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Off-highway vehicles operate under complex duty cycles which consist of handling varying terrain conditions under dynamic loads. A challenge for the equipment operator is to maintain stability of the vehicle during various field operations. The operator must make judgment calls on whether terrain and loading conditions are suitable for vehicle stability. In view of the increasing emphasis being placed on operator comfort and vehicle autonomy, a methodology to predict the degree of vehicle stability in varying terrains and dynamic loads will be an aid in designing safer vehicles. This paper describes a mathematical model capable of predicting the longitudinal overturning behavior of off-highway vehicle. A mathematical kinematic and dynamic model of the system is developed using Newton-Euler approach. This yields a system of non-linear equations which can be solved iteratively by using any commercial software to predict stability for varying terrains and dynamic loads.

Rollover Protective Structures (ROPSs) are used in off-highway vehicles to protect operator in case of accidents involving overturning of vehicle. The role of a ROPS is to absorb the energy of Rollover without violating the protected operator zone. The performance of a ROPS is determined by its ability to absorb energy under prescribed loading conditions. The performance depends upon design parameters, such as tube thicknesses, material grades, ROPS tube cross-sections, etc., that define the structure. In this paper, we describe a method that uses Design of Experiments (DOE) to determine the correlation between the performance of a ROPS for a small tractor and its critical design parameters. The correlation results are discussed for two types of loading conditions, namely “front push loading” and “side push loading”. The correlation obtained is further used to identify the optimal design parameters for maximum energy absorption under constraints on allowable deflections.