Abstract

A three dimensional model that includes significant details is developed for the nonlinear dynamic analysis of large scale multi-body tracked vehicle systems. In this model, the joint articulations of the track chains are taken into consideration so as to allow the developement of a computational procedure for the analysis of the vibrations and the contact forces of the multibody tracked vehicles. The three dimensional vehicle system is assumed to consist of three kinematically decoupled subsystems which include the chassis subsystem, and two track subsystems. A recursive approach for formulating the nonlinear equations of the vehicle based on the velocity transformation is used in this investigation in order to reduce the number of equations, avoid the solution of a system of differential and algebraic equations, and avoid the use of nonholonomic constraints to describe the rotations of the sprockets. The singular configurations of the closed kinematic chains of the tracks are also avoided by using a penalty function approach to define the constraint forces at selected secondary joints of the tracks. Detailed three dimensional nonlinear contact force models that describe the interaction between the track links and the vehicle components such as the rollers, sprockets, and idlers as well as the interaction between the track links and the ground are developed and used to define the generalized contact forces associated with the vehicle generalized coordinates. In particular, body and surface coordinate systems are introduced in order to define the spatial contact conditions that describe the dynamic interaction between the teeth of the sprockets and the track link pins. These conditions provide the forces necessary for driving the tracked vehicle. The effect of the tangential friction forces on the stability of the motion of the vehicle is also discussed in this investigation. A computer simulation of a tracked vehicle that consists of one hundred and six bodies and has one hundred and twenty degrees of freedom is presented in order to demonstrate the use of the formulations presented in this study. A simple formula that can be used to predict the steady state velocity of the vehicle when the sprockets rotate with a constant angular velocity is presented and used to verify the numerical results obtained from the nonlinear dynamic simulation of the multibody vehicle.

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