Edge Effects in Angle-Ply Composite Laminates*

Abstract

This paper presents the results of a zeroth-order solution for edge effects in angle-ply composite laminates obtained using perturbation tech niques and a limiting free body approach. The general solution for [±θ] laminates is applied to the special case of a [±45]s graphite/epoxy lamin ate. Interlaminar stress distributions are obtained as a function of the laminate thickness-to-width ratio h/b and compared to finite difference results. The solution predicts stable, continuous stress distributions, determines finite maximum tensile interlaminar normal stress σz, and provides mathe matical evidence for singular interlaminar shear stresses τ xz and τyz in [±45] graphite/epoxy laminates.

Estimation of transverse/interlaminar stresses in laminated composites – a selective review and survey of current developments

“…Other approximate methods were also attempted to examine the problem such as extension of the higher-order plate theory [10] by Pagano [11], the perturbation method by Hsu and Herakovich [12], a boundary layer theory by Tang [13] and Tang and Levy [14], and approximate elasticity solutions by Pipes and Pagano [15]. Later, based on assumed in-plane stresses and the use of Reissner's variational principle, Pagano [16,17] developed an approximate theory.…”

Finite element analysis of free-edge stresses in composite laminates under mechanical an thermal loading

“…Some pioneering works involve the perturbation technique by Hsu and Herakovich [23], the boundary layer theory by Tang and Levy [11], and the approximate elasticity solution by Pipes and Pagano [24]. Mixed variational principle has been used along with stress assumption by Pagano [9].…”

Variational Formulation and Finite Element Implementation of Pagano's Theory of Laminated Plates

“…u(x) u°(x)+x 3 )+ (X )+x2,p (X )+x3 (x ) (8) u 3(X) = w(xB) (9) This idea was first proposed by Levinson [1980] for the homogeneous, isotropic plate and extended to the laminated composite plates by Bert [19841 Imposing the stress free plate surface conditions on this displacement field, two field variables …”