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This paper presents a study on a design methodology for lightweight automatic transmission parts for vehicles. To improve fuel economy of the vehicle, weight reduction is a primary issue when designing automobile parts. Topology optimization, a particularly flexible type of structural optimization method, is an effective tool for developing lightweight designs. However, topology optimization methods available in most commercial software often provide optimization results that include grayscale areas, which cause the designs to be impractical from an engineering and manufacturing standpoint. To overcome this difficulty, we apply a level set-based topology optimization method that yields clear optimal configurations and therefore facilitates further improvement of the product design by engineers. In addition, we consider the imposition of a uniform cross-section constraint to improve the manufacturability of the obtained optimization results.

This paper proposes a new hierarchical optimization technique for the vehicle body structure, by combining topology optimization and shape optimization based on the traction method. With the proposed approach, topology optimization is first performed on the overall allowable design domain in 3D. The surface is extracted from the optimization result and converted to a thin shell structure. Shape optimization based on the traction method is then applied to obtain an overall optimal body shape. In the shape optimization process, iterative calculations are performed in the course of consolidating parts by deleting those whose contribution is small. The result obtained by applying this method to the front frame structure of a vehicle is explained. The resultant optimal shape has stiffness greater than or equal to the original structure and is 35% lighter. This confirms the validity of the proposed technique. It was found, however, that some issues remain to be addressed.

Computer Aided Engineering (CAE) has been successfully utilized in automotive industries. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to the higher performance without building prototypes. Most automotive designers, however, cannot directly use CAE due to the sophisticated operations. In order to overcome this problem, we proposed a new concept of CAE, First Order Analysis (FOA). The basic ideas include (1) graphic interfaces using Microsoft/Excel to achieve a product oriented analysis (2) use the knowledge of the mechanics of materials to provide the useful information for designers, and (3) the topology optimization method using beam and panel elements. In this paper, outline of FOA and application are introduced

Automotive body frame structures play crucial roles in the achievement of dynamic and crashworthiness performance, and their cross-sections must fulfill various required characteristics. However, cross-sectional shape design is complex and relies on designers' intuitions, since automotive body frames are fabricated from many sheet metal parts having complex interdependencies, a problematic situation for optimization via software. This paper proposes a cross-sectional shape generation method satisfying a range of required cross-sectional properties for early design stages. Shape generation problems are formulated as multiobjectsve optimization problems, solved using genetic algorithms and a variety of cross-sections can be obtained as Pareto optimal solution sets.

Computer Aided Engineering (CAE) has been successfully utilized in automotive industries. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to the higher performance without building prototypes. Most automotive designers, however, cannot directly use CAE due to the sophisticated operations. In this paper, we propose a new breed of CAE, First Order Analysis (FOA), for automotive body designers. The basic ideas include (1) graphic interfaces using Microsoft/Excel to achieve a product oriented analysis (2) use of mechanics of materials to provide the useful information for designs, (3) the topology optimization method using function oriented elements. Further, some prototypes of software are presented to confirm the method for FOA presented here.

Whinning gear noise(final gear noise), one of the causes for automobile interior noise is due to the exciting force of final gear kit and as a general countermeasure for this problem, a reduction of resonance level in transfer system and better meshing of gears have been utilized. However,vibration characteristics of final gear unit have not been considered much in this case. Authors have executed impacting test on final gear unit and confirmed its vibration characteristics. Based on this fact,vibration model consisting of bearings and gears spring system was constructed to evaluate vibration characteristics of final gear unit along with the results obtained from final gear unit of front engine,rear drive passenger car.