Polymeric materials that stretch out when electrically stimulated can benefit from realistic numerical simulations.
Robotic devices are usually composed of hard components such as aluminum and steel, in contrast to the soft tissues that power biological organisms. A study conducted by A*STAR researchers now makes it easier to turn squishy, electroactive polymers into artificial muscles and biomimetic energy harvesters through computer-aided design .
Dielectric elastomers are rubbery, insulating membranes that respond dramatically to electric fields — when sandwiched between two electrodes, they can expand by several hundred per cent in a two-dimensional plane. These special deformation properties have led to applications such as soft-body robotics and sensors. However, the shape-shifting membranes often develop changes in their electrically stimulated response over time, making them hard to optimize for long-term use.
Keith Choon Chiang Foo from the A*STAR Institute of High Performance Computing and his team realized that numerical simulations could help to improve dielectric elastomer devices. They turned to finite element analysis, a tool that predicts the performance of complex objects by modeling them as small interconnected geometric units, to reach this goal. But finding algorithms that replicate smart polymer behavior is not straightforward.
“Existing finite element software doesn’t have the capability to simulate soft rubbery materials that respond to electricity and involve large deformations,” says Foo. “Plus, most simulations of these polymers have been done using ‘in-house’ software, meaning source codes are not available to the scientific community.”
The researchers solved these issues with a model that revealed how repeated movements affected the membrane’s ability to respond to electricity and mechanical forces over time. Their algorithms coupled this property, known as viscoelasticity, to electrostatic charges in the device. They implemented this model into commercial finite element software. “We have made the subroutine freely available to aid other researchers,” adds Foo.
The team’s simulations highlighted examples where viscoelasticity has an impact on the performance of artificial muscle-like devices. For example, when an electrical pulse causes the membrane to stretch out, the elastomer takes a characteristic time to relax to the new configuration. If the pulse cycles at a rate close to this relaxation time, mechanical actuation can be significantly affected.
Further tests showed the improved finite element analysis could quantify the critical time delay between the instant an electrical signal is applied and the maximum polymer actuation achieved. Because the computations agree well with previous experimental data, Foo is confident this technique can reduce trial-and-error approaches to biomimetic devices.
“This simulation tool may prove very capable,” he remarks. “When we work with experimentalists, it helps guide our approach to soft machines.”
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing. For more information about the team’s research, please visit the Soft Matter Group webpage.
 Foo, C. C. & Zhang, Z.-Q. A finite element method for inhomogeneous deformation of viscoelastic dielectric elastomers. International Journal of Applied Mechanics 7, 1550069 (2015).
A*STAR Research | Research SEA
Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University
Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences