Citation

Chisholm CJ. J. Agric. Eng. Res. 1979; 24(4): 417-440.

Copyright

(Copyright © 1979, Elsevier Publishing)

DOI

10.1016/0021-8634(79)90081-7

PMID

unavailable

Abstract

A computer simulation, which had previously been validated by overturning experiments, was used to study the effect of parameters on energy absorbed in a roll over protective structure (ROPS) during overturns down a steep bank. Absorbed energy was generally more sensitive to variation of the roll velocity component of the tractor's kinetic energy than to variation of the vertical velocity component. The ROPS offered a large resistance to roll couple but little to vertical force when the tractor was on its side, because of the height of the ROPS above the centre of mass. When the tractor was more nearly upside-down at impact, however, the vertical force through the centre of mass passed closer to the ROPS impact point and the ROPS had to absorb much of the vertical kinetic energy. The magnitude of this energy was much higher than that of the roll kinetic energy, and excessive deformations were predicted in ROPS of typical strength in these conditions, which could result from an overturn down a bank about 3 m high. The side of the rear wheel absorbed a large amount of energy in all cases, even when the ROPS hit the ground first, but the proportion varied gradually with ROPS width, track width and impact roll angle. Few parameters had consistent effects in the overturning phase but a less steep bank, high tyre friction and narrow track gave the highest roll velocities and hence greatest ROPS deformation. The relationship between ROPS sideways energy and tractor mass proposed for static strength test standards was likely to ensure protection in almost all accidents.

Language: en