13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- 3.3 Effect of water temperature In Fig. 7, maximum radius of a cavitation bubble, Rmax is plotted with AE interval time, Δt. A relationship between maximum radius of a cavitation bubble and bubble collapse time is linear in room temperature. On the other hand, the relationship in experiment with varying water temperature is not linear as shown in Fig. 8. In Fig.9, maximum bubble radius, Rmax is plotted for water temperature, Tw. The maximum radius of a cavitation bubble increases with water temperature. These results suggested that temperature affects the maximum radius and shape of a bubble. The graph in Fig. 10 shows a plot of impact forces of laser irradiation, IL and these of bubble collapse, IB with water temperature. Impact force from laser ablation became smaller than that from laser irradiation with increasing water temperature. Fig. 11 shows a plot of a ratio of impact forces due to laser irradiation and bubble collapse, IB /IF with water temperature. Impact forces from laser irradiation are not affected by water temperature. On the other hand, impact force from bubble collapse became smaller than that from laser irradiation with increasing water temperature and the ratio of IB /IF decrease clearly in Fig. 11. Figure 8. Relationship between maximum bubble radius, Rmax and AE interval time, Δt with varying water temperature 0 1 2 3 4 5 0 200 400 600 800 Maximum bubble radius, R max [mm] AE interval time, Δt [μs] Figure 7. Relationship between maximum bubble radius, Rmax and AE interval time, Δt in room temperature 0 1 2 3 4 5 0 200 400 600 800 Maximum bubble radius, R max [mm] AE interval time, Δt [μs]
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