Thank you for your responses.

I was hoping to learn how the bend mass (or flex factor) is distributed so I can explain why the different behavior shows only for the first mode (in a bend model), and not for the other modes nor a pipe only model?

Why does the first frequency alone increase (845 to 970Hz.) with a finer mesh (with MORE mass participation), when the commonly observed (and explained) fact is that the frequencies decrease with a finer mesh (incl the first one) because of more mass participation?

Thanks again.