DIC Measurements on Single Struts of Ni/PU Hybrid Foams—Damage Behaviour During Three-Point Bending

Abstract

Hybrid foams are an evolution of classic metal foams. They consist of an open-cell foam template coated with a second material. Thereby, the coating material dominates the material behaviour of the hybrid foams. Ni/PU hybrid foams are a suitable example of hybrid foams. An inexpensive polyurethane (PU) foam is coated with nanocrystalline nickel (Ni). The coating strongly increases the stiffness of the material while the price is lower than for an aluminium alloy open-cell foam. The relatively low costs and the high stiffness of the structure are promising to be actually used in real-world applications. But first, a mechanical characterisation of the macroscopic hybrid structure is needed. The macroscopic deformation results in pore deformation on the mesoscale. Pore deformation consists of bending and buckling of struts, therefore, the damage behaviour of single struts during three-point bending needs more investigation. In this contribution, these experiments are presented and the influence of the individual geometry of each single strut on the measured force is shown. For a better comparability of the experiments, a simplification using the Euler–Bernoulli beam theory and the assumption of a constant triangular strut cross section is applied. The resulting stress-strain-curves show matching slopes in the linear elastic part of the curves, which proves the used strategy.