The Dissipation of Frictional Energy from the Interface of an Annular Disc Brake

Abstract

The performance of resin bonded composite friction materials in a particular brake design is strongly dependent upon the dissipation of frictional heat from the interface. This energy transformation has been studied using finite element techniques for a simulation of the braking friction process in an annular disc brake, which combines both brake performance and brake temperature analysis and avoids many of the assumptions necessary in conventional analyses. Negligible amounts of energy interchange, compared with the total kinetic energy dissipated, arise from chemical reactions within the friction material, but the formation of surface layers and interfacial wear products do have a signijicant effect upon heat transfer from the interface. Calculated temperature distributions over indioidual brake applications indicate that interface contact resistance leads to different temperatures at the surfaces of disc and lining so that heat partition between the two mating bodies cannot realistically be assumed constant under braking conditions. The distribution of frictional heat generation over the interface is dependent upon interface pressure distribution and is therefore also affected by material wear and thermal expansion. These effects are incorporated in the analysis, and calculated temperature, interface contact and pressure, and wear distributions are compared with observed and measured experimental results from an annular brake rig. 69/84 Q IMechE 1984

Investigation of disc/pad interface temperatures in friction braking

“…The only alternative means for analysis of effect of the real contact area distribution on the real contact temperature distribution is utilising Finite Element Analysis (FEA). FEA has been proved as an effective method to study the behaviour of friction brakes in terms of stress/strain, temperature, thermoelastic instability (TEI), vibration/noise and service life in vehicle braking [2,[14][15][16][17][18]. Different approaches and assumptions have been used for model simplification in different FE analyses.…”

“…The concept of an Interface Layer or Tribolayer has been used to distinguish the difference between the surface layer and the main bodies of the pad and disc. The Interface Layer formation has became a common and wide accepted phenomenon in vehicle braking [2,[22][23][24] and has been considered in as an important element in modeling of the braking process. For example, Day [2] examined the role of interface contact resistance in the calculation of heat flow and temperature generated in brake friction pairs using FEA using a 'five-phase model', i.e.…”

Design Development of Lightweight Disc Brake for Regenerative Braking – Finite Element Analysis

“…aluminium and associated composite materials such as "metal matrix composites" (MMC) for brake rotors have been studied extensively. Although aluminium is increasingly used in modern brake components, the frictional and thermal requirements of a modern automotive brake have limited its use for brake discs [3]. Friction brakes get hot when used and the heat energy is dissipated by forced convection, conduction and radiation from the exposed surfaces of the brake.…”

“…Much theoretical work has been done to calculate accurately the temperature rise during braking for different speeds and designs of brake discs. [3]- [8] so the extent of the thermal loading on brake discs (rotors) is well-known.…”

Air jet cooling of brake discs

“…The resulting temperature distribution at the friction interface can be quite complex, and directly affects braking performance. It has been investigated by several researchers over many years [1][2][3][4][5][6], who have shown how high temperatures can cause a fall in friction coefficient, or fade, and increased wear of both discs and pads. Both fade and increased wear are affected by local thermal distortions of the disc, which can lead to hot spots [7].…”