Application of a First Invariant Strain Criterion for Matrix Failure in Composite Materials

Abstract

This paper reports an application of the strain invariant failure theory (SIFT) proposed by Gosse to through-thickness failure of composite structures [Gosse, J.H. and Christensen, S. (2001). Strain Invariant Failure Criteria for Polymers in Composite Materials, AIAA-2001-1184]. It includes global 3D finite element analysis on a ply-by-ply basis and the determination of amplification factors for strains in the intrafiber resin and the calculation of thermal residual strain due to manufacturing for intrafiber resin using micromechanical models. The new procedure has been applied to matrix failures for one type of curved beam, two types of I-beam and two types of T-cleat structures. The resulting predictions of the failure loads for both the I-beams and the T-cleats follow experimental trends. The limiting value of the first invariant strain for failure of the resin in the unidirectional tape is 17,000–20,000 ", and in the bidirectional fabric is 26,000–27,000 ".