Abstract. In order to compare the performance of heavy truck suspension system, a 3D dynamic model with 14 degrees of freedom is developed with the dynamic models of the traditional and new air suspension systems to compare the performance of the air suspension systems for reducing the negative impacts on the road surface when vehicle moves on the different road conditions. Dynamic modes of two different types of the air suspension systems are respectively established and a dynamic load coefficient (DLC) is chosen as objective function which uses Matlab/Simulink software to simulate and determine the values of objective function. The results shown that the performance of the new air suspension system is better than the tradition air suspension for reducing the negative impact on road surface under the different operating conditions of vehicle. Especially, the DLC values of wheels at 3rd axle of vehicle with the new air suspension system are respectively reduced by 6.7 %, 7.0 %, 7.4 %, 7.7 % and 8.5 % in comparison with the traditional air suspension system when vehicle moves on the different pavement conditions a velocity of 20 m/s and fully loaded. In addition, the study results not only can provide a reference for designers but also traffic management to reduce the negative impact on road surface.
In order to improve the vibratory roller ride comfort, a multi-objective optimization method based on the improved genetic algorithm NSGA-II is proposed to optimize the design parameters of cab’s isolation system when vehicle operates under the different conditions. To achieve this goal, 3D nonlinear dynamic model of a single drum vibratory roller was developed based on the analysis of the interaction between vibratory roller and soil. The weighted r.m.s acceleration responses of the vertical driver’s seat, pitch and roll angle of the cab are chosen as the objective functions. The optimal design parameters of cab’s isolation system are indentified based on a combination of the vehicle nonlinear dynamic model of Matlab/Simulink and the NSGA - II genetic algorithm method. The results indicate that three objective function values are reduced significantly to improve vehicle ride comfort.
In order to evaluate the performance of heavy truck's semi-active isolation systems, a half-vehicle dynamic model with three control cases including the seat controlled, the cab controlled, and the vehicle controlled is respectively established. Matlab/Simulink software and the fuzzy logic controller (FLC) are applied to simulate and control the semi-active isolation systems of the heavy truck under two types of step and random road surfaces. The weighted root-mean-square acceleration responses and the acceleration responses of the vertical driver's seat and the cab's pitch angle are chosen as the objective functions. The research results show that the vehicle's ride comfort is significantly improved by three control cases. Especially, in two simulation studies, the vertical driver's seat vibration and the cab shake are greatly decreased by using the cab controlled. Therefore, the cab controlled surpasses the other types of control for improving the driver's ride comfort and controlling the cab shake.
Using an irreducible design we experimentally and numerically study a perfect metamaterial absorber, providing excellent absorption at microwave frequencies. The impact of geometric parameters on the absorption is also investigated. The experimental and the simulated results are in good agreement. Finally, we propose a polarization-insensitive absorber for the improvement.
This paper presents a theoretical investigation into the response of the coupled system which consists of a regular or irregular enclosure with different excitation, including noise reduction level and panel vibration energy level. The results show that the noise reduction level curves appear changes in medium and high frequency region when the enclosure change from regular rectangular to irregular trapezoidal, but there is small variation in panel vibration energy. Compared with the incident plane wave perpendicular to the flexible wall, more panel modes are excited by the oblique plane wave, and it means that more noise go through the flexible wall into the enclosure.
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