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Microscopic Mechanism of Environmentally Assisted Cracking by the Inverse Analysis of Measured Data

通过实测数据反演分析环境辅助开裂微观机理

基本信息

批准号：
11450278
负责人：
TAKEMOTO Mikio
金额：
$ 5.25万
依托单位：
AOYAMA GAKUIN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450278/
关键词：
Lamb Wave Cylinder Wave Waveform Simulation Stress Corrosion Cracking Delayed Fracture Potential Fluctuation Over-all Transfer Function Inverse Analysis 波形シミュレーション応用腐食割れ波形シミュレーション法

项目摘要

For the Acoustic Emission (AE), advanced source location and simulation methods for guided waves (pipe and rod) are developed. Source dynamics of hydrogen blister, delayed fracture and void formation (Ti-Pd) were obtained by the wave form simulation of So and L (0,1) waves by the wave form matching of computed to the measured. Here the wave form was computed by the convolution of assumed crack opening with experimental over-all transfer function determined using the expansion of the compression type PZT element. Micro-cracks of delayed fracture of high tension steel was found to be close to the Rayleigh wave velocity and caused sub-cracks by leaking the wave-energy during fast propagation. Extremely fast micro-crack of delayed fracture was first studied by using the AE sensors at marker and the rod specimen where the dispersive low frequency guided waves were monitored, but was slower than those of mechanical fractures of quenched high carbon steel. It was also first that the strong an … More d fast guided wave Aes were monitored during hydrogen absorbing of Ti-Pd alloy rod, possibly by void formation by hydrogen gas. Such Aes are supposed to be produced by rapid void formation by hydrogen gas emitted from titanium hydride.The author first proposed the AE source location method using very few AE sensors. Source locations of guided wave, both in the longitudinal direction and transverse section, were determined only a single AE sensor. Computer soft ware for velocity dispersion and modal analysis, required for such signal analysis were developed at home and now opened on the internet.Trans-granular APC-SCC does not emit Aes while inter-granular one does emit Aes with sufficient amplitudes. Fluctuation dynamics of corrosion potential during APC-SCC were attempted using the over-all transfer function determined by artificial fracture of PVD-TiN film. However, it could not be studied by the inverse processing of potential fluctuation due to it's too slow response. Wavelet analysis (time-frequency domain analysis) revealed that fluctuation frequency higher than 0.2Hz was dominant during the incubation period, but lower frequency during SCC propagation. Less

针对声发射（AE），发展了先进的导波（管和杆）源定位和模拟方法。通过对So波和L（0，1）波的波形模拟，得到了氢泡、延迟断裂和空洞形成（Ti-Pd）的源动力学。在这里，波形计算的卷积的假设裂纹开口与实验的整体传递函数确定使用的压缩型PZT元件的扩展。研究发现，高强度钢延迟断裂的微裂纹与瑞利波传播速度接近，在快速传播过程中能量泄漏，导致亚裂纹的产生。首次利用声发射传感器对延迟断裂的超快速微裂纹进行了研究，并对棒试件进行了低频导波监测，但其速度比淬火高碳钢的机械断裂慢。这也是第一次， ...更多信息在Ti-Pd合金棒吸氢过程中，监测到了3d快导波Aes，这可能是由于氢气在钛合金棒中形成空穴所致。作者首次提出了用很少的声发射传感器进行声发射源定位的方法。利用单个声发射传感器确定了导波源在纵向和横截面上的位置。国内已研制出了分析这类信号所需的速度频散和模态分析的计算机软件，目前已在互联网上公开。穿晶型APC-SCC不发射Aes，而沿晶型APC-SCC发射Aes，但有足够的振幅。利用PVD-TiN膜的人工破裂所确定的整体传递函数，对APC-SCC过程中的腐蚀电位波动动力学进行了尝试。然而，由于其响应速度太慢，无法通过电位涨落的逆处理来研究。小波分析（时频域分析）显示，在孕育期，高于0.2Hz的波动频率占主导地位，而在SCC传播过程中，频率较低。少