Impact Testing and Evaluation

Abstract

The nature of impact testing has changed radically in recent years. Instrumentation and in-line data processing provide a force-deformation record of the impact event and other information; flash photography of the specimen at some predetermined instant during the impact enables correlations to be established between features on the impact response curve and stages in the development of damage; low energy impacts that damage, but do not destroy, the specimen enable the course of damage development to be determined. The three principal test configurations, tensile, flexed beam and flexed plate, are all satisfactory within limits; each has its deficiencies and each has its particular virtues. Whichever method is used, the data generated relate to the specimen rather than to the material from which it is made. The impact resistance of the material has to be inferred, with due allowance being made for the influence that the molecular state of the sample has on experimental results. The relationships between flow geometry features and impact resistance have not yet been quantified adequately but the required experimentation has been identified.

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