Interlaminar shear failure mechanism

Parry TV, Wronski AS, Kinking and tensile compressive and interlaminar shear failure mechanisms in cfrp beams tested in flexure, J Mater Sci, 16,439-450, 1081. 

The properties of the Nicalon /SiC (PIP) system followed a similar pattern (A/c(ou) = 400°C, A rc(omc) = 500°C), though this system failed through an interlaminar shear failure process (delamination) and the property reduction saturated at A T= 600°C. The Nicalon /SiC (CVI) system failed by fracture through fibre planes but its properties (ou, omc, WOF) had the same critical temperature difference, A Tc = 700°C. The pre- and post-quench stress-displacement curves for this material can be seen in Fig. 15.9. However, measurement of the Young s modulus of this system before and after quenching by means of a dynamic mechanical resonance technique showed the onset of decrease at ATC(E) = 400°C, i.e. significantly lower than the A 7C of the other properties. 

In research as well as there in industry, delamination during drilling FRP is recognized as one of the most critical problems. As defined by various researchers, it is an interlaminar or inter-ply failure phenomenon or behavior. When occurred at the topmost surface ply around the drilled hole periphery, it is called peel-up delamination or simply hole entry delamination of the composite workpiece. In addition, this interlaminar shearing of the last ply at the bottommost surface of the FRP composite material is usually more severe and is generally called push-out delamination or in simple words hole exit delamination. Delamination can be introduced by three mechanisms peeling up of the topmost layer, pushing out of the bottommost layer, and an additional cause, called thermal stress mode. 

However, a severe and persistent problem in laminated composites made of anisotropic fiber-reinforced plies is delamination. High interlaminar peel and shear stresses near edges start delamination cracks that grow along the non-reinforced interlaminar planes with little resistance. Delamination substantially reduces the load-bearing capacity and durability of advanced composites and has led to disastrous structural failures. Since the discovery and explanation of the mechanisms of delamination in advanced composites in the early 70s, many researchers have tried to... 

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