Cyclic indentation in aluminum

Cyclic indentation was used to evaluate the dynamic deformation of aluminum. Under the loadcontrolled cyclic indentation, the indenter continuously penetrated into the material and reached a steady state at which the penetration speed (per cycle) was a constant. The amplitude of the cyclic indentation depth was basically controlled by the amplitude of the cyclic indentation load, independent of the mean indentation load and the indentation frequency. The steady state penetration speed decreased with increasing the amplitude of the cyclic indentation load due to the increase in the size of plastic zone. It also decreased with the increase in the mean indentation load due to local strain hardening, while it increased with the increase of the indentation frequency.