Dynamic loading for stationary cracks leads to results that are many times greater in magnitude than their static counterparts. If the dynamic loading is in the form of impact type, stress wave propagation effects become dominant. FRAC3D program comprises enriched element formulation which doesn't require excessive mesh refinement around crack tip for accuracy. Strain energy density (SED) theory parameters and dynamic J-integral are sought in this study to simulate and understand wave propagation phenomenon in detail. Structures under the effect of wave propagations yield more reliable J-integral values by taking the average of the results from multiple domain sizes. Governed by stress waves, space-time variations of minimum energy density locations strongly influence fracture characterization for straight and curved crack fronts. Details given in numerical examples section of this paper make a great contribution to understanding of the response for cracked structures subjected to sudden loading.