In this paper, a study was conducted to reduce the squeal noise caused by contact between the disc and the pad in the brake system of an urban railway vehicle. In that way, parameter optimization of the influencing factor of the brake pad, proposal of a brake pad shape for contact stress relief, and analysis of the field test results and a study on the effect of braking temperature on the analysis of squeal noise were conducted.
The modulus of elasticity, coefficient of friction, and contact stiffness were selected as the effect factors of the brake pad, and a study on parameter optimization was conducted. Squeal noise was analyzed through complex eigenvalue analysis using ABAQUS and a commercial PIDO (Process Integration and Design Optimization) tool; PIAnO was used to optimize the parameters. Using the design of the experiment method, the selected effect factors were used to ascertain the effect on squeal noise generation and the relative importance was identified by ANOM (Analysis of means). Through the parameter study, the effects of the elastic modulus, friction coefficient, and contact stiffness on the magnitude and quantity of the real part were analyzed to confirm the effect of the squeal noise generated in the target system.
In order to propose a brake pad shape for contact stress relief, a finite element model of the disc brake system was used, including the peripheral brake parts to increase accuracy. As for the verification of the analysis model, the reliability of the analysis model was secured through the analysis of the field test results on domestic urban railway lines, and then the shape of the pad that relieves the contact stress was proposed.
And the braking temperature of the brake system was applied to the analytical model to proposes a brake pad shape to reduce the impact of squeal noise caused by nonuniform contact between the brake disc and the brake pad due to braking temperature.
Through this study, it is predicted that the probability of squeal noise generation can be reduced by up to about 65% compared to the present by evenly distributing the concentration of contact stress relatively generated by instability through the application of chamfer to the brake pad and the change in slot shape.
The results from the present study can be used to reduce squeal noise further.