Advanced Structural Analysis/Part I - Theory/Failure Modes/Plastic Failure/Special Members/Welds/Fillet Welds

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f_{uc} = characteristic ultimate stress of parent material
f_{euc} = characteristic ultimate stress of electrode material
f_{wd} = dimensioning ultimate stress of joint
\gamma_n = application partial coefficient
\phi = reduction factor that corresponds to the weld class
F_{\alpha} = transverse load
F_{||} = longitudinal load
A = surface area of investigated cross section
\alpha = angle between transverse load and the investigated cross section

Summary of Formulas[edit]

 F_{R||} = 0.6 A f_{wd}

 F_{R\alpha} = A \frac{f_{wd}}{\sqrt{2 + cos(2 \alpha)}}


f_{wd} = \phi \frac{\sqrt{f_{uc} f_{euc}}}{1.2 \gamma_n}  ;if  f_{uc} < f_{euc}

f_{wd} = \phi \frac{f_{euc}}{1.2 \gamma_n}  ;if  f_{uc} >= f_{euc}

Interaction formula:

 (\frac{F_{S||}}{F_{R||}})^2 + (\frac{F_{S\alpha}}{F_{R\alpha}})^2 <= 1

Partial Coefficients[edit]

 \phi = 0.9 in most cases.  \phi = 1 is acceptable for high quality butt welds.

 \gamma_n = 1.0, 1.1 or 1.2 depending on whether failure repercussions are regarded as mild, severe or very severe.