Stiffness determination of the controlled wheel module of a two-axle vehicle

The conditions of a secure loss of stability of a two-axle wheel vehicle with absolutely hard steering have been found before. The analytically derived conditions of a secure stability loss in case of torsional stiffness are dependent on the relationship between the slipping resistance coefficients, the transverse clutch coefficients on the axes, and the torsional stiffness of the controlled wheel module. In this case, the trail distance is taken into account in the wheel module control system, the mass of the module being neglected. The approach suggested in the paper does take into account the mass of the controlled wheel module. The slipping forces are presented accurate to a cubic term of expansion in slipping angles. The torsional stiffness intervals have been found that provide a secure loss of stability of a two-axle wheel vehicle model. The intervals have been obtained on the basis of a bifurcation analysis of actual bifurcations of the stationary states in the vicinity of the rectilinear motion of the model. Diagrams that illustrate the fulfillment of secure stability loss conditions and allow using the results obtained in designing a wheel module are presented in the paper. The technique used is alternative to the well-known M. Bautin's approach to determination of secure-insecure conditions in case of a divergent loss of stability.