Longitudinal - Torsional Composite Ultrasonic Vibration System

Since1830s, the ultrasonic therapy---this kind of biological effect treatment started to enter the medical field, and lasted until the1970s, with the gradually accumulated experiences and the steadily intensified theoretical research, the ultrasonic surgery became another major application in the medical field, right after the ultrasonic imaging. In recent years, China has lunched a large-scale study of the ultrasonic scalpel. Practice shows that, the ultrasonic scalpel has high cutting speed, the operative time is shorter, and the demand for the physical strength is easier, meanwhile, with all the characteristics such as the synchronization of cutting and coagulation, lesser tissue eschar after the operation, the surgical smoke is lesser which ensure a clearer vision, safe to do the cutting operation, easy for the tissue-separation, all these advantages has made the the application of ultrasonic scalpel broadening from the early ophthalmology and neurosurgery, to the fields such as ultrasonic orthopedic, ultrasonic surgical aspiration and ultrasonic hemostasis, then further used in the thoracic surgery, urology, gynecology, ENT, Head and Neck Surgery and the other relative department.As we know, it’s been years since the study and manufactory of the ultrasonic scalpel both at home and abroad, the research and the development as well as the wide-spread use of the ultrasonic surgery equipment would bring huge social benefits and economic benefits. However, there are still many technical imperfections for the ultrasonic scalpel. For example, the electro-acoustic conversion efficiency is low, the cutter heads as well as the cutlery itself are easy to wear, and the study on the mechanism is not enough. Therefore, to solve this bottleneck problem, this paper will make some study of optimization theoretically on longitudinal-torsional compound vibration system.First, the chapter one introduces the basic structure of the ultrasonic scalpel, mainly composed of two parts, the high-frequency power source and the ultrasonic vibration system, while the ultrasonic vibration system includes another three parts:the ultrasonic transducer, horn (single or compound), and the cutter head, meanwhile, analyzed the working principle of the ultrasonic scalpel, which mainly includes the fragmentation effects (the instantaneous impact acceleration), the micro-acoustic streaming effect, acoustic cavitation and hemostatic effect. Then, through the analysis to the design and the performance of the ultrasonic scalpel transducer and the horn, from the basic equations, by using the four-terminal network, can gain respectively the transfer matrix of both the ultrasonic scalpel compound horn and the longitudinal vibration transducer, since there are many similarities of the horn, start from the theory of one-dimensional longitudinal vibration, could get some relevant conclusions of the longitudinal-torsional compound vibration system. This is not only help us to be more familiar with the four-terminal network method of ultrasonic vibration system, but also allowing us to have a higher efficient use of it, as well as achieve a good results in simplify the computation process.In the3rd chapter of this paper, the longitudinal-torsional compound system with chute is studied. Through specific experiments, the influence to the longitudinal-torsional cylinder resonance frequency, which is decided by the slanting angle of the chute, its position and the length, has been analyzed, finally obtained the formula for the circuit of the chute and the resonance frequency. The last part of this paper, we studied the longitudinal-torsional compound transducer with chute, learned that the compound transducer is made of a sandwiched longitudinal ultrasonic transducer and a transmission cylinder with chute, and gained the equivalent circuit of the longitudinal-torsional vibration system, well on the basis of the equivalent circuit, the formula for the input mechanical impedance of the composite system and the resonant frequency can be gained. Numerous experimental results shows, the slanting angle of the chute, its position as well as its geometric length has effects on the longitudinal and torsional vibration inside the cylinder, and the result for the resonance frequency and the velocity ratio are almost the same as the predicted results, meanwhile, we got the compound movement at the output end of the transmission cylinder, which helped us to master the vibration characteristics of the longitudinal-torsional compound vibration system. This is very important for the study of the Longitudinal-torsional compound ultrasonic transducers.