The generation of electrical charges in response to mechanical deformation is a distinctive feature of piezoelectric materials. This property can be used to avoid mechanical stresses in special materials. A project currently funded by the Austrian Science Fund FWF will make a key contribution to the optimisation of these "intelligent materials".
High levels of mechanical stress reduce the lifespan of construction components. This is true for all types of materials; exposure to mechanical stress is a crucial factor in the duration of their lifespan. When stresses are combined with vibrations they have a particularly negative impact on durability.
Intelligent materials that can actively counteract such effects have been available for special applications for some years now. The solution applied here involves a very sophisticated trick of physics: the so-called piezoelectric effect, that is the generation of an electrical charge through deformation, can be used to actively suppress these forces.
However, piezoelectric materials are also subject to forces which reduce their durability and finding a way of changing this is the challenge that scientist Jürgen Schöftner has set himself.
VIBRATIONS AND STRESSES
A particular characteristic of piezoelectric materials plays a key role in Schöftner's research: "A distinctive feature of piezoelectric materials is their special combination of physical properties. This is responsible for the fact that an increase of mechanical stress can arise even if the mechanical deformation of the material, which was caused by external forces, has already abated."
Such local increases in stress have a negative effect on the durability of the material and Schöftner aims to reduce them. As he explains, he is entering uncharted scientific territory here:
"The research carried out in recent years in this field, which is known as 'structural control', focused mainly on the reduction of vibrations and deformations. These methods are so far well understood. However, the findings on the avoidance of vibrations are of no help when it comes to the avoidance of mechanical stresses. New methods are needed here and we plan to develop the basis for them."
The first stage of Schöftner's project involves the analysis of the so-called constitutive relations for piezoelectric materials. This will enable the deduction of formulations for possible stress suppression in the three-dimensional space. He will then also calculate the basic differential equations for the stress. The aim of these basic calculations is to find workable concepts for the suppression of stresses in so-called lean components.
PASSIVE REGULATION – ACTIVE ENERGY HARVESTING
However, Schöftner is looking even further into the future in his project: "Piezoelectric materials can actually be used to harvest energy. The kinetic energy of a component is transformed into electrical oscillations and, therefore, neutralised. If the piezoelectric material is integrated into an electric network, the charge generated through the mechanical deformation can also be transmitted to a suitable electrical storage medium."
The long-term aim is to design an electrical network for a particular vibrating piezoelectric structure which, depending on requirements, regulates a mechanical stress under a certain level or transforms the vibrational energy into electrical energy through storage. This would require a smart circuit which consists of an active circuit for the stress regulation and a passive circuit for the energy harvesting.
Ideally, the mechanical stress would be regulated from a critical stress level – otherwise, vibrational energy would be converted into usable electrical energy. However, some basic homework will have to be done before such systems become a reality. Thus, in his project, Schöftner is working on the optimal distribution of the electrodes, the sheet resistance and the electrical network in such a system.
"The potential offered by such passively controlled materials is huge – however, before they can actually be used, we must obtain some basic information about the optimisation of these materials. This is precisely what we are doing in this FWF project," adds Schöftner.
Jürgen Schöftner has been a researcher at the Institute of Technical Mechanics at the Johannes Kepler University Linz since 2011. He is an expert in modelling and control of mechatronic problems.
DI Dr. Jürgen Schöftner
Johannes Kepler University Linz
Institute of Technical Mechanics
4040 Linz, Austria
T +43 / 732 / 2468 - 6314
Austrian Science Fund FWF:
Haus der Forschung
1090 Vienna, Austria
T +43 / 1 / 505 67 40 - 8111
Copy Editing & Distribution:
PR&D – Public Relations for Research & Education Mariannengasse 8
1090 Vienna, Austria
T +43 / 1 / 505 70 44
Marc Seumenicht | PR&D - Public Relations für Forschung & Bildung
Researchers devise microreactor to study formation of methane hydrate
23.08.2017 | NYU Tandon School of Engineering
Meter-sized single-crystal graphene growth becomes possible
22.08.2017 | Science China Press
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
23.08.2017 | Life Sciences
23.08.2017 | Life Sciences
23.08.2017 | Physics and Astronomy