超塑变形屈服准则的拉扭复合实验研究

An Experimental Study of Superplastic Yield Criteria under Tension-torsional Combined Loading

本文首次用超塑材料Sn-38Pb的变截面及等截面薄壁管试件做了高精度拉扭复合实验。由实验结果建立了超塑变形屈服准则,从连续介质力学的角度分析,准则的物理意义是变形时比功率为常值;其几何形状为六曲面柱体,它介于Mises圆柱面和Tresca六棱柱面之间, 更接近于后者。实验表明,随比功率或应变速率的增加,超塑屈服曲面均匀地向外扩张。

The high precision tension-torsional combined tests for superpl-astie material have been made .first. The changed section and unique section thin walled tubes of typical room superplastic material sn-38Pb alloy are used. Depending on the experimental results, the superplastic yield criteria has been set out. That is( 1 ) Analysed with continuum mechanics, its physical meaning is that the unit work-rate eguats the constant value during superplastic forming. Its geometric meaning is curved-side hexagon cylinder. It is located between the loci of Mises and Tresca, and is nearer to Tresca locus. The experimental results also show that the yield loci expand out homogeneously with unit work-rate.