Finite element analysis of low-velocity impact on composite sandwich plates

Abstract

The response of composite sandwich plates to low-velocity impact is predicted by a displacement-based, plate bending, finite element algorithm. Fifth order Hermitian interpolation allows three-dimensional equilibrium integration for transverse stress calculations to be carried out symbolically on the interpolation functions so that transverse stresses within the elements are expressed directly in terms of nodal quantities. Nomex honeycomb sandwich core is modeled using an elastic–plastic foundation and contact loading is simulated by Hertzian pressure distribution for which the contact radius is determined iteratively. Damage prediction by failure criteria and damage progression via stiffness reduction are employed. Comparison to experimental low-velocity impact and static indentation data shows the ability to model some of the important features of static indentation of composite sandwich structures. In particular, the slope of the load displacement curve (stiffness), including contact, before damage is well represented. Core failure load is predicted by the analysis within 10% of the experimental value.