Detection and Evaluation of Closed Crack for Aged Structural Materials Using Nonlinear Ultrasound

使用非线性超声检测和评估老化结构材料的闭合裂纹

基本信息

批准号：
15360377
负责人：
MIHARA Tsuyoshi
金额：
$ 6.78万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

In the first year, we built the measurement system in which enable a powerful incidence of ultrasonic wave and accurate measurement of nonlinear ultrasonic wave. Due to the high voltage about 2kV, a commercial transducer with matching coil generated heat and serious damage. Although a PZT transducer without coil was made, an electrode junction part and a an PZT element itself were fractured and the stable measurement was difficult. Then, we adopted the single crystal of 36-degree Y-cutLiNbO_3 as a piezo-electric element and heat-resistant silver paste for electrode junction part. As the result stable transmission of 8MHz ultrasound with high voltage up to 2kV became possible. Highly controlled small crack opening below 10 nm was required for stable measurement of nonlinear ultrasound. During the fatigue crack introduction by three points bending, fracture toughness was controlled to be constant and the amplitude of crack tip echo was monitored using ultrasonic tip diffraction method. U … More sing this procedure, preparing the fatigue crack with adequate crack opening and stable nonlinear ultrasonic measurement for aluminum alloy became possible.In the last year we applied these procedures to SUS316 stainless steel which has serious problem about stress corrosion cracking in nuclear power generator vessel. The fatigue crack introduced with the same technique we also obtained the nonlinear ultrasonic behavior that changed as to the crack propagation. Especially, a subharmonic behavior depended strongly on properties of the crack.In order to investigate the cause of subharmonics, the crack plane contact model with powerful ultrasonic wave was proposed. The simulation based on this model agree well with the experimental result Furthermore, to establish more accurate model, accurate observation for the crack size and shape were required. Although SEM and a laser microscope were applied to estimate crack opening, some more investigation will be required for the quantitative estimation. Less

在第一年，我们构建了测量系统，其中使超声波的强大发生率和非线性超声波的准确测量。由于高电压约2kV，带有匹配线圈的商业传感器会产生热量和严重的损坏。尽管制作了没有线圈的PZT换能器，但电极连接部分和PZT元件本身被破裂，并且很难进行稳定的测量。然后，我们将36度Y-Cutlinbo_3的单晶作为压电电元素和电极连接部分的热耐热银糊。结果，高压高达2kV的8MHz超声的稳定传输变得可能成为可能。稳定的非线性超声测量需要高于10 nm以下的高度控制的小裂纹开口。在疲劳裂纹引入三个点弯曲期间，控制断裂韧性是恒定的，并使用超声尖端衍射法监测裂纹尖端回波的放大器。 u…更多地敲打此过程，以足够的裂纹开口准备疲劳裂纹，并为铝合金稳定的非线性超声测量，这是可能的。在去年，我们将这些程序应用于SUS316不锈钢，这对核发电机容器中的应力腐蚀存在严重问题。通过相同技术引入的疲劳裂纹我们还获得了随着裂纹传播而改变的非线性超声行为。尤其是，在研究亚肝素的原因的情况下，提出了具有强大的超声波波的裂纹平面接触模型。基于此模型的模拟与实验结果一致，为了建立更准确的模型，需要对裂纹大小和形状进行准确的观察。尽管将SEM和激光显微镜用于估计裂纹开放，但定量估计还需要更多投资。较少的