A study of transverse crack formation in fiber-reinforced composites by growth of fiber-matrix debonds

2017 International Committee on Composite Materials. All rights reserved. This paper studies a likely mechanism for formation of a macro-sized transverse crack consisting of growth and link-up of fiber-matrix debond cracks in a unidirectional composite loaded in transverse tension. The model used for this purpose is an embedded cell within a homogeneous composite. The cell has a fiber surrounded by six fibers in a hexagonal pattern. By analyzing the debonding of the central fiber, it is found that once initiated, the debond crack grows in mixed mode along the interface initially unstably and then stably. The analysis also shows that the driving force of a potential kinked crack emanating from debond tip increases and reaches its highest value before a physically relevant contact zone develops at the debond tip. The results suggest that the kinking of the debond crack out of interface and its growth towards neighboring fibers is nearly in pure mode I. Once the kinked crack approaches a neighboring fiber, it induces a high radial tensile stress in the neighboring fiber, causing a possible debonding of that fiber. This debonding followed by kinking out of the interface eventually leads to the formation of a macro-sized transverse crack.

A study of transverse crack formation in fiber-reinforced composites by growth of fiber-matrix debonds Conference Paper