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Understanding CBUSH/PBUSH Input in Femap



I am trying to get a better understanding about Cbush Input in Femap.


01.PNGOrientation refers to CID in CBUSH card?02.PNGOrientation refers to OCID in CBUSH card?03.PNG


Does the orientation field in Model Element writes or refers to CID input in CBUSH Card? Similarly, the orientation CSYS input in PBUSH entry, does it refer to OCID entry in CBUSH card? Just a little confused by two orientation inputs required. 


Re: Understanding CBUSH/PBUSH Input in Femap


The CID field is populated by selecting either "Csys" or "From Property" on the CBUSH dialog.  If you select "Csys" whatever coordinate system is displayed in the drop down will be written to CID.  If you select "From Property" whatever coordinate system that is selected in the "Orientation Csys" drop down on the PBUSH dialog will be written to CID.  When using "From Property" make sure the checkbox next to Orientation Csys on the PBUSH dialog is checked.






The "CSys" orientation option allows multiple CBUSH to reference a single property but have different orientations (i.e. each CBUSH has the same stiffness in each direction, but the directions vary from CBUSH to CBUSH).  The "From Property" option may be more convenient if you have multiple CBUSH with all the same stiffness and all in the same direction.  (The "From Property" option was also the only way to define CID in older versions of Femap.)


The OCID field refers to the coordinate system ID of the CBUSH's offset (See the remarks section for CBUSH in the NASTRAN quick reference guide).  When defining the offset with Femap, OCID will be either -1 (default) or 0.  -1 implies that the offset is between the two grid points of the element.  This is the case if you select "Default," "Location" or "From Property" under the CBUSH dialog's "Offsets" group.  If you select "Vector" OCID will become 0, meaning that the offset is defined in Csys 0.




Re: Understanding CBUSH/PBUSH Input in Femap

Siemens Phenom Siemens Phenom
Siemens Phenom

In addition, you can always preview your input file using the Analysis Manager.


A.Mang.pngpreview Input.png



Re: Understanding CBUSH/PBUSH Input in Femap


Thanks for the lucid explanation Sir. I appreciate it!