Research On The Influence Of The Wheel/Rail Contact Position On The Wheel/Rail Force Measurement

The measurement of wheel / rail interaction is an important research topic in vehicle dynamics. The instrumented wheel set method is the wheel/rail force measuring method which has the highest measuring accuracy and is most widely used currently. Specifically, it uses the instrumented wheel set as the sensor, forms the bridge on the wheel set and establishes the constitutive relation between the strain value of bridge output and the wheel/rail force through the calibration test. Since the change of the wheel / rail force contact point position has great impact on the measuring accuracy of the wheel / rail force, in light of the wheel / rail force measuring accuracy issue of railway vehicles, how to accurately measure the wheel / rail force and the position of the contact point is of great significance to the research of vehicle dynamics and guaranteeing the safe operation of vehicles.(1)The characteristics of the bridging schemes of various measuring bridges were analyzed. Based on general instrumented wheel set measuring methods, solution ideas were raised in terms of the shortcomings existing in this method.(2)The bridge theory of instrumented wheel set was used to establish the finite element model of the instrumented wheel set. The model gives comprehensive consideration to the influences of the lateral force and the vertical force on the measurement of bridge output. The strain distribution characteristics of the instrumented wheel set were analyzed through simulation calculation. Simulation bridging was performed according to the result of the finite element simulation to determine the patch position and the bridging scheme. Sensitivity analysis on the measuring bridges of the lateral force and the vertical force was performed to put forward the solution of improving the output sensitivity of measuring bridges. The position of the smallest coupling was obtained as the position of the bridge patch so as to realize the decoupling of the lateral force and the vertical force.(3)Using regression analysis, the research on the influence of the position of the contact point on the measuring accuracy of the wheel/rail force was performed. Parametric equations were established at different contact point positions through the wheel/rail force to perform data processing like regression analysis on the simulation results, determine the relationship between the wheel/force and the position of the contact point and simplify the three element linear equations containing the lateral force, the vertical force and the position of the contact point in traditional measuring models to two element equations which only contain the lateral force and the vertical force. The simulation results show that the wheel/rail force measuring model which takes the offset error of the contact point into account can improve the measuring accuracy and reduce the calculation complexity at the same time.(4)The calibration test on the instrumented wheel set was accomplished. The result of the calibration test of the instrumented wheel set and the simulation result were compared and the effectiveness luoof the improved wheel/force measuring model was verified, which provided theoretical basis for further test researches on the instrumented wheel set.