A mechanics model of skin penetration

Experiments are performed to show that sharp-tipped needles and high pressure liquid jets pierce skin and silicone rubbers by a similar penetration mechanism. The solid tears to form a crack, which opens to accommodate the punch. A model is presented for the penetration of soft solids, such as skin and rubber, by a sharp-tipped punch. Both the model and the experiments reveal that to penetrate the solid, the average pressure across the punch tip increases with diminishing punch radius. It is also shown that the penetration pressure increases for tougher solids with stronger strain hardening capacities.