Biaxial Flexing of a Unidirectionally Reinforced Aluminum Composite

Abstract

Aluminum disks reinforced unidirectionally with silicon carbide con tinuous fiber were supported circumferentially on one side and loaded at the center of the other side with a pin. Maximal principal tensile surface strains were determined during flexing with strain gages. Failure under monotonic loading initiated on the convex side of the disks with the for mation of multiple surface matrix cracks which were parallel to the fibers. These cracks formed soon after matrix yielding which initiated at a strain 0.0015-0.002. On cyclic ten sile biaxial flexing, surface matrix cracking was found to be the main failure mechanism. A limited number of disks failed by fiber cracking. The endurance strain limit for 107 cycles of life was 0.001. This strain is only 11 % of the uniaxial monotonic tensile strain to failure. Ultrasonic velocity scans successfully identified the damage generated during cyclic loading.