The application of finite element analysis in the design of high intensity ultrasonic systems

This paper describes the application of a noninvasive field measurement approach linked with FE design techniques to optimise the identification and control of pressure node locations (associated with regions of cavitation) within small liquid filled vessels (e.g. 100mm diameter, 150mm height). The measurement technique is based on the interferometric detection of refractive index changes in transparent media due to pressure, coupled with modified tomographic scanning routines, to allow the reconstruction of a three-dimensional map of pressure within cylindrical vessels. Importantly, an adaptive algorithm was developed to control the firing angle of the interferometer in order to compensate for the refractional effects introduced by arbitrary cell structures and hence, maintain the parallel projections essential for reconstruction accuracy. These systems were simulated in the FE domain with good correspondence between the optically measured profiles and theoretical profiles established. The validated virtual prototyping platform was then used to design systems with specific field characteristics for increased probability of cavitational effects. Examples of improved designs utilising variations in cell arrangements and characteristics are presented