Bai Fushi, Saalbach Kai-Alexander, Long Yangyang, Twiefel Jens, Wallaschek Jörg
Institute of Dynamics and Vibration Research, Leibniz Universität Hannover, Appelstr. 11, Hannover 30167, Germany.
Institute of Dynamics and Vibration Research, Leibniz Universität Hannover, Appelstr. 11, Hannover 30167, Germany.
Ultrasonics. 2018 Mar;84:38-44. doi: 10.1016/j.ultras.2017.10.013. Epub 2017 Oct 13.
Ultrasonic cavitation peening is a novel surface treatment technology which utilizes the effect of cavitation bubble collapses to improve the properties of metal surfaces. In order to obtain high impact during ultrasonic cavitation peening, a small standoff distance between a sound radiator and a rigid reflector (the surface of treated specimen) is necessary. However, the effects of different standoff distances on the capability of ultrasonic cavitation peening are not yet clear. In this paper, a simplified model was developed to evaluate the cavitation capability at different standoff distances. Meanwhile, to validate the theoretical model, the plastic deformation or erosion on the peening surface before and after treatment were compared. It was found that at a very small standoff distance the impact pressure generated by cavitation bubbles did not cause much deformation or erosion, as the dynamics of cavitation bubbles was limited. At a large standoff distance, due to much attenuation of sound propagation in the bubbly liquid, little impact pressure was generated by the collapse of cavitation bubbles and reached the treated surface. A fixed vibration amplitude, however, corresponded to a standoff distance which caused the largest deformation or erosion on the treated surface.
超声空化喷丸是一种新型的表面处理技术，它利用空化气泡崩溃的效应来改善金属表面性能。为了在超声空化喷丸过程中获得高冲击力，声辐射器与刚性反射体（待处理试样表面）之间需要较小的间距。然而，不同间距对超声空化喷丸能力的影响尚不清楚。本文建立了一个简化模型来评估不同间距下的空化能力。同时，为了验证理论模型，比较了喷丸处理前后表面的塑性变形或侵蚀情况。结果发现，在非常小的间距下，空化气泡产生的冲击压力不会引起太大的变形或侵蚀，因为空化气泡的动力学受到限制。在较大的间距下，由于气泡液体中声传播的大量衰减，空化气泡崩溃产生的冲击压力很小，无法到达待处理表面。然而，固定的振动幅度对应着一个能在待处理表面引起最大变形或侵蚀的间距。
