超塑性本构模型材料参数识别方法研究

金泉林等提出的超塑性本构关系考虑了三种微观变形机制和晶粒生长过程,但单纯依靠实验很难准确的测定该本构关系的材料参数.应用遗传算法和Levenberg-Marquardt算法,以Ti-6Al-4V为例,识别该超塑性本构关系中的材料参数.计算结果和实验结果符合的很好.最后讨论了各种微观变形机制的体积分数与应变、应变率和晶粒尺寸之间的关系,发现在大部分情况下扩散蠕变机制对超塑变形的贡献可以忽略.

MATERIAL PARAMETER IDENTIFICATION OF SUPERPLASTIC CONSTITUTIVE RELATION

The superplastic constitutive relation developed by the second author of the paper considers three types of microscopic deformation mechanisms and the grain growth process. However, the material parameters are difficult to identify by experiment only. By means of genetic algorithm and Levenberg-Marquardt algorithm, the material parameters included in the superplastic constitutive relation are identified. An example of Ti-6Al-4V alloy is given in this paper. The calculated curves are in agreement with those of the experiments very well. The volume fraction variations of microscopic deformation mechanisms corresponding with strain, strain rate and grain size are discussed. It is found that the contribution due to diffusive creep deformation mechanism can be neglected in most cases.