{"id":359794,"date":"2024-04-01T11:14:17","date_gmt":"2024-04-01T11:14:17","guid":{"rendered":"\/forum\/forums\/topic\/probem-with-modal-analysis\/"},"modified":"2024-04-01T11:14:17","modified_gmt":"2024-04-01T11:14:17","slug":"probem-with-modal-analysis","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/probem-with-modal-analysis\/","title":{"rendered":"Probem with modal Analysis"},"content":{"rendered":"

Hello,<\/p>\n

I’m having some issues with a modal analysis of a full ship model in APDL. The model has all panels and stiffeners in it, when I run the modal analysis I get the first six modes equal to zero which makes sense as it is a free-free model but then the following modes are not the global modes of the entire ship but just of singular panels. Is there a way to eliminate the local modes? I know in FEMAP\/Nastran this would be done with the ASET constraint using master nodes but I don’t know how to do it in APDL?<\/p>\n

Secondly, if I want to use FLUID30 elements to simulate the water around the ship is there a way to just overlay them onto the elements of the ship using something like the ESURF command? My idea was something along the line of: <\/p>\n

et,5,30 
mp,dens,5,1250
mat,5
esel,s,cent,z,0,3800
esurf <\/p>\n

But ESURF does not work here as it only works for line and area elements, is there another way? Any help is much appreciated, thanks in advance! <\/p>\n","protected":false},"template":"","class_list":["post-359794","topic","type-topic","status-closed","hentry","topic-tag-Modal_Analysis-1","topic-tag-ansys-apdl","topic-tag-ansys-mapdl-1","topic-tag-apdl"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t