Hypervelocity impacts into structures produce shock waves propagating through the colliding bodies. SPH has given insight into shock loading of homogeneous materials; nevertheless, shock wave propagation through solids with discontinuous density distribution, has not been considered in depth, yet. In previous studies using SPH, impact loading of laminated or composite materials was modeled by homogenization of the structure or under the assumption of being functionally graded materials. Both models neglect the reflection-transmission effects on the interface of different density materials. To capture these reflection-transmission effects, a holistic treatment for the multi-phase material is proposed, with kernel interaction over all parts of the structure. The algorithm employs a variable smoothing length formulation. A dissipative mass flux term is also introduced in order to remove spurious post-shock oscillations on the interface of different materials. In this paper, the SPH solution is presented, along with a relevant benchmark case. The algorithm’s performance is studied and the necessity of a variable smoothing length formulation is investigated
