Tabakalı kompozit malzemelerin zımba kayma ve darbe davranışlarına termal etkiler

Composites are widely used in many applications thanks to their high strength-weight ratio. Transverse loading can cause serious damage to composite materials such as delamination, fiber breakage and matrix cracking. In this study, the thermal effects on punch shear and low velocity impact behaviors of laminated composite materials were investigated. The punch shear apparatus was fabricated in accordance with the previous researches and the quasi-static tests (QST) were performed by using Universal Shimadzu Tensile Testing Machine with the designed apparatus. Various speeds of crosshead as 1 mm/min., 10 mm/min., 20 mm/min, 40 mm/min and 60 mm/min were chosen for quasi-static tests. Low velocity impact (LVI) tests were carried out by using CEAST Fractovis Plus impact test machine at four different impact energies, 20J, 30J, 50J, and 80J. S2 glass/epoxy and hybrid carbon-kevlar/epoxy composite specimens with dimensions of 100x100 mm were used for both QST and LVI tests. Flat-nose and hemispherical nose impactors with a cylindrical punch diameter of 12.70 mm were mounted to the test machines. The tests were firstly performed at room temperature (23°C) and after with varied degree of temperature namely 40°C ,60°C and 80°C, in order to observe the effects of the temperature. After the experiments, the load-displacement graphs were plotted and the absorbed energy determined. The results of quasi-static punch shear test were compared to those of the low-velocity impact test and conclusion drawn.