Specimen Size and Effective Compressive Stiffness of 3D Fiber Reinforced Foam Core Sandwich Structures

Sandwich composites offer key advantages in automotive and aerospace applications including reduction in weight over metals currently used. Recently, there has been a development of new core materials that may alter their damage tolerance through the use of a three-dimensional, truss-like network of reinforcing fibers inside a lightweight foam core. Given the complex and discrete nature of these 3D Fiber Reinforced Foam Cores (3DFRFC) it is important to have an adequate understanding of the bulk behavior of the material. A detailed model of the 3DFRFC microstructure using the embedded element method within Abaqus is used to investigate the effect of specimen size on the stiffness response in flat-wise compression samples. The results highlight the influence of the highly orthotropic material property interactions of the 3DFRFC and the effect of the cut reinforcement near the specimen edge. The planned use of periodic boundaries for the embedded element models of these materials is also discussed.