Investigation of strain-rate effects in Al foams and Ni/Al hybrid foams on different scales

Abstract

Open-cell metal foams are a new class of cellular materials with structural features resembling those of lightweight loadbearing materials such as cancellous bones and wood. Their high stiffness-to-weight ratio coupled with their typical long, flat stress-strain response make them ideal candidates as cost-effective shock energy absorbers in crashworthiness, impact loading and blast mitigation strategies. The macroscopic mechanical properties of foams are strongly influenced by both the mechanical behaviour of single pores at the mesoscopic level and the struts and their structure at the microscopic length-scale, based on a strong structure-property relationship. This is shown in the present contribution where an experimental-numerical investigation has been conducted demonstrating the existence of strain-rate effects at different hierarchical scales. Micro inertia effects arising due to the pore geometry as well as further strain-rate effects stemming from the rate-sensitivity of the Ni coating in Ni/Al hybrid foams are also outlined.