• 제목/요약/키워드: Impact Response Function

검색결과 245건 처리시간 0.026초

Seismic response of a rigid foundation embedded in a viscoelastic soil by taking into account the soil-foundation interaction

  • Messioud, Salah;Sbartai, Badreddine;Dias, Daniel
    • Structural Engineering and Mechanics
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    • 제58권5호
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    • pp.887-903
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    • 2016
  • This study analyses the seismic response of a three-dimensional (3-D) rigid massless square foundation resting or embedded in a viscoelastic soil limited by rigid bedrock. The foundation is subjected to harmonic oblique seismic waves P, SV, SH and R. The key step is the characterization of the soil-foundation interaction by computing the impedance matrix and the input motion matrix. A 3-D frequency boundary element method (BEM) in conjunction with the thin layer method (TLM) is adapted for the seismic analysis of the foundation. The dynamic response of the rigid foundation is solved from the wave equations by taking into account the soil-foundation interaction. The solution is formulated using the frequency BEM with the Green's function obtained from the TLM. This approach has been applied to analyze the effect of soilstructure interaction on the seismic response of the foundation as a function of the kind of incident waves, the angles of incident waves, the wave's frequencies and the embedding of foundation. The parametric results show that the non-vertical incident waves, the embedment of foundation, and the wave's frequencies have important impact on the dynamic response of rigid foundations.

경계 조건에 따른 지열 응답 함수의 차이가 수직형 지열 교환기 길이 산정에 미치는 영향 (Impact of Different Boundary Conditions in Generating g-function on the Sizing of Ground Heat Exchangers)

  • 김의종
    • 설비공학논문집
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    • 제26권6호
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    • pp.263-268
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    • 2014
  • Eskilson's g-function, a well-known geothermal heat response factor, is widely used for sizing of the ground heat exchangers. Unlike the Eskilson's original model that uses common temperature boundaries for all boreholes and along the borehole height, an analytical-solution-based g-function uses a uniform heat transfer rate over the height with variable heat transfer rates for respective boreholes. To evaluate the impact of such a boundary difference on g-function and the design length, a simple case study was carried out on the cooling-dominant commercial buildings. The results show that the design lengths given by the boundary of uniform heat transfer rates are longer than those given by Eskilson's boundary for all cases tested. The difference in length is more important when the bore field is composed of more boreholes with shorter length of each borehole.

Impact identification and localization using a sample-force-dictionary - General Theory and its applications to beam structures

  • Ginsberg, Daniel;Fritzen, Claus-Peter
    • Structural Monitoring and Maintenance
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    • 제3권3호
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    • pp.195-214
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    • 2016
  • Monitoring of impact loads is a very important technique in the field of structural health monitoring (SHM). However, in most cases it is not possible to measure impact events directly, so they need to be reconstructed. Impact load reconstruction refers to the problem of estimating an input to a dynamic system when the system output and the impulse response function are usually known. Generally this leads to a so called ill-posed inverse problem. It is reasonable to use prior knowledge of the force in order to develop more suitable reconstruction strategies and to increase accuracy. An impact event is characterized by a short time duration and a spatial concentration. Moreover the force time history of an impact has a specific shape, which also can be taken into account. In this contribution these properties of the external force are employed to create a sample-force-dictionary and thus to transform the ill-posed problem into a sparse recovery task. The sparse solution is acquired by solving a minimization problem known as basis pursuit denoising (BPDN). The reconstruction approach shown here is capable to estimate simultaneously the magnitude of the impact and the impact location, with a minimum number of accelerometers. The possibility of reconstructing the impact based on a noisy output signal is first demonstrated with simulated measurements of a simple beam structure. Then an experimental investigation of a real beam is performed.

탄성지지된 구조물의 충격 햄머 실험에서 질량선의 개선을 통한 향상된 강체 특성 규명법 (Identification of Rigid Body Properties of the Mounted Structure with Improved Mass-Lines from Impact Hammer Tests)

  • 안세진;정의봉;황대선
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문집
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    • pp.317-322
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    • 2002
  • There are many researches to identify the rigid body properties from the mass-line obtained by impact hammer testing. The correct rigid body properties of the structure may be estimated if the mass-line of the structure could be obtained exactly. When the structure is mounted by elastic materials, the mass-line cannot be read correctly from the impulse response spectrum. The reason is due to the effects of rigid body modes of mounted structure. In this paper, the effects of rigid body modes of mounted structure to the mass-line are discussed and the method to remove these effects is also presented.

