Cross-country Terrain Research Articles

Optimum vehicle suspension designs by computer simulations

Computer simulation techniques are being used by vehicle suspension designers in an effort to obtain the optimum combination of suspension components to provide the maximum cross-country mobility for a vehicle. The ultimate effectiveness of the suspension will be dependent upon the ability of the computer simulation to accurately compute the dynamic responses of the vehicle as it traverses a cross-country terrain profile. The high degree of accuracy can only be obtained by exercising great care in the mathematical modelling procedures. Actual dynamic characteristics of the vehicle and suspension are required, which include their non-linear and discontinuous characteristics which develop as the vehicle traverses a cross-country terrain profile. When extreme care is exercised during the development of the mathematical model, the computer analysis of vehicle response will correlate within a few per cent of actual full-scale test values. This suspension technique will provide the suspension designer with a reliable method of obtaining an optimum design in a short period of time at a low programme cost.

Factors Affecting the Performance of High-Speed Track Layers

The aim of the paper is to present some fundamental data from which the performance of high-speed track-laying vehicles can be estimated and on which preliminary design calculations can be based. The percentage of the gross engine horsepower that may be available at the driving sprocket is indicated and this must be equated to the resistance to motion that is likely to be encountered. Losses in the track and suspension system are discussed and reference is made to the effect of track tension. Some indication is given of the order of the horsepower required per ton of vehicle weight to achieve a unit of speed on various broad types of terrain. The effort required to climb gradients is also considered and it is shown that operation on cross-country terrain may be treated as an equivalent gradient resistance. Mention is made of the horsepower expended in steering a tracked vehicle and the manner in which the track forces have been found to decrease with increase in turning-circle radius. Since cross-country mobility also involves ability to cross water obstacles, some idea is given of the water resistance of the hulls of these ‘un-shipshape’ forms when afloat, and the overall efficiency that may be expected from the various means of propulsion that can be employed.