Temat: friction model - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: FEM temperature evaluation of model braking test in comparison to selected laboratory test
Autorzy:: Skorupka, Z.
Powiązania:: https://bibliotekanauki.pl/articles/247287.pdf
Data publikacji:: 2015
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: transport
air transport
simulation
friction materials
model braking
Opis:: Friction pair tests or model brake tests are one of the trials done in order to evaluate friction pair materials usefulness in full-scale brakes. Such tests are both time consuming and expensive, so most of the manufacturers want to reduce them as much as possible by using numerical simulations for both time and costs savings. It is not possible to eliminate laboratory tests entirely because of the safety regulations requirements. Without regulatory compliance, no brake material can be used in consumer products such as cars or airplanes. Nowadays most of the FEM programs are capable of simulate braking (friction) process in many of its aspects. Accuracy of calculations varies according to complexity of the model and phenomena taken into account. One of the interesting aspects of braking is the friction temperature generation especially due to its destructive impact on the vehicle brakes. Laboratory evaluation of the temperature can be performed in limited spectrum because of inaccessibility of the friction area. FEM calculations can help to determine temperature changes and temperature value during process. It also helps to determine temperature induced damaging conditions for the friction material or the whole brake design. In this paper author compares FEM of friction temperature calculations and laboratory test performed in Landing Gear Laboratory of Institute of Aviation in Warsaw where author works on daily basis. FEM simulation was created in order to resemble mentioned friction material test and to create model of the geometry of the tested material including test stand parts. All of the calculations were performed using COMSOL MULTIPHISICS software.
Źródło:: Journal of KONES; 2015, 22, 3; 213-219
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Effect of friction force determination method on results obtained from model of gas flow from combustion chamber to the crankcase
Autorzy:: Koszałka, G.
Niewczas, A.
Guzik, M.
Powiązania:: https://bibliotekanauki.pl/articles/245664.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: combustion engine
blowby
piston ring
friction force
mathematical model
Opis:: The paper presents investigation of the influence of the friction force calculation method on the results of simulations run with the use of the model ofgas flow from the combustion chamber to the crankcase and piston rings motion in the grooves. The first series of simulations was run using the gas flow and ring motion model in which the friction force was calculated from the empirical equation. The second series was run with the use of the gas flow and ring motion model fully integrated with the ring lubrication model. In that case the friction force was derived from the hydrodynamic model of ring lubrication. Comparison of the results obtained in the first and second series of simulations indicated that despite the fact that the friction forces calculated with these two methods differed considerably, the method of friction force calculation had insignificant effect. This refers to the ąuantities determined in the simulations which are most important from practical point of view - i.e. displacements of the rings in the grooves, pressure courses in inter-ring regions and blowby rate. It is not necessary to integrate the gas flow and ring motion model with the model of ring lubrication, and doing so to complicate it very much, if the aim of the calculations is simulation of blowby and rings behaviour in the grooves.
Źródło:: Journal of KONES; 2009, 16, 4; 223-239
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Numerical model of fricional damper for glas – making robot lance
Autorzy:: Stembalski, M.
Skoczyński, W.
Roszkowski, A.
Powiązania:: https://bibliotekanauki.pl/articles/247991.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: robot
vibration damping
friction damper
numerical model
damping decrement
Opis:: The need to design a friction damper for glass-making robots arose because of the excessive vibrations, which occur in the course of their work. The robots are commonly used in the manufacture of glassware. The vibrations adversely affect the work of ball gatherers, which results in a large number of defects in the finished glass products. As a result of the vibrations molten glass may become unevenly distributed on the ball's surface and as the material flows down the ball into the mould the thermal conditions of its solidification may change. It is proposed to damp the vibrations by means of a prototype friction damper mounted directly on the ball gatherer lance. The glass-making robot lance with the friction damper was modelled. The vibrations of the glass-making robot lance tip under static load and impact excitation were measured during simulations. Also the relative displacements of the damper rings in the course of the excitations were measured. Moreover, the dependence between the preload force and the system's damping decrement was determined. The main aim was to select proper operating parameters for the proposed structure in order to obtain maximum system damping.
Źródło:: Journal of KONES; 2012, 19, 1; 391-398
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Sensitivity analysis of steering system model
Autorzy:: Żardecki, D.
Powiązania:: https://bibliotekanauki.pl/articles/242406.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: car
steering system
piecewise linear model
simulation
sensitivity analysis
friction
freeplay
stick-slip
Opis:: The method of sensitivity analysis of mathematical model with strong non-linear characteristics is discussed in the paper. This model focuses on friction, as well as freeplay dynamics in a car steering system including stick-slip fenomena. Because of strong nonlinearities of the model, its sensitivity indexes can not be counted by classic sensitivity variation equations and classic mathematical analysis of smooth functions. Fortunately, nonlinear characteristics are described with using special piecewise - linear luz(...) and tar(...) projections. They have an original mathematical apparatus which secures parametrically made simplifications and enough regularity of the model (some details of analytical transformations are shown). Thanks to luz(...) and tar(...) projections the continuity of sensitivity indexes is secured but of course, the calculation of sensitivity indexes has to base on comparative simulation investigations. The paper presents example results of simulations of the steering system action (including stick-slip processes) for different values of friction as well as freeplay parameters (kinetic and static friction in king-pins, backlash in a steering gear). These simulations concern combined open road tests of a passenger car according to the ISO requirements (ISO 7401 - the ramp input on the steering wheel, then ISO 4138 - circular steady state motion, and finally the steering wheel released, all with a constant speed 80 km/h).
