Evaluation of In-Plane Mode II Fracture Toughness Tests in Unidirectional GFRP. Fracture Simulation Using FEM.

Abstract

In-planeMode II fracture toughness tests of unidirectional GFRPs are conducted using a four-point shear loading test method. In the previous paper, the effect of the pre-crack length on the fracture toughness was investigated, and the advantage of this test method was also discussed. In this study, the same test method is used to evaluate the fracture toughness of the unidirectional GFRP. The normalized stress intensity factor concerning an orthotropic body of the unidirectional GFRP is calculated by a finite element method. The mode II fracture toughness is found to be constant regardless of pre-crack length. Using the finite element method, the propagation of the damage zone at the initial failure process is obtained. The analytical mode is shown to be quite effective and the initial failure process is well simulated by this modelization.

Macro-Micro Uncoupled Homogenization Procedure for Microscopic Nonlinear Behavior Analysis of Composites

“…Up to date, above all nonlinear problems were linearized in numerical simulations by means of step-wised linear homogenized material properties, because classical theories on the mechanics of composite materials was for only linear elastic problems. However, the application of elasto-plastic theory [8][9][10][11], for instance, is more reasonable for problems with material nonlinearity, because linearized elastic theory cannot consider residual plastic strain after unloading. Recently, macroscopic elasto-plastic theory was applied also to microscopic fracture propagation [10,11].…”

“…However, the application of elasto-plastic theory [8][9][10][11], for instance, is more reasonable for problems with material nonlinearity, because linearized elastic theory cannot consider residual plastic strain after unloading. Recently, macroscopic elasto-plastic theory was applied also to microscopic fracture propagation [10,11]. Microscopically, however, both alive matrix and fiber behave as elastic body.…”