Biaxial Flexing of a Fiber Reinforced Aluminum Composite

Abstract

Disks of silicon carbide continuous fiber reinforced ([0°/90°] 4s ) aluminum were supported circumferentially on one side and loaded at the center of the other side with a pin. Maxima 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 formation of multiple breaks in the first layer of fibers. With further flexing cracking extended to inner fiber layers. Finally, fracture extended through the convex surface layer of the aluminum matrix. On cyclic flexing, fiber cracking was found to be the failure mechanism whenever the cyclic principal surface strain range was 0.0035 or greater. For cyclic strain ranges less than 0.0035, slip bands and cracks were formed in the matrix in addition to the cracks formed in the fibers. The cyclic strain range limit for 10 6 cycles of life was found to approach 0.0015. The latter limit corresponded to a maximum cyclic fiber strain of 0.00132, which is only 15 % of the fiber strain to failure under monotonic uniaxial composite loading.

Biaxial Flexing of a Unidirectionally Reinforced Aluminum Composite

“…The latter decrease caused an apparent increase in the slope of the load vs. strain curve. In an earlier publication [28] the biaxial tension-tension flexural loading of a [0°/90°]4s composite was investigated. In this composite there was not a principal strain gradient along the Y-axis; thus, shear matrix loading great enough to cause fiber debonding and surface matrix cracking parallel to the fibers did not develop.…”