Źródło:: Journal of KONES; 2009, 16, 1; 571-581
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Modelling of eps type steering systems including freeplay and friction in steering mechanism
Autorzy:: Żardecki, D.
Powiązania:: https://bibliotekanauki.pl/articles/242015.pdf
Data publikacji:: 2011
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: EPS system
freeplay
friction
piecewise linear model
simulation studies of car open tests
Opis:: Electric power steering (EPS) systems are important ingredients of modern cars. Basing on mechanic (steering mechanism), electric (electric motor), electronic (controller) and mechatronic (sensors) components, they are typical servo mechanic devices, which support drivers handling action. The paper presents mathematical modelling of EPS systems treated as multi body mechanisms with power assistance, including strong non-linear phenomena caused by a friction (especially in king-pins) and a feeplay (in gear-box). Mathematical model consists of several variable structure ordinary differential equations with piecewise linear characteristics. Model non-linearities are described with using special piecewise linear luz (…) and tar(...) projections. These projections and their original mathematical apparatus facilitate synthesis and analysis of the model. The model equations are derived from constitutive equations and control rules. This method can be also applied for synthesis of other non-linear multi-body electromechanical systems. The elaborated models of EPS systems have the forms ready to use in simulation programs. Some examples of simulation studies of the open car tests due to sensitivity analysis of steering system model are also presented in the paper.
Źródło:: Journal of KONES; 2011, 18, 1; 689-696
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Analysis of the load carrying capacities and the friction force in the gap of the slide journal bearing lubricated with a non-Newtonian oil described by a power-law model
Autorzy:: Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/244543.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: numerical calculation
load carrying capacities
friction forces
non-Newtonian oil
power law model
Opis:: In this paper, the author presents the results of numerical calculations of load carrying capacities and friction forces in the gap of the slide journal bearing lubricated with an oil on the non-Newtonian's properties. In the studies, the power-law model has been assumed to describe the relationship between the stress tensors and shear rate tensors. The analytical and numerical calculations have been performed for the plain bearing, non-porous with a full wrap angle. It has been assumed isothermal, laminar and steady flow of lubricant in the gap of a slide bearing. Numerical calculations have been performed for the Gumbel’s boundary conditions and dimensionless lengths of the bearings like L=b/R =2;1.5;1; ½ and ¼. The flow-rate index and coefficient of consistency have been adopted based on the results of experimental studies of changes of dynamic viscosity in terms of a shear rate. It has been assumed that the apparent viscosity depends only on the shear rate. Dynamic viscosity of the engine oil, used in a gasoline engine with a capacity of 1800 cm3, has been tested on the Haake Mars III rheometer. The analytical solutions presented in the paper were based on more general derivations carried out by Professor K. Wierzcholski in his article: ‘Non-linear hydrodynamic lubrication in conjugated fields’ (publication in printing). In this paper, the key quantities such as components of vector of the velocity, hydrodynamic pressure and temperature were presented in the form of convergent power series. The values of load carrying capacities and friction forces were determined and compared for the event where the oil has properties of Newtonian and non-Newtonian. Calculations have been made for the dimensionless quantities.
Źródło:: Journal of KONES; 2016, 23, 3; 327-335
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Braking moment comparison and analysis for various brake designs using results from sample and full scale friction material tests
Autorzy:: Skorupka, Z.
Powiązania:: https://bibliotekanauki.pl/articles/242444.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: transport
motor vehicle
brake
brake design
brake tests
full scale tests
model tests
friction material
Opis:: Brake is one of the most important safety feature in every mechanical vehicle from bikes to airplanes. Brakes have to be designed in order to meet safety, reliability, efficiency and economical requirements. One has to remember that not only design of brake is important but also friction material used in its construction. Without proper materials, brakes are not able to generate proper braking moment. Braking moment is the most important parameter of brake from operation point of view. It is directly connected to braking distance as well with amount of force needed to achieve assumed braking parameters for the mechanical vehicle. Stability of braking moment is important in order to get optimized characteristics of the braking process itself. Most of the brake characteristics and efficiency calculations base on assumption that braking moment should be stable during braking process. During years of tests made on full scale brakes and friction material sample tests, author observed that real braking moment curve is not stable during braking process. This phenomenon is likely to affect braking efficiency and in result slightly change braking distance. In this paper author would like to address this issue by showing brake moment curves made for different brakes and friction materials. Tests, which were author’s base for paper contents, were made using full scale brake testing and friction material sample testing. All of the tests described in the paper were performed in Landing Gear Laboratory of Warsaw Institute of Aviation in which author works on daily basis
Źródło:: Journal of KONES; 2013, 20, 1; 303-308
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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