NOTCHED STRENGTH PREDICTION OF CENTER-HOLE CARBON CARBON COMPOSITES/

The present work investigates the behaviour of 2D carbon/carbon (CIC) composites containing centre holes and proposes methodologies for the prediction of the residual strength of such C/C laminates. Two differe nt concepts were adopted in order to understand the fracture behaviour of CIC composites in the presence of holes and to evaluate their stre ngth. The first approach is based on the hypothesis of the existence o f a damage zone around the hole, which originates during tensile loadi ng. The second uses monitoring of the acoustic emission (AE) activity of the centre-hole specimen, loaded up to a stress level well below it s failure strength, as an indication of damage formation, and combines it with a defined calibration curve. Both models predict very accurat ely the strength of notched laminates for a number of specimens tested . (C) 1998 Elsevier Science S.A. All rights reserved.