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This study investigates how hilly road profiles affect the optimal energy management strategy for fuel cell hybrid electric vehicle (FCHEV) with various battery sizes. First, a simplified FCHEV model is developed to describe power and energy flows throughout the powertrain and evaluate hydrogen consumption. Then, an optimal control problem is formulated to find the globally optimal energy management strategy of FCHEV over driving cycles with road elevation profile. In order to solve the optimal energy management problem of the FCHEV, Dynamic Programming, a dynamic optimization method, is used, and their results are analyzed to find out how hilly road conditions affect the optimal energy management strategies. The results show that the optimal energy management with a smaller battery tends to actively prepare (e.g. pre-charge/pre-discharge) for uphill/downhill roads in order not to violate the battery state of charge (SoC) bounds.

This paper describes a method to separate structure-borne noise, which comes from the shock absorber, from the measured vehicle interior sound pressure. The transfer path analysis (TPA) was used. Shock absorber was considered as an input source while the sound pressure at the driver seat as its output. It was found that the sound pressure at the driver seat position and accelerations at the shock absorber mounting points are strongly correlated. Using one-third octave band analysis, the contribution of shock absorber structure-borne noise to the driver seat sound pressure was analyzed. Also the relationship between the measured acceleration and sound pressure was studied.

An accurate vehicle structural vibration analysis, in medium or high frequency range, is necessary for structural redesign to reduce the vehicle interior noise, however, FE analyses in those frequency ranges are usually inaccurate. To overcome this difficulty, a guide for using experimental data instead of finite analysis results was studied. Formulations for the sensitivity of FRFs and harmonic responses are derived, and a structure-acoustic coupling analysis in modal domain was done to cure the structure-bone noise problem. Also, a technique for determining the proper modification positions or regions for reducing the interior noise level is suggested and tested both numerically and experimentally with a 1/2 scale vehicle model.

The goal of this study was to determine the dynamic stress level on the operating crankshaft of a four cylinder automotive engine by direct measurement of acting torsional and bending stresses as varying the rpm and the engine load. The signals obtained are qualitatively compared with the stresses from a theoretical force analysis. It was found that the measured torsional stress is in good agreement with the stress computed due to cylinder pressure and rotating inertia. On the other hand, the bending stress is dominated by the effect of the cylinder pressure and attains its maximum value near 4250 rpm where one of the superharmonics of the rotation speed coincides with the torsional natural frequency.