Stochastic aspects of crack deflection and crack path prediction in short fiber reinforced polymer matrix composites

TL;DR

This paper investigates how the anisotropic and stochastic properties of short fiber reinforced polymer composites influence crack deflection and path prediction, using finite element simulations and statistical models.

Contribution

It introduces a stochastic modeling approach for crack path prediction considering fiber orientation fluctuations and material property variations.

Findings

Statistical fluctuations in fiber orientation affect crack deflection paths.

Finite element simulations reveal bifurcation phenomena in crack propagation.

Stochastic models improve accuracy of crack path predictions.

Abstract

Owing to the production process, short fiber reinforced composites exhibit a pronounced anisotropy of both elastic properties and crack growth resistance. In particular the latter issue has a major impact on crack deflection and inevitably has to be taken into account for the sake of an accurate prediction of crack paths. The perpendicular axes of transverse isotropy are associated with the fiber orientations, whereupon a crack in transverse direction encounters the largest fracture toughness. While the local mean fiber orientations in polymer matrix composites are determined by the injection molding process, their statistical fluctuations can approximately be described in terms of Gaussian random field models. Furthermore, statistical variations of the volume fraction of fibers and the fiber-matrix adhesion give rise to stochasticity of the local ratio of fracture toughness anisotropy. Influencing factors of prediction regions of crack paths obtained from finite element simulations with an adapted J-integral deflection criterion are investigated, just as stochastic aspects of bifurcation phenomena of crack deflection observed under mode-I loading.