High fidelity simulation of low velocity impact behavior of CFRP laminate

In this paper, finite element model which simulates damage extent of CFRP laminate subjected to low velocity impact (LVI) is proposed. It is well-known that face-on LVI against the CFRP laminate can significantly degrade the material performance, although it leaves only barely visible impact damage (BVID). Hence, it is quite important to precisely predict damage of CFRP laminate caused by LVI. The validity of the model is demonstrated by comparing experimental and numerical results. Experimental impact response (i.e. load-history curve) and damage extent of CFRP laminate were obtained from drop-weight test and non-destructive inspection (such as C-scan, radiograph and X-ray CT), respectively. Numerical results were obtained from finite element (FE) analysis done on Abaqus/Explicit 2016, performed using JAXA's supercomputer system, "JSS2". Proposed model in this paper was implemented using user subroutine VUMAT. The FE model of the CFRP laminate is lamina-level, therefore a laminate is divided into each lamina, and lamina is divided into continuum shell elements. In the present model, each damage mode is modeled in each manner. Fiber damage is modeled by smeared crack model (SCM). In-plane ply cracks are modeled by the enhanced continuum damage mechanics (ECDM) model, which is composed of continuum damage mechanics (CDM) and SCM. Pre-peak nonlinear behavior caused by micro cracks, and post-peak softening behavior caused by matrix cracks are modeled by CDM and SCM, respectively. Delamination between laminae is modeled by cohesive behavior based on the contact formulation. The numerical results obtained from the present model show good agreement with experimental results. Regarding the delamination shape and its size, numerical results and experimental results agree very well. The validity of the present model was demonstrated.