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This paper analyzes the performance of three different semi-active control algorithms used to calculate and manage the optimal damping forces generated by a pair of magnetorheological (MR) dampers installed in a two-story building. The semi-active algorithms used are the linear quadratic regulator (LQR) associated with the clipped optimal algorithm, an algorithm based on a prediction model and a dynamic inverse model using nonlinear autoregressive exogenous (NARX)-type artificial neural networks, and a decision-making algorithm based on fuzzy logic. Additionally, the performances of the proposed semi-active algorithms are compared to those of passively used control devices. The results show response value reductions exceeding 50% for all the semi-active control strategies, which considerably outperformed the passive control. The three control strategies are thus confirmed as interesting tools with potential applications as MR damper administrators. [ABSTRACT FROM AUTHOR]

Successful implementation of an active vibration control system is strictly correlated to the exact knowledge of the dynamic behavior of the system, of the excitation level and spectra and of the sensor and actuator's specification. Only the correct management of these aspects may guarantee the correct choice of the control strategy and the relative performance. Within this paper, some preliminary activities aimed at the creation of a structurally simple, cheap and easily replaceable active control systems for metal panels are discussed. The final future aim is to control and to reduce noise, produced by vibrations of metal panels of the body of a car. The paper is focused on two points. The first one is the realization of an electronic circuit for Synchronized Shunted Switch Architecture (SSSA) with the right dimensioning of the components to control the proposed test article, represented by a rectangular aluminum plate. The second one is a preliminary experimental study on the test article, in controlled laboratory conditions, to compare performances of two possible control approach: SSSA and a feed-forward control approach. This comparison would contribute to the future choice of the most suitable control architecture for the specific attenuation of structure-born noise related to an automotive floor structure under deterministic (engine and road-tyre interaction) and stochastic (road-tyre interaction and aerodynamic) forcing actions. [ABSTRACT FROM AUTHOR]

A numerical procedure to predict vibration and acoustic noise due to electromagnetic excitation forces in an axial flux motor (AFM) is presented and applied to a motor with ferrite magnets for electric vehicles. The methodology includes the calculation of radial magnetic forces exerted on stator inner surfaces using electromagnetic solver to account for vibration and noise of the motor. Fundamental and high-order harmonics of the magnetic forces are then obtained via fast Fourier transform process. Structural analyses such as modal and harmonic analysis are conducted to investigate natural resonant frequencies of the motor system and modal shapes highly responsible for vibration of the frame and acoustic noise. Magnitudes of vibration displacement on the motor housing surface and sound pressure level at a given point in the space are predicted using harmonic and acoustic analyses, respectively. Motor performance tests were conducted to validate the model, and the results showed that the model predictions agree well with the observations from the experiments. [ABSTRACT FROM PUBLISHER]

The estimation and calculation of the acoustic sound of electric machinery is of high interest. Various approaches have been presented relying either on analytical or on numerical models. In general, the analytical models are based on the electromagnetic-field theory, and the results are compared to measurements. Numerical models allow for the separation of different exciting forces stemming from various effects. In the studied case of an induction machine (IM) with squirrel-cage rotor the three following effects are taken into account in the analytical model: the fundamental field, saturation, and eccentricity. Nevertheless, the numerical results have to be verified. Hence, they are compared to the physically based analytical results. The radiated noise depends directly on the surface's deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibrations. The combined analysis presented here, allows for the reduction of vibrations and noise optimizing the coupling of stator and housing. The studied IM's housing is mounted with six spiral-steel springs to the stator. With the presented method the impact of different numbers of pins is analyzed. [ABSTRACT FROM AUTHOR]

The estimation and the calculation of the acoustic sound of electric machinery are of particular interest nowadays. Various approaches have been presented, relying either on analytical or on numerical models. The analytical models presented here are based on the electromagnetic-field theory. Numerical models are applied to derive the exciting forces stemming from various sources and effects. The numerical results have to be verified. Hence, they are compared with the physically based analytical results. The radiated noise depends directly on the surface deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibration. The combined analysis presented here allows for the reduction of vibration and noise, optimizing the coupling of the machine's stator and housing. The studied induction machine's housing is mounted with six spiral-steel springs to the stator. With the presented method, the impact of different numbers of springs is analyzed exemplarily. [ABSTRACT FROM AUTHOR]

For calculating the stiffness function of a structure, the differential equation of the vibration of the structure was divided into the differential equation on the original stiffness function that was known, and Fredholm integral equation of the first kind on the undetermined stiffness function that was unknown. And the stable solutions of the integral equation, when the smooth factor was equal to zero, was solved by the extrapolation with p smooth factors. So the stiffness function of the structure is obtained. Applied examples show that the method is feasible and effective. [ABSTRACT FROM AUTHOR]