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"Brake Squeal"
is high frequency and harsh noise from automotive
brakes. The squeal still occurs, although a great
deal of efforts have been paid to prevent it. It
is therefore necessary to analyse the sqeal more
fundamentally and to find out a useful treatment
to prevent the squeal.
In the present study, the mechanism of brake squeal
was analysed experimentally.
A test apparatus was
made to reproduce the squeal. The distributions
of temperatures and contact pressures were measured
on the sliding surface of a disc brake pad using
thermocouples and small load cells, respectively.
The vibration mode of the pad and the rotor was
also measured using small accelerometers.
The contact pressure
around the edge of the pad surface was found to
be stronger in the cooling process in which the
squeal was likely to occur, and the change of contact
pressure around there was clarified to generate
exciting energy for the squeal. In the pad behavior
when squeal occurred, two kinds of vibration modes,
with and without bending, were obserbed. In the
frequency range from 7 to 9 kHz, the bending mode
dominated.
Based on the above
results, a new type adhesive shim has been developed
to decrease the squeal.
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