Relaxation-Controlled Cyclic Delamination Growth in Advanced Thermoset and Thermoplastic Composites at Elevated Temperature

Abstract

In this investigation, cyclic Mode I delamination growth characteristics of unidirectional carbon/epoxy and carbon/polyetheretherketone (PEEK) composites at an elevated temper ature (200°F) were studied. The cyclic delamination growth behavior of the composites was found to be significantly different than their known response at room temperature under load-controlled condition. For both the composites, the elevated temperature response was found to be dominated by process zone formation and growth ahead of the delamination crack. The elevated temperature delamination growth behavior in these ad vanced composites was shown to be best described by a relaxation-controlled process zone growth model.