Elastic performance and installation specifications of rail pads
- What factors affect the elastic performance of under - rail pads?
Material is the core factor. Rubber pads have good elasticity and can effectively absorb vibration. For example, natural rubber pads have better elasticity than synthetic rubber. Plastic pads have relatively poor elasticity, but their performance is stable under specific loads. The thickness and hardness of the pad also have an impact. Under the same material, thicker pads have better elasticity. For example, 10mm thick rubber pads are better than 6mm thick ones. Pads with moderate hardness have good elastic performance. Too high hardness leads to poor elasticity, and too low hardness makes them easy to deform. Internal structures such as foaming and hollow design, foamed rubber pads have better elasticity and shock absorption due to their internal bubble structure, and are suitable for lines with high shock absorption requirements.
- Which scenarios are under - rail pads with different elastic properties suitable for?
High - elasticity pads (such as elastic modulus 20 - 50MPa) are suitable for urban rail transit and high - speed railways, which can greatly reduce vibration and noise and improve ride comfort. Medium - elasticity pads (elastic modulus 50 - 100MPa) are often used in ordinary trunk railways, balancing shock absorption and track stability to meet general operation needs. Low - elasticity pads (elastic modulus above 100MPa) are suitable for heavy - haul railways, with good rigidity, which can bear huge loads, reduce track deformation and ensure line stability. In special scenarios such as subway curves, high - elasticity pads need to be matched with anti - creep devices to both reduce vibration and prevent rail displacement.
- What impact will irregular installation of under - rail pads have on their elastic performance?
Misalignment of the pad during installation will cause uneven stress, and the local elasticity cannot be exerted, leading to increased track vibration. For example, if the pad offset exceeds 5mm, the elastic performance will decrease by more than 30%. Gaps or overlaps between pads will make load transmission unsmooth. The pad at the gap is subject to large impact, and the elasticity decays quickly; the overlapping part has excessive elasticity due to increased thickness, affecting track stability. Failure to clean up debris such as stones and 泥土 during installation will cause excessive local pressure on the pad, resulting in plastic deformation, permanent decline in elastic performance and shortened service life.
- How to detect whether the elastic performance of under - rail pads meets the standard?
Use a pressure testing machine for elasticity testing. Apply a specified load (such as 10kN), measure the compression and rebound of the pad. A rebound rate ≥90% is qualified, indicating good elastic performance. Conduct a fatigue test by simulating train loads. After 1 million cycles of loading, if the elastic attenuation rate ≤15%, the performance is up to standard. During on - site testing, use a vibration meter to measure the track vibration value. The vibration acceleration of the installed qualified high - elasticity pad should be reduced by more than 30% compared with that without the pad. Check the appearance and size of the pad, with no cracks or deformation, and the thickness deviation ≤1mm to ensure stable elastic performance.
- What changes will occur in the elastic performance of under - rail pads over time?
After long - term use, the elasticity of the pad will decrease due to material aging. Rubber pads in sun exposure and high - temperature environments may have their elasticity attenuated by 20% - 30% in 3 - 5 years. Frequent load action causes fatigue of the pad, weakening the compression and rebound capacity. For example, the elastic attenuation rate of pads in heavy - haul railways may reach 25% after 5 years. Environmental factors such as oil pollution and chemical corrosion will damage the pad material, deteriorating the elastic performance. Rubber pads in contact with oil will have a faster decline in elasticity, and even harden and crack.