Assessment of Residual Tensile Strength of Carbon/Epoxy Composites Subjected to Low-Energy Impact

Abstract

This paper presents the results of an experimental study to investigate the effects of impact loading on the residual tensile strength of woven graphite epoxy laminates with a toughened resin system. In this study, both cross-ply, [0∕90]6, and angle-ply, [±45]6, laminate lay-up configurations were studied and compared. Test specimens were subjected to various levels of impact loading, after which tensile pull tests were performed to determine the residual tensile strength properties. The study results demonstrated that impact damage causes a significant reduction in tensile strength properties of woven cross-ply [0°/90°] laminates. For example, cross-ply laminated composite specimens subjected to the lowest impact level, 6.8J, exhibited a 25% decrease in ultimate tensile strength. Angle-ply woven laminates [±45°], however, exhibited an 18% increase in ultimate tensile strength after being subjected to 6.8(J) impact. This characteristic of increasing tensile strength in [±45°] specimens is an example of increased fiber reorientation in composite laminates with limited fiber damage.