Flat Plate Bending Weld Stress

[ENG2194]

Hello, I have scenario where a flat plate is welded inside a ridged cylinder with top and bottom fillet welds all the way around and pressure on top. Im trying to figure out how to calculate the bending stress in the fillet welds. I was thinking I could approximate it like the following beam example where "b" is the circumference of the ID of the ridged cylinder. However, even with this approximation I'm struggling to figure out what to use for "M". For clamped flat plate stress calculations the radial bending is calculated in terms of lbf-in/in then divided by plate thickness squared to get in terms of stress. Not sure what bending moment could be approximated as in terms of lbf-in to be able to fit in the beam weld stress equation below.

 

[JStephen]

To fit that specific model, you could use b as the full circumference and M as full circumference x moment/in. Or use b as 1" and M as moment/inch, should be the same.
If it's a code-related question, refer to the code in question for weld requirements.
That model assumes rigid support and flexible beam. If you consider the rotation of the cylinder wall, you would get lower weld stresses. So if you come up with unreasonable weld sizes, it can be refined.

 

[Snickster]

Could you provide a sketch. I think you are saying you have a flat plate installed in a pipe in the center and from one end to the other, such that it splits the top and bottom evenly into two compartments. The upper compartment is pressurized so that it causes bending of the plate and bending and shear in the welds. Is this correct?