As we have seen from this lecture, the qualitative nature of the free response of a system will depend on the particular initial conditions given to the system. For example, for a two-DOF system released from rest (a zero initial velocity for all points in the system):
| If the initial conditions are in the first mode
the then response will be HARMONIC having a frequency of the first natural frequency and the shape of the response will remain in the first mode. |
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| If the initial conditions are in the second mode
then the response will be HARMONIC having a frequency of the second natural frequency and the shape of the response will remain in the second mode |
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| For ANY initial conditions other than those in a) and b), the response will be (generally) NON-HARMONIC and will be a LINEAR COMBINATION of the two modes. |
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