A concept for experimentally evaluating the effect of friction in the 4-ENF interlaminar toughness test

The 4-point end notched flexure test (4-ENF) has been proposed as a test me thod for measuring the Mode II interlaminar fracture toughness of laminated composites. However, like other Mode II test methods, there are compressiv e stresses acting across the delaminated interface and so the test results may be affected by friction. In this paper a strategy for experimentally es tablishing the significance of friction in the 4-ENF test is proposed and d etails of the fixture designed to implement this strategy are presented.