Development of an Analytical Method for Damaged Composites and Its Application to Damage Tolerance Design of Composite Structures

摘要

In order to evaluate initiation and extension of transverse lamina cracks in structures made of multidirectionally laminated composites, finite element analytical method is newly developed in this study. The analytical procedure for calculation of transverse lamina cracks in multidirectionally laminated composites is implemented in the developed finite element method. An energy balance between the stiffness reduction of a laminate for varying crack density and released energy by the crack growth is used to evaluate the critical strain of the crack growth. Using developed method, the details of the initiation and extension of the cracks in the laminated composites with a macro crack are shown in this study. Furthermore, the approach for damage tolerance design of laminated composite structures is proposed in this study. In this approach, damage zones in a laminated composite are supposed to be zones of local stiffness reduction. The local stiffness reduction can be expressed by polynomial expressions.