Steady‐State and Multiple Cracking of Short Random Fiber Composites

TLDR

The study analyzes pseudostrain‑hardening in brittle matrix composites reinforced with randomly distributed discontinuous fibers using a cohesive crack‑mechanics approach. The authors derive first‑crack strength and strain from fiber, matrix, and interface micromechanical properties and examine how snubbing from local fiber/matrix interactions of randomly oriented crack‑bridging fibers affects composite behavior. Conditions for steady‑state and multiple cracking depend on two nondimensional parameters that capture all relevant micromechanical properties, yielding a general failure‑mechanism map that predicts various uniaxial load‑deformation behaviors for discontinuous‑fiber composites.

Abstract

This paper analyzes the pseudostrain‐hardening phenomenon of brittle matrix composites reinforced with discontinuous flexible and randomly distributed fibers, based on a cohesive crack‐mechanics approach. The first crack strength and strain are derived in terms of fiber, matrix, and interface micromechanical properties. Conditions for steady‐state cracking and multiple cracking are found to depend on two nondimensionalized parameters that embody all relevant material micromechanical parameters. The results are therefore quite general and applicable to a variety of composite‐material systems. Phrased in terms of a failure‐mechanism map, various uniaxial load‐deformation behaviors for discontinuous fiber composites can be predicted. The influence of a snubbing effect due to local fiber/matrix interaction for randomly oriented crack‐bridging fibers on the composite properties is also studied.