Date of Award

Summer 1994

Document Type


Degree Name

Master of Science (MS)


Mechanical & Aerospace Engineering


Engineering Mechanics

Committee Director

R. Prabhakaran

Committee Member

Chuh Mei

Committee Member

James W. Sawyer


Mechanical properties of composite materials under shear loading are difficult to determine. The Iosipescu Shear test, originally proposed for metals, has in recent years been applied to composites. It has the advantages of small specimen size, simple loading and a reasonably uniform shear stress in the test section.

The purpose of this work is to study the validity of the Iosipescu test method for measuring the shear modulus and shear strength of composites. Finite element analyses indicate that optimum specimen geometry and load locations depend upon the degree of orthotropy of the composite. Test results for a quasi-isotropic graphite/epoxy laminate show that modifications in the notch geometry aimed at improving stress distributions result in unexpected changes in the failure mode. Thus, while the Iosipescu Shear test is valid for some composites with a suitable choice of test parameters, its validity for other composites, especially with a higher orthotropy, is doubtful.


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