超塑性薄壁圆筒拉扭作用下应力分析

超塑性材料具有延伸率非常高，可以形成复杂结构件等优点，已得到广泛应用．用塑性增量理论研究了超塑性材料薄壁圆筒受拉扭作用下的应力和应变率之间的关系．导出拉扭问题中，拉应力与切应力之比，等于它们相应的应变率比值K的3倍．讨论了在拉扭等比例应变率加载情况下，正应力和切应力的变化规律；讨论了当应变率相同的情况下，拉扭正应力与单向拉伸正应力之比，拉扭切应力与纯扭转切应力之比的变化规律．计算结果表明：应变率s：越大，以应力值越大．随着应变速率敏感性指数m的增加，az应力值减小，较大的m值使应力σz变化趋缓，较大的应变率εz使σz应力值变化较大；

Stress Analysis of a Superplastic Thin Walled Cylinder under Tensile and Torsional Loads

Abstract Superplastic materials have advantages such as high elongation, forming complex structures easily and so on~ thus they have been widely used. Relation between stress and strain rate of superplastic thin walled cylinder under tensile and torsional loads is studied based on the plastic incremental theory. It is de- rived that tensile stress / shear stress ratio equal to 3 times of corresponding strain-rate ratio（K value）. Vari- ation of normal stress and shear stress under equal-ratio tensile and torsional strain-rate loads is discussed. Variation of the ratio of normal stress under tensile - torsional loads/ under tensile loads and the ratio of shear stress under tensile - torsional loads/ under pure shear loads is discussed. The results show that. （1） The lar- ger the strain-rate ~ is, the larger the stress 6~ is. Increase of strain-rate sensitivity index m will decreasestress σz