A NEW SIMPELIFIED DUCTILE SPALL MODEL

A new simplified ductile spall model is presented using the redefined damage and the strength function given by Cochran-Banner.The correction concerning the volume of the mesh cells is realized by abandoning the assumption of Cochran and Banner to calculate the damage:it is much easier to open microcracks once they are formed than to strain the solid further.It is noted that choosing the redefined damage and a strength function or a stress relaxation equation provides a possibility of determining the damage and excludeing any extra equation of damage evolution.Once the spall strength is reached,the redefined damage in the new simplified ductile spall model will only be determined by a series of closed equations including the stress relaxation relationship given by the strength function,the energy conservation equation,the equation of state and the constitutive equations for the damaged aggregate.Comparison of the theoretical and experimental results for some plane spall tests is performed.The determination of the spall strength and the critical damage included in the presented spall model should make the computed results of spall tests under the appropriate initial and boundary conditions consistent with the experimental free surface velocity profile of target or the stress profile of interfacebetween target and low impedance buffer and the observed damage at spall plane for spall tests.