Hi Samuel A Awe

Thanks for sharing this discussion. Please see the relevant paper below:

Title: An Investigative Overview of Automotive Disc Brake Noise

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.460.9564&rep=rep1&type=pdf

Hope this is of some use

Best Regards

Martin

Hi Martin,

Many thanks for your suggestion.

The main title and the test do not exactly ask the same thing. Regarding the link between disc material aging and the evolution of its modal properties, it seems that strengthening occurs over time, which would lead to an increase in modal frequencies, but I have no clue about the magnitude of variation. I would not be surprised if there was also some damping variation effect. Regarding the effect of disc modal property variations on a brake system instability, we did a lot of numerical studies on the subject. The modal coupling phenomenon that induces the stability can be sensitive to disc brake frequencies. If that is the case, the system unstable modeshape, real part and frequency will vary with the disc modal properties. Refined analysis can be performed in the Component Mode Tuning (CMT) framework we are developing at SDTools (https://www.sdtools.com/pdf/imac10_component.pdf ; https://www.sdtools.com/pdf/JEF10_Squeal.pdf). It is a reduction method where we explicitly use component free modes pulsation as degrees of freedom for reduced parametric studies, so that one can track unstable mode evolution as function of component modal property variations. A more basic approach is to consider a disc Young Modulus variation in a parametric study and analyze how the instability is evolving. There are cases where disc frequency variations by a few percent is enough to remove an instability, or change it in a way that the unstable modeshape on the stator side is significantly different -- thus potentially invalidating squeal mitigation designs. Disc model validation is an absolute necessity to brake simulation quality. It is a feature that I always check. Variation induced by aging thus seems a factor to be accounted for in design for any gray cast iron component if it is significant against mass production tolerances.

According to my research have noted that the grey cast iron is an alloy,therefore to achieve the required properties other metals contribute.It has high comprehensive strength and noises come out due to friction and collision of the shafts around the braking system as the parts can't withstand their comprehensive forces and as they wear out they tend to produce the noises.