Stress analysis of finite anisotropic plates with cutouts under displacement boundary conditions

XI CONGRESO NACIONAL DE MATERIALES COMPUESTOS. Celebrado en Móstoles los días 6, 7 y 8 de julio de 2015The aim of this article is to provide an analytical tool to estímate the stress concentration in anisotropic plates weakened by a circular or elliptical hole; it is achieved by developing Lekhnitskii formalism in order to allow fínite boundary effects to be added (original formulation considers infinite plates). Only membrane problem is herein considered, particularly when prescribed displacements are applied at externa! boundaries, which could simulate boundary conditions of a manhole structure between wing spars. A boundary collocation method in conjunction with a least squares approach is used to solve the problem.Ministerio de Economía y Competitividad de España DPT2012-3718

Closed-Form Methodology for the Structural Analysis of Composite Plates With Cutouts

The use of composite materials in the aerospace industry shows an increasing tendency due to its excellent specific mechanical properties. The long fibre reinforced polymers are well suited for its application in plate and shell structures. These structures are commonly weakened by cutouts of different shapes, which provide access to the internal systems and structures, allow system integration, or simply reduce the weight of the structure. These cutouts lead normally to a concentration of stresses around them, that requires a thoroughly analysis in order to provide an optimum design of the component. To this end, it is usual to perform a structural analysis on the basis of the methodologies in the existing literature: FEM, BEM and closed-form formulations. The closed-form formulations provide a simple and powerful tool for the first phases of the component's design, considering that they are well suited for the resolution of parametric analyses with a competitive amount of computational power compared to FE methodologies. However, these formulations have a limited application, since they rely on a set of hypotheses that should be taken into account, e.g. analytical formulations are solved by assuming that the plate under study is infinite in comparison with the cutout. The main objective of the present dissertation is to develop a closed-form formulation that allows the stress analysis of composite panels with cutouts, and that simulates as detailed as possible the real features that are found in aeronautical parts. In this regard, the formulation must allow, among other features, the introduction of local reinforcements, non-uniform lay-ups over the panel, and the inclusion of stiffeners