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Scaling of motional mass
Posted Feb 10, 2013, 5:06 AM EST Structural Mechanics & Thermal Stresses 1 Reply
Thanks to this forum I have found out how to calculate the motional mass for different vibrational structures. The calculation of (MPF_mod1.u^2)/(TotalMass) and for v and w gives a nice distribution of motional masses, and taking enough eigenmodes sums up to the total mass. However I think there must be a further normalization I do not understand because for the clamped membrane case I find a participation factor of a half the total mass instead of the 1/4 it is in reality. The same is the case for a clamped wire/beam where the motional mass should be half the total but instead is about 0.7 of the total mass. I attach this case.
Am I just confusing the normalization?