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As widely noted by researched in last decades, an automotive brake system works by transforming kinetic energy of vehicle into thermal energy, and dissipating the energy through heat conduction. The typical concerns in this kind of system are the noise problems in high frequency which can be figured the vibration characteristics out though modal analysis of the system. As noted in recent research, the mentioned problem is mainly related with the specific modes of components where potentially can be superposed. The separation of these modes should be handled as a crucial design consideration at the initial stage of development. The rotor is a significant contributor of noise and vibration, hence the modal separation is to be considered in designing detail shapes of the component, since the shape of the object generally affects the mode frequencies. In this study, frequency sensitivity analysis through finite element method by design of experimental process has conducted to find the dominant shape factors among the multiple designable figures of the rotor body. Several shape factors are selected as design variables for the implementation of the modal separation process. The contribution of the shape factor to the mode frequency transition has calculated to achieve the optimal design of given component.

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The timing chain system, which is a typical power transmission technology applied to a vehicle, has been widely used by the automotive industry because it is normally designed to last a car's lifetime. However, the timing chain system may cause some problems due to the shape of the chains and the polygonal behavior on contact between the chain and the sprocket. In addition, noise and vibration caused by transmission error are the most typical problems encountered by major automotive manufacturers and they are considered as the main source of customer complaint. The initial tension of the chain-sprocket system is thought to be the main cause of transmission error, and it is regarded as the source of engine vibration and noise. The initial tension of the chain system should be controlled carefully since a low initial tension can cause twisting, which may lead to a system malfunction, while a high initial tension can reduce the service life due to a worn down contact surface. In this paper, the kinematic analysis model is generated with various initial tensions, which are controlled by changing the shape of the fixed guide with the largest contact surface with chain. The results showed that the transmission error was minimized on a particular range of initial tension, and the tendency showed that the error changed with a higher sensitivity at a lower initial tension.