M.R Khoshravan Azar - Professor, Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran
H Rostamkhanlou - Master of science in Mechanical engineering, Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran

In this research fracture behavior of composite material was investigated in mode III. Test bars with theshape of ECT (Edge Crack Torsion) specimen were made to evaluate strain energy release rate by using compliancecalibration method in mode III loading. Hand lay-up method has been used to make composite specimens with 24layers of 2D woven glass fibers with 51% fiber volume fraction and ML506 epoxy resin as the matrix. Tests on thesesspecimen were carried out on mode III and results were obtained. Then, another set of specimens were made by addingnanosilica particles to evaluate its influence on strain energy. In result the curve of strain energy release rate versuscrack length have been drawn. Influence of different initial crack lengths have been evaluated. Results showed that byadding nanoparticles, the interlaminar fracture energy in the third mode enhanced about 23% compared to the neatcomposites.

composite, delamination, Mode III, energy release rate, nanoparticles