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Modeling the effect of liquid movement on the center of gravity calculation of agricultural vehicles

Farzaneh Khorsandi, Paul D. Ayers, Robert S. Freeland, Xinyan Wang
Journal of Terramechanics, Volume 75, 2018, Pages 37-48, ISSN 0022-4898,

Abstract: Due to a high center of gravity (CG) location, agricultural vehicles are more vulnerable to overturns. The CG location can be calculated using the lifting axle method of ISO 16231-2:2015. But, as a vehicle is lifted, its liquid payloads are not entirely contained. The liquids will shift both in position and form, affecting the CG height calculation. A mathematical model was developed to predict the effect of liquid movement on the CG height calculation of a tilted vehicle. The model was validated using an agricultural utility tractor and a prototype. The developed model was applied to calculate the CG location considering the effect of the liquid shift. Results showed tilting produced a higher calculated center of gravity due to liquid movement, but by increasing the tilting angle, the calculated CG height decreased. The effect of the liquid shift on CG height measurement for the wagon with 16.0% liquid mass was 14.8% and for the tractor with 1.2% liquid mass was 0.41%. The model error was less than 1.3% for all tests. Considering the effect of the liquid shift in CG height calculation, the error in CG height calculation decreased from 11.9% to 2.6% for the wagon.

Keywords: Center of gravity; Stability; ISO 16231-2:2015; Liquid shift; Tractor; Overturn; Safety