Concepts and Simulated Testing of Active Railway-Wheels

The prevention of noise pollution has become one of the major concerns in science in general. Especially transportation systems have come into focus and as a tender point the noise of railways and trains. Several passive methods have been evolved to reduce the noise emission of trains in the past decades. Within the project ”Next-Generation- Train” governed by the German Aerospace Center (DLR) new active methods for noise reduction are reviewed. This paper focuses on sound radiation of wheels and thereby reviews different concepts for including active materials and sensors into a wheel. Firstly patch-actuators are applied to the web and secondly stack-actuators are positioned normal to the web. These concepts are thoroughly simulated for sufficient control of the inherent vibrations of the wheel. The more effective solution is selected. This solution is being transferred into a modal state-space system and exported from the finite element simulation. A tool synthesizes a suboptimal H1-controller for the active wheel using the normal surface velocity as controlled variable. Simulations of the control loop show that active reduction of vibration is possible with the chosen concept. Reductions of normal surface velocity of up to 20 dB are achieved. In comparison to existing passive methods this reduction is quite respectable and encourages further testing on this issue