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The result of rib stiffening is the redistribution of natural frequencies and mode shapes of the plate, which can significantly alter its noise and vibration character. In this paper, genetic algorithms are used as a promising tool for sound radiation minimization problems. The objective of the study is to determine effective, general design methods for determining the optimal dimensions of the stamped rib in a plate to minimize the total radiated acoustic power. Acoustic response under broad-band excitation is considered. Radiated sound power is calculated using a boundary element method, in conjunction with a finite element solver for the solution of the structural problem.

Three constitutive models which capture the amplitude and frequency dependency of filled elastomers are implemented for the conventional engine mounts of automotive powertrain mounting system (PMS). Firstly, a multibody dynamic model of a light duty truck is proposed, which includes 6 degrees of freedom (DOFs) for the PMS. Secondly, Three constitutive models for filled elastomers are implemented for the engine mounts of the PMS, including: (1) Model 1: Kelvin-Voigt model; (2) Model 2: Fractional derivative Kelvin-Voigt model combined with Berg’s friction; (3) Model 3: Generalized elastic viscoelastic elastoplastic model. The nonlinear behaviors of dynamic stiffness and damping of the mounts are investigated. Thirdly, simulations of engine vibration dynamics are presented and compared with these models and the differences between common Kelvin-Voigt model and other constitutive models are observed and analyzed.

Steering returnability is an important index for evaluating vehicle handling performance. A systematic method is presented in this paper to reduce the high yaw rate residue and the steering response time for a light duty truck in the steering return test. The vehicle multibody model is established in ADAMS, which takes into consideration of the frictional loss torque and hydraulically assisted steering property in the steering mechanism, since the friction, which exists in steering column, spherical joint, steering universal joint, and steering gear, plays an important role in vehicle returnability performance. The accuracy of the vehicle model is validated by road test and the key parameters are determined by executing the sensitivity analysis, which shows the effect of each design parameter upon returnability performance.

The sewing machine has been widely used in various aspects of life and it is essential to study its kinematic and dynamic characteristics. A dynamic model of flexible multi-link mechanism for sewing machine including joints with clearance is established to analysis its dynamic response in the present work. The configuration of the sewing machine mainly included five subsystems, feeding mechanism, needle bar mechanism, looper mechanism, shearing mechanism and adjusting mechanism. Since the sewing machine mainly consist of linkage mechanisms that are connected by revolute joints and translational joints, the existence of clearances in the joints and the flexibility of crankshafts and linkage are important factors that affect the dynamic performance. Even little clearance can lead to vibration and fatigue phenomena, lack of precision or even make overall behavior as random.

Electric vehicles driven by in-wheel-motor have the advantages of compact structure and high transmission efficiency, which is one of the most ideal energy-saving, environmentally friendly, and safe driving forms in the future. However, the addition of the in-wheel-motor significantly increases the unsprung mass of the vehicle, resulting in a decrease in the mass ratio of the vehicle body to the wheel, which will deteriorate the ride comfort and safety of the vehicle. To improve the vibration performance of in-wheel-motor driven vehicles, a semi-active inerter-spring-damper (ISD) suspension with in-wheel-motor (IWM) dynamic vibration absorber (DVA) of the electric wheel is proposed in this paper. Firstly, a structure of in-wheel-motor DVA is proposed, which converts the motor into a dynamic vibration absorber of the wheel to suppress the vibration of the unsprung mass.

Free vibration of the blades of one radial-flow turbocharger is analyzed by the finite element method, and the natural frequencies and modes are obtained, the numerical results are in good agreement with the experimental ones. Resonant vibration of the compressor blade and turbine blade is analyzed respectively, then the resonance interference analysis of the blades is presented, the resonance occurrence probabilities of the blades at the rotating operation speed of the turbocharger is obtained, finally the working reliability of the blades is evaluated.

Increased focus on vehicle comfort and ride has led the automotive industry to look into low vibration, noise and hardness alternative designs for powertrain system components. In this paper, the vibration theory and dynamic vibration absorber (DVA) theory is presented. The modal analysis of propeller shaft assembly has been accomplished. Based on dynamic vibration absorber principle, performance parameters of dynamic vibration absorber are matched and structure is also designed. LMS equipment is applied to verify the natural frequency of absorber samples. The matching of stiffness and damping of DVA is presented. The dynamic response of drive shaft system based on the mass ratio of DVA is researched in this paper. Results from simulations and tests indicates that the amplitude of propeller shaft resonance can be effectively reduced by attaching a DVA to the long propeller shaft.

The imbalance of propeller shaft is an excitation to the vehicle structure and causes noise and vibration. This paper presents an experimental study of effects of propeller shaft imbalance on vehicle vibration characteristics. A two-piece propeller shaft with unbalance is used in real vehicle test. The vehicle vibration is characterized by accelerations of the cabin floor and of the bearing which supports the propeller shaft. Through the experiment, some interesting phenomena are observed.