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In this paper, utilizing Herschel-Bulkley model, the equation of MR fluid pressure gradient is derived in order to predict MR damper’s force-velocity behavior. The equation, showing as a complicated nonlinear algebraic expression including various parameters, is then simplified to a nondimensional equation. This is followed by the analysis of the root of this nondimensional equation and an approximate root closely corresponding to numerical result is given.

Abstract. Two de-noising methods, named as the averaging method in Gabor transform domain (AMGTD) and the adaptive filtering method in Gabor transform domain (AFMGTD), are presented in this paper. These two methods are established based on the correlativity of the source signals and the background noise in time domain and Gabor transform domain, that is to say, the uncorrelated source signals and background noise in time domain would still be uncorrelated in Gabor transform domain. The construction and computation scheme of these two methods are investigated. The de-noising performances are illustrated by some simulation signals, and the wavelet transform is used to compare with these two new de-noising methods. The results show that these two methods have better de-noising performance than the wavelet transform, and could reduce the background noise in the vibration signal more effectively.

Abstract. This research aims at the vibration control of vehicle seat suspension system. A three degree of freedom quarter vehicle model is used for semi-active control system in which a magnetorheological damper (MRD) is installed at the position between the vehicle body and the seat. A fully active linear quadratic regulator (LQR) control strategy is used to determine the optimized control force which is then matched by MRD to compute the semi-active control result. Computation result proves that semi-active control with MRD can alleviate the vehicle seat acceleration to improve ride comfort. IntroductionThere are three types of vehicle suspension systems, namely passive control suspension system, active control suspension system, and semi-active control suspension system [1]. In passive suspension system, the stiffness and damping parameters are fixed and are effective over a certain range of frequencies. In active suspension system, an actuator is used to supply adapting force to adapt to changing road conditions. High cost, complexity, need for an external energy source and difficulty in control hardware implementation restrict the development of active suspension system. The semi-active control suspension system is an alternative to the active suspension system and can combine the advantages of both passive and active suspension systems. In semi-active control suspension system, MRD whose damping force can be easy adjusted by changing magnetic fields have been considered by a number of researchers [2][3][4][5].In this paper, A three degree of freedom quarter vehicle model in which the damping force between the seat and vehicle body is supplied by a MRD is used to calculate the control effect of a semi-active seat suspension system. In this semi-active seat suspension system, the optimized control force is determined by a fully active linear quadratic regulator (LQR) control strategy and the actual damping force the MRD can realized.

To accurately analyze the force and deformation of the transmission tower, it is necessary to study performance of bolted joint in the tower. In the paper single shear and double shear bolted joint with number of bolts changed is tested. Based on the actual data in test, nonlinear finite element model of bolted joint is established with ABAQUS, considering the bolt clearance and preload, and shows good agreement with test results, which is proved correct and applicable. Eventually, through a comparison of FEM and test results, the factors that affect bolt slip and the changing relationship of axial force of bolt and friction force is described.