Experimental investigation on the effects of fiber orientation on translaminar fracture toughness for glass-epoxy composite under mixed Mode I/II load

In this paper, the effects of fiber orientation on translaminar fracture toughness of a glass-epoxy composite laminate were evaluated using a compact tension shear (CTS) mixed mode (I/II) fracture specimen. Unidirectional (UD) glass fiber laminates of 0° and 0/90° orientation were considered for the experimental work. The fabrication of the CTS mixed mode (I/II) fracture specimen plates of thickness 9mm for various fiber orientations were done using hand lay-up technique. The CTS specimens of various fiber orientations are machined to form composite plates. The experimental study conducted for CTS specimen was of seven loading angle varying from 0° (mode-I) to 90° (mode-II) with an increment of 15° for various fiber orientation. Experimentally evaluated peak loads from CTS mixed mode (I/II) fracture specimen for various fiber orientations and loading angle are utilized to estimate the translaminar fracture toughness. The experimental results of translaminar fracture toughness of unidirectional (UD) glass fiber shows higher for 0/90° as compared with 0° fiber orientation and highly dependent on loading angle. The factography study clearly indicates that the crack initiation/direction depends on the loading angle.