A simplified dynamic low-velocity impact model for sandwich composites based on three-dimensional quasi-static analyses

This paper describes a nonlinear single-degree-of-freedom (SDOF) model of low-velocity impact on composite sandwich structures. The stiffness parameters of the model are derived from the results of three-dimensional quasi-static contact analyses of a rigid sphere indenting a multi-layer sandwich laminate. During the course of this investigation, it is determined that an additional term, analogous to viscous damping, is required for the model to account for energy loss due to damage and an empirical fit is required to determine its magnitude for each structure. Once determined, comparisons between low-velocity impact experiments and the nonlinear SDOF model are examined for six different foam and honeycomb sandwich configurations. In each case, a single set of parameters retains its fidelity throughout a range of impact velocities and provides accurate predictions of contact force and contact duration.