Razvoj hibridne metode akustične holografije v okviru metodologije dinamičnega podstrukturiranja

magistrsko delo magistrskega študijskega programa II. stopnje Strojništvo

Domen Ocepek (Author), Gregor Čepon (Mentor), Miha Boltežar (Co-mentor)

Abstract

Uporaba metod akustične holografije omogoča, na osnovi izmerjenega dvodimenzionalnega tlačnega polja, rekonstrukcijo akustičnih veličin v tridimenzionalnem prostoru. Iz zveze med tlakom fluidnih delcev in njihovo hitrostjo je moč rekonstruirati polje pomikov, zato metoda predstavlja alternativo konvencionalnim merilnim metodam za merjenje vibracijskega odziva strukture. Značilnost tako dobljenega odzivnega modela je visoka prostorska ločljivost ob nekoliko manjši natančnosti izmerjenega polja pomikov. V magistrskem delu je predstavljen razvoj nove hibridne metode akustične holografije, katere namen je zmanjšati dovzetnost le-te na okoliški šum in napake zaradi slabe pogojenosti problema inverzne akustike. Postopek temelji na uporabi metod dinamičnega sklapljanja, ki omogočajo združevanje ekvivalentnih odzivnih modelov identične strukture. Izvedeno je sklapljanje odzivnega modela na osnovi metode akustične holografije v bližnjem polju z odzivnim modelom na osnovi diskretnih meritev z laserskim vibrometrom. Tako dobljen hibridni odzivni model podeduje visoko prostorsko ločljivost akustične holografije ter natančnost, ki jo v model vnesemo prek meritev z laserskim vibrometrom. Končno je natančnost in zanesljivost hibridne metode prikazana na realni testni strukturi.

Keywords

magistrske naloge;akustična holografija;frekvenčna prenosna funkcija;dinamično sklapljanje;podstrukturiranje v frekvenčni domeni;sklapljanje ekvivalentnih modelov;hibridni model;

Data

Language:	Slovenian
Year of publishing:	2020
Typology:	2.09 - Master's Thesis
Organization:	UL FS - Faculty of Mechanical Engineering
Publisher:	[D. Ocepek]
UDC:	535.4:534.5:53.083(043.2)
COBISS:	16132867
Views:	1094
Downloads:	358
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Improved estimation of FRFs from NAH using dynamic substructuring methodology
Secondary abstract:	Measurement of two-dimensional sound pressure field can be used to determine three-dimensional wave field using Nearfield Acoustic Holography. Reconstructed displacement field can be estimated by knowing the relation that connects source sound pressure field and particle velocity. The method serves as alternative to conventional measuring methods to obtain the vibration response of the structure. Method offers high spatial resolution however it is highly sensitive to background noise and inaccuracies in the microphone position. In addition, ill-posed inverse acoustic problems introduce additional numerical noise into the system. A novel methodology for improved estimation of full-field frequency response functions from acoustic holography is proposed in this thesis by using dynamic substructuring methodology. Recently developed System Equivalent Model Mixing method is used to enable mixing of dynamic models of the same structure into one hybrid model. In the hybrid formulation each model contributes its own advantages to yield best combination of the two. Nearfield Acoustic Holography introduces a high spatial resolution to the hybrid model, while discrete laser measurements improve the accuracy of the reconstructed displacement field. Finally, improved robustness and applicability of the method is presented using experimental validation.
Secondary keywords:	master thesis;acoustic holography;frequency response function;dynamic substructuring;frequency based substructuring;system equivalent model mixing;hybrid model;
Type (COBISS):	Master's thesis/paper
Study programme:	0
Embargo end date (OpenAIRE):	1970-01-01
Thesis comment:	Univ. Ljubljana, Fak. za strojništvo
Pages:	XXII, 64 str.
ID:	11465831