PSI - Issue 8

Francesco Mocera et al. / Procedia Structural Integrity 8 (2018) 118–125 Mocera, Nicolini/ Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 8. (a) Trajectories under investigation, (b) Points of interest in the vehicle starting position

4. Discussion and conclusions

In this paper a Multibody model of a small size tracked vehicle for farming applications is shown. The main purpose of this work was to verify the dynamic behavior of the numerical model under certain assumption. In fact, a simplified model of track-terrain interaction was here considered. The track, modeled as a series of links with a proper contact model, was assembled including all its subsystems: the sprocket idler system, the tensioners and the road wheel. The main body had a simplified shape, but its inertia properties were set in order to replicate the mass distribution of a similar real vehicle. The final model was thus tested considering a few scenarios commonly encountered by this kind of vehicles. A key point of the work was to analyze the kinematic behavior imposing a certain speed law on the sprocket and evaluating the difference between the theoretical vehicle speed and the actual ones. The slip and thus the maximum traction forces play a key role in determining the final speed. Thus this parameter has to be considered when evaluating performance on different terrain models. Moreover, the trajectory analysis allowed to also exploit the lateral behavior that in a more complex contact model depends on the terrain cohesion. Bekker M. G., 1956, Theory of land locomotion - The Mechanics of Vehicle Mobility, Ann Arbor: The University of Michigan Press, pp. 522. Blundell M., Harty D., 2014, The multibody systems approach to vehicle dynamics 2 nd Edition, Butterworth-Heinemann, pp. 768. Bosso N., Spiryagin M., Gugliotta A., Somà A., 2013, Mechatronic modeling of Real-Time Wheel-Rail Contact, Springer, pp. 119 Gao Y., Wong J.Y., 1994, The development and validation of a computer aided method for design evaluation of tracked vehicles with rigid links, Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 208-3, 207-215. Janosi Z., Hanamoto B., 1961, The analytical determination of drawbar pull as a function of slip for tracked vehicles in deformable soils, in Proc of the 1st Int Conf Mech Soil – Vehicle Systems. Turin, Italy. Mocera F., Somà A., 2017, Study of a Hardware-In-the-Loop bench for hybrid electric working vehicles simulation, Twelfth International Conference on Ecological Vehicles and Renewable Energies (EVER), pp 1-8. Pacejka H.B., 2002, Tyre and Vehicle Dynamics, Butterworth-Heinemann, pp. 672. Rubinstein D., Hitron R., 2004, A detailed multibody model for dynamic simulation of off-road tracked vehicles, Journal of Terramechanics, 41, 163-173. References

Shabana A. A., 1989, Dynamics of Multibody Systems, Cambridge University Press, pp. 393. Wong J. Y., 1989, Terramechanics and off-road vehicles, Butterworth-Heinemann, pp. 488.

Wong J.Y., Garber M., Preston-Thomas J., 1984, Theoretical Prediction and Experimental Substantiation of the Ground Pressure Distribution and Tractive Performance of Tracked Vehicles, Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 198-4, 265-285.