Hi everyone! I'm trying to change the beam theory: I usually utilize the beam188 or beam189 element type in my simulations, and I discovered on the internet that this element type is based on the Timoshenko beam theory. I want to know how to change from Timoshenko to Euler-Bernoulli theory since I frequently need to compare my results to analytical results produced from Euler Bernoulli's theory.
I read in various papers that using beam4 instead of beam188 makes this possible, however when I add "et,matid,beam4" below the geometry, the solution fails. So my question is how can i solve this issue?
Thank you in advance.
Thank you very much, sir Claudio Pedrazzi
, for your attention to my question. Sir, I did not understand sir the meaning of the first point (BEAM4 is a legacy (archived) element)?Regarding the error messages I got are as follows:
- Real constant set 1 undefined but referenced by element 1.
- Real constant set 1 undefined but referenced by element 2 ...
In reality, while searching for an answer to my question, I found a case like mine in the Ansys learning forum. An Ansys user looking to use a beam element which is based on Euler Bernoulli's theory. One of the forum members offered him a solution and that was to use the beam4 element. Here is the link to the post I read: https://www.google.co.ma/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiwsbfHxuj0AhXI_qQKHXf1DhoQFnoECAsQAQ&url=https%3A%2F%2Fforum.ansys.com%2Fdiscussion%2F18150%2Feuler-bernoulli-beam-theory&usg=AOvVaw0WERJoRO7K-8fuAStuQ7yE
I tried to follow the same steps but I encountered problems in the definition of the real constants like for exemple the constant of torsion. Thank you once again for your help sir.
Yes that's right sir, me too i didn't find in the Ansys help of BEAM4 an indication of Euler-Bernoulli theory. In your opinion sir, which element should i use or how can i force the beam188 element to behave similarly as an element which is based on Euler-bernoulli's assumptions?
Yes, you are absolutely right sir, the beam element 188/189 is more complete but in my case I am trying to try a beam element based on Euler Bernoulli's theory only to check if the deviation of my numerical results obtained using beam188 is due to the effect of inclusion of shear strain and rotational inertia which are not included in Euler's beam theory used in the analytical calculations with which I compare my results. Thank you so much sir for your precious help.
Dear Hajar Rhylane,
According to ANSYS documents, the KEYOPT(3)=3 of BEAM188 is the equivalent to BEAM4. I surprised after I saw this comment in "ANSYS_Mechanical_APDL_Feature_Archive.pdf", because BEAM4 is a low order element whereas BEAM188 KEYOPT(3)=3 got two internal nodes which makes this element like a quadratic element. It is a little bit confusing to me why they have suggested this comment on BEAM4 element. I doubt that the result will be the same.
As also suggested by Dr. Claudio Pedrazzi
, it would be nice if you do a comparison between these two elements and let the community know whether there were any difference between results or not.
Thank you so much sir for your response. Yes for sur sir Hamidreza Ahmadi Moghaddam, i will in a future do this comparison to see the difference between the two elements.
Hi everyone, i'm interested in the same problem of @Hajar Rhylane, i want to use (in Ansys APDL) a beam according to Eulero-Bernoulli theory in order to comprare simulation results with analytic ones. How did you solved this problem?
Thank you
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