MODE I DELAMINATION FAILURE OF FIBERGLASS COMPOSITES UNDER QUASI-STATIC AND IMPACT FATIGUE LOADING

摘要

The present paper studied delamination in Mode I under quasi-static and impact fatigue conditions. The material tested was a glass/Vinylester composite, manufactured by hand lay-up with different types of fabrics (Matt and Woven Roving). Delamination was carried out employing DCB (Double Cantilever Beam) samples configuration under quasi-static and impact fatigue conditions. Samples with a single crack front (principal crack) and samples with a second defect located between different plies respect to the principal crack were tested for booth load conditions. A quasi-static test was performed under ASTM D5528 standard and GIc values were obtained for the material. A dynamic test was carried out with an in-house Drop Weight Impact Testing Machine applying low energy repetitive impacts to simulate the impact fatigue and crack growth rate. Maximum energy release rate plots were obtained in order to find the Gth value. Transient effects that could be affecting GI parameter in dynamic conditions were not considered. The results obtained from the quasi-static test showed a difference in GIc values depends on the induced delamination location. Results for samples with a second defect showed that this defect affects the delamination when it is located between plies with different GIc. Finally, in dynamic conditions, a low Gth value of 23.68 J/m~2 was obtained.