%0 Journal Article %T Analysis of Free Edge Stresses in Composite Laminates Using Higher Order Theories %A Hamidreza Yazdani Sarvestani %A Ali Naghashpour %J Indian Journal of Materials Science %D 2014 %R 10.1155/2014/253018 %X This paper presents the determination of the interlaminar stresses close to the free edges of general cross-ply composite laminates based on higher order equivalent single-layer theory (HESL). The laminates with finite dimensions were subjected to a bending moment, an axial force, and/or a torque for investigation. Full three-dimensional stresses in the interior and the boundary-layer regions were determined. The computed results were compared with those obtained from Reddy¡¯s layerwise theory. It was found that HESL theory predicts precisely the interlaminar stresses near the free edges of laminates. Besides, high efficiency in terms of computational time is obtainable when HESL theory is used as compared with layerwise theory. Finally, various numerical results were presented for the cross-ply laminates. Also design guidelines were proposed to minimize the edge-effect problems in composite laminates. 1. Introduction Laminated composite materials are being used in several industries due to their high strength-to-weight ratio and stiffness-to-weight ratio. However, they are susceptible to different types of damage such as delamination which occurs due to high stress concentration near the edge of composite laminates. These stresses are induced by mismatch in elastic properties between adjacent plies of composite laminates [1]. It has been shown that the state of stresses in the edge zone of the laminate is three-dimensional (3D) in nature. Many attempts have been made to compute these stresses next to laminate¡¯s free edges [1¨C12]. However, because of intrinsic complexities involved in the problem, no exact solution is known for elasticity equations. Therefore, many approximate methods used to determine the interlaminar stresses are recorded in the survey paper by Kant and Swaminathan [3]. Based on a laminated model containing anisotropic layers, the first approximate solution of interlaminar shear stresses was presented by Puppo and Evensen [4]. Other approximate analytical methods used to examine the problem are the employment of the higher order plate theory proposed by Pagano [2], the perturbation technique by Hsu and Herakovich [5], the boundary-layer theory by Tang and Levy [6], and the approximate elasticity solutions by Pipes and Pagano [7]. An approximate theory is also utilized by Pagano [8, 9] based on assumed in-plane stresses and the use of Reissner¡¯s variational principle. The principle of minimum complementary energy and the force balance method are used by Kassapoglou and Lagace [10] to study the symmetric laminates under uniaxial loading. %U http://www.hindawi.com/journals/ijms/2014/253018/