scholarly journals Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3896
Author(s):  
Roland Biczó ◽  
Gábor Kalácska ◽  
Tamás Mankovits
Keyword(s):  
Dry Friction ◽  
Real Life ◽  
Friction Material ◽  
Energy Scale ◽  
Fiber Reinforced ◽  
Test Conditions ◽  
Test Parameters ◽  
Sorting Tests ◽  
Surface Microgeometry ◽  
Dry Friction Clutch

Wear and surface microgeometry aspects of fiber-reinforced hybrid composite dry friction clutch facings are revealed in a novel way: after different, real life automotive tests during their lifetime. This study examines and reveals the tribological response of friction material surfaces to real life application conditions with two different facing diameters and in two directions. Along the increasing activation energy scale, wear values increased according to two different trends, sorting tests into two main groups, namely ‘clutch killer’ and ‘moderate’. Wear results also highlighted the influence of mileage and test conditions, with clutch killer tests also creating considerable wear-more than 0.1 mm-at inner diameters: 1% higher wear was generated by 90% higher mileage; another 1% increment could be caused by insufficient cooling time or test bench-specific conditions. Surface roughness values trends varied accordingly with exceptions revealing effects of facing size, friction diameter and directions and test conditions: small (S) facings produced significantly decreased Rmax roughness, while large (L) and medium (M) size facings had increased roughness values; Rmax results showed the highest deviations among roughness values in radial direction; tests run with trailer and among city conditions resulted in more than 2% thickness loss and a 40–50% roughness decrease.

scholarly journals Micromechanical model of dry friction hybrid polymer composite clutch facings

2019 ◽  
Vol 4 (1) ◽  
pp. 335-340
Author(s):  
Roland Biczó ◽  
Gábor Kalácska
Keyword(s):  
Dry Friction ◽  
Micromechanical Model ◽  
Friction Material ◽  
Hybrid Polymer ◽  
Mechanical Stiffness ◽  
Clutch System ◽  
Friction Clutch ◽  
Dry Friction Clutch ◽  
Hybrid Polymer Composite ◽  
Tribological Contact

Modelling the complex coupled thermomechanical and tribological contact of a dry friction clutch system between cast iron flywheel and scatter-wound hybrid composite clutch facing requires a thought through investigation of the friction material properties and behaviour. Challenges of the creation of a mechanical stiffness matrix for such a complex material are described in this paper along with simplification ideas and solutions.

An Investigation Into the Thermal Behavior of the Grooved Dry Friction Clutch

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Oday I. Abdullah ◽  
Josef Schlattmann
Keyword(s):  
Dry Friction ◽  
Three Dimensional ◽  
Heat Content ◽  
Friction Material ◽  
Area Ratio ◽  
Friction Clutch ◽  
Transient Simulations ◽  
Dry Friction Clutch ◽  
Element Technique ◽  
Nominal Contact Area

The heat generated during the sliding period at the initiation of engagement in friction clutches is considered to be one of the main reasons for the failure of the friction material. One way to reduce the risk of this problem is to increase the rate of heat transfer by convection or, in other words, reduce the heat content of the friction material (internal energy) and thereby increase the lifecycle of the friction clutch. In this paper, the finite element technique has been used to study the effect of radial circumferential grooves on the temperature distribution and the amount of energy transferred by convection for a dry friction clutch disk during a single engagement, assuming a uniform distribution for the thermal load between the contact surfaces (i.e., uniform wear on clutch surfaces). Three-dimensional transient simulations are conducted to study the thermoelastic coupling of the problem. The effect of the groove area ratio (GR, defined as the groove area divided by the nominal contact area) is investigated. Furthermore, this paper presents the equations for energy considerations and energy balance at any time for the friction clutch system. The numerical results show that the amount of energy transferred by convection from the friction material can be controlled (within a limitation) by adjusting the value of the groove area ratio. Commercial ANSYS13 software has been used to perform the numerical computations in this paper.

scholarly journals Influence of Test Conditions on Sliding Wear Performance of High Velocity Air Fuel-Sprayed WC–CoCr Coatings

