COMPOSITE LAYERING TECHNIQUE FOR USE IN A EULERIAN SHOCK PHYSICS CODE

The high strength and low density characteristics of fiber reinforced composite materials have made them applicable to a large variety of applications. As these applications grow, their performance in high strain rate shock environments has increased. The modeling and simulation of such materials is difficult due to their anisotropic behavior and complex internal geometries. Fiber reinforced composite materials consist of a collection of layers that create a laminate. Each layer is typically transverse isotropic or orthotropic consisting of a fiber and matrix material. One approach is to explicitly model each layer, while accurate, this is often not feasible for full system calculations as the laminate layer count increases in size. Additionally, modeling each layer given the finite thickness proves to be a challenging process and typically a smearing approach is used to represent the laminate response removing the identity and material response of each layer. The creation of a layering capability is a good compromise between the inaccuracy of smearing and the computational cost of explicitly modeling each layer. The layering is done using a sub-grid technique in an individual grid cell. The grid cell is partitioned based on layer location in the laminate and the material deformation. The volume occupied by the given layer is computed and the layer calculates a material response based on the cell strain field. The resulting material stress and state variables are volume weighted with the remaining layers in the given grid cell yielding a cell response. The result is a technique that requires less computation time than modeling each layer while increasing the accuracy over smeared approximations.