The sand erosion behavior of polymethyl methacrylate (PMMA) has been studied by the falling particle test. The impact velocity of glass beads (Vp) was varied from 12 to 35m/sec, and the impact angle was from 20 to 85 deg.
As the result of testing, a unique phenomenon showing two erosion peaks at about 30 and 70 deg. was found. At low impact velocity, the peak of erosion rate at 30 deg. was higher than the other peak at 70 deg. At high impact velocity, on the other hand, the peak at 30 deg. became lower and then disappeared at 25m/sec. The erosion rate was proportional to Vp2 at low impact angles but to Vp5 at high impact angles.
In order to investigate the erosion mechanism at these two angle range, optical microscopic observations were further made. The results showed that the material was removed to form pits at a low impact angle, but was eroded just like spalling from transverse cracks propagated near under the specimen surface at a high impact angle.
In conclusion, PMMA revealed two different erosion behaviors and mechanisms depending upon the impact angle and velocity.
