On modeling matrix failures in composites

This paper discusses the dilemma and difficulties in formulating a physically consistent modeling approach for matrix tensile failures in structural composites. The focus is placed on a class of unidirectional composites, in which the onset and growth behaviors of matrix-related failures are closely related to the composite microstructure at the fiber-matrix scale. Modeling of such failures has been difficult, as both conceptual and practical difficulties are still being encountered; and these have here-to-fore defied a satisfactory modeling approach. This paper discusses some of the difficulties within the confines of the mechanics for composites. Four interrelated areas are discussed: (1) that related to microstructure characterization; (2) that related to composite homogenization; (3) that related to failure theorization; and (4) that related to computation of stress fields at the fiber-matrix scale. An inter-scale modeling approach is also outlined here, attempting to circumvent some of the difficulties. The approach is used to model matrix tensile cracks in laminates made of a unidirectional ply systems, along with some numerical results are for illustrative purpose.