Strategies for vibration control of lightweight structures : Acoustic black holes and architected materials Seminar

This seminar deals with vibration control of structures when they are subjected to weight reduction constraints.

In the transportation industry in particular, weight reduction is a major issue for reasons of energy consumption. The classical methods for reducing vibrations levels using visco-elastic coating, although effective, are then unsuitable. The objective of this work is to develop alternative strategies for the design of structures (beams, plates, shells) that are stiff, light and non-resonant by taking advantage of physical effects that allow the control of their vibro-acoustic properties.

A large part of the work concerns vibration damping by the Black Hole Acoustic effect, a passive technique based on the propagation properties of bending waves in thin inhomogeneous structures. Its typical implementation consists in locally decreasing the thickness of the structure by following a polynomial profile coated with a viscoelastic film. The resulting local inhomogeneity leads to trap vibrations and to dissipate them particularly efficiently.

Theoretical and numerical developments combining "wave" and "mode"  points of view lead to a thorough physical understanding of the effect. Different design variants that can combine this effect with other physical effects lead to experimental demonstrations in which the reduction of vibration levels is typically of the order of 10 to 15 dB above a threshold frequency.

A second strategy concerns vibration filtering in structures designed as the periodic repetition of an elementary structural pattern and/or including local resonances. This type of architected structures typically results in the existence of stop bands in which vibrations do not propagate.

Theoretical analyses, first developed on academic structures, allow to better understand how the geometrical and material parameters of the elementary pattern can drive the frequency position and width of these bandstop filters. Numerical optimization approaches then allow to tune the performances on a targeted frequency template or to obtain total filters, able to filter all types of waves in the same frequency range.

Speaker: Dr Adrien Pelat, Le Mans University

Adrien Pelat is an assistant professor at Le Mans University. His research, developed at the Lab of Acoustics (LAUM) concerns the vibro-acoustic control of mechanical structures by architecting their geometrical and material features in order to taylor the elastic waves propagation properties. He is particularly interested in the physical understanding and application of the Acoustic Black Hole effect; the design of vibration filters using periodic, locally resonant or graded materials; the use geometric or contact non-linearities. It involves theoretical and numerical modelling as well as experimental evidence on practical demonstrators to analyse the application potential. He manages both academic and industrial research programs related to this scientific field. His teaching activities are carried out at ENSIM (School of engineering of Le Mans University) in the field of vibration and acoustical engineering, with related numerical modelling and experimental methods.

 

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+44 20 3794 0272,,639248430#   United Kingdom, London

Phone Conference ID: 639 248 430#