Hunting oscillation

About: Hunting oscillation is a research topic. Over the lifetime, 89 publications have been published within this topic receiving 674 citations.

The dynamics of railway vehicles—from Stephenson to Carter

Abstract: The special feature of the dynamics of railway vehicles, i.e. the propensity to oscillation in the lateral plane, arises from the use of the wheelset with its solid axle and coned wheels. This paper traces the early history of the wheelset and how it was incorporated in the design of locomotives and rolling stock and discusses the ensuing dynamic problems. The development of ideas about stability and steering in curves is then considered up to the time of Carter, who in 1916 can be said to have been the first to formulate essentially correct equations of motion and solve them.

The geometrical contact between track and wheelset

Abstract: SUMMARY In previous publications the author has described a so-called first-order theory for the motion of a railway vehicle wheelset on a tangent track. In the present report the geometrical aspect of this theory is further evaluated and a method for solving the constraint equations between the coordinates of the wheelset is indicated.

Effect of lateral linear stiffness on nonlinear characteristics of hunting motion of a railway wheelset

Abstract: Railway wheelset experiences the problem of hunting above a critical speed, which is a kind of self-excited oscillation. At the critical speed, it is known that the system undergoes a subcritical Hopf bifurcation. Therefore, for clarifying the nonlinear characteristics of hunting it is very important to detect, for example, the nonlinear forces in the wheelset due to the creep forces acting between the wheels and rails, and the nonlinear component of the resorting forces by the suspensions. However, it is impossible to determine each force quantitatively. In the present paper, it is first shown, by using the center manifold theory and the method of normal form, that the nonlinear characteristics of the bifurcation in a wheelset model with two degrees of freedom are governed by a single parameter, hence each nonlinear force need not be detected when examining the nonlinear characteristics. Also, a method of determining the governing parameter from experimentally observed radiuses of the unstable limit cycle is proposed. Next, we experimentally investigate the variation of the parameter due to the presence of linear spring suspensions in the lateral direction and discuss the variation of the nonlinear characteristics of the hunting motion, which depends on the lateral stiffness. As a result, the improvement of the stability of the wheelset against the disturbance by the linear spring suspensions is clarified.

A mechatronic approach for effective wheel slip control in railway traction

Abstract: This article proposes a radically new approach for detection of wheel slip/slide and re-adhesion control of AC traction motors in railway applications, which provides an important alternative and advantageous technique in traction/braking control systems to maximize the use of adhesion in poor contact conditions. The proposed concept explores the variations in the wheelset dynamic properties caused by the condition changes at the wheel–rail contact, and detects and controls the slip conditions from the dynamic behavior of a wheelset, indirectly. All the dynamic motions of rail wheelset, which are closely related to wheel–rail contact mechanics, are included in the study; the influence of contact conditions on the relevant modes is assessed, which is essential in development of a mechatronic solution based on dynamic interactions. This is different from the more general approaches in many other studies on traction controls where the inclusion of only wheelset rotation and longitudinal motions are considered as sufficient. The development of the slip detection and re-adhesion control schemes is presented and comprehensive simulation results are produced to support the proposed idea.