Abstract
ABSTRACT A high performance, newly-developed wire-woven bulk diamond (WBD) ventilated brake disc is introduced to reduce the operating temperatures and mass of conventional brake discs. The use of the highly porous material requires a deeper understanding of the mechanical stresses developed within a brake disc to be developed to improve the disc core strength to withstand the high stresses developed during braking. In this study, experimentally determined solid brake disc stress distribution results, separated into the compressive stresses due to the pad clamping force and the shear stresses due to the applied brake torque, were applied to the reinforcement ofthe WBD core brake disc. The analysis was based on the maximum predicted deceleration conditions of a medium sized truck (Mercedes-Benz Atego). While the WBD core material possessed sufficient strength to withstand the shearing due to the braking torque, the pad clamping load was predicted to cause disc failure. Consequently, straight radial ribs were designed to reinforce the ventilated core, with final rib dimensions of 74x14x2.5 mm, manufactured from mild steel (SAE1006). A total of 10 ribs at 36° intervals were added to reinforce the core, increasing the mass by 0.20 kg compared to the original disc. The newly reinforced WBD brake disc remains lighter than a commercially available pin-finned disc, and is expected to maintain superior thermal performance while possessing the required mechanical strength. Additional keywords: Ventilated disc, mechanical stresses, braking, stress distribution
Highlights
Vehicle advancement requires components to be lightweight
As an approximation to account for the localised deformation effects at the woven bulk diamond (WBD) disc/pad contact interface, the ratio represents a stress concentration factor (SCF = 4.05) that is applied to the average shear stress to predict the WBD maximum shear stress, which is 1.76 MPa
Referring to the solid brake disc clamping load test results in Section 4, it was shown that the compressive stresses due to the clamping load were concentrated at the disc/pad contact interface and negligible elsewhere
Summary
Vehicle advancement requires components to be lightweight. Reducing vehicle weight improves the fuel economy of internal combustion vehicles, reduces their CO2 emissions, and is a practical way to reduce logistic costs [1,2,3]. The highly porous cellular wire-woven bulk diamond (WBD) has been shown to be an excellent medium for the ventilated core of a brake disc [10,11,12,13] to improve the heat dissipation characteristics of a brake disc as the convective cooling is enhanced. The porous ventilated WBD brake disc core must possess the disc strength to resist failure due to both the compressive clamping and frictional shearing loads at the upper limit of the applied braking pressure. Thick cross sections adversely affect the convective heat transfer performance of the brake disc [11] This led to the introduction of a cellular metal material into the ventilated core of a patented WBD brake disc by Mew et al [10]. The "diamond" truss nomenclature arises from the side view of the structure which reveals a diamond shape [14]
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