RESIDUAL PROPERTIES OF AN INJECTION-MOLDED POLY(PHENYLENE ETHER KETONE) CARBON COMPOSITE DURING FLEXURAL FATIGUE

The present work investigates the effects of cyclic fatigue loading on the residual properties of an injection-molded composite, carbon-fibe r-reinforced poly(phenylene ether ketone) (CF/PEK-C), and damage devel opment in this material under fatigue lending. Test specimens, which h ad been conditioned to various preselected fatigue damage stages, were measured for their residual properties. The results indicated that cy clic fatigue loading alters the constitutive behavior of the injection -molded composite, especially in the non-linear portion of the stress/ strain curve. The residual strength decreases with increase in the num ber of fatigue cycles as a consequence of the accumulation of fatigue damage, which is dominated by the growth of microcracks. While the res idual modulus increases slightly with cyclic fatigue loading, this is probably due to the oriented hardening resulting from creep deformatio n which is induced during cyclic loading. (C) 1997 Elsevier Science Li mited.