Dynamic characterization of layered and graded structures under impulsive loading

Relatively thick graded and layered structures have significant potential armor applications, and have recently been manufactured with some degree of consistency. The mechanical behaviors of the individual layers within such a structure play an important role in determining the structure's resistance to impact. This work examines layered and graded plates made of metal-ceramic composites with the volume fraction of ceramic reinforcement varying through the thickness. In a previous work (Acta Mater 46 (1998) 5633), the results of high-strain-rate experiments have been used to develop a model for the viscoplastic response of metal-matrix composites of varying volume fraction. Using this model, numerical results are presented on the propagation of large amplitude stress waves through layered and graded structures. The results show that the wave propagation within layered and graded structures involves a complex coupling of elastic and viscoplastic response. It is demonstrated that the choice of gradation has great significance for impact applications.