Discussion Forum

Hello, I know this is is likely one of the most asked questions on this site but I think that this will ultimately serve as a guide and also I just have some clarifying questions. First I would like to note that the powerpoint that COMSOL here:

www.comsol.com/paper/effective-mass-calculations-using-comsol-multiphysics-for-thermomechanical-calib-15962

I'm almost certain gives an incorrect way to find effective modal masses. The reason I believe this is because every other guide on finding effective masses does not use their technique of integration. Instead what I have found is this..

Given a structural mechanics and eigenfrequency study once I have created my resonator that has certain fixed boundary constraints (imagine a doubly clamped beam for concreteness) . Now from what I understand in order to find the effective mass ratio we need to first tell COMSOL that we want it to compute modal participation factors. To do this we go to Study1 and find eigenfrequency study and change the output from RMS to mass matrix. Now if I compute the study and then go to the results and make a new global evaluation and evaluate the modal participation factors and can be found in the study tab and then I calculate the square of each participation factors and divide by the mass the get the effective mass of that direction. Is this true?