The magnetorheological-fluid dampers are shock-absorbing devices containing a liquid that becomes far more viscous when a magnetic field is applied.
Earthquake-engineering researches at the Harbin Institute of Technology in China work to set up a structure on a shake table for experiments to study the effects of earthquakes. Purdue University civil engineering students are working with counterparts at the institute to study the reliability of models for testing a type of powerful damping system that might be installed in buildings and bridges to reduce structural damage and injuries during earthquakes. (Photo courtesy of Harbin Institute of Technology)
"It normally feels like a thick fluid, but when you apply a magnetic field it transforms into a peanut-butter consistency, which makes it generate larger forces when pushed through a small orifice," said Shirley Dyke, a professor of mechanical engineering and civil engineering at Purdue University.
This dramatic increase in viscosity enables the devices to exert powerful forces and to modify a building's stiffness in response to motion during an earthquake. The magnetorheological-fluid dampers, or MR dampers, have seen limited commercial use and are not yet being used routinely in structures.
Research led by Dyke and doctoral students Gaby Ou and Ali Ozdagli has now shown real-time hybrid simulations are reliable in studying the dampers. The research is affiliated with the National Science Foundation's George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES), a shared network of laboratories based at Purdue.
Dyke and her students are working with researchers at the Harbin Institute of Technology in China, home to one of only a few large-scale shake-table facilities in the world.
Findings will be discussed during the NEES Quake Summit 2013 on Aug. 7-8 in Reno. A research paper also was presented in May during a meeting in Italy related to a consortium called SERIES (Seismic Engineering Research Infrastructures for European Synergies). The paper was authored by Ou, Dyke, Ozdagli, and researchers Bin Wu and Bo Li from the Harbin Institute.
"The results indicate that the real-time hybrid simulation concept can be considered as a reliable and efficient testing method," Ou said.
The simulations are referred to as hybrid because they combine computational models with data from physical tests.
"You have physical models and computational models being combined for one test," Dyke said.
Researchers are able to perform structural tests at slow speed, but testing in real-time – or the actual speed of an earthquake – sheds new light on how the MR dampers perform in structures. The real-time ability has only recently become feasible due to technological advances in computing.
"Sometimes real-time testing is necessary, and that's where we focus our efforts," said Dyke, who organized a workshop on the subject to be held during the NEES meeting in Reno. "This hybrid approach is taking off lately. People are getting very excited about it."
Ozdagli also is presenting related findings next week during the 2013 Conference of the ASCE Engineering Mechanics Institute in Evanston, Ill.
The simulations can be performed in conjunction with research using full-scale building tests. However, there are very few large-scale facilities in the world, and the testing is time-consuming and expensive.
"The real-time hybrid simulations allow you to do many tests to prepare for the one test using a full-scale facility," Dyke said. "The nice thing is that you can change the numerical model any way you want. You can make it a four-story structure one day and the next day it's a 10-story structure. You can test an unlimited number of cases with a single physical setup."
The researchers will present two abstracts during the Reno meeting. One focuses on how the simulation method has been improved and the other describes the overall validation of real-time hybrid simulations.
To prove the reliability of the approach the researchers are comparing pure computational models, pure physical shake-table tests and then the real-time hybrid simulation. Research results from this three-way comparison are demonstrating that the hybrid simulations are accurate.
Ou has developed a mathematical approach to cancel out "noise" that makes it difficult to use testing data. She combined mathematical tools for a new "integrated control strategy" for the hybrid simulation.
"She found that by integrating several techniques in the right mix you can get better performance than in prior tests," Dyke said.
The researchers have validated the simulations.
"It's a viable method that can be used by other researchers for many different purposes and in many different laboratories," Dyke said.
Much of the research is based at Purdue's Robert L. and Terry L. Bowen Laboratory for Large-Scale Civil Engineering Research and has been funded by the NSF through NEES. A portion is supported by the Sohmen Fund, an endowment established by Purdue alumnus Anna Pao Sohmen to facilitate faculty and student exchange with the Harbin Institute of Technology and Ningbo University. The fund is managed by International Programs at Purdue.
Writer: Emil Venere, (765) 494-4709, firstname.lastname@example.org
Source: Shirley Dyke, 765-494-7434, email@example.com
Note to Journalists: Information about the NEES annual Quake Summit 2013 is available at http://nees.org/quakesummit2013. An electronic copy of the SERIES research paper is available from Emil Venere, 765-494-4709, firstname.lastname@example.org
Emil Venere | EurekAlert!
Smart buildings through innovative membrane roofs and façades
31.08.2017 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP
Concrete from wood
05.07.2017 | Schweizerischer Nationalfonds SNF
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...
Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.
Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...
10.10.2017 | Event News
10.10.2017 | Event News
28.09.2017 | Event News
16.10.2017 | Physics and Astronomy
16.10.2017 | Earth Sciences
16.10.2017 | Physics and Astronomy