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，但是由于需要克服一些实际困难，因此该技术尚未在实践中使用。通过绕过车轮的键来测量完整的轮对的可能性将极大地减少检查时间，但尚未证明。实际上，路径中信号的衰减使所生成波的解释变得复杂。本文旨在说明模拟和实验数据的组合如何允许优化测试设置，以使输出数据具有明确的解释。本文提出的主要创新是：（i）以低能量波在热弹性烧蚀极限下工作的可能性，同时保持令人满意的对比度水平以进行缺陷检测；（ii）实施包括波的产生和传播的完整有限元模型（FEM）在固体领域和在空气中传播。以前的文章中从未考虑过最后一步。该模型允许定义最佳实验条件，以使被测信号具有足够的信噪比（SNR> 6 dB），并定义可靠且可与当前标准相媲美的缺陷检测实验程序。该研究为列车轴诊断的创新方法奠定了基础，该方法可在列车非常规维护干预期间使用。