# Stress Concentration Factor – Why a Specific Range?

I was trying to find the stress concentration factor for a specific situation and I found two different resources for it. Ref: Shigley's mechanical engineering design Ref: Roark's Formulas for Stress and Strain

However, I found both resources were only applicable for d/w <0.3

Why is it data can only be found in this specific range? The example I have has a value of 0.5 and is therefore outside the range so I am unsure how to proceed and what the implications are of it being outside the stress concentration factor range.

Any help is greatly appreciated, thanks

From what I see, in this picture from the Shigley book, if I really had to, I would extrapolate to 0.5 (or more precisely interpolate between the limit cases). The limit cases for very thick plate (d/h=0) and very thin plate ($$d/h\approx \infty$$) have values for d/w close to 0.7. (I would hazard a guess that these solutions are based on analytical assumptions for plane stress and plane strain)