Explicit Dynamic Finite Element Analysis of Laminated Composite Automotive Structures Using a New Composite Plate Element

Abstract

Abstract Composite materials are being considered for use in the front end structures of vehicles to help reduce overall vehicle mass and, thus, improve fuel efficiency. Acceptance of composite material in structural members will depend on their ability to do crash energy management. Numerical simulations can greatly aid in the design of these critical structures and reduce the number of crash tests. A new finite element, which is based on laminated plate theory with cubic zig-zag approximations, was developed to model the relevant mechanics that occur in composite materials during crash events. The element was cast in the internal force format for use with explicit integration solvers. In the plate theory, the in-plane displacement fields in a laminate are assumed to be piecewise cubic functions and vary in a zig-zag fashion through the thickness of the laminate. The zig-zag functions are obtained by satisfying the continuity of transverse shear stresses at layer interfaces. This in-plane displacement field assumption accounts for discrete layer effects without increasing the number of degrees of freedom as the number of layers is increased. The transverse normal strain predictions are improved by assuming a constant variation of transverse normal stress through the thickness in a laminate. The finite element is developed with the topology of an eight-noded brick. Each node has five engineering degrees of freedom, three translations and two rotations. Thus, this element can be conveniently implemented into general purpose finite element codes. Consistent and lumped mass matrices are derived. The developed element is implemented into Argonne National Laboratory’s in-house code, NEPTUNE, which utilizes explicit direct integration method. In NEPTUNE the internal force vector is calculated from the developed element at each time step. Numerical performance of the current element is investigated in this research.