On the tension strength of carbon/epoxy composites in the presence of deep scratches

Fiber reinforced plastic composites are currently used in structures operating in a variety of environments where various forms of damage may occur. One form of possible damage in composite structures can be in the form of deep scratches causing a discontinuity in the load bearing plies. These scratches may occur accidentally by abrasion of the composite structure on a sharp object during normal operating conditions. Scenarios for these possibilities are discussed in the aerospace environment. Experimental and numerical studies performed show altered failure modes and J-Integral mode mixity affecting the tension behavior of the carbon/epoxy composites examined.

► We model the effects of deep scratches on fiber-reinforced plastics as function of layup and interface plys.
► We perform experiments on aircraft grade carbon/epoxy composite.
► We perform experiments showing initiation and failure loads affected by interface at base of scratch.
► J-Integral values in 3D models indicate large degree of mode mixity along crack front.
► Delamination failure mode aggravated by loss of symmetry in laminate caused by scratches.