• Title/Summary/Keyword: 진동 인텐시티

Search Result 100, Processing Time 0.053 seconds

Structural Intensity Analysis of Local Ship Structures (선체 구조요소의 진동인텐시티 해석)

  • Cho, Dae-Seung;Kim, Sa-Soo;Lee, Dong-Hwan;Choi, Tae-Mook
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2000.06a
    • /
    • pp.881-887
    • /
    • 2000
  • The interest in evaluation of structural intensity arises for practical reasons, because net energy flow distribution offers information of energy transmission path, positions of sources, and sinks of vibration energy. In this paper, structural intensity analysis of local ship structures using finite element method(FEM) is carried out. The purpose of this analysis is to evaluate the relative accuracy according to mesh fineness. The structural intensity of a stiffened plate varying their mesh fineness is analyzed and the results are compared with those obtained by the assumed made method. As results, the proper mesh size in qualitative/quantitative structural intensity analysis of plate structures is proposed. In addition, the propagation phenomenon of vibration energy is investigated for the L-type plate and box-girder structures.

  • PDF

Measurements of In-Plane Vibration Intensity of a Semi-Infinite Beam (반무한보의 면내 진동인텐시티 측정)

  • 김창렬;길현권;전진숙;홍석윤
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2002.05a
    • /
    • pp.1185-1188
    • /
    • 2002
  • The objective of this paper is to apply experimental methods to measure the in-plane vibration intensity of a semi-infinite beam. Two experimental methods have been implemented to measure the in-plane vibration intensity of the beam. The first method is the cross spectral intensity measurement method using two accelerometers. The second method is the frequency response method using the only one acrelerometer. It has the advantages of shortening measurement time and reducing accelerometer phase error. Experimental results showed that those experimental methods can be effectively used to measure the structural In-plane vibration intensity.

  • PDF

Relation Between Welding Shapes and the Vibration Energy Flows of Steel Plate (강판의 용접형상과 진동에너지의 변화에 관한 연구)

  • Yu, Y.H.
    • Journal of Power System Engineering
    • /
    • v.6 no.4
    • /
    • pp.36-42
    • /
    • 2002
  • In the structures of automobiles and ships which have engines for works, the vibration energies generated by the engines are transferred to dissipation parts through the structures which is welded and bolted with beams and plates. The vibration energies generated by resonance frequencies are the reasons of the resonance phenomena. To solve these problems, up to the present, we have studied to avoid the resonance, and add the higher damping characteristics. However, we need to understand the structural energy flows, to design the structures clearly which have the characteristic of welding. The object of this study is to make differences clear in the characteristics of structures which have some welded part on an homogenous flat plate. In this investigation, we study the flows of structural vibration energy experimently, and then, some knowledge for dynamic structural design is obtained.

  • PDF

Measurement of Vibration Intensity of a Semi-Infinite Beam Using the Principle of Reciprocity (가역성 원리를 이용한 반무한보의 진동 인텐시티 측정)

  • 양귀봉;길현권;홍석윤
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.11b
    • /
    • pp.1073-1077
    • /
    • 2001
  • The objective of this paper is to apply an experimental method based on the principle of reciprocity to measuring the structural intensity. Since only one accelerometer is used in this method it has the advantages of shortening measurement time. reducing accelerometer phase error. overcoming the limitation that the situation should be stationary during the experiment. It has been used to measure the vibration intensity of an infinite beam (beam with damped ends) and a semi-infinite beam (beam with simply supported and damped ends). Results showed that the experiment method based on the principle of reciprocity can be effectively used to measure the structural intensity.

  • PDF

Power Flow Analysis of Vibration of Coupled Plates Excited by a Point Force In an Arbitrary Direction (임의의 방향 점가진력에 의한 연성 평판 진동의 파워흐름해석)

  • 최재성;길현권;홍석윤
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.11 no.6
    • /
    • pp.181-192
    • /
    • 2001
  • The power flow analysis (PFA) has been performed to analyze the vibration of coupled plates excited by a point force in an arbitrary direction. The point force generates the out-of-plane vibration associated wish flexural waves and the in-plane vibration associated with longitudinal and shear waves. The energy governing equation for each type of waves was introduced and solved to Predict the vibrational energy density and intensity generated by the out-of-plane and in-plane components of the point force in an arbitrary direction. The wave transmission approach was used to consider the mode conversion at the joint of the coupled plates. Numerical results for vibrational energy density and intensity on the coupled plates were presented. Comparison of the results by PFA with exact results showed that PFA can be an effective tool to predict the spatial variation of the vibrational energy and intensity on the coupled plates at high frequencies.

