Torsional constant for Complex Mullion sections
Torsional constant for Complex Mullion sections
(OP)
I am looking for an efficient and quick way to calculate torsional constant,J for mullion sections which are unique are highly complex (http://www
It is time consuming and inefficient to hand calc the J(torsional constant). A worksheet wont work as each section is unique.
The values of area, moment of inertia, radius of gyration can be calculated for these complex sections in matter of seconds using AutoCad, it is the J, "torsional constant" I am have problems with.
What I really am looking for is a program that calculates J for non conventioanal sections, or if AUtoCad has a LISP developed that covers J.





RE: Torsional constant for Complex Mullion sections
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Torsional constant for Complex Mullion sections
RE: Torsional constant for Complex Mullion sections
RE: Torsional constant for Complex Mullion sections
J = Ix + Iy
Where Ix and Iy are the moments of inertia about the x and y axes through the centroid.
Don
Kansas City
RE: Torsional constant for Complex Mullion sections
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Torsional constant for Complex Mullion sections
To use the program, you have to region a shape in AutoCAD and then explode the shape and save the AutoCAD file as a DXF file.
Then open Section Maker and do file - import - then you will be allowed to change the material of the shape to Steel, Aluminum, etc - then move the shape to the centroid and it will have a table listing the J value (along with the Ix, Ix, Sx, etc values of the shape).
RE: Torsional constant for Complex Mullion sections
It's likely that the mullions are cold formed elements and if so, I would defer to the Cold Form Design Handbook or texts by Wei Wen Yu on the matter. unfortunately most cold form design is about calculating section properties.
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Torsional constant for Complex Mullion sections
I have Mechanical AutoCAD 2006 which has a Finite Element program in it - will that give me the Torsional Constant of complex mullions? If so, how do I get it to do this?
-SilenceJes
RE: Torsional constant for Complex Mullion sections
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Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Torsional constant for Complex Mullion sections
You need a 3D FEA package, for reasons that Greg gave (you have open/reentrant/non-circular sections which will warp when twisted). AutoCad Inventor Professional comes with a bundled "lite" version of Ansys FEA, for instance, if you wanted to stay with Autocad (but you'll have to learn how to use Inventor - not hard, and you can import the 2d section from Autocad directly and extrude it to form a beam). Similar products exist for ProE and Solidworks (SW can also import autocad files). And NEi offers a good price for their stand-alone FEA modeller.
RE: Torsional constant for Complex Mullion sections
In other words how do I use the AuotCad equivalent command for "SUBTRACT".
RE: Torsional constant for Complex Mullion sections
http://virtual2002.tau.ac.il/users/www/34085/Roark's%20Formulas%20for%20Stress%20and%20Strain%20(7th%20Edition)/2542x_10.pdf