A Failure Criterion for Laminates Governed by Free Edge Interlaminar Shear Stress

Abstract

Interlaminar shear stresses in balanced and symmetric laminates with free edges and failure due to these stresses were studied. It was shown that the average interlaminar shear stress τ xz near the free edge is linearly related to the mismatch of the extension-shear coupling of the top and bottom sublaminates separated by the interface of interest. A simple failure criterion based on the mismatch of the extension shear coupling was introduced to predict laminate failure stress and strain. The validity of this criterion was verified by experiments using AS4/3501-6 graphite/epoxy composite laminates.

Interlaminar Stress Concentrations in Layered Structures: Part I - A Selective Literature Survey on the Free-Edge Effect since 1967

“…In the case of the considered ½AE Slayups the thermal stresses had a strengthening effect on the ultimate load of the laminate. Joo/Sun [87] devoted their work to the delamination behaviour of laminates whose interlaminar stress fields are dominated by interlaminar shear stresses and applied some mesh refinements in the free-edge regions. In 1993, Kress [88] applied elements of the serendipity class and used mesh refinements in the vicinity of the free laminate edge.…”

“…Since it is felt that the experimental observation of free-edge effects and the conduction of corresponding failure analyses is a very special field and worth a separate review work, we will only cite some references on this topic, yet we will not go into more details. The interested reader may refer to some experimental studies reported in for example [4][5][6]10,12,37,58,68,72,81,87,88,120,[124][125][126] and may consult further references cited therein.…”

Free-corner Effects in Cross-ply Laminates: An Approximate Higher-order Theory Solution

“…A broad variety of methods has been used here as well, ranging from the finite-difference method (this mainly concerns older works, see [35][36][37][38][39]) or the finite-element method with standard or special-purpose elements (for a selection of papers and reports see e.g. [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]) to miscellaneous other methods, see [56,57] for example. The nature of the stress singularities directly at the free edge has been the topic of discussion in the papers [58][59][60][61][62][63][64][65][66][67].…”

A mesh-independent interface technology for simulation of mixed-mode delamination growth

“…Their methodology for predicting delamination employs simultaneously strength and fracture mechanics approaches. Joo and Sun (1994), Ko et al (1992), Mohammadi et al (1998), Zhao et al (1999) and Chang and Springer (1986) predicted delamination initiation by a strength approach very similar to the one of Chakraborty and Pradhan (1999). A three-dimensional finite-deformation cohesive element and a class of irreversible cohesive laws was developed by Ortiz and Pandolfi (1999) and Pandolfi et al (1999).…”