Compressive behavior of aluminum foams at low and high strain rates

Abstract

The mechanical behavior of two aluminum foams including open cells and closed cells with a variety of densities at room temperature and under compression loading was studied. Their response to strain rate was tested over a wide range of strain rates, from 1.0×10⁻³ to 1.6×10³ s⁻¹. The dynamic compression tests were made by Split Hopkinson Pressure Bar (SHPB) and the quasi-static tests were conducted using a displacement controlled CMT5305. Within this range, the experimental results show that all the compressive stress-strain curves of aluminum foams have three deforming regions such as linear elastic region, collapse region, and densification region. Aluminum foams have strengths that increase with increasing relative density and fall well below predictions of the Gibson-Ashby theory. For the open cell foam the stress is sensitive to the strain rate. However, the stress of the closed cell foam exhibits little or no strain rate sensitivity. Two aluminum foams with different cell structures exhibit different deforming models in the compressive tests. During the deformation of closed cell foams the deformation is not spatially uniform. However, there is no apparent collapse band and plastic deformation is homogeneous for open-cell foams.

Keywords

aluminum foams / compressive behavior / high strain rate / deformation mechanisms