HIGH-SPEED LIQUID IMPACT ONTO WETTED SOLID-SURFACES

The mechanics of impact by a high-speed liquid jet onto a solid surfac e covered by a liquid layer is described. After the liquid jet contact s the liquid layer, a shock wave is generated, which moves toward the solid surface. The shockwave is followed by the liquid jet penetrating through the layer. The influence of the liquid layer on the side jett ing and stress waves is studied. Damage sites on soda-lime glass, PMMA (polymethylmethacrylate) and aluminium show the role of shear failure and cracking and provide evidence for analyzing the impact pressure o n the wetted solids and the spatial pressure distribution. The liquid layer reduces the high edge impact pressures, which occur on dry targe ts. On wetted targets, the pressure is distributed more uniformly. Des pite the cushioning effect of liquid layers, in some cases, a liquid c an enhance material damage during impact due to penetration and stress ing of surface cracks.