Abstract
A theoretical treatment of the phenomena of impact is presented which indicates that rupture under dynamic stress-strain conditions results from the same basic considerations as those governing static or flexural failure. This thesis is proved experimentally by reducing the problem to one of stress rather than the usual method of energy evaluation. When this is done with the aid of newly developed high-speed electronic techniques, it is conclusively demonstrated that impact loading is merely a special case of static loading whereby the stress-strain conditions are identical except for a slight elevation in strength under dynamic conditions. It is shown that the existing methods of impact-strength evaluation such as the standard Izod and Charpy tests lead to erroneous results since the machines in use are apparently of too light a construction, and the technique is oversimplified. It is suggested that the static flexural-test technique when properly carried out to evaluate the energy required for fracture and the notch sensitivity, is sufficient to predict the service characteristics of essentially brittle materials under conditions of both static and impact loading.
