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首页> 外文会议>Annual Symposium on Quantitative Nondestructive Evaluation; 19980719-24; Snowbird,UT(US) >ULTRASONIC TESTING OF RAILS INCLUDING VERTICAL CRACKS - NUMERICAL MODELING AND EXPERIMENTAL RESULTS
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ULTRASONIC TESTING OF RAILS INCLUDING VERTICAL CRACKS - NUMERICAL MODELING AND EXPERIMENTAL RESULTS

机译：包含垂直裂纹的轨道的超声测试-数值模拟和实验结果

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摘要

The good qualitative agreement between the measurements and the numerical simulations for the different testing situations shows the accuracy of the developed numerical code. By the help of the simulations, all mode conversions at the crack and rail surfaces were cleared up leading to a better understanding and interpretation of the received signals. A significant attenuation of the rail bottom echo for the three different crack locations were found for both, shear and longitudinal waves. The most important difference between the two wave modes is the fact that the interaction between primary shear wavefront and the crack or rail surfaces does not produce new echoes in the A-scan like head-waves or secondary echoes as described for the P-wave. It should be mentioned that the method using piezoelectric shear wave transducers is unpracticable for fast testing of real rails in railway tracks due to coupling-problems. But this can be solved by using EMA-transducers. Further investigations should involve more realistic crack geometries and various crack parameters such as width, length, depth, orientation, surface roughness and so on, different frequencies and moreover, shear waves with a polarization plane perpendicular to the rail cross-section. The latter problem can be treated with a special three-dimensional EFIT model that consists of only one grid cell in the direction of the longitudinal rail axis if a strip-like transducer is still taken as a basis. A broader future perspective of the investigations should involve a classification of typical rail defects in the pulse-echo mode of ultrasonic testing.
机译：在不同的测试情况下，测量结果与数值模拟之间的良好定性一致性证明了所开发数值代码的准确性。通过仿真，裂缝和轨道表面的所有模式转换都得以清除，从而可以更好地理解和解释接收到的信号。对于剪切波和纵向波，三个不同裂纹位置的轨道底部回波都显着衰减。两种波模式之间最重要的区别在于，主剪切波前与裂缝或轨道表面之间的相互作用不会像在P波中所描述的那样，在A扫描中产生像头波或次级回波那样的新回波。应该提到的是，由于耦合问题，使用压电剪切波换能器的方法无法快速测试铁路轨道中的实际轨道。但这可以通过使用EMA换能器解决。进一步的研究应涉及更切合实际的裂纹几何形状和各种裂纹参数，例如宽度，长度，深度，方向，表面粗糙度等，不同的频率以及具有垂直于钢轨横截面的偏振面的剪切波。后一种问题可以通过特殊的三维EFIT模型来处理，如果仍以条形传感器为基础，则该模型仅在纵向轨道轴线的方向上仅由一个网格单元组成。研究的更广阔的未来前景应涉及在超声波测试的脉冲回波模式下对典型钢轨缺陷进行分类。

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