how to model border conditions :part welded to a non rigid body
how to model border conditions :part welded to a non rigid body
(OP)
Hello Everybody,
I’m now working a welded structure. The purpose of the study is to decrease the weight and keep a safety factor equal to 1.5
I tried to do a local study of one part of this structure, so I decided to isolate this part (to refine mesh and gain calculation time). The problem is that this part (formed by plates and sections) is assembled to the whole structure by welding.
I m asking how to model the border conditions in case of an isolated study of a part welded to a non rigid body. (Zero displacements border condition seams to give wrong results).
Thank you and Best regards.
I’m now working a welded structure. The purpose of the study is to decrease the weight and keep a safety factor equal to 1.5
I tried to do a local study of one part of this structure, so I decided to isolate this part (to refine mesh and gain calculation time). The problem is that this part (formed by plates and sections) is assembled to the whole structure by welding.
I m asking how to model the border conditions in case of an isolated study of a part welded to a non rigid body. (Zero displacements border condition seams to give wrong results).
Thank you and Best regards.





RE: how to model border conditions :part welded to a non rigid body
corus
RE: how to model border conditions :part welded to a non rigid body
1) calculate the equivalent spring stiffness of the rest of your part, or at least the parts to which your local model is attached, and attach springs to your local model, then fix your springs with stiff boundary conditions. This is particularly easy if your local model is welded to beams.
2) use your global model to determine displacements at locations specific to your local model, then apply prescribed displacements to contort your local model. You may have to be creative about how you apply the displacements so that you don't end up with some localized stresses overpowering your "real" results, but it can be done.
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: how to model border conditions :part welded to a non rigid body
RE: how to model border conditions :part welded to a non rigid body
If it were me, I'd take rb1957's suggestion to model the supports as elastic. The question is how elastic? That's something you'll have to experiment with--forgetting about Poisson's entirely, just changing the stiffness of the elastic support could or could not change your results significantly. If you use springs, you could estimate the spring constant by dividing the Young's modulus of the support structure you are trying to model by the thickness of said support structure where the welds are used. It's not perfect, but it gives you something to start with.