Frequent braking may generate severe low frequency vibration due to non-uniform frictional contact between disk and pads. Under critical conditions, this non-uniform contact leads to locally concentrated heating, growing to hot spots in disk brake. Finally hot spot roughness induces the judder which makes the vehicle control difficult and even dangerous. Judder phenomenon for high quality of automotive brake design cannot help understanding the relationship of number of hot spots and judder vibration frequencies. This paper is to analyze the role of hot spots in judder vibration of automotive disk brake. Vibration and hot spot was measured in accordance with rotation of disk and pressure of master cylinder for finding the factors that causes hot spot phenomena. The vibration modes of disk brake are experimentally measured and analytically examined by the finite element method. Judder vibration measurements were conducted by using chassis-dynamometer. Hot spot measurements were photographed by using infrared camera. As results, the relationship between hot spot phenomena, and mode shape, pressure of master cylinder and rotation speed of disk respectively, was achieved by hot spot measurement and frequency analysis. The following conclusions can be drawn: (1) Main mode frequencies related to hot spots are 1156Hz, 2650Hz, 4252Hz and 5900Hz that can generate the number of 4, 6, 8 and 10 hot spots. (2) The number of hot spots is related to vibration modes of disk. When amplitude of pressure between disk and pad is sufficiently high, it could excite high frequency band and the number of hot spot is increased. (3) As well as non-linearity of frictional contact boundary condition is changed, material properties transition of disk are occurred by hot spots that have high temperature. These characteristics make natural frequency of disk move to low frequency direction. (4) When rotation order component and 1/2 f0 sub-harmonic vibration component is in resonance of steering system, hot spots growth increases amplitude of these components. This can make severe judder vibration in vehicle.
Analysis of judder vibration origin in automotive disk brake
Analyse des Ursprungs von Schlagschwingungen in Fahrzeugscheibenbremsen
2006
8 Seiten, 6 Bilder, 3 Tabellen, 7 Quellen
Conference paper
Storage medium
English
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