Abstract
Failure of composite materials may often occur as a result of local delaminations. The double cantilever beam (DCB) and the end notched flexure (ENF) tests are employed in an investigation of the critical interlaminar strain energy release rate in mode I, G sub IC , and mode II, G sub IIC , loading conditions of various fabric reinforced thermoplastic composite materials. In addition a unidirectional epoxy matrix composite and fabric reinforced epoxy matrix composite were tested, in order to find out differences in fracture behavior. The influence of different data reduction methods on the value of interlaminar fracture toughness is discussed. The interpretation of the test results was performed from observation made during the tests. The influence of the geometry of reinforcement, resin toughness and type of fibers is discussed.