High strain-rate compression test on metallic foam using a multiple pulse SHPB Apparatus

Abstract
The high strain-rate compressive behaviour of a structural aluminium foam (manufactured by IFAM) has been investigated using both the Split Hopkinson Pressure Bar (SHPB) and the direct impact tests. The tests have been carried out with the Hopkinson bar set up in the Experimental Mechanics Laboratory of the 2 Engineering Faculty of the Politecnico di Torino. In order to obtain high level of strain in the specimen (70–80%), a multiple pulse test technique has been developed. With this solution the specimen is subjected, within the same test, to repeated pulses due to the reflection of stress waves in the input bar. A multiple point strain-gage measurement and a third bar positioned after the output bar allow a correct reconstruction of the dynamic stress-strain characteristic of the foam specimen. Correction for wave propagation by means of the Pochhammer-Chree method was used to improve the quality of the response and to correct errors. Tests with strain-rate up to 3000 s ^{- 1} were performed and quasi-static tests comparison has been carried out. The influence of several parameters, especially density, has been examined.