Generation of Frictional Heat During Uniform Sliding of Two Plane-Parallel Strips

The thermal problem of friction for a tribosystem consisting of two plane-parallel strips is studied. It is assumed that the relative sliding speed is constant. The convective cooling on free surfaces of strips and the heat transfer through a contact surface are considered, too. The evolution of the contact temperature and its spatial distribution in materials of frictional pair such as aluminum/steel, was investigated

The comparable analysis of temperature distributions assessment in disc brake obtained using analytical method and FE model

In this paper the one-dimensional analytical formulation as well as the two-dimensional FE model to study the temperature distributions in the pad/disc brake system during an emergency braking process was proposed. Both the time-dependent pressure variation and the convective cooling conditions on the free surfaces of a pad have been incorporated in the contact analytical model. The one-dimensional thermal problem of friction of the strip-foundation system during braking was formulated. An exact solution of the problem using the mathematical device of the integral Laplace transform related to Duhamel theorem was obtained. In the FE formulation to discretize the heat conduction equation for the two-dimensional problem, the Galerkin method was employed. The temperature distributions were calculated exclusively for the disc employing the heat partition ratio. Furthermore, due to the symmetry of the problem the computations were restricted to the half of the entire disc. The finite element analysis of the transient heat transfer problem for the pad/disc system was carried out using the MSC Patran/Nastran program package. On order to confront and compare the resulting temperatures distributions, equal operation parameters, the thermophysical properties of materials as well as the dimensions of the brake components were used within the numerical and analytical calculation. The obtained results from the finite element analysis reveal that both the contact temperature evolution and its values in depth of the brake rotor agree well with the analytical solution and experimental data

Non-stationary thermal problem in frictional elements

Otrzymano analityczne rozwiązanie zagadnienia przewodnictwa cieplnego i odpowiedniego zagadnienia quasi-statycznej termosprężystości dla układu tarciowego, złożonego z podłoża (półprzestrzeni) i ślizgającej się po jego powierzchni ze stałą prędkością warstwy. Dla pary tarciowej aluminium-stal zbadano ewolucję i rozkład po głębokości od powierzchni tarcia temperatur, strumieni cieplnych i przemieszczeń.The analytical solution of a boundary-value problem of heat conductivity and corresponding boundary problem of thermoelasticity for tribosystem, consisting of semi-infinity substrate and sliding on its surface a layer is obtained. For materials of frictional pair aluminum-steel it is studied evolution and distribution on depth from a surface of friction of temperatures, thermal fluxes and thermoelastic displacements

Dwa zagadnienia przewodnictwa ciepła z uwzględnieniem nagrzewania tarciowego podczas hamowania

Analytical solutions to a boundary-value problem of heat conduction for friction pairs consisting of the half-space sliding (braking at uniform retardation) on a surface of the strip deposited on a semi-infinite foundation and the strip sliding on a surface of the homogenous half-space, are obtained. For materials of the frictional system: cast iron – metal ceramics-steel and metal ceramics-cast iron, evolutions and distributions on depth from the surface of friction for temperatures are studied.W pracy otrzymano analityczne rozwiązania początkowo-brzegowych zagadnień przewodnictwa ciepła dla dwóch układów par tarciowych: 1) półprzestrzeń – warstwa – półprzestrzeń, 2) warstwa – półprzestrzeń. Założono, że prędkość ślizgania się elementów tarciowych w rozpatrywanych układach zmniejsza się liniowo z czasem, od wartości początkowej do zera. Dla właściwości materiałowych: żeliwo – metaloceramika – stal oraz metaloceramika – stal, zbadano rozkład oraz ewolucję temperatury w powyższych układach. Zbadano wpływ grubości warstwy na wartość maksymalnej temperatury na powierzchni kontaktu. Wyniki przedstawiono w formie wykresów

Comparative study on the effect of fibre substitution on the properties of composite railway brake shoe

During the design process, railway friction materials are subject to extensive testing which allows for a thorough assessment of their compliance with versatile requirements and expected characteristics. These tests include, among other, laboratory tests of mechanical, physicochemical, thermophysical and tribological properties. For a designer it is crucial to understand how formulation modification influences characteristics of the friction material. One of the key ingredients in the formulation of friction materials is reinforcing fibre. In this study, two composite, organic railway brake shoes with equal amount of two different reinforcing fibres, namely steel wool and glass fibre, were tested according to the procedures of a railway friction materials manufacturer. Test results were analysed and compared. The substitution of reinforcing fibre had a noticeable effect on each of the properties of the composites considered in this study

Dwa schematy obliczeń do opisania naprężeń termicznych wywołanych nagrzewaniem tarciowym podczas hamowania

Thermal stresses in three-element (disc/pad/metal slice) and two-element (disc/pad) models of frictional heating during braking are analysed. Evolutions and distributions of the lateral normal stresses in depth from the surface of friction are studied for the following frictional system materials: cast iron/ metal ceramics/steel and metal ceramics/cast iron.W pracy przeanalizowano rozkład naprężeń termicznych w trzy- (tarcza/nakładka/zacisk) oraz dwu- (tarcza/nakładka) elementowych układach nagrzewanych tarciowo podczas hamowania. Dla materiałów tarciowych: żeliwo/metalo- ceramika/stal oraz żeliwo/metalo-ceramika, zbadano ewolucję oraz rozkład normalnych naprężeń termicznych

O pewnym matematycznym modelu procesu laserowego termorozłupywania

Distribution of the transient temperature field and the corresponding quasi-static thermal stresses were examined in the system consisted of a bulk substrate and a thin coating of different material deposited on it. Such a system is heated through the outer surface of coating by the pulsed heat flux generated due to absorption of laser pulse irradiation of rectangular or triangular time shape. The dependencies of temperature and stresses on geometrical and thermophysical properties of the substrate and the coating were studied. It was proved that there is the possibility of applying the obtained results to modelling of thermal splitting for brittle materials.Zbadano nieustalone pole temperatury i związane z nim quasi-stacjonarne termiczne naprężenia w układzie składającym się z podłoża i cienkiej warstwy naniesionej na to podłoże (nagrzewanie impulsowym strumieniem ciepła). Znaleziono zależności temperatury i naprężeń od geometrycznych i cieplno-fizycznych właściwości podłoża i warstwy. Pokazano, że istnieje możliwość wykorzystania otrzymanych rezultatów do modelowania procesu sterowanego termicznego rozdzielania (rozłupywania) kruchych materiałów

Effect of the temporal profile of the friction power on thermal stresses during braking

In this paper influence of the temporal profile of frictional heat flow density on the distributions of temperature and thermal stresses in a friction element during single braking was investigated. For this purpose a one-dimensional boundary-value heat conduction problem for a half-space body (which simulates a brake rotor) heated on the outer surface by the heat flux with different intensities was formulated and solved by means of Duhamel’s theorem. Solutions were obtained for ten temporal profiles of specific friction power, which are proportional to the intensity of frictional heat flow. Based on received transient temperature fields and Timoshenko’s model of thermal bending of a thick plate with unfixed edges, the analytical distributions of quasi-static thermal stresses in a friction element were found. Achieved solutions allow conducting numerical analysis of the distributions of temperature and thermal stresses in a brake rotor with different time profiles of the specific friction power