FRACTURE-MECHANICS ASPECTS OF COMPOSITE-MATERIALS

The applicability of the precepts of classical fracture mechanics to notched fiber-reinforced laminates was investigated. In center- and edge- notched on- and off-axis specimens of T300/914C material, the notch-opening displacements, specimen elongations and crack lengths were measured. A finite element technique was used to evaluate stress intensity factors and energy release rates for mode I and II. An interaction diagram was established for the crack initiation at the notch tip. A similar analytical approach to multidirectional laminates proved infeasible because of the complexity of the damaged zone. The measurement of notch-opening displacements showed, however, that limits of linear response, first pronounced jumps and final fracture are essentially the same in laminates with center- and edge-notches of different 2a/W ratios. The general applicability of current fracture models is questioned.