09-03-2010, 02:46 PM
I have done quite a lot of FEM analysis and below are points which I think they may be valuable to you. Examples below are based on STAAD Pro and it applies to other software like SAP2000, RISA similarly. Only thing difference is SAP2000/RISA may use a different CAD element for plate/shell in CAD. For STAAD Pro it uses 3DFACE element in AutoCAD for Shell/Plate element
1. For complicated model with lots of connectities between shells/plates and beam/column, manual meshing in CAD like AutoCAD, save as DXF, and import to STADD Pro is the most efficient way.
2. To avoid the connectivities problem after import into STADD Pro, you can
1) Export the STAAD model need meshing as DXF
2) Open that DXF in CAD lioke AutoCAD
3) Start meshing in AutoCAD using the exported model. For Plate/Shell element in STAAD, just draw 3DFACE
4) AutoCAD has powerfull 3D Orbit and manipulate tool for you to copy, mirro, array set UCS view, to get the meshing done easily, none of th Structural Software has such integratel tool for you to do that
5) Do the cleanup before import back, delete all grid line etc for helping meshing otherwise they will be imported back as beam
6) Save the finehed model in AutoCAD as 3D DXF file
7) Import the DXF back to STADD
8) Due to floating point tolerance, some nodes X,Y,Z value like 0.0 it will imported in STADD as 1E-015. To make eleminate issues like this, in STADD you can set tolerance as 0.001m, check duplicate nodes and merge them, similar check like check orphan node, duplicate plates, colinear member, plate/beam connectity , warping plate etc
9) After all above checking and correct findings, now you get a perfect model!
1. For complicated model with lots of connectities between shells/plates and beam/column, manual meshing in CAD like AutoCAD, save as DXF, and import to STADD Pro is the most efficient way.
2. To avoid the connectivities problem after import into STADD Pro, you can
1) Export the STAAD model need meshing as DXF
2) Open that DXF in CAD lioke AutoCAD
3) Start meshing in AutoCAD using the exported model. For Plate/Shell element in STAAD, just draw 3DFACE
4) AutoCAD has powerfull 3D Orbit and manipulate tool for you to copy, mirro, array set UCS view, to get the meshing done easily, none of th Structural Software has such integratel tool for you to do that
5) Do the cleanup before import back, delete all grid line etc for helping meshing otherwise they will be imported back as beam
6) Save the finehed model in AutoCAD as 3D DXF file
7) Import the DXF back to STADD
8) Due to floating point tolerance, some nodes X,Y,Z value like 0.0 it will imported in STADD as 1E-015. To make eleminate issues like this, in STADD you can set tolerance as 0.001m, check duplicate nodes and merge them, similar check like check orphan node, duplicate plates, colinear member, plate/beam connectity , warping plate etc
9) After all above checking and correct findings, now you get a perfect model!