敲擊法是使用最廣泛的表面機械處理或應力改質技術，其目的在於使材料表層產生壓縮應力，用以消除機械元件或結構的應力侵蝕裂化，提高材料的負載強度及疲勞壽命。本研究針對超音波空蝕敲擊技術進行初步的研究。就系統設計而言，使用有限元素法將壓電、結構及聲學等模組加以耦合，建立完整之分析模型，使系統效能達到最佳化。其次再依據分析結果，進行空蝕場觀測及敲擊實驗。初步結果顯示，超音波空蝕敲擊足以有效改變材料表面的機械性質（硬度及表面粗糙度），唯所產生壓縮應力的大小及深度尚需進一步的量測。

　　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.

[1].馬振基主編,“奈米材料科技原理與應用”, 全華科技圖書,民國92年
[2].姚明宗,“共振式聲化學反應器之分析與實驗”, 國立成功大學機械工程研究所碩士論文, 民國98年
[3].W.T. Richards and A.L.Loomis,“The chemical effects of high frequency sound waves l.A Preliminary survey.” J. Am. Chem. Soc., Vol. 49, No. 12,pp.3068-3100,(1927)
[4].Parag R. Gogate, Aniruddha B. Pandit, “Sonochemical reactors: scale up aspects.” Ultrasonics Sonochemistry, 11 105–117(2004)
[5].Yoshiyuki Asakura a,b,*, Tomoyuki Nishida b, Tatsuro Matsuoka b, Shinobu Koda b, “Effects of ultrasonic frequency and liquid height on sonochemical efficiency of large-scale sonochemical reactors” Ultrasonics sonochemistry ,15 244–250(2008).
[6].P.R. Gogate and A.B. Pandit, “Sonochemical Reactors: Scale Up Aspects,” Ultrasonics Sonochemistry, Vol.11, pp.105-117, (2004).
[7].Wagner L, “Mechanical surface treatments on titanium, aluminum and magnesium alloys,” Materials Science and Engineering A, 263, 210-216 (1999)
[8].Curtis S, de los Rios ER, Rodopoulos CA, Levers A, “Analysis of the effects of controlled shot peening on fatigue damage of high strength aluminum alloys,” International Journal of Fatigue, 25(1), 59-66 (2003)
[9].Masse JE, Barreau G, “Laser generation of stress waves in metal,” Surface & Coatings Technology, 70(2-3), 231-234 (1995)
[10].Peyre P, Scherpereel X, Berthe L, Carboni C, Fabbro R, Beranger G, Lemaitre C, “Surface modifications induced in 316L steel by laser peening and shot-peening. Influence on pitting corrosion resistance,” Materials Science and Engineering A, 280(2), 294-302 (2000)
[11].Montross CS, Wei T, Ye L, Clark G, Mai YW, “Laser shock processing and its effects on microstructure and properties of metal alloys: a review,” International Journal of Fatigue, 24(10), 1021-1036 (2002)
[12].Peyre P, Sollier A, Chaieb I, Berthe L, Bartnicki E, Braham C, Fabbro R, “FEM simulation of residual stresses induced by laser peening,” European Physical Journal-Applied Physics, 23(2), 83-88 (2003)
[13].Statnikov ES, Korolkov OV, Vityazev VN, “Physics and mechanism of ultrasonic impact,” Ultrasonics, 44 (Supplement), e533-e538 (2006)
[14].Odhiambo D, Soyama H, “Cavitation shotless peening for improvement of fatigue strength of carbonized steel, “ International Journal of Fatigue, 25(9-11), 1217-1222 (2003)
[15].Soyama H, Park JD, Saka M, “Use of cavitating jet for introducing compressive residual stress,” Journal of Manufacturing Science And Engineering-Transactions of The ASME, 122(1), 83-89 (2000)
[16].Rodopoulos CA, Kermanidis AT, Statnikov E, Vityazev V, Korolkov O, “The effect of surface engineering treatments on the fatigue behavior of 2024-T351 aluminum alloy,” Journal of Materials Engineering And Performance, 16(1), 30-34 (2007)
[17].Turski M, Clitheroe S, Evans AD, Rodopoulos C, Hughes DJ, Withers PJ,“Engineering the residual stress state and microstructure of stainless steel with mechanical surface treatments,” Applied Physics A, 99,549-556 (2010)
[18].K.S. Suslick,“The chemical effects of ultrasound”, Scientific American,Vol.2,pp.80-86, (1989)
[19].T.G. Leighton,“What is ultrasound?”, Progress in Biophysics and Molecular Biology, Vol. 93, pp. 3-83, (2007).
[20].D. Goldenberg,Genetic Algorithms in Search,
Optimization and Machine Learning, Addison Wesley, 1989.