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A dynamic stability analysis model of a five-axle tractor semitrailer vehicle is developed using the MATLAB/SIMULINK application tool. The linearized vehicle model is utilized to investigate the impending instability limits under various design, and operating conditions. Computer simulations are performed for step steer and a typical highway maneuver as input conditions to generate the yaw response characteristics. The model development is accomplished in a modular form to accommodate interactive re-runs of the model with design variations. SIMULINK modeling provides greater flexibility in development and incorporation of active control system modules in the model in order to investigate possible enhancement of vehicle stability limits.

A directional dynamic model of a partially filled liquid tank vehicle is developed to investigate its dynamic characteristics during typical straight-line braking maneuvers. The computer simulation model is developed by integrating the fluid slosh model of a partially filled tank to the pitch plane vehicle model. The dynamic behavior of liquid within the tank is modeled using an equivalent mass-spring system. The analogous mechanical system model for the partially filled cleanbore cylindrical tank is developed by utilizing the potential flow theory for longitudinal oscillations. An approximate summation method is developed in order to obtain the mechanical system parameters and are validated against experimental results available in literature. Computer simulation of the tank vehicle for typical braking maneuvers is then performed by incorporating the slosh forces and moments computed using the mechanical analogy model into the vehicle model.

Dynamic analysis of vertical seat suspensions of off-road vehicles is performed via computer simulation models in order to establish their ride performance. The PC-based computer simulation program is capable of analyzing various commercially available seat suspensions under different input excitations. The software is developed using the Visual Basic interface on Microsoft Windows platform and is entirely menu driven. The software is organized in a systematic fashion with the pre-processor, analysis and post-processing modules and has the option to choose any module from the initial selection screen. A database of various seat-suspension characteristics, along with other off-road vehicle input parameters is available in the pre-processor module. Analysis of the dynamic system is performed using a generalized two-degree of freedom model characterizing the vertical seat and suspension motion.

The directional dynamics of partially filled articulated tank vehicles is investigated via computer simulation assuming constant forward velocity. The directional response characteristics of an articulated tank vehicle is investigated for various steering manoeuvres and compared to that of an equivalent rigid cargo vehicle to demonstrate the destabilizing effects of liquid load shift. It is concluded that during a steady steer input, the distribution of cornering forces caused by the liquid load shift yields considerable deviation of the path followed by the tank vehicle. The lateral load shift encountered in a partially filled tank vehicle during lane change and evasive type of highway manoeuvres gives rise to roll and lateral instabilities.