FEA help and linearisation ..........
FEA help and linearisation ..........
(OP)
Hello ppl ,
I have a query regarding a FEA analysis of a pressure vessel:
Suppose i have a shell and inside to it a bracket is welded and along with a pad ,
I have got the stress results form Ansys , i see that the maximum stress in the shell is the corner of the bracket pad .these are due to the stress singularities in the model or due to the contact stresses.
Now i want to do the linearisation for the model. what i have been told is to check the results at one node away from the maximum node ,
Now after doing linearisation at the one node away from maximum , i am into confused state , on comparing the membrane stresses and membrane+bending stresses.
I have heard of a term called the linearisation at local area and linearisation at transition area where we compare the local area linearisation membrane stresses to allowable and membrane +bending to 1.5 Allowable.
and linearisation stress at transition area-- membrane stress is compared to 1.5 allowable and membrane +bending to 3 times of allowable .
Now my query is which location will be the local area and which one will be the transition area in a analysis .
Please find the attachment.
I have a query regarding a FEA analysis of a pressure vessel:
Suppose i have a shell and inside to it a bracket is welded and along with a pad ,
I have got the stress results form Ansys , i see that the maximum stress in the shell is the corner of the bracket pad .these are due to the stress singularities in the model or due to the contact stresses.
Now i want to do the linearisation for the model. what i have been told is to check the results at one node away from the maximum node ,
Now after doing linearisation at the one node away from maximum , i am into confused state , on comparing the membrane stresses and membrane+bending stresses.
I have heard of a term called the linearisation at local area and linearisation at transition area where we compare the local area linearisation membrane stresses to allowable and membrane +bending to 1.5 Allowable.
and linearisation stress at transition area-- membrane stress is compared to 1.5 allowable and membrane +bending to 3 times of allowable .
Now my query is which location will be the local area and which one will be the transition area in a analysis .
Please find the attachment.





RE: FEA help and linearisation ..........
You don't say what code you design to but if you are doing this to ASME VIII Div.2 there is guidance in that code where to take the linearization at.
Mikeg7
RE: FEA help and linearisation ..........
Yes i am using ASME code for the design.
RE: FEA help and linearisation ..........
RE: FEA help and linearisation ..........
RE: FEA help and linearisation ..........
RE: FEA help and linearisation ..........
is it correct approach.
RE: FEA help and linearisation ..........
This whole business of starting one node away is meaningless. I have no idea what your mesh density is - nor should it matter. Follow the guidelines in Annex 5-A, we out it in for a reason...
If you think that some peak surface stresses will mess up your linearization (they won't), then do an elastic-plastic analysis.