An analytical model is developed to examine a impulsive projectile impact on a fully clamped sandwich beams by considering the coupling responses of the core and the face sheets.Firstly, based on the dynamic properties of foam cores, the sandwich beam is modeled as two rigid ideally-plastic beams connected by rigid ideally-plastic springs.Different from the previous sandwich beam model, the transverse compression and bending/shear effect of the foam core are considered in the whole deformation process.Base on this model, different coupling mechanism of sandwich beams are constructed so that an analytical solution considering small deformation is derived.The coupling dynamic responses of sandwich beams with different core strength are investigated.The results indicate that this model improves the prediction accuracy of the responses of the sandwich beams, and is available for the situation when the foam core makes the large global deformation.