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FEMAP 1D Tube with internal pressure



I am experiencing some errors when trying to simulate 1D elements (Pipe) with internal pressure.


I use the tube property and pipe in the property box as below:


 TUBE Element Type.png


Using NX nastran:




Then, i get the following error:




NX Nastram really does not support 1D Tubes with internal pressure? Is there any other way to simulate a 1D element of a tube or beam with internal pressure ? 


Using: Windows 7 with Femap 11.2.


Any help is appreciated.

Thanks in advance,




Re: FEMAP 1D Tube with internal pressure

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Igor,

Yes, believe or not in NX NASTRAN we don't have yet an 1-D CPIPE element to apply the internal pressure. The CTUBE element is the same as the CROD element except that its section properties are expressed as the outer diameter and the thickness of a circular tube. The extensional and torsional stiffness are computed from these tube dimensions.

The workaround you have in NX Nastran is to define a 1-D bend element named CBEND. The CBEND element is a one-dimensional bending element with a constant radius of curvature (circular arc) that connects two grid points. This element has extensional and torsional stiffness, bending stiffness, and transverse shear flexibility in two perpendicular directions.

You can use the CBEND element to analyze either curved beams, pipe elbows or miter bends. For example, you can use CBEND to model pressurized pipe systems and curved components that behave as one-dimensional members.


How to define a straight beam?. Well, use a big radius.

The only way we have to get a pure CPIPE element in NX NASTRAN is to file an ER at GTAC to let know SIEMENS that is critical to have this element available in the NX NASTRAN finite element library, we need to be more users requesting this feature, OK?.

Best regards,

Blas Molero Hidalgo, Ingeniero Industrial, Director
Blog Femap-NX Nastran:

Re: FEMAP 1D Tube with internal pressure


I see, thank you very much for your answer.