Effect of Cavitation Impacts on Crack Propagation in Epoxy Resin Subjected to Tensile Loading

Investigation of the crack growth mechanism in epoxy resin specimen subjected to both tensile load and cavitation impact was conducted in this work. An experimental apparatus for conducting the test was self-manufactured so that a tensile load can be applied to the specimen while at the same time receiving repeated impacts loads from collapsing cavitation bubbles. The tests were done inside a tank filled with distilled water with fixed temperature. An initial crack was introduced to the specimen in order to analyze the propagation mechanism. Then, the crack growth rate was evaluated under several different loading conditions. As the results, when cavitation load was applied without a tensile load, the initiated crack did not propagate whereas erosion damages were generated on the specimen surface. When tensile load only was applied, the initiated crack propagated at a slow speed. However, when both tensile load and cavitation impacts were applied, the crack growth rate was significantly accelerated by approximately 10,000 times compared to that without cavitation load. According to the captured images, all specimens regardless of the loading condition, fractured in a similar process which began with a blunted crack, crack propagation, cracks merger, and finally specimen rupture. This finding suggests the importance of incorporating both tensile and cavitation impact loads in estimating the life-service of a component in turbomachinery application.