Abstract A design process to improve the structural performance under contact conditions of automatic transmission of vehicles is presented. The proposed process uses newly developed nonlinear contact optimization techniques. Additionally, useful structural optimization techniques such as 3D topography and the beta method are described. As a demonstrative problem, we consider the improvement of a 6- speed AISIN FWD automatic transmission which is subjected to static loadings and nonlinear contact conditions. Introduction For competitive reasons, the design of automatic transmissions requires to utilize the least amount of material possible while satisfying a variety of technical and performance requirements such as stress constraints. In addition, we are interested to reduce contact clearance on places where tight contact is required to avoid oil leakage. Structural optimization is becoming increasingly important technology for mass reduction. For example, to optimize casing of Automatic Transmission, topography optimization is used. Because of topography optimization, the entire surface of casing is set as design variable and enables us to find areas with thickness increase/decrease. Previously, we proposed reduction of sound pressure using topography optimization [ 1]. In this paper, we proposed reduction of mass and stress using topography optimization considering contact constraints.Nonlinear analysis for contact is now well understood, but structural optimization with contact conditions is not as well developed or used due to the difficulty to implement it and the cost of the nonlinear sensitivity analysis. Herskovits et al. proposed a bi-level method and applied it to shape optimization problems [2]. Park et al. [ 3], utilizing the equivalent static load method coupled two commercial programs: ABAQUS, for the nonlinear analysis, and NASTRAN, for the optimization; in their work they avoided using expensive nonlinear sensitivities. Our method is similar to the bi-level method in that we divide the problem into two. First, we solve the nonlinear analysis and then we solve an approximate problem that uses the solution of the nonlinear analysis. In our approach we use linear sensitivities assuming that in a given design cycle the contact condition will not change much. Because we repeated the process several times, discrepancies on the contact location, due to changes in the design variables, are taken care of. Our method, in this sense, is also similar to reference [ 3] where linear sensitivities are used. However, unlike in reference [ 3], our method does not use equivalent static loads, since we only use one program, GENESIS [4], in which our development is implemented. The rest of the paper is organized as follows. First, analysis and optimization that we used in this design process, contact analysis, topography optimization, and the beta method are discussed. Then, design consideration of automatic transmissions, the detailed model descriptions of an example problem, and the goal of optimization are described. Next, the optimization results using the proposed design process are presented. Finally, the proposed process and benefits are summarized in the conclusion.Structural Optimization with Contact Constraints Applied to the Design of Automatic Transmission of Vehicles2014-01-0407 Published 04/01/2014 Hiroyuki Kitajima AW Engineering Co., Ltd. Takanori Ide Aisin AW Co., Ltd. Juan Leiva, Brian Watson, and Shrinivas Lankalapalli Vanderplaats R&D CITATION: Kitajima, H., Ide, T., Leiva, J., Watson, B. et al., "Structural Optimization with Contact Constraints Applied to the Design of Automatic Transmission of Vehicles," SAE Technical Paper 2014-01-0407, 2014, doi:10.4271/2014-01-0407. Copyright © 2014 SAE InternationalDownloaded from SAE International by University of Auckland, Saturday, August 04, 2018Analysis and Optimization In order to solve the problem we use optimization techniques