On creep, recovery, and stress relaxation of carbon fiber-reinforced epoxy filament wound composites

Abstract

This work encompasses an analytical procedure and experimental tests for the study of creep/recovery, stress relaxation, and viscoelastic behavior, focusing on the glassy state, of carbon fiber-reinforced epoxy filament wound composites of distinct fiber orientation: [0]4, [30]4, and [60]4. The laminate with longitudinally aligned fibers did not show significant creep and its storage modulus was the highest in comparison to the other angles. Both creep and recovery responses were studied based on a Weibull distribution approach at two stress levels (2 and 5 MPa) and the results were found more comprehensive for the highest level. Stress relaxation modulus was calculated using 1% strain and decreased with the fiber orientation angle. The results were corroborated by those of isothermal tests based on non-linear regression.