Active Junction Control and Piezoelectric Hybrid Damping for Improving the Acoustic Performance of Lightweight Structures
Doktorsavhandling, 2011

Weight reduction is a key factor in lowering the fuel consumption and thereby the greenhouse emissions from vehicles. However, reducing the weight normally results in a deterioration of the acoustic performance. Thus, the purpose of this thesis is to investigate damping treatments for lightweight vehicle panels. Combining active control and passive damping in hybrid control treatments have shown promising. Compared to pure active control, hybrid treatments can have advantages such as reduced control effort or improved fail-safe characteristics. The thesis is dived into two parts, investigating two different concepts for hybrid damping. In the first part of the thesis, a concept of active junction control is developed. Active inputs are used at structural junctions in order to confine vibrational energy to highly dissipative parts of the structure. Theoretical models of beam junctions including active forces and moments are employed to conduct parameter studies. Results show that such an approach can offer advantageous compared to pure active control, e.g. by reducing the control effort. However, it is very sensitive to variations in the properties of the structure. In the second part of this thesis, piezoelectric elements are used for controlling vibrations and/or sound radiation. The piezoelectric element is either shunted by a passive electrical network or by a voltage source in series with a passive electrical network. Analytical models of plates and beams with surface-bonded piezoelectric elements are developed, and experimentally verified. Parameter studies are conducted in order to find the shunt which is optimal under different conditions and control criteria. Results show that for lightly damped structures, passive shunt damping may offer efficient reduction of both the kinetic energy and radiated sound power over a wide frequency range. A properly designed shunt network may also improve the characteristics of an actively driven piezoelectric element, e.g. by reducing the control effort.

Hybrid passive-active control

Piezoelectric shunt damping

Sound radiation

Active junction control

VG
Opponent: Professor Paolo Gardonio

Författare

Jonas Svensson

Chalmers, Bygg- och miljöteknik, Teknisk akustik, Vibroakustik

Feedforward control of bending waves in frequency domain at structural junctions using an impedance formulation

Journal of Sound and Vibration,; Vol. 323(2009)p. 555-573

Artikel i vetenskaplig tidskrift

On the design of structural junctions for the purpose of hybrid passive-active vibration control

Journal of Sound and Vibration,; Vol. 329(2010)p. 1274-1288

Artikel i vetenskaplig tidskrift

Active scattering control of flexural waves at beam junctions: The influence of beam properties on power flow and control effort

Journal of Sound and Vibration,; Vol. 313(2008)p. 418-432

Artikel i vetenskaplig tidskrift

Vikt är en avgörande faktor när det gäller att reducera bränsleförbrukningen och därmed utsläppen från fordon. Att reducera vikten leder dock vanligtvis till en ökning av ljud och vibrationer i och omkring fordonet. Eftersom traditionella metoder för ljud- och vibrationsbekämpning innebär en påtaglig viktökning är de inte alla avseende inte lämpade. Därför måste nya metoder utvecklas. Denna avhandling berör två alternativa metoder för ljud- och vibrationsdämpning. Den första handlar om att med hjälp av aktiva metoder för att begränsa vibrationsenergin till områden där der finns passiv dämpning behöver inte hela strukturen behandlas med dämpningsmaterial. Den andra metoden handlar om att med hjälp av piezoelektriska material omvandla mekanisk energi till elektrisk energi och introducera dämpningen på den elektriska sidan. På detta sätt krävs inga tunga dämpningsmaterial. Detta arbeta kan förhoppningsvis bidra till ökad förståelse kring ljud- och vibrationsdämpning för lättviktskonstruktioner.

Weight reduction is a key factor in lowering the fuel consumption and thereby the greenhouse emissions from vehicles. However, reducing the weight normally results in a deterioration of the acoustic performance. Traditional methods for sound and vibration reduction are usually associated with a significant an increase in mass, they are not always suitable. Thus, the purpose of this thesis is to investigate alternative methods for sound and vibration reduction. Two approaches are studied in this thesis. The first concerns using active inputs to confine vibrational energy to parts of a structure which contains passive damping. That way the entire structure does not need to be treated with damping materials. The second approach concerns using piezoelectric materials to convert mechanical energy to electrical energy and introduce the damping an the electrical side. This was no heavy damping materials are required. This work can hopefully contribute to the understanding of sound and vibration reduction for lightweight structures.

Styrkeområden

Transport

Building Futures

Ämneskategorier

Annan materialteknik

Strömningsmekanik och akustik

ISBN

978-91-7385-496-2

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3177

VG

Opponent: Professor Paolo Gardonio

Mer information

Senast uppdaterat

2018-11-21