400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2007-01-1016 A Molecular Dynamics Analysis of the Traction Fluids H. Washizu, S. Sanda, S. Hyodo and T. Ohmori Toyota Central R&D Labs., Inc. N. Nishino and A. Suzuki Toyota Motor Corporation Reprinted From: Na notechnology for Automotive Applications (SP-2113) 2007 World Congress Detroit, Michigan April 16-19, 2007 Downloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Wednesday, September 19, 2018By mandate of the Engin eering Meetings Board, th is paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under the supervision of the session organizer. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-776-3036Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: Customer [email protected] ISSN 0148-7191Copyright © 2007 SAE InternationalPositions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE.The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Wednesday, September 19, 2018ABSTRACT Non-equilibrium all-atom MD simulations are used to study the traction properties of hydrocarbon fluids. A fluid layer is confined between two solid Fe plates under the constant normal force of 1.0 GPa. Traction simulations are performed by applying a relative sliding motion to the Fe plates. Shear behaviors of nine hydrocarbon fluids are simulated on a sufficiently large film thickness of 6.7 nm, and succeeded in reproducing the order of the experimental traction coefficients. The dynamic mechanism of the momentum transfer on layers of fluid molecules are analyzed focusing on the intermolecular interactions (density profile, orientation factor,pair-correlation function) and intramolecular interactions (intramolecular interaction energy, conformation change of alicyclic ring). In contrast to the case of n -hexane, which shows low traction due to a fragile chain-like interaction, other mechanisms are obtained in the high traction molecules of cyclohexane, dicyclohexyl and santotrac 50. In cyclohexane, alicyclic rings face each other in a highly ordered molecular layer, and the motion of the conformational changes cooperates. In dicyclohexyl and santotrac 50, alicyclic rings, which distribute across the low ordered molecular layers,behave as a stiff bulky mass, and momentum transfers to the end of the molecular axis. The traction mechanisms of nine hydrocarbon fluids are also obtained during the course of the analysis. INTRODUCTION The traction properties of fluids used in a continuously variable transmission (CVT) largely depend on the structure of the fluid molecules 1, 2. In order to minimize and achieve a higher CVT capacity, improved fuel economy and protect the environment, the molecular design and development on a molecular level of high traction coefficients are needed. On the other hand, as the lubrication condition of a working traction fluid is under elast