Welding
Welding
(OP)
Hi,
I want to determin the minimum safety factor of a statically loaded weld. Does this task require any weld-specific considerations, or can I simply approximate the case by connecting the welded parts with a separate weld-like part?
Pingen
I want to determin the minimum safety factor of a statically loaded weld. Does this task require any weld-specific considerations, or can I simply approximate the case by connecting the welded parts with a separate weld-like part?
Pingen





RE: Welding
RE: Welding
I think most analysts simply ignore the weld bead on large, complicated models and we look at the areas that would be welded for stress beyond the "heat effected zone" knock-down value. If it appears to be a problem, we model local areas and add the weld beads.
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: Welding
You guys, describe weldments as complex structures that can be analysed with different levels of detail. I have a feeling that the relation between the amount of time spend on the analysis and the accuracy of the obtained results is quite non-linear, and that it sometimes takes much additional time to achieve slightly better results. Usually, I don't need to obtain super accurate results, but they must be on the safe side and reasonable. I need a happy-medium-method that I can trust.
Furthermore, I'm not very experienced in FEA and I think it would be interessting to know how other professionals analyse weldments.
Thanks again,
Pingen
RE: Welding
RE: Welding
This article can be helpful:
www.aws.org/wj/supplement/Weaver/ARTICLE2.pdf
For a fillet weld, the required conditions are as follows:
1) equivalent stress < tensile ultimate strength / (beta_w * gama_M2)
2) normal stress prependicular to the weld throat < 0.9 * tensile ultimate strength / gama_M2
where,
beta_w : correlation factor function of the grade of the steel
gama_M2 (= 1.25) : safety factor for welded assemblies
In spot weld analysis, no spot tensile shearing may be lower than a given shear force based on the thickness of a sheet e, the diameter of the weld nugget, the material and the tensile shear ultimate strength.
Tables give this type of data.
If two sheets of different thicknesses are welded together, e is the thickness of the thinner of the two.
In this case you can use a coarse FE mesh to transfer loads only.
Regards,
Torpen
RE: Welding
All the above are valid answers and, as you said it yourself, cover the subject way deeper than you need.
Going back to the core of your question: for simple applications it is reasonable to consider that you don't need to model the weld, as long as you probe the results in the areas where the weld is and compare these results with allowable values for welds. As JStephen said, there are "documents" where you can find these comparison values globally accepted as reference documents, namely the AISC, DIN or FEM norms and codes (ex. FEM 1.001) - which actually take into consideration the type of weld, loading direction, etc.
Just make sure your application can be considered a "simple" one, with no asymmetric or particular stress concentrating welds.
dulmant