Parametric identification of viscous damping models in the context of linear vibration theory is studied. Frequency domain identification methods based on measured frequency response functions (FRFs) are considered. Existing methods are classified into two main groups: matrix methods which use directly the measured FRF matrix, and modal methods which use modal parameters deduced from the FRFs. ...

A method for electromagnetic shunt damping (EMSD) will be presented in this paper. Compared to piezoelectric shunt damping, the proposed EMSD vibration controller has a number of bene ts. It requires small shunt voltages, can provide large stroke and can dampen larger mechanical structures. A passive control strategy is validated through experimentation on a simple electromagnetic mass-spring-d...

To improve the stability of the magnet-girder assemblies in the ESRF storage ring, vibration investigations have been carried out for in situ magnet-girder assemblies and a prototype. Characterisation tests were performed : operating response measurements, static stiffness measurements, modal testing. A finite element modelling (FEM) is being carried out for the prototype assembly. First result...

We consider a model for the vibration of a beamwith a damping tip body that appeared in a previous article. In this paper we derive a variational form for the motion of the beam and use it to prove that the model problem has a unique solution. The proofs are based on existence results for a general linear vibration model problem, in variational form. Finite element approximation of the solution...

Abstract: We consider the solvability of a hybrid model for the vibration of a vertical slender structure mounted on an elastic seating. The slender structure is modeled as a Rayleigh beam and gravity is taken into account. The seating and foundation block are modeled as rigid bodies connected by elastic springs with damping mechanisms. We show how an existence result for a general linear vibra...

An important environmental aspect of building and facility design is the evaluation of vibration transmitted to the site, through the ground, from external sources. Such external sources may include highway traffic, surface and subsurface railways, and machinery in nearby locations. To properly predict excitation levels at a building due to such sources, one must be able to predict how much vib...

Minimizing the modal vibration induced by on-off thrusters is a challenging problem for designers of flexible spacecraft. This thesis presents the first study of PulseWidth, Pulse-Frequency (PWPF) modulated thruster control using the method of command input shaping. Input shaping for systems with linear actuators has been successfully developed to reduce modal vibrations. Recently, this method ...

The whole body vibration from the seat and foot board was measured during ten years from 11 different snowmobiles to evaluate the exposure and the need for technical improvements. In a questionnaire more than half of the drivers had back pains but only a few of them considered the whole body vibration as a health hazard. However in the literature there is often comments on spinal injuries relat...

A defective vibration system is a special linear vibration system which can not be completely uncoupled by linear transformation. Previous studies have shown that the modal models of defcctiw vibration systems are determined by modal parameters (modal frequencies, damping ratios and mode shape vectors), as well as the structural matrices of the vibration systems. So the whole identification of ...

79 L~ST OF ILLUSTRATIONS 1. Elastic Hysteresis 2. Overdamped Vibration 3. Critically Damped Vibration 4. Underdamped Vibration 5. Optimum Damping Factor for Specified Error 6. Free Gyroscope 7. Inclined Plane 8. Sliding Shoe 9. Kingsbury Thrust :Bearing 10. Circular Pad Air :Bearing 11. Cylindrical Pad 12. Oil-Ring-Bearing 13. Lo\-T Friction Ball :Bearing 14. Low Friction Roller Bearing 15. Sec...