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The main purpose of this research is to reduce the transmitted engine vibration to the subframe structure via improving the mobility of engine mountings. In fact, the main focus is on the geometry optimization of the subframe part, implementing the design of experiments method, to increase the dynamic stiffness of the part to reduce the vibration transfer function in the mountings location. In order to perform the optimization process, the front end model of the reference vehicle including the suspension, steering system, engine and deriveline system is generated in FE software. According to the prevalent guidelines, the mobility of engine mountings should be greater than target value which is usually obtained through benchmarking. To do so, some structural parameters that are apt to influence on the mobility function, e.g the section of subframe, thickness of subframe and vehicle body are selected as design variables for doing the design of experiments analysis.

Improvements of aerodynamics and wind noise are two important objectives for automotive engineers. Improvement of aerodynamics behavior and the reduction of wind noise have been always greatly concerned by automotive engineers since they negatively affect passengers comfort, fuel consumption, car performance and, stability. In this paper, optimum levels of four dominant rear shape parameters for a simplified car model are investigated considering drag coefficient and aerodynamic noise objectives. C-Pillar angle, trunk angle, boat tail angle and rear box length are considered as variable parameters. Taguchi method is used for finding aerodynamic and acoustic optimum levels. Numerical simulation for base case is compared with experimental results in the literature. Numerical results show good agreement with experimental test. Afterwards, optimum levels for parameters regarding objectives are calculated using Taguchi method.

Nowadays, by the introduction of significant advances in automotive industries, noise, vibration and harshness (NVH), in the position of the main comfort attribute, plays a crucial role in marketing and passenger satisfaction. In order to cope NVH problems, three main actions are taken by NVH engineers for reducing perceived level of noise in cabin: Noise reduction in sources, Noise path treatment and Noise control at receiver. Among these approaches, those pertain to modification of noise pass, through structure and air, to the cabin are more prevalent in automotive applications. Accordingly, identification of noise paths that dominantly contribute to sound and vibration transfer to cabin phenomenon should be dealt with importance. In practice, engine vibration transmitted through sub-frame attachments to body can induce high level of noise and vibration to the passenger cabin.