  • PDF

Identification of Airborne-noise Source and Analysis for Noise Source Contribution of a GDI Engine Using Sound Intensity Method (음향 인텐시티법을 이용한 GDI 엔진 소음원 규명 및 소음 기여도 분석에 관한 연구)

  • Kim, Byung-Hyun;Lee, Sang-Kwon;Yoon, Joon-Seok;Shin, Ki-Chul;Lee, Sang-Jik
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.10
    • /
    • pp.985-993
    • /
    • 2012
  • In this paper, a new method is proposed to estimate the sound pressure generated from gasoline direct injection (GDI) engine. There are many noise sources as much as components in GDI engine. Among these components, fuel pump, fuel injector, fuel rail, pressure pump and intake/exhaust manifolds are major components generated from top of the engine. In order to estimate the contribution of these components to engine noise, the total sound pressure at the front of the engine is estimated by using airborne source quantification (ASQ) method. Airborne source quantification method requires the acoustic source volume velocity of each component. The volume velocity has been calculated by using the inverse method. The inverse method requires many tests and has ill-condition problem. This paper suggested a method to obtain volume velocity directly based on the direct measurement of sound intensity and particle velocity. The method is validated by using two known monopole sources installed at the anechoic chamber. Finally the proposed method is applied to the identification and contribution of noise sources caused by the GDI components of the test engine.

Study on sound radiation estimation using a reciprocity technique and p-p method by finite element simulation (상반성 기법과 p-p method를 이용한 구조물 방사소음 유한요소해석 기법 연구)

  • Ji Woo Yoo;Hun Park;Ji Un Lee
    • The Journal of the Acoustical Society of Korea
    • /
    • v.42 no.1
    • /
    • pp.1-6
    • /
    • 2023
  • Sound radiated from a structure in vibration is an important physical characteristic to evaluate vibro-acoustic problem. Although sound radiation power can be typically obtained by intensity measurement, long measuring time and strict measuring condition remain difficult. As an alternative method, simulation-based estimation can be taken into account and its accuracy is known to be acceptable. However, difficulty still lies in that specialized softwares may be necessary to obtain sound radiation power and radiation efficiency. In this context, this study suggests two methods using an ordinary FE method to calculate sound radiation power. They are well-known reciprocity technique and p-p method, which are basically test methods. It is shown that either method can practically estimate sound radiation in the frame of conventional Finite Element Method (FEM). The methods and their corresponding limit are discussed with some results.

Noise Reduce in the Rotary Compressor for air-conditioner using Structural Modification (구조 변경을 통한 공조용 압축기의 소음저감)

  • Kim, Jin-Soo;Lee, Seung-Mock;Ha, Jong-Hun;Lee, Jang-Woo;Ha, Sam-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2010.10a
    • /
    • pp.556-563
    • /
    • 2010
  • The main noise source of the rotary compressor for air conditioner was analyzed by using the measurement of sound intensity, modal analysis and operational deflection shape(ODS) analysis. In this study, the key noise source of rotary compressor was an accumulator, and noise was sharply increased due to the accumulator's resonance which has a big contribution to the noise. To reduce the excessive noise generated from accumulator, structural modification through ODS analysis were applied. Its validation was conducted by the measurement of noise and vibration on the accumulator's surface. The total noise was significantly reduced by 4.2dB(A).

  • PDF

Noise Characteristics of Rapier Loom by Noise Source Analysis (소음원 분석에 의한 직기 구조물의 소음 특성)

  • Na, Hae-Joong;Chun, Du-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.05a
    • /
    • pp.254-257
    • /
    • 2005
  • Locations and emission characteristics of noise source of rapier loom are important factors greatly. So, noise characteristics of rapier loom were investigated by the noise source identification as a part of experimental methods in this study. To identify the noise sources of the rapier loom sound intensity was measured under machine operation. In addition, frequency spectra of the sound at operator position was measured along with sound intensity to help identify the noise characteristics of the rapier loom. The results indicate that the sound power level occurs along the rapier loom.

  • PDF

Source Identification and Reduction of Noise for the Outdoor Unit of Room Air Conditioner (에어컨 실외기의 소음원 규명 및 소음저감)

  • 서상호;임금식;이내영;진심원
    • Journal of KSNVE
    • /
    • v.8 no.6
    • /
    • pp.1043-1052
    • /
    • 1998
  • The noise sources in the outdoor unit of RAC are identified by the sound intensity method. The main noise sources are compressor noise and fluid noise which is caused by the fan. heat exchanger and shroud. First. the fluid noise is reduced through the design of new fan and shroud. reduction of the system resistance by rearrangement of heat exchanger. and optimization of the complex parameter between the fan and shroud. Next, in order to reduce the compressor noise, the new shape of compressor mount and sound-proof material was applied. As a result, the overall noise was reduced by 4∼5dB (A).

  • PDF