Characterization of the in-plane homogenized mechanical properties of a hexagonal honeycomb core
The in-plane homogenized elasto-plastic behavior of a hexagonal aluminum honeycomb core has been investigated using experiments and finite element analysis of an idealized representative volume element. In-plane uniaxial tension and compression experiments are carried out along the principal material and off-axis directions to obtain the homogenized elasto-plastic mechanical properties. The homogenized stress strain behavior was simulated using a representative volume element which employed a bilinear traction-separation law to capture the node bond failures. The experimentally validated model was utilized to generate in-plane yield and node bond failure envelopes for the bulk core. The experiments showed that the stress-strain responses of the hexagonal aluminum honeycomb core vary greatly depending on the loading direction. Due to the in-plane shear modulus being of the same magnitude as the Young’s modulus along the ribbon direction, the bulk core exhibits a unique off-axis behavior. The in-plane Young’s modulus is a maximum along a characteristic off-axis direction (~40°) in contrast to the behavior of common orthotropic materials. The finite element model proves that the behavior of the irregular hexagonal honeycomb core can be captured by using a representative volume element from an idealized core.