Analysis without constraining
Analysis without constraining
(OP)
Is it possible to do analysys without any constrain in the model?
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Analysis without constraining
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RE: Analysis without constraining
Well there is an option of inertia relief while defining the solution under the parameters tab in NX Nastran. If you'll work with this parameter the solution will work fine. I hope it helps.
Regards
Tejras
RE: Analysis without constraining
but if you're applying real loads, even if they are a balanced load and reaction set (ie no nett load) you still need to constrain the 6 rigid body motions.
another day in paradise, or is paradise one day closer ?
RE: Analysis without constraining
________________________
FEMAP v11.1.0
MSC Nastran v2013
RE: Analysis without constraining
another day in paradise, or is paradise one day closer ?
RE: Analysis without constraining
________________________
FEMAP v11.1.0
MSC Nastran v2013
RE: Analysis without constraining
one talked about inertia relief ... ok, that's applying inertia body forces to react the applied load. I guess it barely possible that a FE code could determine the balancing body force to an applied set of loads, but I haven't seen/used it. and if I'm being pedantic I could call that a constraint, in that the analysis would be determining the nett force applied to the body, the body's CG, and the six accelerations required to provide equilibrium, and the internal reactions to these (similar to constraining the CG in 6 dof).
another day in paradise, or is paradise one day closer ?
RE: Analysis without constraining
Though, IMO, the question is vague as it stands and since nobody asked for clarification, I thought I would.
It's getting late, enjoy the weekend!
________________________
FEMAP v11.1.0
MSC Nastran v2013
RE: Analysis without constraining
No i am not doing model analysis. I am still at the learning stage. So am not aware of inertia relief. Can u pls explain in detail what is it? How and in which situation i can use it? Constraining for me is big problem, there are manny cases where i dont want to constarin at all but i have to. For eg. Pressure vessels, since the pressere is equal in all direction, wherever i constrain the high stress will be adjecent to the constraining point. I learned that in axisymmetric model i can work with only one degree of freedon fixed but if i use same model in solid i have to fully constrain it. Why is it so?
RE: Analysis without constraining
All stress analysis FEMs need to be restrained in 6 dof (to take out rigid body motion, to "nail" the model in space). these constraints should not generate reactions. if they do it means your loads are not balanced, or your constraints are over constraining the model. in a pressure vessel you should be able to constrain 3 nodes (xyz, xy, x) to take out rigid body motion. if you are new the FEA, read up on this.
If you tell the FEA that this is an axisymmetric model, then it applies the relevant constraints, and so maybe you need fewer rigid body constraints. read up on this. if you have solid elements in your model, you have only three dof at each node ("fully constrain" is usually used to describe constraining all 6 dof).
another day in paradise, or is paradise one day closer ?
RE: Analysis without constraining
Inertia relief command has worked for me and i am getting my results. My preesure vessel now dont need any constraining in any direction.
Hello rb1957,
I now little bit understood about inertia relief. Thanks to u But i want to learn it in detail, i searched in help file but there is very little written about it. If u know any reference then pls suggest me.
And yes i understand the requirement of restraining the model in all degrees of freedom as its in space.
I need to read more about it can u pls suggest me something?...