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The vehicle vibrations result from the exciting forces which are caused by air force, engine firing, tire mass unbalance, and tire uniformity. Especially, the shake and shimmy phenomena in the steering system are closely related to the vehicle vibration, the tire unbalance, and the tire uniformity. This paper presents the shimmy phenomenon due to the tire mass unbalance and the tire uniformity in order to investigate their effects.

Extensive researches are being performed on a world wide basis with the aim of enhancing occupant protection on the side impact. The test methodology for side impact can be divided into two general groups; Sub-System Tests Full Scale Tests. However, the advantages of full scale test is that it is possible to make an integrated statement on the protective potential of the structural stiffness of the struck vehicle and the padding for a selected collision speed and type of collision. The advantages of sub-system test methodology can be simulates more exactly for wide range of accident(i.e. collision directions, impact points etc.). The latter test procedure can be carried out at a relatively earlier stage in the development of a new vehicle, and also can be reduce the time and cost. The Computer Controlled Composite Test Procedure(CC-CTP) presented in this paper has been developed by CCMC (Committee of Common Market Automobile Constructors).

The tendency of high speed and low-weight of passenger car may result in the bad feeling of ride comfort and controllability so that new design concept and technology has been required to solve the problems. Especially, the tangential vibration of the steering wheel makes the driver uncomfortable seriously at high speed [1-5]. So to trace the origin, we use T.L.H. coordinate which is a standard in vehicle design, besides the steering wheel system and the frame are modeled by 20 D.O.F. to estimate dynamic characteristics of new cars with possible changes of the locations of linkages and material properties. Generally, the vehicle frame is considered as a rigid body in the vibration analysis of a vehicle. In this study, however, we have modeled the frame as a elastic body. Moreover, the effects of the dry friction in ball joint and tie-rod, king pin inclination and the side slip of the tire are included in the present analysis to supply design parameters required for new vehicles.

Shake and shimmy problems of steering wheel give a great deal of harshness to drivers, and can even cause handling problems in driving. In this paper, several steering wheel vibration problems were studied, and detailed analysis was carried out to see the characteristics of the source and response systems. A dual mode steering wheel dynamic damper was developed to control the shake and shimmy problems simultaneously. By using experimental and analytical methods its design parameters were tuned to damp out both vibration problems. Experimental results after applying this damper showed a comprehensively good attenuations of both vibration levels of steering wheel. This also showed a possibility of control two different vibration problems using only one dynamic damper without increasing weight and cost.

The vibration characteristics of steering wheel in front drive small-sized passenger cars are discussed. Vertical and lateral accelerations at the steering wheel are measured on typical road. Transfer functions between various sources and the steering wheel are identified from the experimental data using 2 channel FFT analyzer. The effect of engine vibration, road excitation and structural system characteristics are identified by experimental and analytical methods. A significant reduction in the vertical vibration is demonstrated in the data and has been achieved using several improvement in the structure and system.