Shear Fatigue Degradation and Fracture of Random Short-Fiber SMC Composite

Abstract

Cyclic degradation and fracture of a random short-fiber SMC composite subjected to shear fatigue was studied. Experiments were conducted on double V-notched Iosipescu SMC-R50 specimens under completely reverse cyclic shear loading. Owing to the random microstructure of the SMC-R50 composite, homogeneous fatigue damage was treated in a continuum sense. The cyclic shear stress-strain behavior was studied first. Macroscopic shear stiffness degradation and the rate of damage evolution during the shear fatigue were investigated also. Cyclic shear stiffness reduction up to 25 percent of its initial value was common in most cases studied. A power-law relationship among the rate of damage, the cyclic shear stress amplitude, and the fatigue loading history was determined. The shear-fatigue fracture, resulted from nonhomogeneous growth of fatigue damage, was well-behaved, and a cyclic shear stress-life diagram was constructed for the SMC-R50 material.

Compressive Stability of Delaminated Random Short-Fiber Composites, Part II—Experimental and Analytical Results

“…The letter R refers to randomly oriented, chopped fiber strands, and the number following indicates the weight percent of reinforcing fibers.) This particular short-fiber composite was used because its mechanical properties were readily available in the literature [2][3][4][5][6][7][8][9][10]. The reinforcement was OCF 433AB-114 roving glass filaments, chopped to a length of 25.4 mm (1.0 in.).…”

Effect of transverse clamping force on the tensile behavior of a novel pultruded carbon fiber–reinforced polymer joint: Fatigue test

“…After some time, enough sliding will have occurred and all free space between the CFRP plate and the steel plate will be occupied; thus, higher displacement results in higher accuracy. Wang et al (1984) found that the specimens responded to the continued cycling by exhibiting less resistance to the applied stress as indicated by the continuous change in shape and size of the hysteresis loops. The reduction in shear stiffness is observed owing to a continuous decrease in tangent (or secant) modulus measured from the load-displacement curves.…”

Fatigue Degradation in Centrally Notched Quasi-Isotropic Laminates

“…Until now many cumulative damage theories have ben proposed for the purposes of assessing fatigue damage caused by operation a' any given stress level and the addition of damage increment to predict failure under conditions of spectrum loading, for example, the linear damage theory, Marco-Starkey cumulative damage theory [5], Henry cumulative damage theory [6], and Hwang-Han cumulative damage theory [7]. The problems of stiff ness reduction, residual strength, fatigue life, and cumulative damage in composite materials have been investigated in References [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”