Technical Reports

Describing Function Techniques for the Non-Linear Analysis of the Dynamics of a Rail Vehicle Wheelset

  • 01
  • Jul
  • 1975
AUTHOR: Devendra P. Garg
OFFICE: RPD
REPORT NUMBER: FRA-OR&D-75-83
SUBJECT: Evaluation
KEYWORDS: Rail Systems Dynamics, Describing Function Analysis, Hunting
ABSTRACT: The describing function method of analysis is applied to investigate the influence of parametric variations on wheelset critical velocity. In addition, the relationship between the amplitude of sustained lateral oscillations and critical speed is derived. The non-linearities in the model include the difference in rolling radii as a function of lateral displacement of the wheelset from its mean position, profile conicity, and gravitational stiffness in the lateral and yaw directions. The proposed method is validated by applying it to a wheelset example cited in the literature. Comparable results are obtained using the proposed technique. The describing function method presented in the report is quite general and is applicable to dynamic models exhibiting severe non-linear characteristics in profile. Critical speed, frequency of limit cycles, gravitational force, effective conicity, gravitational stiffness and creepage, etc., can be easily computed using the proposed algorithm.

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