Multiscale Modeling of Failure in Composite Materials

Abstract

Failure in composite materials is known to initiate at the level of constituents. Further development of the failure process and ultimate failure of the composite structure depend on the fiber architecture and other geometrical details. A composite failure analysis must therefore be at multiple length scales. This paper will outline a multiscale modeling scheme and illustrate the approach with two examples: tensile fiber failure and transverse matrix cracking. For the case of fiber failure, a five-cylinder axisymmetric finite element model containing an initially broken fiber at the center will be used to conduct stress analysis and formation of a failure plane will be simulated by a crack growth procedure. The transverse crack formation will be analyzed as a linking up of fiber-matrix debond cracks. Formation of these cracks will in turn be analyzed by an energy-based criterion. The local scale modeling will take account of the manufacturing induced irregularities and defects by appropriate representation of these in the failure analysis. Finally, an assessment of the multiscale approach as a rational alternative to the currently used failure theories, which are formulated on homogenized composites, will be presented and the challenges remaining to address in future will be outlined.