Criteria for determining when a substance has this property are often mapped by separating hydrostatic and deviatoric components via projection onto the pi plane. Drucker’s postulate is a sufficient condition for the stability of materials with this property. EPFM theory must be used when a zone with this property around cracks is large. The Frank-Read mechanism leads to the creation of dislocations in materials with this property, (15[1])increasing the material’s (*) toughness. A material has this property when a certain vector lies outside a cylinder by the von Mises criterion. Work hardening is used to strengthen materials with this property, the onset of which is given by the (-5[1])yield point and sees materials (-5[1])undergo necking. For 10 points, name this solid property where an applied force causes a permanent shape change, in contrast to elasticity. ■END■ (10[2])