Effect of wave-front width on micro-jet from a shocked aluminum surface

This work investigates the relation between shock wave risetime and the amount of micro-scale fragments ejected from a grooved aluminium surface under shock loading condition. Using smoothed particle hydrodynamics, we calculate the formation of micro-jet from the groove of metal surface, and analyze the dependence on the width of loading wave front. The simulation results compare well with the experiment ones, and reveal the dependence of the micro-jet on the wave front: both the mass and the maximal velocity of the ejection will decrease with the increasing of the width of wave front. It is also found that the micro-jet originates from the folium near the groove, which can acquire axial velocity and impact at axis when the shock wave releases at the metal/vacuum interface. The folium becomes smaller as the wave front widens. This is because some matter will satisfy the lock condition of jet strength and can eject no more.