ABSTRACT

Rail accelerations can be used on the defect detection and health monitoring of railway vehicle and track components; therefore, mathematical models that predict this response are of interest for reproducing its behaviour in a wide range of situations. The numerical track models based on the Timoshenko beam theory introduce a non-physical response, which is especially noticeable in the rail accelerations. It is due to the lack of dynamic convergence of the Timoshenko finite element (FE). This paper addresses this phenomenon employing an enhanced formulation of the Timoshenko FE that includes internal degrees of freedom (iDoF). The iDoF shape functions are derived from the Timoshenko beam dynamic governing equations. Firstly, the formulation is presented, and its performance is compared with a similar Timoshenko FE formulation. Secondly, the proposal is assessed in the dynamic modelling of railway track structures. The use of iDoF efficiently corrects the non-physical response of rail accelerations by improving the FE dynamic convergence. Subsequently, a filtering criterion for accelerations is proposed, which removes the remaining non-physical response while guaranteeing the conservation of coherent frequency content. Finally, practical cases are simulated for which the proposed methodology is proved to be more efficient and reliable than the standard approach.

摘要

轨道加速度可用于铁路车辆和轨道部件的缺陷检测和健康监测；因此，预测这种反应的数学模型对于在广泛的情况下重现其行为很有意义。基于 Timoshenko 梁理论的数值轨道模型引入了非物理响应，这在轨道加速度中尤为明显。这是由于 Timoshenko 有限元 (FE) 缺乏动态收敛。本文使用包括内部自由度 (iDoF) 的 Timoshenko FE 的增强公式来解决这一现象。iDoF 形状函数源自 Timoshenko 梁动态控制方程。首先，提出了该公式，并将其性能与类似的 Timoshenko FE 公式进行了比较。第二，该提案在铁路轨道结构的动态建模中进行了评估。iDoF 的使用通过提高有限元动态收敛性来有效地纠正轨道加速度的非物理响应。随后，提出了加速度的过滤准则，该准则消除了剩余的非物理响应，同时保证了相干频率内容的守恒。最后，模拟了实际案例，证明所提出的方法比标准方法更有效和更可靠。这消除了剩余的非物理响应，同时保证了相干频率内容的守恒。最后，模拟了实际案例，证明所提出的方法比标准方法更有效和更可靠。这消除了剩余的非物理响应，同时保证了相干频率内容的守恒。最后，模拟了实际案例，证明所提出的方法比标准方法更有效和更可靠。