Tensile Fracture of Notched Composite Laminates

摘要

Extensive research and development has been conducted with the aim of increasingthe application of composite materials in aircraft, particularly in the structure of airframes. A major area of study involves the notch sensitivity of composite laminates. The results of these investigations have produced a variety of analytical techniques ranging from comprehensive numerical methods to simplified fracture models. This report describes the determination of empirical parameters for a fracture model which can be used to predict the uniaxial tensile strength of composite laminates containing notches of various sizes. The parameters required are the characteristic dimension and the unnotched tensile strength of the subject laminate. Data bases including notched and unnotched mechanical strength of the subject laminates and elastic ply properties were generated for the determination of these parameters. Three second generation high toughness graphite fibre reinforced composites and two first generation brittle graphite/epoxy composites were used to fabricate the specimens containing either 'through the thickness' cylindrical holes or countersunk holes.