Study on the Active Sound Cancellation Control of Railway Wheel/Rail Noises by On-vehicle-type Devices

(1)首先通过边界元分析对铁路轮轨系统滚动噪声和冲击噪声的声辐射特性进行了理论研究，并通过实际常规铁路线路的现场测量进行了实验研究。(2)提出了利用车载装置对铁路轮轨噪声进行主动消声控制的概念，并对其可行性进行了理论和实验验证。首先，通过引入吸波控制原理，在整个可见空间内消除车辆开口下区辐射的噪声，构造了传感器和执行器在装置中的放置方法，并基于二维边界元法进行了仿真，验证了其概念在板条轨道和道砟轨道两种情况下的有效性。(3)然后，设计并制造了一个设备原型单元及其模拟控制器。并进行了实验室级实验。实验采用Γ-shaped蜂窝板模拟某汽车的底板和侧壁薄板，以平面波扬声器和60kg长8m的电磁激振器激励轨道为主要噪声源。结果表明，对于扬声器噪声源和随机激励轨道噪声源，在分离的下两点得到了几乎等效的-8dB(a) ~ -9dB(a)的主动控制效果，实际上也得到了-3dB(a) ~ -6dB(a)的主动控制效果。由此，从根本上确定了主动消声控制概念的可能性。最后，通过边界元仿真对其实际应用前景进行了展望，并暗示了该概念实现的实际可能性。

Results of present project are summarized as follows :(1)Sound radiation characteristics of rolling noise and impact noise of railway wheel/rail system were first investigated theoretically by using BEM analysis and besides experimentally by field measurements of actual conventional railway line.(2)The concept of the active sound cancellation control of the railway wheel/rail noises by on-vehicle-type devices was proposed and its possibility was examined theoretically and experimentally. First, by introducing the wave absorbing control principle to cancel the noises radiated from the open under area of the vehicle over the whole lower seeable space, the methods of placement of sensor and actuator in device were constructed, and the validity of its concept in both cases of slab and ballast tracks was verified by the simulation on the basis of the two-dimensional Boundary Element Method.(3)Then, one prototype unit of devices was designed and manufactured in addition to its analog controller. And the laboratory-level experiments were carried out. In the experiments, the floor and side thin plates of a vehicle were simulated by using the Γ-shaped honeycomb panels, and both of a plane-wave speaker and a 60kg rail of length 8m excited by the electro-magnetic shaker were used as the primary noise sources. As a result, it was verified that almost equivalent active control effects of -8dB(A)〜-9dB(A) are obtained at the separated lower two points for the case of the speaker noise source and also for the noise source of randomly excited rail, active control effects of -3dB(A)〜-6dB(A) are actually obtained. Thus, the possibility of proposed concept of active sound cancellation control was fundamentally ascertained. Finally, the future prospect for practical use was examined by BEM simulation and the practical possibility of realization of the presented concept was implied.