Acoustics and Vibration Animations
Daniel A. Russell, Ph.D.
Graduate Program in Acoustics
The Pennsylvania State University
All text and images on this page are ©2004-2011 by Daniel A. Russell
and may not used in other web pages or reports without permission.

Multiple DOF Systems

A 1-degree-of-freedom system has 1 mode of vibration and 1 natural frequency



mpeg movie

A 2-degree-of-freedom system has 2 modes of vibration and 2 natural frequencies


mpeg movie
Note: the movie shows the two mode shapes, but does not correctly show the natural frequencies. In reality, the two modes vibrate at distinct frequencies.

A 3-degree-of-freedom system has 3 modes of vibration and 3 natural frequencies


mpeg movie
Note: the movie shows the three mode shapes, but does not correctly show the natural frequencies. In reality, all three modes vibrate at distinct frequencies.

A 4-degree-of-freedom system has 4 modes of vibration and 4 natural frequencies


mpeg movie
Note: the movie shows the four mode shapes, but does not correctly show the natural frequencies. In reality, all three modes vibrate at distinct frequencies.

A continuous system has an infinite number of vibrational modes natural frequencies

The animation at left shows the first four mode shapes for a fixed-fixed string. This is the only animation on this page which correctly shows the different modes at their correct relative resonace frequencies. For an alternate look at the vibration of a fixed-fixed string in terms of Standing Waves see the Vibration of a Fixed-Fixed String.

Back to the Waves and Vibrations Demo Page