Cavuto A, Martarelli M, Pandarese G, Revel G M, Tomasini E P
Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy.
Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy.
Ultrasonics. 2021 May;113:106368. doi: 10.1016/j.ultras.2021.106368. Epub 2021 Jan 28.
Laser-Ultrasonics Testing (LUT) is a Non-Destructive Technique (NDT) with good potential for application in the railway sector, nevertheless this technique is not yet used in practice because there are some practical difficulties to overcome. The possibility of measuring on a complete wheelset by bypassing the keying of the wheel will allow drastically reducing the inspection time but it has not yet been demonstrated. In fact, the attenuation of the signal in the path makes complex the interpretation of the generated waves. This paper aims at illustrating how the combination of simulated and experimental data allows to optimize the test setup for having output data of unambiguous interpretation. The main innovations presented in this paper are: (i) the possibility to work with low energy waves in the thermoelastic-ablative limit while maintaining satisfactory contrast levels for the purpose of defect detection and (ii) the implementation of a complete Finite Element Model (FEM) including the generation and propagation of waves in the solid domain and the propagation in air. This last step has not considered before in previous papers. The model allows to define the optimal experimental conditions to have a measured signal with an adequate signal-to-noise ratio (SNR > 6 dB) and to define an experimental procedure for defect detection reliable and comparable with current standards. This study lays the foundations for an innovative approach for train axle diagnostics which can be used during train extraordinary maintenance interventions. The laser ultrasonics system presented in this paper can be likely integrated in the pit lathe and exploited to monitor the railway wheels during their re-profiling phase, without having to remove them from the vehicle.
激光超声检测（LUT）是一种无损检测技术（NDT），在铁路领域具有良好的应用潜力，然而该技术尚未在实际中得到应用，因为存在一些实际困难需要克服。绕过车轮键槽在完整轮对上进行测量的可能性将大幅减少检测时间，但这尚未得到证实。事实上，信号在传播路径中的衰减使得对所产生波的解释变得复杂。本文旨在说明模拟数据与实验数据的结合如何能够优化测试设置，以获得易于解释的输出数据。本文提出的主要创新点包括：（i）在热弹性烧蚀极限下使用低能量波进行检测的同时，保持用于缺陷检测的令人满意的对比度水平；（ii）实现一个完整的有限元模型（FEM），该模型包括固体域中波的产生和传播以及在空气中的传播。此前的论文中尚未考虑到这最后一步。该模型能够定义最佳实验条件，以获得具有足够信噪比（SNR > 6 dB）的测量信号，并定义一种与当前标准可靠且可比的缺陷检测实验程序。本研究为一种创新的列车车轴诊断方法奠定了基础，该方法可用于列车的特殊维护干预。本文所展示的激光超声系统很可能集成到不落轮镟床中，并在铁路车轮的再加工阶段对其进行监测，而无需将车轮从车辆上拆卸下来。
