Kirsch equations

The Kirsch equations describe the elastic stresses around the hole in an infinite plate in one directional tension. They are named after Ernst Gustav Kirsch.

Result

Loading an infinite plate with circular hole of radius a with stress σ, the resulting stress field is (the angle is with respect to the direction of application of the stress):

$\sigma _{rr}={\frac {\sigma }{2}}\left(1-{\frac {a^{2}}{r^{2}}}\right)+{\frac {\sigma }{2}}\left(1+3{\frac {a^{4}}{r^{4}}}-4{\frac {a^{2}}{r^{2}}}\right)\cos 2\theta$

$\sigma _{\theta \theta }={\frac {\sigma }{2}}\left(1+{\frac {a^{2}}{r^{2}}}\right)-{\frac {\sigma }{2}}\left(1+3{\frac {a^{4}}{r^{4}}}\right)\cos 2\theta$

$\sigma _{r\theta }=-{\frac {\sigma }{2}}\left(1-3{\frac {a^{4}}{r^{4}}}+2{\frac {a^{2}}{r^{2}}}\right)\sin 2\theta$

References

• Kirsch, 1898, Die Theorie der Elastizität und die Bedürfnisse der Festigkeitslehre. Zeitschrift des Vereines deutscher Ingenieure, 42, 797–807.