DEVELOPMENT OF LOW FREQUENCY ACOUSTIC MICROSCOPE

低频声学显微镜的研制

基本信息

批准号：
08555024
负责人：
KAWASHIMA Koichiro
金额：
$ 8.06万
依托单位：
NAGOYA INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

The purpose of this project is to develop a low frequency acoustic microscope which measures precisely the velocities and attenuation of the leaky surface waves and visualize small defects within solids, with lens-less focused ultrasonic transducers operated at frequency less than 5OMHz and digital signal processing. The main results are summarized in the following.1. A digital measurement system has established for precise velocity measurement of the leaky creeping, surface SY and Rayleigh waves as well as attenuation measurement of the leaky Rayleigh wave.2. The mass density within a surface layer has estimated with the measured velocities and 'attenuation mentioned above and equation of leaky surface waves. The measured density of aluminum alloy and fused quartz agrees with bulk density within 10%.3. With dynamic finite element method, the wave propagation in water and solid has analyzed for a model of line focused transducer and aluminum plate. The velocities of the leaky creeping and Rayleigh waves thus calculated agree with the measured within 2%.4. The change in Young's modulus in a functional gradient Al2O3/Ni ceramics has been estimated with the measured velocities of the leaky Rayleigh and longitudinal waves.5. A sizing method of minute defects far less than the focused beam diameter is proposed, where the reflection amplitude from defects is reduced by that of the wide plane at the same depth. The spherical voids of 50 mu m in ceramics is estimated within 20%.6. The growth or healing of spall damage within a target plate under repeated high velocity impacts is well visualized with a lens-less point focused PVDF transducer, from which we can monitor nondestructively the evolution process of internal voids or cracks.

该项目的目的是开发一个低频声学显微镜，该显微镜精确地测量了漏水的速度和衰减表面波，并可视化固体内的小缺陷，其中无镜头集中的超声传感器以小于5omhz和数字信号处理的频率运行。主要结果总结在以下1。已经建立了一个数字测量系统，以精确的速度测量，渗出的蠕变，表面SY和雷利波以及渗漏的雷利波的衰减测量。2。表面层内的质量密度估计了上面提到的测量速度和“衰减以及泄漏表面波的方程式”。测得的铝合金和融合石英密度与10％.3以内的散装密度一致。使用动态有限元方法，水和固体中的波传播已经分析了浓缩换能器和铝板模型的模型。因此，计算出的漏水和雷利波的速度与2％.4之内的测量值一致。在功能梯度AL2O3/Ni陶瓷中，Young模量的变化已通过测得的渗漏雷利和纵向波的速度进行了估计。5。提出了一种小小的缺陷的大小方法，远小于聚焦梁直径，其中，在相同深度下，宽平面的反射幅度降低了。陶瓷中50 mu m的球形空隙估计在20％以内。在重复的高速撞击下，目标板中剥离损伤的生长或愈合可以通过无镜头集中的PVDF换能器进行了很好的可视化，我们可以从中可以从中监测内部空隙或裂纹的进化过程。