回顾了1926年Lode在做屈服准则实验验证时,为了考虑中间主应力的影响而提出的参数μσ.指明其在应力Mohr圆中的几何意义,推证了μσ与应力偏张量第三不变量J3和应变增量比dε2/dε1及dε3/dε1的定量关系,进而指明胁给实际成形工序在Mises圆柱上的定位提供了依据,作为工程上的定性分析,胁值的符号(正或负)可以作为应变类型的判据。
The geometric significance of Lode parameter μσ which was proposed by Lode in 1926 to illustrate the effect of middle principal stress on yield criterion is pointed out. The relationship betweenμσ and J3, and also the formula concerning μσ and the strain incrementratios dε2/dε1 and dε2/dε1 are given. It is shown that μσ is a basic parameter to determine the position of different forming processes on the Mises yield cylinder. The value of μσ can be used to quatitively decide the deformation type for engineering problems.