Design and Optimization of Defense Hole System for Hybrid Loaded Laminates

Abstract

Stress concentration associated with circular holes in hybrid loading (i.e., tension-compression ratios of 0.25, 0.50, and 0.75) achieved maximum reduction of 31.7%. This reduction is obtained by introducing elliptical defense holes along the principal stress direction. Finite element analysis is used to optimize the size and location for defense hole system. The effect of the stacking sequence, the fiber orientation, and the stiffness of both the fiber and the matrix are investigated.

Reduction of the Local Stress Field around Holes through Porous Shaped Structures

“…Meguid [8] introduced the so-called defense hole system in a uniaxially loaded plate with a reduction of 7.5-11 % of the stress concentration factor. In addition, other authors employed the defense hole systems for reducing the stress concentration factor [9], [10]. Jindal [11] investigated the influence of auxiliary holes on the static stress concentration around a central hole numerically by the finite element method (FEM) and experimentally by a two-dimensional photo-elastic method.…”