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Characteristics of Forced Vibration System According to the Frequency of External Exciting Force

외부 가진력의 주파수에 따른 강제진동시스템의 특성

  • Kim, Jong-Do (Industry Academic Cooperation Foundation, Jungwon University) ;
  • Yoon, Moon-Chul (Department of Mechanical Design Engineering, Pukyung National University)
  • 김종도 (중원대학교 산학협력단) ;
  • 윤문철 (부경대학교 기계설계공학과)
  • Received : 2021.07.19
  • Accepted : 2021.09.20
  • Published : 2021.09.28

Abstract

The characteristics of forced vibration by an external excitation force having a frequency were analyzed according to the amplitude and frequency of the excitation force. To obtain displacement, velocity, and acceleration, numerical analysis was performed to obtain the frequency response, and in particular, each FRF(Frequency Response Function) was analyzed to reveal the location of the system natural frequency and excitation frequency in the frequency domain. In the vibration model caused by external excitation, the natural frequency and distribution of the surrounding excitation mode in displacement, velocity and acceleration FRF. The FRF was also shown in the power spectrum and FRF of real and imaginary parts. The external excitation force was approximated with the excitation force of a sine wave by giving the amplitude and frequency, the mode generated by this excitation force could be distinguished. After numerical analysis by changing the equivalent mass, damping and stiffness, the forced vibration response characteristics by external excitation force were systematically analyzed.

주파수를 갖는 외부 가진력에 의하여 강제 진동의 특성을 가진력의 진폭과 주파수에 따라 그 특성을 분석하였다. 변위, 속도 및 가속도를 얻기 위해 수치해석을 수행하여 주파수 응답을 얻었고 특히 주파수 영역에서 시스템 고유진동수와 가진 주파수의 발생 위치를 밝히고자 각각의 FRF의 분석을 하였다. 외부 가진에 의한 진동모델에서 변위, 속도 및 가속도의 거동과 주파수 응답함수에서 고유진동 주파수와 주변의 가진 모드 분포도 파워 스펙트럼과 실수부와 허수부의 FRF 에서 나타났으며 각 모드 특성도 구하였다. 진동의 응답은 가진 신호의 크기와 주파수를 주어 정현파의 가진력으로 외부 가진력을 근사화 하였고 이런 가진력에 의하여 발생하는 모드를 구별할 수 있었다. 상당 질량, 감쇠 및 강성을 변화시켜 수치 분석 후 외부 가진력에 의한 강제 진동 응답 특성을 체계적으로 분석하였다.

Keywords

Acknowledgement

This work was supported by the Jungwon University Research Grant(2020-047)

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