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Events 18 July 2020 By Raminelli

Shaking table with magnetorheological damper

João Guilherme Raminelli

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This page presents the device constructed at UTFPR to help us advance the knowledge of structural engineering. It is a shaking table connected to a magnetorheological (MR) damper. On one side of the table, we connected the actuator; on the opposite side of the table, we connected the MR damper. We carried out experiments for the shaking table with the MR damper.

Shaking table connected to a magnetorheological (MR) damper. It will help us understand some aspects of structural engineering. For instance: What are the effects of earthquakes in real-time buildings? We are looking for an answer to this question.

This work aims to generate a mathematical model capable of describing the nonlinear, hysteretic behavior of the damper. After, we use this model in a small-scale building subject to quick movements, aiming to emulate earthquakes in real-time buildings. What are the effects of earthquakes in real-time buildings? We are looking for an answer to this question.

For MR dampers, the damping and stiffness properties can be modified by a control signal. But controlling MR dampers is difficult because many of them use magneto-rheological fluids that have hysteretic behavior. Hysteresis is a nonlinear behavior in which the input and output show memory effects, so it is necessary to account hysteresis in the control formulation of shock absorbers.

Example figure produced with this method.
Figure 1: Data measured from the equipment.

A laboratory testbed was assembled. Its function is to excite the damper with different combinations of displacement and frequency, and an electronic circuitry was responsible for measuring and recording the corresponding data. The goal was to generate data that allow us to calculate the parameters of the model. Data from the model was compared to data from the physical system, see the figure.

Using the model, we will study the model of a two-story building subject to an earthquake signal. We want to check the building's behavior in three different scenarios.

First scenario: the structure will be detached from the MR damper. Second scenario: the structure will be linked to the shaking table, but no voltage will be applied in the MR damper. Third scenario: it is equal to the second, but the voltage will be applied in the terminals of the damper.