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효율적인 음향 해석을 위한 padé 근사법과 모델차수축소법의 비교연구
구성열(Seongyeol Goo),국정환(Junghwan Kook),현재엽(Jaeyub Hyun),왕세명(Semyung Wang) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In a large-scale problem which needs to be calculated in wide band of frequencies, an analysis of acoustic system via a finite element method usually requires significant computation time since it solves only one target frequency at once. To shorten such a long computation time, two numerical methods can be used. The one is a pade approximation and the other one is a model order reduction scheme based on Quasi-Static Ritz Vector. Pade approximants is the best approximation of a function by a rational function of given order. In this reason, pade approximants outperform the Taylor expansion and give a good approximation over a wide frequency ranges. Model order reduction scheme based on QSRV also shows good approximation in engineering systems. In this paper, analysis of acoustic system such as muffler was carried out by those two numerical methods. After calculating transmission loss of muffler by using pade approximants and model order reduction scheme, we compare the accuracy and error of transmission loss in each case. Furthermore analysis was also carried out in a large scale system such as 3D muffler and we compare the efficiency, accuracy and CPU time.
정재순(Jaesoon Jung),구성열(Seongyeol Goo),왕세명(Semyung Wang) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A metamaterials is an artificially engineered structure having stop bands (or band gaps) that are frequency bands in which waves cannot propagate. Taking advantage of the stop band the vibration isolation and wave focusing become possible. Using these phenomenon of metamaterial, this paper presents applications of the metamaterial for improvement of vibro-acoustic performances of mechanical systems. Based on the vibration isolation the possibility of structure-borne noise reduction is presented. Furthermore, based on the wave focusing phenomenon the improvement of radiation efficiency of flat panel speaker is presented.