Cavitation erosion was analyzed from the propagation of stress waves in 3-layer damping materials (first layer : metal, second layer : plastic, third layer : metal). The metals used were SS400 steel, pure copper and pure aluminum. The thickness of the first layer T
i varied from 1mm to 20mm. The damping materials were exposed to vibratory cavitation. The cavitation impact load acting on the surface decreased as T
i decreased below the critical thickness T
c, which is about 3 mm irrespective of kind of metals. This is because the intensity of the compression wave is reduced by the reflected tension wave emitted from the boundary between the first layer and the damping sheet. Therefore, the critical thickness T
c also observed in terms of mass loss rate. The T
c for both impact load and mass loss rate is calculated by T
c=Δt·c/4, where Δt is the time interval of impact load and c is the longitudinal wave velocity. The mass loss rate m, when T
i is less than T
c, is given by m={1+α-4·α·T
i/(Δt·c)}
2×m
o, where α is the reflection coefficient between the first layer and the damping sheet, and m
o is the constant mass loss rate when T
i is greater than T
c. The calculated values of T
c and m correspond well with the experimental results.
抄録全体を表示