Study of the effect of mesh quality on stress concentration factor of plates with holes using finite element analysis

Abstract

In this dissertation, the effect of mesh quality on stress concentration factor in structural discontinuities has been investigated. The effect of mesh quality on stress concentration around the circular holes in an infinite plate subjected to uniform tensile force at the edges of the plate, which very much conforms to the structural problems faced in configuring the structures with discontinuity is highly significant. Because structural discontinuity problems are difficult to solve analytically, a leading general purpose finite element software NASTRAN-PATRAN has been presented to perform the analyses computationally. The main purpose of this thesis is to determine how structural discontinuities alter stress distributions and how the mesh quality influences these stresses. Different models have been used in this study with variable number and quality of elements from model to model. Four-node quadrilateral membrane element (2 degrees of freedom per node) has been used in meshing the computational domain. The mesh quality has been defined as a combination of two criteria such as element quality and enough number of elements in the mesh. The quality of the surface mesh should be good to get acceptable finite element results. Element quality is defined by two factors namely: Distortion factor and Aspect ratio. Based on these two factors an object oriented C++ program named “MESH QUALITY_2012” has been developed. The results have been shown in tabular form and graphically. The computed results show good agreement with the published theoretical results. Finally a correct meshing approach is prescribed to model structures with single or multiple holes which is essential for a finite element analyst.