由两组力学实验曲线得到的启示

INSPIRATION FROM TWO MECHANICAL EXPERIMENT CURVES

研究由拉伸实验和纯扭转实验得到σe—εe曲线有明显的差异的两个原因,其一为不均匀效应的影响,其二为Poisson效应的影响。论证不考虑材料的Poisson效应对拉伸等效应变的影响时,相当于使材料软化,致使σe—εe曲线落在真实的σe—εe曲线的右下方。在此基础上,应用正交流动法则和关联流动理论,合理考虑Poisson效应,推导可压缩材料的塑性增量本构关系,将之退化到不可压缩材料,可得著名塑性力学专家Hill给出的塑性本构关系。

Two reasons ＂that theσe-εe curves which obtained from tension test and torsion test had obvious difference＂ were studied. The first reason was the influence of unsymmetrical effect. The second reason was the influence of Poisson＇s effect. When Poisson＇s effect of material affecting on tension equivalent strain was not considered, it was demonstrated that it amounted to the softening material and caused the σe-εecurve to situate the right-hand under the real curve. By considering Poisson＇s effect reasonably, it derivated compressible materials＇ plastic incremental constitutive relation by the normality of flow rule and associated flow theory, then degenerated into the uneompressible materials, it could obtain the plastic constitutive relation which was given by Hill, the famous mechanics specialist.