ISSN: 0884-6804
Page Count: 9

Three-Dimensional Analysis of [0/90]^s and [90/0]^s Laminates with a Central Circular Hole
Raju, IS
Associate research professor and senior engineer, Joint Institute for Advancement of Flight Sciences, George Washington University, School of Engineering and Applied Science, NASA Langley Research Center, VA

Crews, JH
Associate research professor and senior engineer, Joint Institute for Advancement of Flight Sciences, George Washington University, School of Engineering and Applied Science, NASA Langley Research Center, VA

Abstract

Stress distributions were calculated near a circular hole in [0/90]^s and [90/0]^s laminates, using a three-dimensional finite-element analysis. These stress distributions were presented in three ways: through the thickness at the hole boundary, along radial lines at the 0/90 and 90/0 interfaces, and around the hole at these interfaces. The interlaminar normal stress σ^z and the shear stress σ^zϑ distributions had very steep gradients near the hole boundary, which suggested interlaminar stress singularities. The largest compressive σ^z stress occurred at about 60° from the load axis; the largest σ^zϑ occurred at about 75°. A simple procedure was introduced to calculate interlaminar stresses near the hole boundary. It used strains calculated by an exact two-dimensional analysis of a laminate with a hole as input to a quasi-three-dimensional model. It produced stresses that closely agreed with those from the three-dimensional finite-element model. For laminates with holes, this simple procedure may become a viable alternative to three-dimensional finite-element analyses.

Keywords:
composite materials, stress concentration, stresses, circular hole, three-dimensional finite-element analysis, interlaminar stresses, edge stresses

Paper ID: CTR10773J
DOI: 10.1520/CTR10773J
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