Fracture prediction of thin plates under localized impulsive loading. Part II: discing and petalling

The onset of fracture and subsequent propagation of radial cracks of thin clamped circular plates under localized impulsive loading were predicted analytically and numerically for discing and petalling stages with increasing intensity of applied impulse and various radii of loaded area. The equivalent plastic strain times the average stress triaxiality was introduced as a ductile fracture criterion in the numerical simulation. The strain hardening law and critical damage/fracture function was calibrated from tensile test on round specimen and a parallel numerical simulation. Based on the critical damage value, and calculated distributions and histories of stress and strain, the initiation site and extent of fracture were predicted for a range of loading radii and intensity of applied impulse. It was clearly demonstrated that the crack length and final deformed shapes of plates are strongly influenced by the spatial distribution and intensity of impulsive loading. A comparative study on the propagation of radial cracks was also presented. Finally, the numerically obtained crack length was shown to agree well with the closed form solution derived earlier by one of the present authors.