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3074
Author(s):  
Kaveh Torkashvand ◽  
Vinod Krishna Selpol ◽  
Mohit Gupta ◽  
Shrikant Joshi
Keyword(s):  
Wear Rate ◽  
Test Performance ◽  
Sliding Wear ◽  
Normal Load ◽  
Specific Wear Rate ◽  
Wear Behaviour ◽  
Wear Performance ◽  
Test Conditions ◽  
Test Parameters ◽  
Sliding Distance

Sliding wear performance of thermal spray WC-based coatings has been widely studied. However, there is no systematic investigation on the influence of test conditions on wear behaviour of these coatings. In order to have a good understanding of the effect of test parameters on sliding wear test performance of HVAF-sprayed WC–CoCr coatings, ball-on-disc tests were conducted under varying test conditions, including different angular velocities, loads and sliding distances. Under normal load of 20 N and sliding distance of 5 km (used as ‘reference’ conditions), it was shown that, despite changes in angular velocity (from 1333 rpm up to 2400 rpm), specific wear rate values experienced no major variation. No major change was observed in specific wear rate values even upon increasing the load from 20 N to 40 N and sliding distance from 5 km to 10 km, and no significant change was noted in the prevailing wear mechanism, either. Results suggest that no dramatic changes in applicable wear regime occur over the window of test parameters investigated. Consequently, the findings of this study inspire confidence in utilizing test conditions within the above range to rank different WC-based coatings.

scholarly journals Modeling Wear for Heterogeneous Bi-Phasic Materials Using Discrete Elements Approach

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Matthieu Champagne ◽  
Mathieu Renouf ◽  
Yves Berthier
Keyword(s):  
Friction And Wear ◽  
Numerical Models ◽  
Real Life ◽  
Limited Range ◽  
Friction Material ◽  
Contact Interface ◽  
Discrete Elements ◽  
Proper Understanding ◽  
Scale Models ◽  
Automotive Brake

A proper understanding of the processes of friction and wear can only be reached through a detailed study of the contact interface. Empirical laws, such as Archard's, are often used in numerical models. They give good results over a limited range of conditions when their coefficients are correctly set, but they cannot be predicted: any significant change of conditions requires a new set of experimental coefficients. In this paper, a new method, the use of discrete element models (DEMs), is proposed in order to tend to predictable models. As an example, a generic biphasic friction material is modeled, of the type used in aeronautical or automotive brake systems. Micro-scale models are built in order to study material damage and wear under tribological stress. The models show what could be achieved by these numerical methods in tribological studies and how they can reproduce the behavior and mechanisms seen with real-life friction materials without any empirical law or parameter.

Analysis of friction-induced vibration leading to "EEK" noise in a dry friction clutch

2005 ◽  
Vol 53 (4) ◽  
pp. 138 ◽  
Author(s):  
Pierre Wickramarachi ◽  
Rajendra Singh ◽  
George Bailey
Keyword(s):  
Dry Friction ◽  
Friction Clutch ◽  
Dry Friction Clutch ◽  
Friction Induced Vibration

Modelling a Friction Damper: Analysis of the Experimental Data and Comparison With Numerical Results

2006 ◽  
Author(s):  
Christian M. Firrone ◽  
Daniele Botto ◽  
Muzio M. Gola
Keyword(s):  
Experimental Data ◽  
Dry Friction ◽  
Negative Impact ◽  
Real Life ◽  
Forced Response ◽  
Nonlinear Frequency ◽  
Friction Damper ◽  
Typical Application ◽  
Static Test ◽  
Underplatform Damper

High cycle fatigue is one of the main causes of failure of blades in turbomachinery. The negative impact of HCF on turbomachinery blades can be reduced by dry friction vibration damping. A typical application of dry friction damping in gas turbine is the so called “underplatform damper”. In this work a ‘real life’ asymmetric underplatform damper is experimentally tested with two real blades. A static test rig is used to obtain the nonlinear frequency response function of a mock-up made with two real blades with an underplatform damper between them. This paper addresses an underplatform damper model taking into account damper rotation. The proper mathematical formulations have been developed and forced response calculation of the system have been performed. Comparison with experimental data are carried out for different values of excitation forces and for pre-load similar to real centrifugal force values.

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