Investigation of the generation mechanism of squeal noise under non-negative damping conditions

Abstract

The traditionally known generation mechanism of squeal noise is generally agreed to be the negative damping theory, which is represented by the negative slope of friction creepage curve. Recently, however, it was found that squeal noise still can be generated when the negative slope is eliminated. To investigate this phenomenon, water-based and oil-based friction modifiers are applied on a test rig to create non-negative damping conditions. The adhesion ratios at various rolling speeds are measured, and it is found that the negative slopes of friction curves can be eliminated when using friction modifiers, but squeal noise still exists. To investigate this phenomenon, a model involving the effect of vertical dynamics on squeal noise is developed in this research. The results show that the involvement of vertical dynamics has negligible effect on wheel vibration velocity when the friction creepage curve has a negative slope. When the friction creepage curve has a zero or positive slope, however, the results show that a stable lateral vibration still can be generated when vertical dynamics is involved. The generation mechanism of wheel squeal involving vertical dynamics is illustrated from the perspective of power input. Furthermore, the sound pressure levels of squeal noise are simulated using this model and the results correlate well with experimental measurements. Therefore, the results indicate that the vertical dynamics may be the reason why squeal noise still exists under non-negative damping conditions.

Study on “decoupling” of inerter

“…Where Z b is the vibration vector of the equilibrium position and λ is the eigenvalue of the system. After substituting Equation (12) into Equation (10), and then substituting Equation (10) into Equation (11), the quartic equation with one variable can be obtained. The real part σ and the imaginary part ω represent the amplitude and vibration frequency in the X direction and Y direction, respectively.…”

“…By referring to the classical brake disc model [14] and the dynamic model [12] of Dr. Liu Xiaogang, the physical properties of the contact surface are replaced by stiffness, and the large weight of the body is regarded as ground. The braking system model with two degrees of freedom was established, and the system is improved by adding the inerter in the y direction.…”

“…Paul established the deviation Angle model and analyzed and predicted the occurrence and growth of wheel screech noise under the mode coupling mechanism by using the effective mathematical model of the nonlinear limit cycle and complex eigenmode analysis [11] . Liu Xiaogang also made a further study on this problem, adding the three-degree-of-freedom model and analyzing the influence degree of each variable on the noise problem in detail [12] . From the perspective of the above problems, the nonlinear vibration is mainly suppressed by changing the material in modeling and simulation.…”

Investigation of the effect of longitudinal creepage on wheel squeal

“…Models in the literature have got the dynamics in the lateral direction and vertical direction included. For instance, an interaction model including the coupling between lateral and vertical dynamics was formulated to investigate curve squeal numerically (Pieringer, 2014); furthermore, a model involving the effect of vertical dynamics on squeal noise generated by lateral vibration was developed, the results show that a stable lateral vibration can be generated when vertical dynamics is involved (Liu and Xiao, 2021). Although the effect of lateral and vertical dynamics has been analysed in the literature, the effect of longitudinal creepage on wheel squeal has not been analysed theoretically yet.…”