Study on Steerability of Tracked Vehicle on Soft Ground (Part 1)

Theoretical Analysis

Abstract

This paper describes a theoretical analysis of stationary turning motion of the tracked vehicles on level soft ground.
In developing the equations of stationary turning motion on soft ground, we intend to take into account factors concerning steering problems such as the track slip-sinkage and plowing, the distribution of normal and shear stresses beneath the track shoe under the road wheel, the load transfer due to track tensions and vehicle structure, namely, vehicle weight, nominal track contact length, vehicle tread, track contact width, number of road wheel, etc.
These equations have been numerically solved on a digital computer. The results are summarized as follows;
(1) The specific slip radii of tracks increase rapidly with the increase of steering ratio ε, however, beyound ε=1.3 they are almost constant.
(2) Both the driving and braking forces increase with the increase of steering ratio ε, and then, they become almost constant.
(3) The sinkages of tracks are related to steering ratio ε. The sinkage of inner track increases proportionally to steering ratio ε, while the sinkage of outer track increases gradually with ε.
(4) The accurately computed value of turning radius is approximately 1.7 times larger than the calculated value based on a simple geometrical relation which neglects the effects of longnitudinal track slippages.