Date of Award

3-2000

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Anthony N. Palazotto, PhD

Abstract

A higher-order shell theory is used to analyze compressive and tensile loads on a graphite/epoxy laminated cylinder containing a square cutout. The Hashin failure criterion is used to determine failure in the fiber, matrix, or lamination. Once failure occurs, the appropriate stiffness terms are reduced. This failure causes a redistribution of stress, leading to further failure. In order to account for the loss of residual strength due to cyclic loading, the stiffness matrix is further reduced at each new increment of load or displacement. The objective is not to determine the S-N curve for the material, but rather to determine the damage, displacement, and stress distribution in a complex configuration under fatigue loading using a progressive failure and stiffness reduction approach. The failure progression for static loads is determined and used as an indicator for the cyclic loads. It is shown that as the stiffness decreases, the global displacements increase, resulting in more failure until the entire panel fails.

AFIT Designator

AFIT-GAE-ENY-00M-03

DTIC Accession Number

ADA380342

Comments

The author's Vita page is omitted.

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