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Cracks frequently change their shape at geometric discontinuities such ascorners or holes. Using the MTU automatic fatigue crack propagation softwareCRACKTRACER this phenomenon is investigated for a simple specimen with squarecross section and drilling hole. The analysis shows that the change in crack shape takesplace as soon the discontinuity is reached and can be interpreted as being triggered bythe resulting change of intersection angle with the free boundary. This leads to aviolation of the previously existing equilibrium conditions and a sharp increase of thelocal stress intensity factors (K-factors). Thereupon, the crack rapidly convergestowards a new equilibrium configuration.