USE OF LS-DYNA SHELL ELEMENTS IN THE ANALYSIS OF COMPOSITE PLATES WITH UNBALANCED AND UNSYMMETRIC LAYUPS

In order to obtain the desired coupling between deformation modes that can occur in composite material plates having unbalanced and/or unsymmetric lamination schemes, the appropriate shell element formulation must be selected from the available formulations in LS- DYNA. An investigative study was conducted to determine which of the shell element formulations in LS-DYNA 950 can be used for modeling such plates prior to performing in- depth studies on the behavior of more complex composite material structures. Unbalanced/symmetric and balanced/unsymmetric lamination schemes were studied for single-element and four-element “patch” tests. The elastic response of these models to in- plane tensile loads and out-of-plane bending loading was investigated. The shell elements were used with material model 54 (MAT_ENHANCED_COMPOSITE_DAMAGE). The study focused on determining which of the shell element formulations would produce the expected coupling between deformation modes. The Belytschko-Leviathan shell formulation was found to be the best choice for coupled elastic response. Progressive failures of laminates under in-plane tensile and compressive loads were also investigated using this element formulation.