Theoretical Correction Method and Application of German-Standard Insertion Loss Rate of Vibration Damping Track

To accurately and efficiently evaluate the vibration damping performance of tracks, the German standard DIN V 45673 -4 provides a method for efficiently calculating the insertion loss rate, which can eliminate interference from stochastic factors such as line operation conditions and track irregularities. However, this method neglects the contribution of track bending stiffness in its equivalent model, leading to errors in identifying the resonant frequency of the wheel-rail system and the vibration damping frequency band of tracks. To increase the calculation precision, the model for calculating the German-standard insertion loss rate was improved on the premise that the computational efficiency was maintained. By employing the elastic foundation beam theory to approximate the actual structural dimensions and stiffness characteristics of tracks and considering the contributions of elastic components and track bending stiffness, the stiffness of the model was corrected. The plans for optimizing track dimensions and vibration damping performance of elastic components were discussed in terms of the 1–80 Hz vibration damping frequency band required by China’s environmental impact assessment by taking the floating slab tracks with vibration damping pads for example. The results show that after stiffness correction, the error in the resonant frequency of the wheel-rail system is reduced from 76% to 4.9%. The increase in the fastener loss factor can achieve the overall vibration damping performance within the 1–80 Hz frequency band. However, within the range of 30–90 kN/mm for fastener stiffness, reducing (increasing) the fastener stiffness improves the insertion loss rate of the 60–80 Hz (30–60 Hz) frequency band and decreases the rate of the 30–60 Hz (60–80 Hz) frequency band. This does not meet the overall vibration damping performance for the 1–80 Hz frequency band which can only be achieved when the fastener stiffness exceeds 90 kN/mm. Furthermore, lower stiffness of vibration damping pads or thicker floating slabs indicate higher improvement in fastener stiffness.