IMPACTOR MASS AND SPECIMEN GEOMETRY-EFFECTS IN LOW VELOCITY IMPACT OF LAMINATED COMPOSITES

There is no proven scaling law for reliably predicting the damage tolerance of brittle composite structures based on the results of laboratory coupon testing. Tests were performed to examine the influence of impactor mass and specimen plan size on the low velocity impact performance of a variety of woven fibre reinforced composite laminates. The damage extent was assessed by visual inspection and by ultrasonic c-scanning. It is demonstrated that for a given specimen size thc materials subjected to varying impactor masses suffer damage only according to the magnitude of the impact energy-not according to impact of mass or velocity separately. It is shown that increasing the diameter of a specimen increases the impact energy to cause the same damage signature. Two approaches were used to separate the energy absorbed in the damage process from that absorbed elastically by the specimen. A simple procedure is proposed for predicting the impact response of a plate based on a knowledge of the impact performance of a test specimen of different plan size. The resultS of initial tests investigating this prediction method are encouraging.