Relationship between the elastic modulus of the rail pad and track vibration
- What is the reasonable range of the elastic modulus of under-rail pads?
The elastic modulus of under-rail pads for ordinary railways is generally 80 - 120MPa, which can meet the vibration buffering needs of medium and low-speed train operation. High-speed railways have higher requirements, with an elastic modulus of 100 - 150MPa, which can reduce high-frequency vibration while providing sufficient support. Urban rail transit has a slightly lower elastic modulus of 70 - 100MPa due to short station intervals and frequent start-stops to absorb more vibration energy.
- What impact will excessively high elastic modulus have on track vibration?
Excessively high elastic modulus reduces the cushioning performance of the pad. Vibration during train operation cannot be effectively absorbed, and the vibration is transmitted to the sleeper and ballast, leading to intensified vibration of track components and accelerated wear. At the same time, vibration transmitted to the train will increase passenger discomfort, and the vibration noise of the train body will also increase.
- What problems will excessively low elastic modulus bring?
Excessively low elastic modulus makes the pad prone to excessive deformation, increases rail settlement, makes it difficult to maintain track geometric dimensions, and makes gauge and height deviations easy to exceed the limit. Long-term use will cause permanent deformation of the pad, failure of elastic performance, requiring frequent replacement, increasing maintenance costs and workload.
- What are the differences in elastic modulus among under-rail pads of different materials?
Rubber pads have a low elastic modulus, generally 70 - 100MPa, with good elasticity, suitable for urban rail transit. Polyurethane pads have a medium elastic modulus, 100 - 130MPa, with better wear resistance and aging resistance than rubber, used for ordinary railways. Polyethylene pads have a higher elastic modulus, 120 - 150MPa, with high strength, suitable for high-speed railways.
- How to adjust the elastic modulus of under-rail pads according to track vibration?
Measure the vibration acceleration with a track vibration monitor. If the vibration is too large (exceeding 0.3g), replace the pad with a lower elastic modulus, reduce by 5 - 10MPa to enhance buffering. If the track settlement is obvious and the vibration is small, select a pad with a higher elastic modulus, increase by 5 - 10MPa to increase support. After adjustment, re-detect vibration and track geometric parameters to ensure compliance with requirements.