Concerning direction to draw lines!
Concerning direction to draw lines!
(OP)
When you work with line elements and draw lines between keypoints, then you have to think to draw them on the same direction, else you may get strange result when doing a torque diagram so I have been told.
That is something i found troubling especially if you have a fem model with many lines interacting with each outer, if you get a problem you may think that it may be because I have drawn the lines in the wrong direction
Any advices or tips to calm me.
Kindly Paul-Martin
That is something i found troubling especially if you have a fem model with many lines interacting with each outer, if you get a problem you may think that it may be because I have drawn the lines in the wrong direction
Any advices or tips to calm me.
Kindly Paul-Martin





RE: Concerning direction to draw lines!
I have the same problem, when I mesh lines with beam elements with axis offset. Since the offset direction is dependent on the line direction, some beams are offset in the wrong direction. So I have to correct this problem by manually inverting the lines (lreverse).
Regards,
Alex
RE: Concerning direction to draw lines!
RE: Concerning direction to draw lines!
Regards,
Alex
RE: Concerning direction to draw lines!
I have defined an orientation keypoint and it doesn't work! I still have to manually revert the lines! I assign the orientation keypoint to the lines through latt and the orientation of the lines determine if the orientation keypoint means "positive element y coordinate" or "negative element y coordinate". If I would directly generate the beams, it would work, but that would be to complicated.
RE: Concerning direction to draw lines!
RE: Concerning direction to draw lines!
RE: Concerning direction to draw lines!
Also, based on your description of how difficult these changes are to make, I am lead to assume you are building this model in the GUI. I would recommend using command input text files. This makes these modification much easier, and facilitates the use of APDL, which is great for this type of modeling (allow parametric changes to size, increase in accuracy, etc).
RE: Concerning direction to draw lines!
I (allmost) never use the GUI, I have a good understanding of cross sections and coordinate systems. Nevertheless I have the described problem (see above).
It seems to me, that the orientation kp and the orientation of the line determine the offset direction of the cross sections. That means, the OKP designates not the positive Z axis but just the z axis. Whether the OKP lies on the positive or negative side of the z axis depends on the line orientation.
So the line orientation plays an inportant role. Since the line orientation is practically randomly choosen, I have to look at the lines and correct the wrong oriented ones.
I assume you have a very good understandig of this things, so perhaps you can confirm or infirm this to me...
Regards,
Alex
RE: Concerning direction to draw lines!
I could not look into this until I was working in ansys again. Well, now I am. If you are still watching this thread, let me know. I drew a line, issued latt, meshed, and noted orientation of my non-semetrical cross section. Then I cleared the mesh, reissued latt, remeshed, and finally noted that the two meshes looked identical. Please confirm you have seen otherwise, and provide specifics so we can figure out what is going on here. Any chance your OKP is perpendicular to the real Z axis (i.e., do you have your axis crossed).
Regards,
Mason
RE: Concerning direction to draw lines!
Hallo again,
like I said, in my post from 3 Apr 06 3:14, the OKP determines the direction of the z axis. The sign of the sign axis is determinate by the line orientation. So in my opinion, you must allways check the mesh and, if necessary, reverse the lines.
Regards,
Alex