A reliable methodology for the preliminary design of multidirectional composite open-hole plates using the coupled criterion

Abstract

In the aerospace industry, composite structures are preferred for their high strength-to-mass ratio and fatigue strength. However, using advanced non-linear Finite Element models for the strength prediction of composite laminates during preliminary design and optimisation can lead to long computing times. Thus, linear elastic fracture mechanics is suitable for preliminary design. In this work, the coupled energy–stress criterion has been successfully applied to predict translaminar failure of open-hole tensile and compression specimens, considering three different stacking sequences with varying degrees of orthotropy. This criterion uses stress and energy criteria as necessary conditions for fracture, since neither of them is sufficient alone. The approach involves a characteristic length dependent on the composite’s properties and geometry. The characteristic length is used to satisfy both criteria simultaneously, avoiding the need for correction factors. The current approach includes the material anisotropy in both elastic and fracture parameters. The onsets of symmetric and antisymmetric crack patterns are investigated, considering where failure is predicted from the ply properties.