modeling elements mass21

[marcomer]

Bye to all,
I am doing the modal analysis of an ansys building, for which the cover is not inserted in the model, but takes into account defining it as a structural mass (mass21); I have defined the element and the real constants, but I do not understand how to apply these masses to certain points of the model (I want to apply them to the top part of the masonry and that is where the coverage actually downloads).

Does anyone know how to do that?

 

[stefano.garbin]

see ansys mechanical apdl - modeling and meshing guide - chapter 11 "coupling and constraint equations". (commands "cp" and "ce")
Are you sure the cover does not significantly contribute to the ways of vibrating? ? ?

 

[marcomer]

but these commands allow to create internal constraints between two bodies? because I don't really have to shape the cover, but only consider its contribution with these massive knots21 in which I concentrate mass and inertia. The problem is that I can't find guides explaining how to apply these masses, because not having shaped the cover I thought they had to apply to the supports between cover and masonry but I saw that in this way I change all the modal forms and obtain of the very low frequencies. .

 

[Michele1980]

Hi.

I also have the same problem, did you happen to understand how to apply the masses?

 

[giuma]

I also had this problem but I didn't have to deepen it because the professor made me change the model.. .

 

[Michele1980]

I somehow made it.
1 - add the mass21 element in the list of elemnts
2 - in the real props, you have to add a new property that will be linked to the mass 21
3 - therefore the three masses mx, my, mz plus ixx, iyy, izz (normally mx=my=mz) and the moments if possible calculate with a cad if geometry is complicated.
4 - you enter the meshatore, and in my case, since I wanted to add the mass on one point, I have keypoints filter and I assigned the mass, so you mesha and the game is done.

I hope I was useful, only do I not understand if instead of selecting keypoints instead I assigned the mass to a line, the mass is broken down on the length of the line?