Monitoring directional stability of elastic vehicles

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Monitoring directional stability of elastic vehicles

Böhm, F.

Vehicles of different type follow, if treated as rigid body systems, the same equations of motion. The necessary control for directional stability needs a preview equation for the path of center of gravity and for the angle of attack of the contacting medium as air, ground, water or the output of a rocked nozzle. In case of an elastic vehicle the angle of attack is often strongly disturbed by bending or torsional deformations of the body or gears. Limit circles occure and should be handled in computation together with the motion of the whole system. Energy sources and sinks exist at different parts of the vehicle and should be known precisely for self-exitation and damping potential. Finite Element (FEM) and Multi-Body Modelling (MB) computations do not hold for arbitrary deflection from a reference configuration. No exact zero roots exist for the motion of free systems in FEM, while otherwise MB produces infinite impact-velocity through the system. So the body of the vehicle is mainly modelled as a particle system realizing symmetric matrix structure with exact zero roots, energy and momentum control. Monitoring of nonconservative forces and resulting motions is then possible for all travelling conditions. Examples for cars, sailingboats, airplanes and rockets are given.