ABSTRACT
ABSTRACT: Delamination is an important damage pattern in composite laminates and has a great damaging influence on the mechanical properties of composite structures. In this paper, carbon fiber reinforced bismaleimide resin prepregs were used to fabricate the quasiisotropic composite laminates with pre-inserted delamination through autoclave process. Then ultrasonic C-scanning was adopted to study the delamination propagation and the effect of pre-inserted delamination on the damage behavior of the composite laminates. The results show that (1) In the case of h > 2.034 mm, where the PTFE film was pre-inserted above layer 18, the delamination damage initiated and propagated in plane obviously at the same depth with the pre-inserted delamination. (2) In the case of 1.356 < h < 2.034 mm, where the PTFE film was pre-inserted between layer 12 and layer 18, there was merely damage propagation before ultimate failure. (3) The ultimate damage of the quasi-symmetric laminates occurred at h = 2.034 mm (1/4 thickness of the laminates). (4) The delamination was more sensitive to compressive stress than tensile stress.
