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Belt-drive systems are a commonly used for power transmission in automotive applications, notably in engine and vehicle auxiliary subsystem drives. In order to characterize the physics of a belt drive system and its response to speed and load excitations, a comprehensive model of belt elasticity and of belt-pulley contact and friction is required. In practical applications such models are utilized in parametric design and optimization studies, and computational efficiency is therefore also a key requirement. In this paper a belt drive dynamics model is presented, in which the belt is modeled by means of geometrically exact cables that can undergo large rigid body motions but whose strains remain small. The Finite Element approach is used in order to efficiently discretize these elastic components. In addition, a state-of-the-art dynamic friction model (LuGre) is used in order to model the friction loads between the belt and pulleys.

Push-belt (or Van Doorne-type) CVT systems are used for power transmission in automotive applications, including notably in engine-transmission subsystems. In order to characterize the physics of a Van Doorne CVT, two modeling options are commonly used. High fidelity models track each push-belt block as well as the dynamics of the bands that connect the blocks. The main disadvantage of this technique lies in its large number of degrees of freedom and resulting long CPU time. A second approach relies on a lesser-fidelity model with few degrees of freedom that can subsequently be used in long simulations, e.g. vehicle drive-cycles. In this work, we review different modeling techniques at this modeling level, and propose a fast-running model that overcomes some of the limitations of lesser-fidelity models yet is still suitable for long simulations. Typical fast-running models enforce kinematic constraints between the pulleys, i.e. the CVT bands and blocks are assumed to be rigid.

A new model of spur gear contact and gear dynamics was developed for use in studies of dynamic response of mechanical systems involving geartrains. The model is general; in this paper it is applied to geartrain dynamics in valvetrain gear drives. The model dynamically uses a gear contact formulation based on exact involute geometries of gear teeth and can therefore account for varying, non-linear mesh stiffness. It can also account for gear torsional stiffness as well as shaft stiffness at gear centers. The paper further proposes an alternative to dynamic calculation of instantaneous gear tooth contact conditions. The proposed method uses a varying effective mesh stiffness pre-computed through static calculation of contact conditions between teeth of a gear pair, for one mesh, or tooth engagement-disengagement, period. The technique is shown to significantly reduce computational time, while closely matching the predictions of the full model.

A model of roller chain and sprocket dynamics was developed, aimed at analyses of dynamic effects of chain drive systems in automotive valvetrains. Each chain link is modeled as a rigid body with planar motion, with three degrees of freedom and connected to adjacent links by means of a springs and dampers. The kinematics of roller-sprocket contacts are modeled in full detail. Sprocket motions in the chain's plane, resulting from torsional and bending motions of attached camshafts are also taken into account. One or two-sided guides can be treated as well as stationary, sliding or pivoting tensioners operated mechanically or hydraulically. The model also takes into account the contact kinematics between chain link rollers and guides or tensioners, allowing for guides/tensioners of arbitrary shape, or simpler (flat and circular) geometries. The model is first applied to study the chain drive and valvetrain of a 1-cylinder motorcycle engine.