The excess energy approach to the impact testing of plastics

This paper evaluates the excess energy approach to impact testing of plastic samples. This approach assumes that providing the impact energy is excessive, the rate of strain during a test may be assumed to be constant. This allows a direct transformation of time to displacement during a test and consequently to a simplification of the integration procedure. The force-time and force-displacement responses of samples to impact have been measured simultaneously using an instrumented falling weight impact machine. It is concluded that the excess energy approach is acceptable providing the available impact energy exceeds the impact strength of the sample by a factor of ten.