Modeling of tensioner hysteresis for belt accessory drive system under random excitations

Tensioner is one of the key components of a belt accessory drive system (BADS), so accurately characterizing its hysteresis characteristics is important for calculating dynamic responses of a BADS. The existing tensioner models have some disadvantages, such as ignoring the variations of friction coefficient of the friction pair inside a tensioner during working, and cannot characterize the output torque of tensioner with the excited amplitude and frequency. Based on Duhem model, a unified model for tensioner considering the variations of friction coefficient inside tensioner is proposed in this paper, and the variations of friction coefficient in a tensioner are characterized by Stribeck effect in the unified model. The already published tensioner models, such as Duhem model and dry friction model, are special cases of the unified model. According to the oscillation state of tensioner arm, a method for estimating dynamic responses of tensioner under random excitations is proposed. The proposed method deals with the issue of how to determine the output torque of unified model under excitations without steady excited amplitude. Under harmonic excitations and random excitations, the measured and calculated output torque of a tensioner are compared to validate the unified model. The K-V model, dry friction model and Masing model, which are commonly used tensioner models, are compared with the unified model by comparing their dynamic responses. Taking a single-degree-of-freedom system containing a tensioner as a studying example, the step response and random response of the system are calculated and analyzed when different tensioner models are utilized.