Loading-Unloading Cycles of 3D-Printing Built Bi-Material Structures With Ceramic and Elastomer

This paper studies the loading-unloading behaviors of a 3D-printing built bi-material structure consisting of an open-cellular plaster frame filled with silicone. The combination of the plaster (ceramic phase) and silicone (elastomer phase) is hypothesized to possess a non-linearly elastic property and a better ductility. Four-point bending test with programmed cycles of preceding deformations was conducted. The results show that there exists a linear-nonlinear transition when the bending deflection is around 2 mm in the first cycle bending. As the cycle proceeds, this transition is found at the maximum deflection of the previous cycle; meanwhile, the bending stiffness degrades. It is believed that the occurrence of micro-cracks inside the plaster frame is the mechanism behind the phenomenon. The ductile silicone provides a strong network suppressing the abrupt crack propagation in a brittle material. The effects of the frame structure and plaster-silicone ratio were also compared. A high plaster content and large cell size tend to have a higher stiffness and obvious linear to non-linear transition while it also has more significant stiffness degradation.