finite element analysis
finite element analysis
(OP)
Is there any basis for allowing a stress equal to 1.5 times yield stress at a hot spot, assuming the structure will "adjust" for the load and the yield stress will increase due to strain hardening? I am unable to find any refernce for this hypothesis. How does one determine if this 1.5 times yield stress will cause failure or just a distortion? The material is steel with 50 ksi yield and 70 ksi ultimate stress levels. The material is assumed to be ductile. Von Mises indicates I am in failure territory. Any comments are very helpful.





RE: finite element analysis
The following previous threads will likely provide you with the information you are looking for:
Explanation of Very high local stresses in FEA Results Thread727-52443
&
Ignoring high local stresses in FEA Thread727-52469
You may also want to use a more descriptive subject line in future posts.
Best regards,
Matthew Ian Loew
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: finite element analysis
RE: finite element analysis
Also, this assumption can't be considered universal as it neither recognizes the distinction between various levels of ductility nor the nature of stress redistribution that occurs for different geometries.
So, is it used? Yes. Do I recommend it? No, not in the most general sense, but neither do I condemn the practice.
Brad
RE: finite element analysis
I think first you need to review FEA model with FEA analysts to see if there are any possiblity of high stress from modeling method. Be care of high stress in
1. Between component interface in assembly
2. Boundary condition applied areas
High stresses in those areas usually could be ignored or at least be reviewed carefully.
If modelling is fine, you also have to look at the stress level around these "hot spot". If the surround area is much low than yield stress, these high stresses would be redistributed and wouldn't cause any yield.
In addition, non-linear analysis may also help... I am not very sure.
Never take a "rule of thumb" (1.5 or 2.0)for silver bullet. For example, if somebody put a sharp corner in a high stress area. The stress will continues grow to infinite with finer mesh. You will get a stress a million times yield stress