When a wheel rolls over a railway rail, it ‘sees’ a varying stiffness downwards because the rail is periodically supported by sleepers, leading to parametric excitation of the rail/wheel system. This study investigates the importance of parametric excitation on railway noise generation. Because the problem is non-stationary, it is modelled in the time domain. Rail and wheel impulse response functions, together with an iteration scheme to match boundary conditions in the rail/wheel contact patch, yield rail and wheel response plus contact force at each wheel position on the rail. Forward velocity and rotation of the elastic wheel are accounted for. Feedback coupling between response and force takes part in the excitation. Numerical simulations show that, for a rail on stiff pads, parametric excitation is a major excitation mechanism, above all leading to increased excitation and noise levels in a broad frequency region around the pinned–pinned frequency.

当车轮在铁路轨道上滚动时，它会“看到”向下变化的刚度，因为轨道会定期由轨枕支撑，从而导致对轨道/车轮系统进行参数激励。这项研究调查了参数激励对铁路噪声产生的重要性。由于问题是非平稳的，因此在时域中对其进行建模。轨道和车轮脉冲响应功能，以及与轨道/车轮接触贴片中的边界条件匹配的迭代方案，可产生轨道和车轮响应以及在轨道上每个车轮位置的接触力。考虑到弹性轮的前进速度和旋转。响应和力之间的反馈耦合参与了激励。数值模拟表明，对于刚性垫板上的轨道，参数激励是主要的激励机制，