NONLINEAR STRAIN ENERGY BASED FAILURE CRITERION FOR TRIAXIAL LOADING OF COMPOSITE LAMINATES

摘要

An analytical model to predict the nonlinear stress-strain response, failure initiation, and postinitialfailure behavior of fibrous composite laminates under triaxial loading has been developedbased on a strain energy formulation. The total strain energy of an orthotropic lamina is dividedinto several energy components from which their contribution to various failure modes is takeninto account. The effects of hydrostatic stress on each failure mode as well as the effects ofthermal residual stresses (accumulated during the curing of composite laminates) have beenincluded. A cubic spline interpolation scheme has been utilized to represent the nonlinearuniaxial response of the material along its material directions. A failure mode dependentexponential stiffness reduction technique is used to predict material response beyond the initialfailure. This paper includes a series of comparative stress-strain curves and failure envelopes tocompare model predictions to published experimental data. The strain energy based failuremodel is found to provide good agreement with the experimental observations studied in thiswork and as demonstrated in the first and second World Wide Failure Exercises.