On the damage behavior of poly(methyl methacrylate) impacted by high-velocity water jet

The damage behavior of poly(methyl methacrylate) targets subjected to water jet impact was experimentally studied. Parameters including water jet velocity, incident angle and target thickness were considered. Three damage modes are observed for thin targets based on different jet velocities and incident angles: (i) penetration; (ii) radial cracks; (iii) surface damage. Besides, with the increase in incident angle, the mechanism that triggers the damage changes from stress wave to flexure. For thicker targets, only surface damage and subsurface ring crack are observed and the surface damaged area increases parabolically with the increase in impact velocity. A modified damage mechanism is presented and the significance of subsurface ring crack is identified as the root cause of surface ring crack and bulk removal. The damaged area is correlated with an empirical equation, and the obtained material coefficient can be used for the preliminary assessment of the damage caused by waterdrop impact.