Full-field analysis of notch effects of 3D carbon/carbon composites

Carbon fiber reinforced carbon matrix composites (C/Cs), as important candidate aviation and aerospace materials, have good prospects for application in extreme environments. However, notch effects of C/Cs have not been studied adequately. In this work, the notch effects of 3D-C/C composites were investigated by the full-field measurement digital image correlation method. Six kinds of specimens with different notch patterns including one central hole, multi-holes, and double edge notches, were examined to analyze their mechanical properties. The tests were carried out on MTS 809 testing machine and the deformations of specimens were monitored by a CCD camera. Using the full-field measurement, both the local mechanical properties (stress concentration, shear damage, and fracture behavior) and the globe properties (notch sensitivity and tensile behavior) were studied. The results indicated that the fracture stress on the net cross section was constant and it was independent on the material heterogeneity, notch patterns, and notch depth.