13. Normal Modes of Vibration

Try these first

1. 1.

   Define what normal modes of vibration are.

   Hint

   Think about how a swing moves naturally.

2. 2.

   What is a natural frequency?

   Hint

   Consider the rate of a pendulum's swing.

3. 3.

   What are normal modes?

   • A. Natural vibrations of a system
   • B. External forces acting on a system
   • C. Damping effects on a system

   Hint

   Think about how a swing moves freely.

4. 4.

   True or False: Each normal mode has an associated natural frequency.

   • True
   • False

   Hint

   Consider how different musical notes correspond to different vibrations.

5. 5.

   Given a three-storey MDOF system, compute the characteristic equation to determine the natural frequencies.

   Hint

   Focus on understanding how the equation is derived from modal analysis.

6. 6.

   Analyze the effect of adding damping to an already calculated modal response. Discuss how it alters mode shapes.

   Hint

   Consider how energy dissipation might affect vibrations.