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탄성지지된 구조물의 충격 햄머 실험에서 질량선의 개선을 통한 향상된 강체 특성 규명법 (The Identification of Rigid Body Properties with Improved Mass-Lines from Impact Hammer Tests of The Mounted Structure)

  • Ahn, Se-Jin;Jeong, Weui-Bong;Hwang, Dae-Sun
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문초록집
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    • pp.336.2-336
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    • 2002
  • There are many researches to identify the rigid body properties from the mass-line obtained by impact hammer testing. The correct rigid body properties of the structure may be estimated if the mass-line of the structure could be obtained exactly. When the structure is mounted by elastic materials, the mass-line cannot be read correctly from the impulse response spectrum. The reason is due to the effects of rigid body modes of mounted structure. (omitted)

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주파수 응답함수를 이용한 고정밀장비의 진동 허용규제치 결정기법에 관한 연구 (A Study on the Determination Vibration criteria for High Technology Facilities using FRF - Impact Test-)

  • 이홍기;박해동;김두훈;김사수
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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    • pp.377-385
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    • 1996
  • In the case of a precision equipment, it requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga class semiconductor wafers. This high technology equipments require very strict environmental vibration standard in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria are usually obtained either by the real vibration exciting test on the equipment or by the analytical calculation. the former is accurate but requires a great deal of time and efforts while the latter lacks reliability. this paper proposes a new method to solve this problem at a time. the permissible vibration level to a precision equipment can be easily obtained by analyzing a process of Frequency Response Function. This paper also demonstrates its effectiveness by applying the proposed method to finding the vibration criteria of a Computer Hard Disk Drive by impact Test.

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접지면 중앙에서 3차원 방향의 충격 가진에 의한 타이어의 3차원 진동형이 축에 미치는 영향 (3-D Vibration Modes of the Tire in Ground Contact and Its Effects on Axle When Excited by a 3-D Impact at the Center of Contact Patch)

  • 김용우;남진영
    • 한국자동차공학회논문집
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    • 제11권6호
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    • pp.171-182
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    • 2003
  • Tire vibration modes are known to play a key role in vehicle ride and comfort characteristics. Inputs to the tire such as impacts, rough road surface, tire nonuniformities, and tread patterns can potentially excite tire vibration. In this study, experimental modal analysis on the tire in ground contact are performed by a 3-D impact at the center of contact patch to investigate which modes of tire influence the vibration of wheel and axle. Through the experiment, the vibration transmission properties from tire to axle are examined. And we have compared the influential tire modes when the tire is excited by a vertical impact with those when excited by the 3-D impact. Additionally, the modes of ground contact tire are compared with those of the suspended tire.

컴퓨터의 충격해석 및 실험적 검증 (Evaluation of Drop/Impact Performance of Laptop Computer)

  • 윤영한;임경화;김진규;안채헌
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 추계학술대회논문집
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    • pp.737-741
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    • 2000
  • Portable communication devices such as laptop computers suffer impact-induced failure in their usage. Drop/impact performance of these products is one of important concerns of product design. Because of the small size of this kind of electronics products, it is very expensive, time-consuming and difficult to conduct drop tests to directly detect the failure mechanism and identify their drop behaviors. Finite element analysis provides a vital, powerful vehicle to solve the problems. The models are created with HYPERMESH, and the analysis is carried out with LS-DYNA3D. The analysis is focused on HDD impact behavior in acceleration peak values.

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실험모드해석에 의한 다점지지된 연속원통셸의 진동특성에 관한 연구 (A Study on the Vibrational Characteristics of the Continuous Circular Cylindrical Shell with the Multiple Supports Using the Experimental Modal Analysis)

  • 한창환;이영신
    • 한국소음진동공학회논문집
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    • 제11권4호
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    • pp.43-51
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    • 2001
  • An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.

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초전도 자기베어링-플라이휠 시스템의 베어링 모델링 (Bearing Modeling of Superconducting Magnetic Bearings-Flywheel System)

  • 김정근;이수훈
    • 소음진동
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    • 제9권5호
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    • pp.891-898
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    • 1999
  • The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

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