Macroscopic Constitutive Behaviors of Aluminum Honeycombs Under Dynamic Inclined Loads

Macroscopic constitutive behaviors of aluminum 5052-H38 honeycombs under dynamic inclined loads with respect to the out-of-plane direction are investigated by experiments. The results of the dynamic crush tests indicate that as the impact velocity increases, the normal crush strength increases and the shear strength remains nearly the same for a fixed ratio of the normal to shear displacement rate. The experimental results suggest that the macroscopic yield surface of the honeycomb specimens as a function of the impact velocity under the given dynamic inclined loads is not governed by the isotropic hardening rule of the classical plasticity theory. As the impact velocity increases, the shape of the macroscopic yield surface changes, or more specifically, the curvature of the yield surface increases near the pure compression state. The material constants of the proposed yield criterion are determined as functions of the impact velocity based on the least squares fits of the experimental results. The proposed macroscopic constitutive relations for honeycombs under dynamic inclined loads with respect to the out-of-plane direction are needed for computational simulations of crushes of honeycomb barriers in vehicle crash tests.