Effect of maximum load on cyclic crack growth in UD E-glass/vinyl ester composites with constant and alternating stitch density

Abstract

Abstract DCB specimens, manufactured from composites with constant and alternating stitching density, are tested under pure mode I for static and cyclic loading. The tests are carried out for different maximum load values, but keeping the same R-ratio. The crack growth is recorded from pictures at different cycle intervals, and the energy release rate (ERR) is computed using an approach based on the J-Integral. Along with the crack-tip, the length of the fracture process zone (FPZ) is recorded with the number of cycles. A curve relating the crack growth rate (CGR) and the cyclic fracture resistance, ΔJ, which can be directly applied in the design/repair process of composite structures, is derived.