Abstract
This paper investigates the impact response and damage mechanisms of carbon fibre composites with modified bismaleimide matrix and compares the results with those for composites with epoxy matrix. Using a drop weight tester the impact force and energy were obtained as functions of displacement. Analysis of the whole impact event leads us to suggest that there are two energy thresholds, one for initial damage and the other for critical damage. Ultrasonic C-scan, X-ray radiography and scanning electron microscopy were used to examine the damaged regions. Because of the higher toughness of modified bismaleimide and the improved adhesion between the fibres and matrix, the impact resistance and damage tolerance of bismaleimide matrix composites are sig nificantly higher than those of epoxy matrix composites. The mechanisms for impact en ergy absorption are discussed.