Strain-based Failure Prediction for Composite Specimen Model Using Strain Amplification Factor

摘要

Increasing use of composite materials in the aerospace industry, the research for a failure prediction of composite structures is regarded greatly as important in the design process. For composite structures, the initial damage is caused by the dilatational or distortional deformation in the fiber and matrix phase. This failure mechanism cannot be predicted in the macro-mechanics concept but the micro-mechanics based failure criterions predict the failure modes of fiber or matrix phase. So far, the micro-level of the composite failure criteria were proposed by Hashin and Sun, etc In recent years, SIFT (Strain Invariant Failure Theory) is proposed by Gosse that a more efficient method to predict the failure of micro-level. The SIFT complements the weakness of classical failure theories for composite materials as estimating each criterion for the fiber and matrix. Also, strain amplification factor used in SIFT is very important parameter for connecting the micro-level and macro-level strain tensor. In this study, the failure analysis based on SIFT was performed by in-house code for a composite specimen model. For this analysis, finite element modeling and static analysis were established by MSC. Patran/Nastran. In the procedure of analysis, first, the stress and strain tensors were calculated by FE analysis. And then, RVE (Representative Volume Element) model is used for estimating the matrix of strain amplification factors. Finally, the result of failure analysis is verified by comparing with existing theories.