Fracture Mechanics Analyses for Interface Crack Problems - A Review

Abstract

Recent developments in fracture mechanics analyses of the interfacial crack problem are reviewed. The intent of the review is to renew the awareness of the oscillatory singularity at the crack tip of a bimaterial interface and the problems that occur when calculating mode mixity using numerical methods such as the finite element method in conjunction with the virtual crack closure technique. Established approaches to overcome the nonconvergence issue of the individual mode strain energy release rates are reviewed. In the recent literature many attempts to overcome the nonconvergence issue have been developed. Among the many approaches found only a few methods hold the promise of providing practical solutions. These are the resin interlayer method, the method that chooses the crack tip element size greater than the oscillation zone, the crack tip element method that is based on plate theory and the crack surface displacement extrapolation method. Each of the methods is validated on a very limited set of simple interface crack problems. However, their utility for a wide range of interfacial crack problems is yet to be established.

Design and finite element assessment of fully uncoupled multi-directional layups for delamination tests

“…However, when multidirectional sequences are considered, complications arise, due to the fact that modal components of ERR, as obtained from VCCT, may be mesh dependent. 27 As explained in Krueger et al, 27 their computation may be a difficult task, involving a certain degree of uncertainty.…”

“…5,26 Furthermore, a strong dependence of the experimentally determined G c on ERR mode mixity was observed. 26,27 As VCCT allows to explicitly separate modal components of ERR, it has been widely used to study delamination in composite materials. 26 Using VCCT, the ERR modal components can be obtained at each node of the crack tip in a FE model; for further details the reader is addressed to Krueger.…”

Effect of the proximity to the 0°/90° interface on Energy Release Rate of fiber/matrix interface crack growth in the 90°-ply of a cross-ply laminate under tensile loading

“…13 Different approaches have been applied to model the initiation and growth of debonds. 14 The Cohesive Zone Model (CZM) has been used to mimic the propagation of debonds along fiber interfaces; coupled with a failure criterion for the matrix, it has provided simulations of the growth of transverse cracks starting from a virgin material. [15][16][17][18] The strength of the CZM, and its main requirement for a correct implementation, lies in the elimination of the stress and displacement singularity that exists at the crack tip in the Linear Elastic Fracture Mechanics (LEFM) solution, as the crack tip is not explicitly modeled and the failure process is ''smeared'' over the finite length of the cohesive element.…”

On the calculation of energy release rate and mode mixity in delaminated laminated beams

“…In particular, based on linear elastic fracture mechanics (LEFM), the energy release rate, G, is the most used parameter to predict the initiation and growth of delamination cracks. On one hand, analytical and numerical models are developed to compute the expected values of G in laboratory specimens or real structural components [6,7]. On the other hand, experimental techniques are used to assess the critical energy release rate, or interlaminar fracture toughness, c G , of specific materials [8].…”