Systems with Rigid Body Modes
Below is a set of simulation results for a two-DOF translational system having a rigid body mode resulting from zero initial stretch/compression in the spring and initial velocities for the two masses.
- Note that the rigid body mode in this case has the two masses moving together with NO strain and NO oscillations (always true of a rigid body mode).
- The second mode is a vibrational mode corresponding to a frequency of the second natural frequency. Here the second mode has the two particles moving 180 degrees out of phase with respect to each other.
- The total response is a sum of the rigid body mode and the vibrational mode. This results in an "inchworm" type of motion for the system.
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