A Mechanistic Approach to Matrix Cracking Coupled with Fiber–Matrix Debonding in Short-Fiber Composites

Abstract

A micro–macro mechanistic approach to damage in short-fiber composites is developed in this paper. At the microscale, a reference aligned fiber composite is considered for the analysis of the damage mechanisms such as matrix cracking and fiber–matrix debonding using the modified Mori–Tanaka model. The associated damage variables are defined, and the stiffness reduction law dependent on these variables is established. The stiffness of a random fiber composite containing random matrix microcracks and imperfect interfaces is then obtained from that of the reference composite, which is averaged over all possible orientations and weighted by an orientation distribution function. The macroscopic response is determined using a continuum damage mechanics approach and finite element analysis. Final failure resulting from saturation of matrix microcracks, fiber pull-out and breakage is modeled by a vanishing element technique. The model is validated using the experimental results found in literature as well as the results obtained for a random chopped fiber glass–vinyl ester system. Acoustic emission techniques were used to quantify the amount and type of damage during quasi-static testing.

Micromechanical modelling and simulation of chopped random fiber reinforced polymer composites with progressive debonding damage

“…In this final stage, extremely complex interactions between various damage mechanisms occur. This can be reproduced numerically by a vanishing element technique as suggested by Tvergaard (1986) and Nguyen et al (2005). This consists in reducing gradually the material stiffness at the integration point.…”

“…A damage model based on a self-consistent framework was proposed by Nguyen and Khaleel (2004). Nguyen et al (2005) proposed a modelling based on the Mori-Tanaka model. The stiffness reduction induced by damage is introduced by exponential or polynomial functions of the damage variable coupled to the stiffness of the virgin material.…”

Transverse cracking of orthotropic composite laminates: a fracture mechanics approach

“…In particular, the stress field in angle-ply fiber-reinforced composite laminates is solved [4] for the case of multiple cracks. Strengths and matrix cracking in composites under tension and shear have been predicted in [5]; gradual failure of fibre/polymer laminates was investigated in [6]; matrix cracking interacted with fibre-matrix debonding in short-fiber composite materials was studied in [7]; the effect of transverse matrix cracking on the performance of cross-ply laminates has been evaluated in [8]; intra-laminar and inter-laminar progressive failure analyses of composite panels with circular cutouts have been conducted in [9]; the effects of constituent scale on stress transfer and matrix cracking have been considered in [10]; stiffness reduction of cracked cross-ply laminates has been analyzed in [11]; prediction of ply crack formation and failure in laminates has been made in [12]. Moreover, Gudmundson and Alpman [13] tried to establish initiation and growth criteria for transverse matrix cracks in composite laminates; Adolfsson and Gudmundson [14] investigated matrix crack initiation and progression in composite laminates subjected to bending and extension.…”

Multiple cracking of fiber/matrix composites—Analysis of normal extension

“…In particular, the problem of matrix cracking has been investigated by many authors. For example, in situ strengths and matrix cracking in composites under tension and shear have been predicted by Camanho et al (2006); gradual failure of fiber/polymer laminates was investigated by Knops and Bogle (2006); matrix cracking interacted with fiber-matrix debonding in short-fiber composite materials was studied by Nguyen et al (2005); effect of transverse matrix cracking on the performance of cross-ply laminates has been evaluated by Qu and Hoiseth (1998); intra-laminar and inter-laminar progressive failure analyses of composite panels with circular cutouts have been conducted by Goyal et al, 2004; effects of constituent scale on stress transfer and matrix cracking have been considered by Karbhari (1992); stiffness reduction of cracked cross-ply laminates has been analyzed by Hashin (1986); prediction of ply crack formation and failure in laminates has been made by McCartney (2002). Moreover, Razvan and Reifsnider (1991) studied the fracture behavior and strength degradation of unidirectional graphite epoxy composite-materials; Gudmundson and Ostlund (1992) predicted the thermoelastic properties of composite laminates with matrix cracks; Adolfsson and Gudmundson (1999) investigated matrix crack initiation and progression in composite laminates subjected to bending and extension, and Gudmundson and Alpman (2000) tried to establish initiation and growth criteria for transverse matrix cracks in composite laminates.…”