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
Breaking bad metals with neutrons
16.01.2018 | DOE/Argonne National Laboratory
White graphene makes ceramics multifunctional
16.01.2018 | Rice University
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Ecology, The Environment and Conservation
17.01.2018 | Physics and Astronomy
17.01.2018 | Awards Funding