Comparison of woven and stitched out-of-autoclave E-glass/epoxy composites subjected to quasi-static and cyclic tensile loads

Tensile quasi-static and fatigue behaviors of out-of-autoclave, quasi-isotropic, E-glass/epoxy composites with woven and stitched fiber architectures are compared. Some specimens were cyclically loaded to failure, while others were tested for residual modulus and ultimate strength. Both laminates survived 10⁷ cycles at a maximum stress of 94.8 MPa but failed prior to 10⁷ cycles at a maximum stress greater than or equal to 124.1 MPa. For the stress-lifetime diagram and residual strength, the woven laminate had superior properties below 10⁴ cycles and the stitched laminate had superior properties above 10⁵ cycles. While intralaminar crack density was higher in the stitched laminate, the woven laminate demonstrated a higher percentage of delaminated area.