A hierarchical multiscale strategy for analyzing the impact response of 3D braided composites

Abstract

A hierarchical multiscale framework has been developed to predict the impact response of 3D braided composites, in which a bridging model(unit cell model), was employed as a bridge between micro- and macro- scale. A paraboloidal elastic-to-plastic damage model for the epoxy, including the hydrostatic effect, was conducted, where a robust algorithm has been implemented to enhance the convergence and accuracy. At the microscale, nine RVEs (representative volume elements) with different fibers distributions were generated in order to enhance reliability and to reduce the size effect for the micromechanical analysis; At the macroscale, firstly, a unit cell model was proposed as a virtual meso-scale based on the geometric topology of 3D braided composites, and then the unit cell model was implicitly introduced into the macromodel based on the transformation matrix. The homogenization method was adopted for transferring the mechanical properties between scales. These constitutive models were implemented by two user defined subroutines (UMAT and VUMAT) in ABAQUS/Standard and ABAQUS/Explicit for micromechanical analysis and impact simulation, respectively. Furthermore, the failure envelop was carried out for matching a better strength criteria for the braiding yarn. Finally, the high-speed impact simulation was employed to validate the effectiveness of the multiscale framework. The results show that the numerical results are agreed with the experiments well.