| A dynamic model based on the axially moving material model is developed to study vibration in roller chain drives without a tensioner. A unique feature of the work presented in this study is that impact, polygonal action and external periodic load have been included in the model through chain tension and boundary conditions, and periodic length change is also considered. The impact between the engaging roller and sprocket surface is modeled as a single impact between two elastic bodies and the modeling of the polygonal action is based on a four bar mechanism (rigid four bar at low speeds, elastic four bar at moderate and high speeds).; At low and medium operating speeds, the system equation of motion for the chain span is expressed as a mixed type partial differential equation with time-dependent coefficients and time-dependent boundary conditions. At high operating speeds, the system equations of motion are two partial differential equations for transverse and longitudinal vibrations respectively and they are nonlinearly coupled. The effects on transverse vibration of center distance, the moment of inertia of the driven sprocket system, static tension, and external periodic load are presented and discussed. Solutions are obtained by a finite difference method and Galerkin's method.; A dynamic model for analysis of the performance of a roller chain drive with a tensioner is also presented. The model is based on the axially moving material model and includes the effects of polygonal action, impact, and the periodic span length changes.; Three equations of motion are obtained--one for the tensioner and one for each of the chain spans. The motion of the tensioner interacts with the motions of the chain spans through the chain tension, the contact angles, and the transverse displacement changes of the contact points. The effects of the periodic length change, tensioner stiffness, tensioner damping, tensioner position and external periodic load are investigated. Some of the results are compared to those obtained for a comparable chain drive without tensioner. Solutions are obtained by a finite difference method. |
