Development of an inverse method for material characterization using a biaxially loaded cruciform composite specimen

When performing biaxial tests, the mechanical material parameters cannot be obtained as with classical uniaxial tests due to the heterogeneous stress and strain distribution in the specimen. Therefore, an inverse method for the indirect identification of the four in-plane elastic orthotropic parameters of a biaxially loaded cruciform composite specimen was developed. Strain fields obtained by a Digital Image Correlation Technique are used as experimental data. In parallel, a Finite Element (FE) model leads to a numerical representation of the strain fields. The material parameters are obtained by updating the initial parameters in the FE model until the numerical strain fields match the experimental strain fields. In a first stage, the inverse method was developed to obtain the orthotropic elastic material parameters of a plane cruciform composite specimen. This paper presents the proceeding of the research, in order to use the inverse method in biaxial fatigue tests. These tests require a tool to study the degradation development of the orthotropic elastic parameters.