A Study of the Relationship between Leading offset and Squeal Noise

This paper introduces the experimental test results of an investigation to understand the relationship between the leading offset and squeal propensity. In addition Transient Analysis (TA) and Complex Eigenvalue Analysis (CEA) are used simultaneously as a means to compare the experimental approach to two different numerical tools, so evaluating the validity of each theoretical approach. To confirm the CAE results. An ODS was recorded of the brake using a 3D laser scanning vibrometer. Even though the CEA approach is very popular in the study of brake squeal noise, there are some limitations and difficulties in replicating the real phenomenon especially containing unstable behavior. The differences are due to weak pad contact stiffness and friction characteristics which are dependent on the relative interface velocity between pad and rotor. It is necessary to consider stick-slip vibration and time domain analysis in addition. This paper introduces the differences between the transient analysis and the complex eigen-value analysis in their ability to replicate a squeal noise occurrence. There are some analogies between a floating type caliper and an opposed piston type caliper in terms of predicting squeal noise caused by a leading offset at the piston side and the finger side. In addition this study shows that a leading offset at the finger side and pad side will result in squeal noise using both the experimental approach and numerical approaches. Finally a flutter instability and a friction interface analysis is introduced to give an understanding of the relationship between noise propensity, pad length, disc wavelength and force balance of trailing and leading side.