Squealing characteristics of worn brake pads due to silica sand embedment into their friction layers

• Silica sand particles (SSP) modify the contact interaction by changing the effective contact area.
• The tribological properties of brake pads are improved with large particle sizes.
• The presence of large sized particles plays crucial role in the destruction of third body structures.
• The high angularity of silica sand particle contributes to the intensification of failure mechanisms (scratching, grabbing, etc.).

Disc brake squeal is a very annoying sound and a source of considerable discomfort that leads to customer dissatisfaction. There are various possible mechanisms that could trigger brake squeal generation either from a structural dynamics and/or tribological point of view. This research investigates a characterization of worn surface of friction material squealing with external silica sand particles (SSP). The objective is to study the embedment mechanisms of these particles with different size in the case of a brake pad/disc system in order to correlate their effect to the friction and dynamic behaviour. In the first stage, the squealing characteristics, the friction coefficient, and the wear of brake pads is examined without silica sand. Then, three different sizes of silica sand particles are introduced into the brake pad/disc interface. Surface topography and friction layers of the squealing brake pad with and without the presence of silica sand particle are examined. A correlation between SSP size, squeal and friction behaviours and embedment mechanism is established to highlight the impact of the introducing particle on the friction layer.

Recapitulation of silica sand particle size effect.Figure optionsDownload high-quality image (257 K)Download as PowerPoint slide