Influences of thermal cycling and low-energy impact on the fatigue behavior of carbon/PEEK laminates

[[abstract]]Effects of low-energy impact and cyclic thermal loading on fatigue behavior of carbon fiber reinforced polyetheretherketone (carbon/PEEK) laminates have been examined. The fatigue behavior of the virginal composites, low-energy impacted composites, and low-energy-impacted and thermally exposed composites were investigated. Cyclic thermal loading was performed in the temperature range between 60 and -60 degrees C. Residual tensile strength was measured to aid in understanding the influence of low-energy impact on the retention of tensile strength. Fatigue testing involved a stress ratio of 0.1, with a frequency of 3 Hz. The Weibull distribution function was used to evaluate the ultimate tensile strength and fatigue life. S-N curves were plotted and the influence of thermal cycling and the low-energy impact on the fatigue sensitivity of the carbon/PEEK laminates was investigated. Stiffness variation during fatigue testing was monitored and differences in stiffness reduction for three rest conditions were compared. C-scan was used to investigate the damage zone under different low-energy impacts and to understand damage propagation during fatigue testing. Moreover, scanning electron microscopy (SEM) was used to examine the fracture morphologies of carbon/PEEK composites in both tensile failure and fatigue failure conditions. (C) 1999 Elsevier Science Ltd. All rights reserved.[[fileno]]2020226010011[[department]]動機