Constant amplitude fatigue of short glass and carbon fiber reinforced thermoplastics

The fatigue lives (i.e., the number of cycles to failure) of short fiber reinforced thermoplastic matrix composites were investigated. First, S-N curves were generated at stress ratios of R = 0 and R = - 1 for short glass fiber reinforced Copolyamide coupons with 0 degrees (30% or 50% fiber content by weight), 45 degrees (50% fiber content) and 90 degrees (30% or 50% fiber content) fiber orientations. Second, these S-N curves were compared to data reported in the literature for a wide range of short glass and short carbon fiber reinforced thermoplastics materials. On the basis of these comparisons, all available data were collapsed on two S-N curves, one for R = 0 and one for R = -1.