Three-dimensional analyses of ductile failure in metal reinforced by staggered fibres

Abstract

Ductile matrix failure in a metal reinforced by short parallel fibres is studied numerically in terms of full three-dimensional cell model analyses. The model is extended here, relative to the simplest possible cell, such that transversely staggered fibres are accounted for and such that effects of different sizes of two neighbouring fibres can be studied. The matrix material is described in terms of a porous ductile material model, which accounts for the nucleation and growth of voids to coalescence. Most predictions are based on an isotropic hardening model, but results for kinematic hardening are used to study the effect of a metal that forms a rounded vertex on the yield surface. The damage evolution tends to first show the formation of an open crack near the ends of the longer fibres, by void coalescence in the matrix, and subsequently a similar crack evolves near the ends of the shorter fibres.

Numerical modelling in non linear fracture mechanics

“…Continuations of the 3D fracture study have been carried out recently in analyses that do not directly focus on crack growth, e.g. the failure of a metal matrix composite [11] or of a Charpy V-notch specimen cut through a weld [12]. Some attempts to include a damage dependent material length scale in this constitutive model have been carried out by Leblond et al [13] and Tvergaard and Needleman [14], using an integral condition on the rate of increase of the void volume fraction.…”

Debonding or Breakage of Short Fibres in a Metal Matrix Composite

“…see Nutt and Needleman [8], Tvergaard [9,10] and Finot et al [11]. Three dimensional cell model analyses have been used to study ductile failure in the metal matrix between brittle fibres [12], also for cells containing different size fibres [13]. The axisymmetric models considering a number of different size fibres inside a cell are a generalization of the staggered fibre model in [9,10].…”