This paper presents the performance of a new magnetorheological elastomer-based semi-active/passive variable stiffness and damping isolator (VSDI) in a scaled building system. The force of the VSDI can be controlled in real time by varying the applied magnetic field. To demonstrate the performance of the VSDI, four prototypes are built and utilized in a scaled three-story building. A Lyapunov-based control strategy is employed and it is demonstrated that it works well for the scaled building system under the scaled El Centro earthquake motion. Experimental results show that the VSDIs significantly reduce the acceleration and relative displacement of the building floors.

https://iopscience.iop.org/article/10.1088/0964-1726/23/4/045014/pdf

Performance of a new magnetorheological elastomer isolation system

https://iopscience.iop.org/article/10.1088/1361-665X/aa549c/pdf

Modeling of magneto-mechanical response of magnetorheological elastomers (MRE) and MRE-based systems: a review

This paper presents a conceptual adaptive tunable vibration absorber (ATVA) with soft magnetorheological elastomers (MREs) for vibration reduction of vehicle powertrain systems. The MRE material used in this application has a rubbery silicone polymer matrix and ferrous fillers in a fraction of 27.6% by volume. For such a soft MRE the elastic modulus significantly increases due to the MR effect. Thus, the ATVA can work effectively in a wide frequency range (the increase in frequency is more than ten times) instead of a narrow bandwidth as a conventional dynamic absorber does. Numerical simulations of a powertrain fitted with the ATVA are used to validate its effectiveness. The obtained results show that the powertrain vibration can be significantly suppressed. This novel ATVA will be applicable to the vibration reduction of powertrains.

https://iopscience.iop.org/article/10.1088/0964-1726/18/7/074009/pdf

A dynamic absorber with a soft magnetorheological elastomer for powertrain vibration suppression

A nonlinear and fractional derivative viscoelastic model for rail pads in the dynamic analysis of coupled vehicle-slab track systems

During the transient stage of acceleration, the powertrain experiences a period of high level vibration because the engine speed passes through one or several powertrain natural frequencies. This paper presents a concept design of an adaptive tuned vibration absorber (ATVA) using a new magnetorheological elastomer (MRE) for powertrain transient vibration reduction. The MRE material used to develop the ATVA is a new one, which is synthesized from a highly elastic polymer and carbonyl iron particles of 3–5 and 40–50 µm. Under a magnetic field of 0.3 T, the MRE material has a giant increase, which is more than two orders, in both the storage and loss moduli. To facilitate the ATVA design, effective formulae for the storage modulus and loss factor were derived as explicit functions of the applied magnetic field density. With the derived formulae, ATVA parameters such as the stiffness and damping coefficients were converted effectively from the magnetic field density. Thus, the ATVA frequency can be tuned properly according to the excitation frequency. Numerical simulations of a powertrain system fitted with the ATVA were conducted to examine the ATVA proposed design. By using the MRE-based ATVA, the powertrain natural frequencies can be actively tuned far away from the resonant area of excitation frequency. Also, the time histories of powertrain frequencies depending on the magnetic field density before and after installing the ATVA have been compared to show that the resonant phenomena have been dealt with completely. As a result, the powertrain transient vibration response is significantly suppressed. In addition, the effect of the ATVA's moment of inertia, stiffness and damping on the ATVA's effectiveness during the transient stage was investigated to choose the ATVA's optimal parameters. The MRE-based ATVA will be a novel device for powertrain vibration control not only for the steady stage but also for transient vibration.

http://iopscience.iop.org/article/10.1088/0964-1726/20/1/015019/pdf

An adaptive tunable vibration absorber using a new magnetorheological elastomer for vehicular powertrain transient vibration reduction

A simplified methodology to predict the dynamic stiffness of carbon-black filled rubber isolators using a finite element code

A nonlinear rubber material model is presented, where influences of frequency and dynamic amplitude are taken into account through fractional order viscoelasticity and plasticity, respectively The problem of simultaneously modeling elastic, viscoelastic, and friction contributions is removed by additively splitting them Due to the fractional order representation mainly, the number of parameters of the model remains low, rendering an easy fitting of the values from tests on material samples The proposed model is implemented in a general-purpose finite element (FE) code Since commercial FE codes do not contain any suitable constitutive model that represents the full dynamic behavior of rubber compounds (including frequency and amplitude dependent effects), a simple approach is used based on the idea of adding stress contributions from simple constitutive models: a mesh overlay technique, whose basic idea is to create a different FE model for each material definition (fractional derivative viscoelastic and elastoplastic), all with identical meshes but with different material definition, and sharing the same nodes Fractional-derivative viscoelasticity is implemented through user routines and the algorithm for that purpose is described, while available von Mises' elastoplastic models are adopted to take rate-independent effects into account Satisfactory results are obtained when comparing the model results with tests carried out in two rubber bushings at a frequency range up to 500 Hz, showing the ability of the material model to accurately describe the complex dynamic behavior of carbon-black filled rubber compounds

A Nonlinear Rubber Material Model Combining Fractional Order Viscoelasticity and Amplitude Dependent Effects

Frequency and amplitude dependence of the axial and radial stiffness of carbon-black filled rubber bushings

An engineering design formula for the torsion stiffness of a filled rubber bushing in the frequency domain, including the amplitude dependence, is presented. It is developed by applying a novel sep ...

Torsion stiffness of a rubber bushing : a simple engineering design formula including amplitude dependence

A novel and promising approach for the prediction of the dynamic stiffness of hydrobushings is presented, combining Finite Element and CFD methods. The rubber structure of the mount is modelled in ABAQUS and the flow of fluid through the inertia track is calculated in FLUENT. The obtained results from the latter simulation are incorporated in the finite element code for the final stiffness prediction. The calculation is very sensitive to both rubber and fluid properties. The dynamic behaviour of rubber material has accurately been characterised with a new simple shear specimen in a forced non-resonant test. Satisfactory results are obtained when comparing numerical simulations to experimental tests in a practical application. Discrepancies between simulations and tests are mainly due to the simplifications assumed when creating the model. Nevertheless, stiffness of the mount is well predicted and so is the damping, although the frequency at which its maximum value is achieved is underestimated by 4-6 Hz, result that could be improved if non-stationary boundary conditions were considered when solving the fluid flow and incorporating it to the finite element code.

/pdf/predicting-the-dynamic-behaviour-of-hydrobushings-14o0o5bjvp.pdf

N. Gil-Negrete

Papers

A simplified methodology to predict the dynamic stiffness of carbon-black filled rubber isolators using a finite element code

A Nonlinear Rubber Material Model Combining Fractional Order Viscoelasticity and Amplitude Dependent Effects

Frequency and amplitude dependence of the axial and radial stiffness of carbon-black filled rubber bushings

Torsion stiffness of a rubber bushing : a simple engineering design formula including amplitude dependence

Predicting the dynamic behaviour of hydrobushings