Design and instrumentation of low velocity drop-weight impact testing machine for estimation of energy absorption capacity in aluminum based composite foam

In this paper, the energy absorption capacity of A356 aluminum foam reinforced by SiC particles under impact loading was studied. The foam was manufactured by direct foaming of melts with blowing agent CaCO3. The drop-weight impact testing machine was designed and fabricated. The dynamic load-cell circuit was designed and mounted on the impactor. The impact test was carried out using a hemispherical indenter with a velocity of 6.70 m/s on the foam specimens, and the load-time history data was obtained. The results were compared with the results reported by a piezoelectric force sensor and validated. The obtained impact response of A356/SiCp composite foam is stable, which represents a suitable design of the machine and its reliable output. This is emphasized by comparison of material behavior with the results of other researchers. The response includes three stages: an initial linear behavior, a plateau of load and failure of the foam. In plateau region, the plastic deformations can be tolerated by the foam at nearly constant load. The end of plateau region and beginning of the failure region occur at the moment when the rate of energy absorbed by the foam is decreasing. The values of plateau load and absorbed energy estimated from load-cell are 1.62 kN and 22.04 J respectively, which has a relative error of 1.8% and 7.7% in comparison with piezoelectric sensor. The value and percent of absorbed energy were obtained as 6.07 J, 6.58 J, 9.39 J and 27.5%, 29.9%, 42.6% for elastic, plateau and failure regions respectively.