ricoka2
Civil/Environmental
- Mar 7, 2003
- 1
Hi,
I am trying to model the shell-to-base joint of a cylindrical tank on elastic foundation and have some problems. Concerning the model:
- For reasons of simple analysis and fast calculation I'd like to keep the problem 2D with axisymmetric elements.
- To get the reactions, especially the moments in the region I made a coarse model of the cylinder with Shell51 elements.
- As the foundation has an nonlinear material behaviour, which I'd like to consider later, I decided to model it with plane182 elements.
- To model the contact between the two bodies, I used Targe169/Conta171 pairs.
And now my questions:
1. I used the simple case of a plate under uniform normal pressure to verify the deflection of the plate. The deformation of the foundation is correct (F=C.u), the deflection of the steel plate is a little bit too big, due to penetration. Can anybody tell me how to deal with penetration. Which influence has penetration in more complex cases with bending moments etc.? Can it always be substracted from the deflection to obtain more precise results? Can it be avoided?...
2. As I already said, I'd like to submodel the shell-to-base joint region to consider the fillet and to analyse fatigue behaviour, etc. Is this possible with 2D Models? Can I use Plane182 for this? I got the following error message when I tried it: "No interpolation nodes lie on or near the selected elements. The CBDOF operation produced no results." Is it due to a bad input file or is it just because it is not possible to build a model/submodel pair with the used elements?
3. Later I want to introduce the nonlinear material behaviour of the foundation. The material cannot afford tension, but only compression. Once it deformed it cannot deform back, so that each deformation is plastic. The path of the stress/strain diagram is linear. How can I model this? Can anybody tell me which material models in ANSYS can be used for this purpose.
Any help is really welcome and I'd like to thank you in advance.
Best Regards
Dipl.-Ing. E. Holtzhauer
University of Karlsruhe
P.S. Just in case of doubt, I am not a student but work as a structural engineer at the Institute for steel constructions.
I am trying to model the shell-to-base joint of a cylindrical tank on elastic foundation and have some problems. Concerning the model:
- For reasons of simple analysis and fast calculation I'd like to keep the problem 2D with axisymmetric elements.
- To get the reactions, especially the moments in the region I made a coarse model of the cylinder with Shell51 elements.
- As the foundation has an nonlinear material behaviour, which I'd like to consider later, I decided to model it with plane182 elements.
- To model the contact between the two bodies, I used Targe169/Conta171 pairs.
And now my questions:
1. I used the simple case of a plate under uniform normal pressure to verify the deflection of the plate. The deformation of the foundation is correct (F=C.u), the deflection of the steel plate is a little bit too big, due to penetration. Can anybody tell me how to deal with penetration. Which influence has penetration in more complex cases with bending moments etc.? Can it always be substracted from the deflection to obtain more precise results? Can it be avoided?...
2. As I already said, I'd like to submodel the shell-to-base joint region to consider the fillet and to analyse fatigue behaviour, etc. Is this possible with 2D Models? Can I use Plane182 for this? I got the following error message when I tried it: "No interpolation nodes lie on or near the selected elements. The CBDOF operation produced no results." Is it due to a bad input file or is it just because it is not possible to build a model/submodel pair with the used elements?
3. Later I want to introduce the nonlinear material behaviour of the foundation. The material cannot afford tension, but only compression. Once it deformed it cannot deform back, so that each deformation is plastic. The path of the stress/strain diagram is linear. How can I model this? Can anybody tell me which material models in ANSYS can be used for this purpose.
Any help is really welcome and I'd like to thank you in advance.
Best Regards
Dipl.-Ing. E. Holtzhauer
University of Karlsruhe
P.S. Just in case of doubt, I am not a student but work as a structural engineer at the Institute for steel constructions.