Response of an Alumina Fiber Reinforced Aluminum Composite to Combined Tension-Torsion
ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
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The introduction of fiber reinforced composites in structural design has generated the need to develop new test procedures for rating these materials. The assessment of the performance of such composites under combined tensile-torsional loading should increase their reliability. Specimens such as the cruciform, the thin wall cylinder, and the center cracked plate have been used extensively to investigate the response of isotropic materials to biaxial loading. These specimens, however, may not be appropriate for all types of fiber reinforced composites. It has been shown that, in certain composites, premature failure by fiber debonding can occur at points of stress concentration or where there is a change in the specimens contours. Because of these trends, the cruciform and the center cracked plate could be poor candidates for combined tensile-torsional testing of fiber reinforced composites. On the other hand, the thin wall cylindrical specimen could be promising for certain applications e.g. pressure vessels. Aluminum coupons reinforced unidirectionally with continuous alumina fibers were loaded in combined tension-torsion. Experimental results indicated that the superimposition of a 0.0025 shear strain reduced the tensile strain to failure by 67. Similarly, the superimposition of a 0.0007 tensile strain reduced the shear strain to failure by 81.
- Laminates and Composite Materials