• Title/Summary/Keyword: Acceleration Noise

Search Result 618, Processing Time 0.025 seconds

Optimum parameters and performance of tuned mass damper-inerter for base-isolated structures

  • Jangid, Radhey Shyam
    • Smart Structures and Systems
    • /
    • v.29 no.4
    • /
    • pp.549-560
    • /
    • 2022
  • The optimum damping and tuning frequency ratio of the tuned mass damper-inerter (TMDI) for the base-isolated structure is obtained using the numerical searching technique under stationary white-noise and filtered white-noise earthquake excitation. The minimization of the isolated structure's mean-square relative displacement and absolute acceleration, as well as the maximization of the energy dissipation index, were chosen as the criteria for optimality. Using a curve-fitting technique, explicit formulae for TMDI damping and tuning frequency for white-noise excitation are then derived. The proposed empirical expressions for TMDI parameters are found to have a negligible error, making them useful for the effective design of base-isolated structures. The effectiveness of TMDI and its optimum parameters are influenced by the soil condition and isolation frequency, according to the comparison made of the optimized parameters and response with different soil profiles. The effectiveness of an optimally designed TMDI in controlling the displacement and acceleration response of the flexible isolated structure under real and pulse-type earthquakes is also observed and found to be increased as the inertance mass ratio increases.

Modification of acceleration signal to improve classification performance of valve defects in a linear compressor

  • Kim, Yeon-Woo;Jeong, Wei-Bong
    • Smart Structures and Systems
    • /
    • v.23 no.1
    • /
    • pp.71-79
    • /
    • 2019
  • In general, it may be advantageous to measure the pressure pulsation near a valve to detect a valve defect in a linear compressor. However, the acceleration signals are more advantageous for rapid classification in a mass-production line. This paper deals with the performance improvement of fault classification using only the compressor-shell acceleration signal based on the relation between the refrigerant pressure pulsation and the shell acceleration of the compressor. A transfer function was estimated experimentally to take into account the signal noise ratio between the pressure pulsation of the refrigerant in the suction pipe and the shell acceleration. The shell acceleration signal of the compressor was modified using this transfer function to improve the defect classification performance. The defect classification of the modified signal was evaluated in the acceleration signal in the frequency domain using Fisher's discriminant ratio (FDR). The defect classification method was validated by experimental data. By using the method presented, the classification of valve defects can be performed rapidly and efficiently during mass production.

A Study on the Interior Noise Reduction of EMU by Contribution Analysis (기여도 분석에 의한 전기동차 실내소음 저감대책 연구)

  • 문경호;김재철;유원희
    • Proceedings of the KSR Conference
    • /
    • 1999.05a
    • /
    • pp.218-225
    • /
    • 1999
  • Speed-up and mass reduction of EMU(Electrical multiple unit) causes increase of interior noise. One of the best ways to reduce the interior noise is to identify noise sources. In this study, we evaluated interior noise by contribution analysis. This method is to predict the interior noise contribution of carbody by using transfer function between acceleration and sound pressure. The plan of the interior noise reduction based on the test results was also presented.

  • PDF

Measurement of Static and Dynamic Displacement by Image Processing and Study for Prediction Method of Velocity and Acceleration (영상처리를 이용한 정동적 변위 계측과 속도, 가속도 추산방식 연구)

  • Heo, Seok;Kwak, Moon-Kyu;Lee, Ho-Bum
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2010.10a
    • /
    • pp.527-532
    • /
    • 2010
  • This paper is concerned with the measurement of static and dynamic displacement by image processing(IP) and study for prediction method of velocity and acceleration. To measure the displacement visually, the measurement system consists of a telephoto zoom camera, ccd image device and a computer. The specific target on the white board is used to calculate the displacement of the structure. The captured image is then converted into a pixel-based data and then analyzed numerically. The limitation of the system depends on the image capturing speed and the pixel-size of image. In this paper, we developed for the displacement measurement using the image processing method. The proposed method enables us to measure the vibration measurement, velocity and acceleration directly without any contact. The current resolution of the displacement measurement is limited to 1/100 millimeter scale.

  • PDF

Dynamic Analysis of a High-speed Wheel Moving on an Elastic Beam Having Gap with the Consideration of Hertz Contact (간격이 있는 탄성 보 위를 고속 주행하는 바퀴의 Hertz 접촉을 고려한 동역학적 해석)

  • Lee, Ki-Su;Kim, Seok-Seung
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.3
    • /
    • pp.253-263
    • /
    • 2012
  • With the local Hertz deformation on the contact point, the dynamic contact between a high-speed wheel and an elastic beam having a gap is numerically analyzed by solving the whole equations of motion of the wheel and the beam subjected to the contact condition. For the stability of the time integration the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Especially the acceleration contact condition on the gap is formulated, and it is demonstrated that the contact force variation computed by the velocity contact constraint or by the acceleration contact constraint agrees well with that computed by the displacement contact constraint. The numerical examples show that, when the wheel passes on the gap, the solution is governed by the stiffness of the local Hertzian deformation.

Dynamic Stability Analysis of an Axially Accelerating Beam Structure (축 방향 가속을 받는 보 구조물의 동적 안정성 해석)

  • Eun, Sung-Jin;Yoo, Hong-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.05a
    • /
    • pp.877-882
    • /
    • 2005
  • Dynamic stability of an axially accelerating beam stucture is investigated in this paper. The equations of motion of a fixed-free beam are derived using the hybrid deformation variable method and the assumed mode method. Unstable regions due to periodical acceleration are obtained by using the Floquet's theory. Stability diagrams are presented to illustrate the influence of the dimensionless acceleration, amplitude, and frequency. Also, buckling occurs when the acceleration exceeds a certain value. It is found that relatively targe unstable regions exist around the first bending natural frequency, twice the first bending natural frequency, and twice the second bending natural frequency. The validity of the stability diagram is confirmed by direct numerical integration of the equations of motion.

  • PDF