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

本课题的研究成果总结如下：(1)首次采用边界元分析方法对轮轨系统滚动噪声和冲击噪声的声辐射特性进行了理论分析，并通过对实际常规铁路线的现场测量，对轮轨噪声进行了实验研究。(2)提出了车载式装置有源消声控制轮轨噪声的概念，并从理论和实验上验证了其可行性。首先，通过引入吸波控制原理，消除整个下可视空间内车辆敞口区域辐射的噪声，建立了传感器和执行器在装置中的放置方法，并基于二维边界元方法进行了仿真验证，验证了其概念的正确性。(3)在模拟控制器的基础上，设计并制造了装置的样机单元。并进行了实验室级实验。在实验中，采用Γ蜂窝板模拟了车辆的地板和侧面薄板，并以平面波扬声器和电磁振动器激励的60 kg长8m的钢轨作为主要噪声源。结果表明，对于扬声器噪声源和随机激励钢轨噪声源，在分离的下两点获得了几乎等价的-8dB(A)~-9db(A)的主动控制效果，实际获得了-3db(A)~-6db(A)的主动控制效果。从而从根本上确定了提出有源消声控制概念的可能性。最后，通过边界元仿真，对未来的实际应用前景进行了展望，并指出了该概念实现的现实可能性。

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.