Fracture toughness

Summary

Fracture toughness is the resistance of a material to the growth of a crack. In linear elastic fracture mechanics it is the critical value $K_{Ic}$ of the mode I stress intensity factor. At this value a crack under plane strain starts to grow. It is a material constant, measured on standard cracked specimens, and it is used to compute the largest crack a part can tolerate. Ductile metals have a high fracture toughness and glasses and ceramics a low one.