THE CHARACTERISTICS OF INSTABILITY IN SOLID MATERIALS
固体材料不稳定性的特征

Based on analyzing the second variation of potential functional, one of the char-acteristics of the instability occurred in solid materials is proved as basically depending on the deterioration of material behavior. Another important feature is demonstrated that the funda-mental straining path is used to be disturbed and shifted into a mode of limiting an axial strain at instability. Sheet materials perforated periodically are numerically analyzed by finite-element method to exemplify how the strain localization around small holes eventually turns the strain-ing path into a failure mode of strain limitation. Metal forming tests on steel sheets loaded by flat-bottom punch also indicates such shift of straining path when approaching to failure.