P. Grzes

The FEM-Modeling of the Frictional Heating Phenomenon in the Pad/Disc Tribosystem (A Review)

This article is concerned with frictional heating phenomenon playing a central role in disc brake (clutch) systems performance. It was of great interest to carry the description of existing numerical solutions of the problem. The level of the calculations was categorized into three problems. The first is a common approach, drawn primarily on the assumption that the heat flow rate generated at the disc/pad interface is a known quantity. Heat generation was substituted by the intensity of heat flux depending on contact pressure, coefficient of friction and evolution of angular velocity, and radius of the disc product. A more complex description of the braking action was given by the assumption of mutual relation between mating parts of the disc brake system. In this case, the thermoelasticity theory was applied to the model. The facts of existing critical speed is established, in which hot spots caused mainly by contact pressure variations frictionally-excited thermoelastic instability phenomenon entered commonly into consideration.

Finite Element Analysis of Heat Partition in a Pad/Disc Brake System

The heat partition ratio is an important input parameter in simulation carried out by the finite element method (FEM) of the transient temperature fields in such elements as brakes, a pad, and a disc. Therefore, the aim of this article is to study the influence of nine various (experimental and theoretical) formulas for heat partition ratio on temperature in a pad/disc tribosystem. The real dimensions, operating conditions, and thermophysical properties of materials of two different disc brake systems were adopted for the finite element analysis. The evolutions of the temperature on the contact surface of the pad, obtained for different heat partition ratios, are compared with corresponding experimental data. The results revealed a significant influence of heat partition ratio on the evolution of pad maximal temperature, whereas the disc contact temperature was reasonably stable and coincided with most cases under consideration.

Numerical Analysis of Thermal Stresses in Disk Brakes and Clutches (A Review)

An operation of a brake at robust thermal loads leads to high-temperature gradients in brake components. This in turn may induce thermal stresses due to thermal expansion. In this article, both uncoupled and coupled problems of thermoelasticity for the frictional heat generation in disk brakes and clutches using the finite element method are presented and analyzed. The article covers a wide range of studies providing the concluding remarks and key factors affecting a change in the distribution of stresses in different types of the disk brakes and clutches, operating parameters, materials, etc.

Axisymmetric Finite Element Model for the Calculation of Temperature at Braking for Thermosensitive Materials of a Pad and a Disc

Formulation of temperature dependence of thermophysical properties of materials in the braking systems involves the difficulty of mathematical and numerical description of the problem, and is typically ignored assuming their constancy regardless of the magnitude of load and the working time. The purpose of this article is to study an effect of thermal sensitivity of a pad and disc materials on the temperature distributions during single braking. In the first stage, a boundary value axisymmetric problem of heat conduction with temperature-dependent thermal conductivity and specific heat was formulated. The analytical temperature dependence of these properties for four various materials of the pad and the disc were obtained by approximation of the corresponding experimental data. Taking account of these relations, the solution of the boundary value problem of heat conduction by using the finite element method was obtained. The determined values of temperature for thermosensitive materials were compared with the corresponding results for constant thermophysical properties of the same materials. In the vast majority of the types of used materials, an insignificant influence of the variations of their thermophysical properties on the temperature was revealed both in the pad and disc; an exception was the titanic pad. A possible explanation is very strongly associated, unlike other materials, with the temperature dependence of the thermal effusivity of titanium on the resulting temperature of the pad and disc.

FINITE ELEMENT ANALYSIS OF THERMAL STRESSES IN A PAD-DISC BRAKE SYSTEM (A REVIEW)

Abstract Rapid temperature change in components of the sliding systems induces thermal stresses due to thermal expansion. This effect is particularly evident in disc brakes working under high thermal loads. This paper deals with the finite element modelling of frictional heating process in disc brakes and clutches to study the temperature and stress distributions during operation

Determination of the maximum temperature at single braking from the FE solution of heat dynamics of friction and wear system of equations

ABSTRACT A system of equations of heat dynamics of friction and wear (HDFW) for a pad–disc tribosystem during a single braking has been formulated. It takes into account the coefficient of friction dependent on the maximum temperature, which is the sum of the mean temperature of the nominal contact region (the macro contact) and the flash temperature on the real contact area (the micro contact), temperature-dependent properties of materials and wear. Numerical solution of the initial problem of motion and the nonlinear boundary-value heat conduction problem was obtained. Computations were performed using the axisymmetric FE contact model for the metal ceramic pad and the cast-iron disc.