Targeted Pressure to Modify Material Properties
Highly Efficient Dampers Made of Conventional Material
At the 2nd WAK symposium held in Fürth in the South of Germany, on February 23, Prof. Igor Emri from the Center of Experimental Mechanics (CEM) at the University of Ljubljana, Slovenia, announced a breakthrough: He explained that his patented idea could lead to sound and vibration damping by several orders of magnitude higher than at present. The idea is not about new materials, but about applying existing materials under changed conditions.
Dissipation Process Is Crucial
His solution is based on the recognition that the energy dissipation of a material is not based on the material as such. It is rather determined by the pressure a material is submitted to. Applying (relatively high) hydrostatic pressure can therefore improve a material’s damping behavior significantly, because this enables higher absorption values for the desired vibration frequencies.
However, the problem with elastomers is their poor resistance to high uniaxial loads. Emri’s trick is to use pellets of the right particle sizes, so that they behave like a fluid. According to his statements, this can improve absorption by a factor of approx. 10,000, at 6000 bars pressure, in theory. Virtually speaking, pressures up to approx. 1000 bars can be handled.
Proof of Concept
In order to prove the functionality of the concept, Emri built a prototype with simple means, where shredded waste tires are compressed by a plunger in a tubular container. He states that he reached 109 bars and energy absorption was improved by 12, after all.
Emri considers the approach suitable for applications with no harmonic vibrations, but rather with impulse vibrations such as earthquakes, or for regular operation in railroad ties, washing machines or industrial machines. At present, he is working on a field test for the system, while there are plans for later marketing.