Quasi-static response of two-dimensional composite granular layers to a localized force

The quasi-static response of two-dimensional composite layers to a localized external force is investigated based on the discrete element method. The transmitting features of contact forces under various composite modes of granular layers are mainly considered. From simulating results, we find that the contact forces under various composite modes exhibit distinct different features comparing with that inside a monodisperse granular system. The rigid granular layers may commonly promote the propagation of the contact forces to pass through the interface. However, the soft granular layers play roles of disintegration and constrain to contact forces which try to get inside. In addition, for a rigid–soft composite granular system, we find that the thickness ratio of soft layers to total layers has a significant influence on the distributing feature of floor pressure, which implies different propagating processes of contact forces. Finally, a primary phase diagram is proposed to further explicate three propagating modes of contact forces.