Rajabi Majid, Mojahed Alireza
Sustainable Manufacturing Systems Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran.
Sustainable Manufacturing Systems Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran.
Ultrasonics. 2018 Feb;83:146-156. doi: 10.1016/j.ultras.2017.06.002. Epub 2017 Jun 13.
The interaction between harmonic plane progressive acoustic beams and a pulsating spherical radiator is studied. The acoustic radiation force function exerted on the spherical body is derived as a function of the incident wave pressure and the monopole vibration characteristics (i.e., amplitude and phase) of the body. Two distinct strategies are presented in order to alter the radiation force effects (i.e., pushing and pulling states) by changing its magnitude and direction. In the first strategy, an incident wave field with known amplitude and phase is considered. It is analytically shown that the zero- radiation force state (i.e., radiation force function cancellation) is achievable for specific pulsation characteristics belong to a frequency-dependent straight line equation in the plane of real-imaginary components (i.e., Nyquist Plane) of prescribed surface displacement. It is illustrated that these characteristic lines divide the mentioned displacement plane into two regions of positive (i.e., pushing) and negative (i.e., pulling) radiation forces. In the second strategy, the zero, negative and positive states of radiation force are obtained through adjusting the incident wave field characteristics (i.e., amplitude and phase) which insonifies the radiator with prescribed pulsation characteristics. It is proved that zero radiation force state occurs for incident wave pressure characteristics belong to specific frequency-dependent circles in Nyquist plane of incident wave pressure. These characteristic circles divide the Nyquist plane into two distinct regions corresponding to positive (out of circles) and negative (in the circles) values of radiation force function. It is analytically shown that the maximum amplitude of negative radiation force is exactly equal to the amplitude of the (positive) radiation force exerted upon the sphere in the passive state, by the same incident field. The developed concepts are much more deepened by considering the required power supply for distinct cases of zero, negative and positive radiation force states along with the frequency dependent asymmetry index. In addition, considering the effect of phase difference between the incident wave field and the pulsating object, and its possible variation with respect to spatial position of object, some practical points about the spatial average of generated radiation force, the optimal state of operation, the stability of zero radiation force states and the possibly of precise motion control are discussed. This work would extend the novel concept of smart carriers to and may be helpful for robust single-beam acoustic handling techniques. Furthermore, the shown capability of precise motion control may be considered as a new way toward smart acoustic driven micro-mechanisms and micro-machines.
研究了谐波平面行进声束与脉动球形辐射器之间的相互作用。推导了施加在球体上的声辐射力函数，该函数是入射波压力和球体单极振动特性（即振幅和相位）的函数。提出了两种不同的策略，通过改变辐射力的大小和方向来改变辐射力效应（即推和拉状态）。在第一种策略中，考虑具有已知振幅和相位的入射波场。分析表明，对于规定表面位移的实虚部平面（即奈奎斯特平面）中属于频率相关直线方程的特定脉动特性，可实现零辐射力状态（即辐射力函数抵消）。结果表明，这些特征线将上述位移平面分为正（即推）辐射力和负（即拉）辐射力两个区域。在第二种策略中，通过调整入射波场特性（即振幅和相位）来获得辐射力的零、负和正状态，该入射波场以规定的脉动特性照射辐射器。证明了对于入射波压力特性属于入射波压力奈奎斯特平面中特定频率相关圆的情况，会出现零辐射力状态。这些特征圆将奈奎斯特平面分为两个不同的区域，分别对应辐射力函数的正（圆外）和负（圆内）值。分析表明，负辐射力的最大振幅恰好等于同一入射场在被动状态下施加在球体上的（正）辐射力的振幅。通过考虑零、负和正辐射力状态的不同情况所需的电源以及频率相关的不对称指数，进一步深化了所提出的概念。此外，考虑入射波场与脉动物体之间的相位差的影响及其相对于物体空间位置的可能变化，讨论了关于产生的辐射力的空间平均值、最佳运行状态、零辐射力状态的稳定性以及精确运动控制可能性的一些实际问题。这项工作将把智能载体的新概念扩展到鲁棒的单束声学处理技术，并可能对其有所帮助。此外，所展示的精确运动控制能力可被视为迈向智能声学驱动的微机械和微机器的一种新途径。
