金属材料弹塑性加、卸载时弹性变形大小与分布

The Magnitude and Distribution of Elastic Deformation of the Metal Materials in the Conditions of Elastoplastic Loading and Unloading

弹性变形与塑性变形是两种不同性质的物理现象。弹、塑性变形过程中,两者性质互不影响,其中弹性变形能大小遵守热力学第一定律,变形能分布形式遵守热力学第二定律。现有塑性力学求解时,仅使用了平衡条件、屈服条件与本构关系,求出的应力解仅符合热力学第一定律,但应力解对应的变形能不是最小值,变形场处在不稳定的平衡状态,这样应力解不符合热力学第二定律,不符合实际情况。用现有弹塑性理论作指导,不能正确解答金属结构弹塑性加、卸载试验现象。

Elastic deformation and plastic deformation are two physical phenomena with different proper- ties. In the process of elastic-plastic deformation, the properties of elastic and plastic deformation can not affect each other. Of which the magnitude of deformation energy of the elastic deformation will follow the first law of thermodynamics, and the distribution of deformation should follow the second law of thermody- namics. In the current plastic mechanics, only the equilibrium conditions, the yield criterions and the constitutive relations are used to solve the questions, and the solutions obtained are consistent with the first law of thermodynamics. However, the deformation energies corresponding to these solutions are not the minimum and the deformation fields are in the unstable equilibrium state. Therefore, the solutions ob- tained in this way don＇ t conform to the second law of thermodynamics and they are impossible to appear in reality. Using the current elastic-plastic theory, it is unlikely to explain the experimental phenomena of metal structures in the conditions of elastoplastic loading and unloading exactly.