| Noise, vibration, and harshness (NVH) is one of most important performances for automobiles, which can be felt and evaluated directly by customers. It has a great effect on their total satisfaction for customers. Braking harshness, called brake judder, means excessive vibrations of steering wheel, brake pedal and seats, which drivers and passengers can feel during braking process. Brake judder is one of important parts for automobile NVH, which has a great effect on vehicle comfort and fatigue of related components. It will affect vehicle safety, so it is extremely necessary to study brake judder.The article is mainly classified as two parts including research on mechanism of brake judder and modeling for vibration transfer paths. The root resources of brake judder are analyzed in terms of heat, friction and load. Firstly the temperature field of brake disc is analyzed using heat spot method in theoretical way. The theoretical solution for brake disc deformation is acquired based on temperature field combined with thermal elastic theory and the effects of brake disc parameters on thermal distortion is made to predict the brake DTV. Secondly the mathematical modal for brake vibration transfer paths is established containing suspension, steering and rotating wheel system. The parameters'effects on transfer characteristics are analyzed in the end.The effects of brake disc's structural parameters on thermal deformation have been studied and comparison has been made based on their effects. Brake disc's DTV is calculated academically. The transfer path analysis for brake judder is also made. The results show that stiffness and damping of suspension, rubber bushing's damping, and steering axle's damping mostly affect vertical body vibration, lateral body vibration and steering wheel angle's amplitude respectively. |
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