2009-01-0330 Firoz Ali Jafri, Martin Fuß and George Bailey LuK USA LLC Chi-Kuan Kao General Motors Corporation Syed T. Razzacki╪ Chrysler LLC Eli Avny╪ Ford Motor Company Copyright © 2009 SAE International ABSTRACT Under the initiative of the United States Council for Automotive Research LLC (USCAR§) Transmission Working Group, a collaborative effort was made with LuK USA LLC to study the influence of the friction interface parameters on the shudder durability of a wet launch clutch. Clutch configurations with different combinations of four friction materials (A, B, C and D), three groove patterns (waffle, radial and waffle-parallel) and two separator plate conditions (nitrided and non-nitrided) were considered. Du rability testing consisted of a test profile, with 110 kJ energy per test cycle, developed earlier in this project. Materials A, B and C with nitrided separator plates reached the end of test criteria for the torque gradient and showed shudder. Materials B and C were more wear resistant as compared to materials A and D. The loss of friction coefficient (µ) was lower for materials B, C and D as ╪ : USCAR Transmission Working Group member § : United States Council for Automotive Research LLC (USCAR) is a joint venture of Chrysler LLC, Ford Motor Company and General Motors Corporation compared to material A. Material D showed good friction properties but failed via material break-out. The radial groove pattern showed lower wear and µ loss but higher pore plugging than the waffle and the waffle-parallel pattern. Materials C and D showed lowest pore plugging. The durability life of the waffle-parallel pattern was lower than the waffle and the radial groove pattern. The non-nitrided separator plates showed high µ loss and high wear although they did not show shudder. Reducing the friction contact area by 50% showed significant µ loss, wear, pore plugging and black spotting due to heat on the separator plates. INTRODUCTION In recent times, launch devices in automotive transmissions often include a wet clutch system. Considerable amount of effort is being dedicated toward development of the wet launch clutch [1,8]. The launching device should fulfill the requirements of providing a smooth launch, good NVH behavior and durability. Essentially, the wet launch clutch is a multi-friction-plate system immersed in an oil bath. Therefore, the performance requirements of a friction clutch including, but not limited to, high friction coefficient (µ), positive friction gradient ( i.e. positive µ-v relationship, where v is the sliding velocity), low wear, stable µ over ╪Shudder Durability of a Wet Launch Clutch Part II – Durability Study SAE Int. J. Engines | Volume 2 | Issue 1 246Downloaded from SAE International by University of Minnesota, Wednesday, August 01, 2018life and durability are essential for desirable performance of the wet launch clutch. Shudder, or friction induced vibrations, is a commonly known undesirable phenomenon in friction clutches [2,4,9]. An initiative was made by the United States Council for Automotive Research LLC (USCAR §) Transmission Working Group to study the influence of friction interface parameters on the shudder durability of a wet launch clutch, in collaboration with LuK USA LLC. A shudder test bench was developed for this study. Clutch configurations with different combinations of four friction materials (A, B, C and D), three groove patterns (waffle, radial and waffle-parallel) and two separator plate conditions (nitrided and non-nitrided) were considered. In an earlier stage of this project, a durability test profile with 110 kJ energy per engagement was developed for this study [3]. The test clut ch is a mechanically actuated DCT clutch with four friction plates. In the subsequent sections the durability test profile is described. The durability results and friction properties measurements have been presented. The different materials, groove p