Relationship between dynamic stiffness and service

The new point of view on the material and service life prediction of the toothed belt (synchronous belt) is dynamic stiffness, which can better predict the service life of the toothed belt (synchronous belt) than other properties currently used. A joint study by Kenneth Dalgarno and DuPont John Pillow of the Department of Mechanical Engineering at the University of Leeds showed that in order to meet the requirements of future toothed belts (synchronous belts), it is worth further research on ethylene acrylic elastomer (AEM). Dalgarno’s argument is straightforward. ? The elastomer properties are not sufficient to show how well the materials perform in use. He believes that the dynamic stiffness of the material can more effectively indicate the stiffness and deformation behavior of the teeth, so it can also more effectively predict the service life of the transmission belt (synchronous belt). In the 1995 Swedish Rubber Conference, it was pointed out that the dynamic storage modulus is higher than 1.4MPa, and the performance of the toothed transmission belt (synchronous belt) can be higher than the average level. A much lower dynamic storage modulus ratio will cause the tooth to deform significantly under load, leading to early cracking of the tooth root. The future automotive industry's requirements for toothed belts (synchronized belts) are: service life up to 250,000-300,000 Km. Operating temperature is -35°-150°C, instantaneous high temperature can reach 175°C. Oil resistance> CR, can The service life can reach 3000h under 150C recycling, and the low temperature performance is not sacrificed when improving oil resistance. The toothed belt (synchronized belt) uses glass fiber cords twisted alternately in the S and Z directions as a strong layer. These cords are combined with rubber to form the belt backing and teeth, and the teeth are reinforced with polyphthalamide surface layer. It has begun to use hydrogenated nitrile rubber (HNBR) and modified chlorosulfonated polyethylene (Acsi-um) with a resistance to 135°C for 1000h instead of CR to manufacture toothed belts (synchronous belts). A peroxide-cured saturated HNBR with a life of up to 1000h at 150°C has also been developed, but it still cannot meet the needs of future automotive users. The dynamic modulus of AEM reinforced with aromatic polyphthalamide fiber pulp is 1.46MPa, which is expected to reach the target of using 3000h at 150°C, and the instantaneous temperature can reach 175°C. This material can meet the development requirements of timing belts used at higher temperatures.