| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 100 === Peening is the most common means for mechanical surface treatment or surface stress improvement. Compressive stress is introduced during the peening process so that stress corrosion cracking induced by tensile residual stress is eliminated and the yield stress and tensile strength as well as the fatigue life of metallic materials are improved. This study provides a preliminary development of ultrasonic cavitation peening (UCP) technique. First, finite element method is used for building a numerical model, in which piezoelectrical, structural, and acoustical modules are coupled together to simulate the complete system. Optimization is then performed for system design. Finally, UCP experiments are carried out. Surface hardness and roughness of the treated material are measured. It is shown that UCP can effectively change the mechanical properties of the material. However, the strength and depth of the compressive stress field need to be further quantified.
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