Expe rime ntal Damage Evolution and Failure Me chanis ms in GFRP Compos ite Laminate s with Ope n Hole s

In the pres ent s tudy, effects of the geometric dis continuity, here is a circular hole in a laminate, on the damage progres s ion and failure mechanis ms of the glas s /epoxy general s ymmetric compos ite laminates are inves tigated. Different damage mechanis ms in micro -s cale including matrix cracking, delamination and fiber fracture caus e the failure of laminates . The s tres s -s train data for s amples with cros s -ply and quas i-is otropic layup configurations under quas i s tatic uni-axial tens ile dis placement control loading condition are obtained. The s tacking s equence and thicknes s effects on the s trength of the laminates are inves tigated. The experimental obs ervations s how that by increas ing t he number of off-axis plies in cros s ply laminates and by doubling the number of plies in quas i-is otropic laminates the s trength is reduced. For thes e laminates , at applied s train of about 0.3~0.4% , the s tres s -s train curve is bended and the s tiffnes s of the laminate is reduced mainly due to the matrix crack evolution and delamination progres s ion in high s tres s concentration region near the hole. The final failure mechanis m for cros s ply laminates is fiber fracture while in others the pull out of off-axis plies caus es the rupture of the s pecimens .