Towards an ASTM standardized test for determining G _IIc of unidirectional laminated polymeric matrix composites

Progress is described towards creating a standardized end-notched flexure test for determining the mode II delamination toughness of laminated, continuous fiber polymeric matrix composites. A methodology for creating static mode II precracks is presented and compared to approaches that use mode I or fatigue mode II loading. Numerical and experimental studies are used to choose a preferred data reduction method and the associated specimen and test geometries. It is shown that the combination of the above approaches allows toughness values from the insert and from a mode II precrack to be obtained from the same specimen. Outstanding issues and current and planned approaches for their resolution are described.