Large deformation of sandwich wide panel

Abstract

This work addresses the general nonlinear static and dynamic formulations of sandwich panels with compressible cores under large deformation, within the framework of Extended High-order Sandwich Panel Theory. The commonly-used assumption named large displacement with moderate rotation, is assessed. Within a total Lagrange manner, the weak form of the nonlinear equation of equilibrium is derived via the principle of virtual work and further linearized through the Newton-Raphson iteration. Both the static and dynamic governing equations are acquired with respect to the nodal degrees of freedom. Numerical techniques involving Newton-Raphson method for the static analysis, and Newmark-Beta method for the time domain integration are employed to get the solutions. The static and transient mechanical response of simply supported sandwich panels under static pressure and dynamic blast is conducted respectively. The closed linear solutions and finite element models are accomplished to validate. Conclusions are drawn that the deformation gradient, as well as the displacement and rotation, critically determines the structural stiffness and internal force, and their relationship is originally provided in this paper. The structural stiffness at large deformation is stronger than that at small deformation. The assumption of large displacement with moderate rotation is inadequate for sandwich structure in large deformation.