Boundary conditions for a grid tube under combined loading

AI Thread Summary
The discussion focuses on modeling the linear buckling behavior of a cylinder using BEAM4 elements in ANSYS Mechanical under combined axial compression and bending moments. The user seeks guidance on setting appropriate boundary conditions to maintain rigidity at the ends while allowing motion due to loading. They encountered issues where the buckling modes under combined loading matched those from pure axial compression, despite applying the CERIG command and clamping one end. The user reports that the static analysis results appear correct, with expected curvature and compression, but they are uncertain about the boundary condition setup. Clarification on the correct approach to boundary conditions is requested to resolve the modeling discrepancies.
Vigardo
Messages
87
Reaction score
7
Dear experts,

I´m trying to model in ANSYS Mechanical (v14.5) the linear buckling behavior of a cylinder made of BEAM4 elements under combined loading (axial compression and bending moment) applied at the ends.

How should I set up the boundary conditions of a cylinder to keep rigid the ends while allowing their motion under both compressive force and moment?

After rigidifying one end of a cylinder made of BEAM4 elements with the CERIG command (CERIG,P) I´ve found confusing results: the buckling modes under combined loading are equal to the modes obtained only under pure axial compression. All nodes from the other end were fully clamped. I think that I successfully selected master and slave nodes and that the results from the initial static analysis seem ok, i.e. the moment applied at the master node node leads to some curvature and the axial force to some compression while the end nodes keep rigid.

What am I doing wrong? Any comments would be highly appreciated.

Thanks a lot in advance!
 
Engineering news on Phys.org
Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 

Thread 'Race car suspension Class'

Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
View full post »

Thread 'Cantilever help'

I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
View full post »
Thread 'What's the most likely cause for this carbon seal crack?'

Thread 'What's the most likely cause for this carbon seal crack?'

We have a molded carbon graphite seal that is used in an inline axial piston, variable displacement hydraulic pump. One of our customers reported that, when using the “A” parts in the past, they only needed to replace them due to normal wear. However, after switching to our parts, the replacement cycle seems to be much shorter due to “broken” or “cracked” failures. This issue was identified after hydraulic fluid leakage was observed. According to their records, the same problem has occurred...
View full post »

Similar threads

Column buckling under axial+transverse combined load
Replies
2
Views
2K
ANSYS Mechanical APDL - Rotating Boundary Conditions
Replies
1
Views
4K
Airframe FEA boundary conditions
Replies
1
Views
2K
How Does ANSYS v12 Enhance Rotordynamic Analysis?
Replies
23
Views
37K

Hot Threads

Recent Insights

Back
Top