Abstract
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.
Highlights
In automotive applications, the purpose of utilizing a clutch is to transfer kinetic energy in the form of modulated torque of a rotating crankshaft coupled to a power source towards a transmission system and further to the wheels of the vehicle. [1] The commonly used single disc clutch system consists of a flywheel, a clutch disc with composite friction facings and the clutch itself with the releasing diaphragm spring
Clutch killer created significantly higher wear diameters; was to thetests vehicle (VTRS, VTC) or there were hillvalues startsat oninner purpose (VTRS, VRS), or a similar load case was simulated on a test bench (TH)
Tribological aspects of fiber-reinforced hybrid composite dry friction clutch facings were examined in a novel way: after different, mainly non-laboratory automotive tests, that were characterized by different surface activation energy values
Summary
The purpose of utilizing a clutch is to transfer kinetic energy in the form of modulated torque of a rotating crankshaft coupled to a power source towards a transmission system and further to the wheels of the vehicle. [1] The commonly used single disc clutch system consists of a flywheel, a clutch disc with composite friction facings and the clutch itself with the releasing diaphragm spring. Despite the many investigations carried out regarding the friction behavior of dry sliding hybrid composite clutch facings, there are not many approaches that examine samples from facings after real life or test track usage in actual vehicles, and comparison of tribological performance of the same material with different preliminary activation energy levels on the friction surface and its effects on the stability of the coefficient of friction. To understand our current aim–to integrate tribological aspects, such as effects of varying load cases on wear and surface roughness into a thermomechanical model–a short summary is required to sum up the thermomechanical identification results In this friction material, the long fiber reinforcement, the so-called yarn, consisted of glass fiber, aromatic polyamide, copper, and poly-acrylic-nitrile (PAN), while the matrix is an industrial secret, the required identification.
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