Failure analysis of composite laminate under low-velocity impact based on micromechanics of failure

Previous researches on the impacted composite laminates were mainly carried out according to the macromechanics-based homogenous strength theories, which ignore the local stress nonuniformity and strength difference between the fiber and matrix. In this paper, a new multiscale analysis method which combines the micromechanics of failure (MMF) theory for intralaminar damage and cohesive model for interlaminar failure is proposed. This approach is able to identify the failure modes of fiber and matrix in microscale as well as delamination between laminas. The finite element model of the multidirectional carbon fiber reinforced plastic (CFRP) laminate subjected to low-velocity impact is built on ABAQUS/Explicit platform. User material subroutine VUMAT is developed to analyze the micro stresses and determine the possible failure modes of fiber and matrix. Cohesive elements with bi-linear traction-separation law are employed to capture the onset and propagation of delamination. Finally, the structure response, fiber and matrix failure mode and delamination area are compared with experimental data under different impact energies, and the good agreements validate the effectiveness and accuracy of the novel method.