Study of Next Cavitation Shotless Peening

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The main results obtained are as follows :1.The cavitating jet in air was observed and it was revealed that the periodical cavitation-cloud-shedding around the high-speed water jet and the fluctuation of the low-speed water jet were interfered each other.2.Pure aluminum specimen was treated by the cavitation shotless peening. It was revealed by means of recrystallization-etch technique that the plastic deformation was induced by the cavitation shotless peening.3.The cavitation impacts energy was measured by the cavitation impact counter. It was revealed that the cavitation impacts induced by the cavitating jet in air were more intense compared with that of the cavitating jet in water.4.The stress distribution of cavitation impacts was estimated by the shape of plastic deformation pits. In order to apply the cavitation shotless peening to tribology area, the introduction of compressive residual stress into titanium alloy was revealed.5.In order to establish monitoring method of cavitation shotless peening, the relation between the impact energy measured by the PVDF sensor and the vibration measured by the laser doppler velocity meter were revealed.6.The proposed shotless peening and the conventional shot peening were compared. The difference of the peening methods in view point of introduction of compressive residual and the improvement of fatigue strength was revealed.7.In order to control the cavitation impact intensity, the plastic deformation pits produced by cavitation shotless peening were measured precisely. The pressure distribution of cavitation impact was successfully controlled by the injection pressure of the low-speed water jet and the standoff distance.8.The injection pressure of the low-speed water jet and the standoff distance, which were the main parameters of the cavitation shotless peening, were optimized.