- Conventional continuum predictions of deformation and ductility are size-scale independent, although at times, big things behave differently from little things. In ductile solids under dynamic loads, material inertia leads to a size dependent response. Consider geometrically similar bars of different lengths subjected to similar strain rates. Under dynamic loading conditions, a linear elastic analysis would show that the stress carried by the bar is proportional to the end velocity. For a constant strain rate, stress increases linearly with size. Needleman and Tvergaard (1991) showed size effects associated with dynamic crack propagation. Results of failure analysis conducted by Knoche and Needleman (1993) showed necking type failures in ductile solids.