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A new parameter was proposed to evaluate the fatigue life of toothed belts. The parameter is the frictional work spent on the belt tooth surface for driving and driven pulleys. It can be estimated only with the 2D finite element model of the belts previously developed by the authors. As well as the frictional work, an alternative parameter, maximum tooth load (widely used in the literature) was also used to evaluate the fatigue life of toothed belts. In order to prove the effectiveness of the present parameter, fatigue tests were conducted using S8M belts at a constant power. The test results show that the maximum tooth load can explain the fatigue degradation of the toothed belts to some extent while the proposed parameter, the frictional work can evaluate the fatigue life of the belt due to wear of the belt facing fabric more appropriately than the maximum tooth load.

A concept and a (nonlinear finite element) model of how to analyze load distribution of toothed belts having curvilinear tooth profiles for automotive engines at steady states was developed by utilizing a general nonlinear finite element program considering contact problems as well as geometrical nonlinear problems. A toothed belt in the model consists of circularly linked beam elements for endless tension members and two dimensional solid elements for a belt body. A curved pulley surface is supposed to be rigid. Interaction between surfaces of belt teeth and pulleys is considered as moving boundaries. A quite good agreement between experimental and computed results for frictional forces and tooth load confirms that the proposed model is presently the only one practical approach for analyzing load distribution of toothed belts which none of the existing theories can do. Some numerical simulations were performed by changing parameters such as belt pitch, dimensions of teeth and so on.

The purpose of this paper is to analyze the force distribution between pulleys and blocks of a newly developed CVT belt. Three components of the force (transmitting force, normal force and frictional force) were measured directly using a newly devised pulley. The experimental results reveal that the transmitting force distribution on the driving pulley is similar to that on the driven pulley as long as blocks do not slip while the distribution of the normal force component for both pulleys does not resemble each other as well as the distribution of friction force in the radial direction of the pulley. It is also found that no idle arc exists in the contact arc of both driven and driving pulleys even in the case that the transmitting torque is low. The experimental force distribution is compared with a theory based on the discrete spring model taking no consideration of slippage between the pulley and the blocks.