节点文献
高强度聚焦超声压力特性测试技术研究
Research on Pressure Measurement Technology of High Intensity Focused Ultrasound
【作者】 高强；
【导师】 汪炜；
【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2009， 硕士
【摘要】 功率超声技术是一种新兴的、多学科交叉的科学技术,它将超声技术、功率电子技术以及材料科学等科学技术结合起来,在医疗、化工、材料处理和改性等许多方面都有着广阔的应用前景。为实现高强度聚焦超声的能量可控,对其声场特性的研究与测试显得尤为重要。在课题组前期研究基础上,本文以高强度聚焦超声为研究对象,对其辐射力声场进行了数值模拟,并采用荷重天平、压电陶瓷水听器和自行研制的PVDF压力传感器进行了声场压力特性测试实验研究。主要研究内容包括:1.根据惠更斯原理,对高强度聚焦超声声场进行了数值模拟,并通过KZK方程对超声传播过程中的非线性效应进行理论研究,为超声压力特性测试实验研究奠定了理论基础。2.使用辐射压力法测量了高强度聚焦超声功率,得到了电、声功率随激励电压变化的规律,验证了超声换能器与激励电源工作的一致性和稳定性;采用压电陶瓷水听器对超声聚焦区域压力进行了测试,得到了一定的连续脉冲个数产生的峰值压力与激励电压的关系。3.研制高频响的PVDF压力传感器,对超声聚焦区域压力特性进行了进一步测试研究,得到了峰值压力随激励电压及阵元个数变化的规律。根据实测压力波形,初步研究了由非线性效应产生的激波的形成过程,为高强度聚焦超声技术机理研究提供了基础实验依据。4.最后,对高强度聚焦超声的热效应进行了有限元分析计算和仿真,计算结果证明,减少连续超声持续作用时间,可以有效降低热效应对压力测试造成的影响。
【Abstract】 Power ultrasonic technology is a new interdisciplinary science and technology, which combines a variety of techniques as ultrasonic technology, power electronics technology, material science, and etc. This technology has broad application prospects in areas of medical, chemical, materials strengthening treatment and surface transformation. For achieving energy controllable, measuring the characteristics of ultrasound is apparently important. On the basis of the preliminary research work, the sound field of high intensity focused ultrasound (HIFU) is simulated, and the load balance,piezoelectric ceramic hydrophone and polyvinylidene fluoride (PVDF) piezoelectric film transducer are used to measure the pressure characteristics of ultrasound.Following are main recearch work:1. According to the Huygens Principle, the sound field of high intensity focused ultrasound is simulated. And the non-linear effect of ultrasound is studied theoretically on the basis of the non-linear equation KZK. These theoretical studies provide a theoretical basis for pressure measurement.2. The method of radiation forcer balance is used to measure the sound power of ultrasound. The relationship between electric power, sound power and input voltage is obtained. And the consistency and stability of ultrasound transducer and power supply are verified. Than the the piezoelectric ceramic hydrophone is adopted to measure the pressure of ultrasound. The peak pressure generated by a certain number of pulses, and the relationship between peak pressure and input voltage is obtained.3. A new kind of PVDF (polyvinylidene fluoride) piezoelectric film transducer with high frequency response is developed to further study the pressure characteristics of focused ultrasound. The relationship between peak pressure, input voltage and the number of elements are obtained. Based on the measured pressure waveform, the forming process of shock wave generated by the non-linear effect is studied preliminary. This test provides an experimental basis for the research on mechanism of ultrasonic processing technology.4. Finally, the thermal effect of ultrasound is analyzed by finite element method. The result shows that, the measure of reducing the duration of ultrasound is helpful for weakening the impact of thermal effects in the pressure test.