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Chap 3. Harmonically Excited Vibration

Homogeneous Soln : complementary function Particular Soln : particular integral Let. Chap 3. Harmonically Excited Vibration. Consider pure harmonic excitation for understanding the behavior of a simple system. Nondimensional Amplitude. Complex Frequency Response.

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Chap 3. Harmonically Excited Vibration

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  1. Homogeneous Soln : complementary function Particular Soln : particular integral Let Chap 3. Harmonically Excited Vibration Consider pure harmonic excitation for understanding the behavior of a simple system Intelligent System Design Lab.

  2. Nondimensional Amplitude Intelligent System Design Lab.

  3. Intelligent System Design Lab.

  4. Complex Frequency Response Frequency Response Function (System Transfer Function) Intelligent System Design Lab.

  5. 3.2 Rotating Unbalance Equation of motion is Intelligent System Design Lab.

  6. Intelligent System Design Lab.

  7. c 3.5 Support Motion x y Intelligent System Design Lab.

  8. Intelligent System Design Lab.

  9. Intelligent System Design Lab.

  10. c F 3.6 Vibration Isolation To protect a delicate object from transmitted forces, F Intelligent System Design Lab.

  11. Histeresis loop : area enclosed by force-displacement curve. proportional to the energy lost per cycle. where is the energy lost per cycle due to a camping force 3.7 Energy Dissipated by Damping Damping is present in all system internal molecular friction – Structural damping sliding friction – Coulomb damping fluid resistance – Viscous damping Since mathematical description of damping is quite complicate, simplified damping modal such as viscous has been developed to evaluate the system response. Intelligent System Design Lab.

  12. 3.8 Equivalent Viscous Damping Equivalent damping Ceq: equate the energy dissipated by the viscous damping to that of the nonviscous damping force with assumed harmonic motion Intelligent System Design Lab.

  13. 3.9 Structural Damping From experiments of most structural metals, damping is independent of the frequency and proportional to the square of the amplitude Intelligent System Design Lab.

  14. 0 x H(r) -y Compare to viscous damping at resonance Intelligent System Design Lab.

  15. 3.10 Sharpness of Resonance Intelligent System Design Lab.

  16. Intelligent System Design Lab.

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