Weld Section Modulus
Weld Section Modulus
(OP)
I am looking at the weld of a 5/8" diameter bar to a 3/4" bar post. Given the tolerances I know I can't get an adequate fillet weld all around. So my question is this, I am looking at Blodgett's book and his table showing the section moduli for different weld shapes. He shows the modulus for a circular weld, but is there any way that I could find the section modulus of two arcs instead of a full circle to account for no effective weld at the narrow sides of the connection? I have attached a quick sketch showing what I mean.





RE: Weld Section Modulus
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Weld Section Modulus
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Weld Section Modulus
I'm not so sure. This would produce a serious over estimate in the strong axis direction and a serious underestimate in the weak axis direction.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Weld Section Modulus
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Weld Section Modulus
In addition to that "better painted" (better plastic-coating ?) , it will be (over time) much stronger because of no "ends" of the continuous weld, rather than 4x "end points" of the two interruppted side weld arcs.
RE: Weld Section Modulus
Are you using the line properties method?
RE: Weld Section Modulus
KootK: That's a very good idea. Thank you.
racookpe1978: There will in fact be weld all around. Due to the geometry though, it's unreasonable to assume a full sized fillet all the way around. That is the reason I wanted to determine what the amount of effective weld is. The weld drawn in the sketch is what I assumed it to be. In the sketch the welds are cut off at 45 degree angles, but the actual weld is all around.
BUGGAR: Thanks for that. I didn't know that AutoCAD would do that for me. Yes, I was using the Blodgett method of considering it a circular line. (S=pi*d^2/4)
RE: Weld Section Modulus
or type "massprop" into the command line
RE: Weld Section Modulus
RE: Weld Section Modulus
You have this in CAD already, make the weld a "region" then get the "massprop" of the region to determine the moment of inertia. You can determine the section modulus form there.
RE: Weld Section Modulus
The error in his approximate calculation will probably be less than the variability in the finished weld, so it's "good enough".
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"