A general solution for stresses around holes in symmetric laminates using stroh formalism

Cutouts are required in the laminates for access to interior equipment or for maintenance requirements. In case of critical applications such as in aircrafts, ship decks, etc., the residual strength determination of such laminates is very important. Data on maximum stress and its location would be useful to prevent eventual catastrophic failures. However, it is essential to determine make a parametric study on the influence of various parameters such as, shape of hole, type of loading, and material anisotropy on the maximum stress. Several solutions are D.K. Nageswara Rao, M. Ramesh Babu, A. Srihari Rao, T.Srihari 2 available in the literature with varying degree of accuracy and complexity for determining the stresses around the cutouts. A brief review [1-6] on the salient features and limitations of various solutions available in the literature is presented. The present solution has the edge on the other solutions in the following aspects. This solution considers the shapes polygonal holes that have straight edges with small corner radius. Anisotropic and isotropic materials can be considered. A remotely applied inplane loading of any kind can be considered. Further, the equations are derived for a general kind of inplane loading that the same solution will yield the results for various types of inplane loading. A generalized form of mapping function is introduced into the basic Stroh formalism [7, 8] to obtain the results for any shape of hole. Results are obtained by introducing appropriate mapping function constants [9]. Arbitrary biaxial loading condition by Gao [10] is introduced in to the basic formulation The stress function for the given plate with a traction free hole and loading at infinity is obtained by superposing the stress functions for the plate without hole and uniform stress due to loading at infinity and the stress function for a negative loading on the boundary of the hole.