Papers by Keyword: Isolator

Abstract: The purpose of this research is to develop a vibration isolator using auxetic viscoelastic sheet technology. The procedure for the design and elaboration of the insulator using polymers and by means of fatigue analysis using impacts is exposed, the absorption of energy by cycles is compared and the damage that is produced in the viscoelastic is observed with an optical microscope. This is to compare the variation in the force that the fatigue equipment exerts to deform the sheet in the same magnitude and to be able to establish, through the ratio of absorbed energy and returned energy, criteria on the useful life of the element for future designs.

Abstract: It is proposed to apply a composite sheet of viscoelastic material encapsulated in ABS plastic to be used in the design of a prototype of vibration isolator in the use of motor bases. The cyclical impact tests presented are carried out with an insulator unit named as a viscoelastic sheet that takes advantage of Hooke's law 3D. Using a vibrating equipment, reproductions of impacts are made to study the ability of the vibration isolator to resist impacts and evaluate its useful life. Through the analysis of force and variation in the response to its natural frequency of vibration, the evaluations and its behavior to the tests are established, and its change to a passive type of isolator. The evolution of the damage in the viscoelastic and the appearance of cracks is also shown.

Abstract: The paper presents the model of a seismic mass with viscoelastic linear connections, following the Voigt-Kelvin model, with the fundamental unidirectional harmonic kinematic excitation of an earthquake. The motion is caused by seismic action. Thus, the parameters and the motion laws of the mass, the inertial force and the force transmitted to the fixed base are determined. Also, the relations for the amplitude and the transmissibility of the motion are established in function of the elastic and viscous parameters of the composed model Voigt-Kelvin.Based on the established relations the dissipated energy function of the acceleration of the earthquake and of the dominant pulsation and the viscoelastic characteristics are determined.

Abstract: Magnetorheological elastomer (MRE) is a controllable smart material that demonstrates changes in rheological properties depending on the magnetic field strength. This paper presents thedevelopment of a new concept of MRE isolator in terms of design and magnetic simulation. All features of geometry parameters were considered and altered expeditiously in order to provide ample and uniform magnetic field. Finite Element Method Magnetics (FEMM) was used to design the electromagnetic circuit to generate magnetic fluxes penetrate through the MRE. The study, eventually, leads to the conclusion of different design parameters approach; selection of materials, diameter of the shaft, shape of MRE, length of shaft and thickness of housing.

Abstract: A novel tunable stiffness and damping vibration isolator based on magnetorheological nanocomposites filled with carbon nanotubes (CNMRE) was proposed. The stiffness and damping is controlled by the current applied to the magnetic excitation coil. Under the combined ON–OFF control law, the proposed vibration isolator shows satisfying isolation effect. The simulation results indicate that, in comparison to MRE isolator with ON–OFF stiffness and damping control, CNMRE isolator with ON–OFF control not only has high stiffness and damping capacity, corrosion resistance, and high failure strength which are demanded in industries, but also significantly suppresses vibration under sinusoid excitation, random excitation, and pulse excitation. The proposed vibration isolator is very simple and easy to be applied in practical system.

Abstract: The combined variable stiffness and damping on-off control strategy is investigated using a magnetorheological elastomer (MRE) isolator. A one-degree-of-freedom system has been adopted to assess the efficiency of different control strategies under sinusoidal and random and pulse excitations. The obtained results illustrate that a single tunable stiffness control with maximal damping values under both excitations can simultaneously performs better control of displacement than using minimal damping if the relative displacement and relative velocity of load are in contrary directions . Moreover, on-off variable stiffness control plays a more important role than damping control, therefore it is feasible to only control magnetic field to change MRE elastic and damping property for simplicity.

Abstract: In order to attenuate the deformation of spray boom, a finite element model built based on ANSYS, according to the reasults of numerical modal analysis and modal texting, the reliability of the finite element model was affirmed. Then, an isolator was introduced between spray boom and frame, a frame-isolator-spray boom model was built in ADAMS. The effect of the isolators which have different parameters was research, the reasult shows: The isolator has much effect on attenuating spray booms deformation, the stiffness of isolators spring dampers has little effect on spray booms deformation, but the damping of isolators spring dampers has effect on spray booms deformation.

Abstract: Mounting machinery by isolators can reduce vibration transmitted to the base and attenuated environmental noise. In this paper the machine having cylindrical shell such as electric motors is modeled by thin-wall cylindrical shell motion equation. The reaction force exerted by isolator is considered as point force and integrated in the shell equation. The typical vibration excitation of machinery is represented by point and line excitations. The forces transmitted to the base through isolators are then calculated under different excitations. Conclusions with respect to machinery and isolation system design are presented based on numerical results.

Abstract: Through the analysis and comparison of the results of static and dynamic performance testing of a series of laminated steel pieces isolators used in the vibration isolation of warships, in the number and thickness of laminated steel pieces of the same circumstances, laminated steel arc and preload of test samples had a certain impact on the values ​​of static stiffness, dynamic stiffness, damping ratio as well as dynamic and static stiffness ratio.

Abstract: Magnetorheological (MR) elastomers are a new type of MR material. At present, most studies in this field are at laboratory stage, and practicability was rarely considered preparation of MR elastomer materials. Consequently, the existing materials with low overall properties cannot be applied in engineering. In this paper, the performance requirements for MR elastomers to be used in isolators were proposed. Then a type of practical MR elastomers for isolators was prepared, and its mechanical performance and MR effect were tested. The results show that the designed MR elastomers have high mechanical performance and high MR effect, and thus can be used in isolators.