FAILURE ENVELOPES FOR NOTCHED CSM LAMINATES UNDER BIAXIAL LOADING

The failure strength and characteristics of plain and notched E-glass chopped strand mat (CSM) reinforced polyester laminates, subject to un iaxial and biaxial loading, are investigated. Flat plate square specim ens are tested in a novel, specially designed test rig which enables i ndependent tension/tension, tension/compression and compression/compre ssion testing in all stress quadrants. The influence of altering the l oading history on the failure strength is discussed. Biaxial failure e nvelopes are presented for plain specimens and for notched specimens, i.e. D/W = 0.27, 0.214, 0.178, 0.07. Results for the plain specimens a re compared with the maximum stress, maximum strain, maximum shear str ess and the quadratic interactive stress criterion. A finite element a nalysis is performed to predict the residual strength of the notched s pecimens.