibre are considered as brittle elastic materials. The interface between the fibre and matrix, and the interface between different plies were represented by cohesive softening model which is similar to the cohesive zone model (CZM). It was possible to model a quarter of the laminate due to symmetry, in order to reduce the computational time. The specimen was supported by two walls and impacted by a rigid ball which represented the projectile. The matrix cracking, debonding between fibre-matrix and delamination between plies were simulated successfully using the DEM model. It can be observed from the numerical results obtained from the three-dimensional DEM modeling that the delamination initiated at the beginning of the impact and propagated into the specimen with the penetration of the impacting ball. Numerical results show that the geometry of the delamination area agrees well with existing experimental and finite element results [3]. The accumulated damage of the specimen increases with the impacting displacement, while the impacting velocity decreases with an increase in the impacting displacement which is represented by the computation steps here. However, the model will need further modifications to incorporate more realistic fibre models and the DEM micro parameters should be calibrated via a series of mechanical experiments in the future work, especially the ply interface strength which can be estimated by double cantilever beam test. Also, a larger DEM model which includes hundreds thousands of particles would better represent the details of the microstructure of the laminate and could be another focus of future work.