Impact response of a finite crack in plane extension

The transient stress and displacement fields around a finite crack opened out by normal and shear tractions applied to its surface are obtained using integral transforms coupled with the technique of Cagniard. The tractions are applied suddenly to the crack which simulates the case of impact loading. By subtracting a uniform state of stress, the present solution also applies to the problem of the sudden appearance of a crack in a pre-stressed body. The results show that significant differences exist between the dynamic stress-intensity factors obtained in this problem and those resulting from static loading. In particular, the energy released by the dynamically loaded crack which is associated with the stress-intensity factor varies with time reaching a maximum very quickly and then oscillates about the static value. The information gained is useful in determining the condition of crack propagation under impact.