PROFESSOR VICTOR V. KRYLOV
My research interests
are in a wide range of areas in Acoustics and Vibration. These include:
Rayleigh waves in inhomogeneous media;
Laser ultrasonics;
Acoustic emission from developing cracks;
Wedge elastic waves;
Ground vibrations from rail and road traffic (including high-speed trains);
Vehicle interior noise;
Low-frequency noise and vibration;
Wave-like aquatic propulsion by localised flexural waves;
Acoustic black holes for flexural waves and their applications for vibration damping.
EXAMPLES OF SOME RECENT RESEARCH
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WAVE_LIKE AQUATIC PROPULSION BY LOCALISED FLEXURAL WAVES
Photo: Underwater view of the model boat with a propulsive rubber plate (keel) supporting propagation of a localised flexural wave; about two flexural wavelengths are clearly visible along the plate edge.
This research involved the developing and experimental testing of a reduced-scale working model of the mono-hull marine craft (boat) propelled by localised flexural waves propagating in the attached immersed vertical plate (see the photo above) in a way similar to that used in nature by stingrays. The developed fully autonomous and robotically-controlled model boat with wave-like aquatic propulsion has achieved impressive speeds in open water of the order of one its body length per second. The wave-like aquatic propulsion under consideration can be a viable alternative to a traditional screw propeller. Its important advantages over the latter are very low under-water noise and safety for people and marine animals.
Photo: Graduate student Ewan Porteous and his supervisor, Prof. Victor Krylov, at the national SET Award Ceremony 2007 in the Alexandra Palace, London. This prestigious award (often called a 'student's Oscar') has been conferred on Ewan for the best final-year project entitled 'Wave-like aquatic propulsion of small marine craft'.
ACOUSTIC BLACK HOLES FOR FLEXURAL WAVES AND THEIR APPLICATIONS FOR VIBRATION DAMPING
‘Acoustic black holes’ are relatively new physical objects that have been introduced and investigated mainly during the last decade. They can absorb almost 100% of the incident wave energy, which makes them attractive for such traditional engineering applications as vibration damping and sound absorption.
The main principle of the ‘acoustic black hole effect’ is based on a gradual power-law-type decrease in velocity of the incident wave with propagation distance, linear or faster, to almost zero, which should be accompanied by efficient energy absorption using the attached highly absorbing materials, e.g. polymeric films. So far, this effect has been investigated mainly for flexural waves in thin plates for which the required gradual reduction in wave velocity with distance can be easily achieved by changing the plate local thickness according to a power law, with the power-law exponent being equal or larger than two.
Experimental investigations at Loughborough have been carried out on a variety of plate-like and beam-like structures. Such structures included plates or beams bounded by the attached power-law wedges, with the addition of small amounts of absorbing materials at the sharp edges. The above-mentioned wedge-like structures at the edges materialise one-dimensional acoustic black holes. Other structures that have been investigated were plates with tapered indentations (pits) of power-law profile drilled inside the plates. In the case of quadratic or higher-order profiles, such pits materialise two-dimensional acoustic black holes for flexural waves. To increase the efficiency of damping, ensembles of several black holes have been used.
The results of the experimental investigations demonstrated that in all of the above-mentioned cases the efficiency of vibration damping based on the acoustic black hole effect is substantially higher than that achieved by traditional methods. The key advantage of using the acoustic black hole effect for damping structural vibrations is that it requires very small amounts of added damping materials, which is especially important for vibration damping in light-weight structures used in aeronautical and automotive applications.
Photo: Visit of Prof. Francois Gautier (Le Mans, France) to Loughborough in summer 2009 to do collaborative work on damping structural vibrations using ‘acoustic black holes’.
From left to right: Mr. Viktor Kralovic (PhD student), Prof. Francois Gautier, Prof. Victor Krylov, Dr. Daniel O’Boy.
A two-dimensional acoustic black hole in a steel plate, a pit of power-law profile, can be seen at the bottom left of the picture.