The principal vibration-isolating characteristics of rubbers based on natural rubber and a combination of synthetic isoprene and butadiene rubbers were determined. The static and dynamic moduli, the hysteresis losses, and the logarithmic decrement were measured on an Yerzley mechanical oscillograph (manufactured by the US company Tavdi) in accordance with ASTM D-945. The changes in these characteristics were measured in the process of heat ageing. To convert the data to room temperature, the Arrhenius equation was used. The main changes in the static modulus occur in the first three years, and the main changes in the dynamic modulus in the first five years. Their ratio and the natural frequencies are different for various rubbers and for different storage and service times. The resonance zones are also different. It is concluded that, when predicting the useful life of the vibration isolator, it is necessary to assess all the dynamic and static parameters for each individual case.
Increasing axial loads including the development of heavy movement on Russian railroads network require the best solutions for improvement of the railway track structure. Research by Russian and international scientists indicates that rail elastic pads reduce vibrations transferred from reinforced concrete sleepers to crashed stone, including the joint area. This study examines possibilities of using rail pads for reducing the dynamic effects of the rolling stock on the track in the joint area. Assessment of the rail pads construction material shock-absorbing properties was conducted considering the elastic properties of the rail support with static and dynamic loads. Results of mode ling the elastic properties of the rail support with rail pads of different rigidities using the software complex “Universal mechanism” are presented. The results were used as basis for calculation of indicators of dynamic interaction of the track and rolling stock at the joint using the coeffi cient establishing the link between bendings of the solid rail and the rail with joint. The expediency of using rail pads at the place of the joint is justifi ed based on assessment of the results.This study reveals that elastic rail pads based on isoprene rubbers are suitable for track structures that improve indicators of the track and rolling stock interaction. When using rubber pads, the growth of accelerations on the sleeper is less dependent on the speed, causing the track stability to increase. The results are supported by tests consistent with calculations and justify the necessity for further studies in this fi eld.
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