金属板材屈服行为与塑性失稳力学模型在微尺度下的应用

板材屈服准则与塑性失稳模型是精准描述高性能构件成形或服役过程的基础与前提。在板材塑性成形过程中,试样几何尺寸、材料晶粒大小、自由表面粗化和织构分布等都会对材料的塑性变形行为产生不可忽略的影响,导致单一尺度下的本构模型和断裂准则不能有效预测微观尺度下的材料变形行为和各种缺陷,大大限制了合金板材在航空、航天、汽车、医疗等工业上的应用。对现有屈服准则的研究进展进行了较为全面的回顾,从Hill、Hershey-Hosford和Drucker这3个系列出发,分别进行了对比分析,并总结了目前国内外用于验证屈服准则的金属板材双向拉伸实验机发展状况。基于不同的破裂失稳机理,将失稳模型分为宏观失稳准则、韧性断裂准则和耦合材料损伤演化的韧性断裂准则,并分别进行了归纳和阐述。此外,随着微成形技术的逐步推广,也对宏观塑性成形理论在微尺度下的应用进展进行了说明,指出了宏观屈服准则和失稳模型在微尺度下的不足和缺陷。最后讨论了宏观屈服准则和失稳模型今后的发展趋势以及宏观塑性成形理论在微尺度下的应用前景。

Mechanical Model for Yielding Behaviour and Plastic Instability of Sheet Metals and Its Application at Microscale

The yield function and failure criterion of sheet metals are the basis and premise for accurately describing the forming or service of high-performance component. In sheet metals forming, the geometrical dimensions of specimen, the grain size, the free surface roughening and the texture distribution have significant influence on the plastic deformation behavior of material. As a result, the deformation behavior and various defects at micro-scale cannot be precisely predicted through the constitutive model and failure criterion at a single scale, which greatly limit the application of alloy sheets in aviation, aerospace, automotive, medical and other industrial fields. In this paper, the research progress on the phenomenological yield function was reviewed comprehensively, and Hill, Hershey-Hosford and Drucker series were compared and analyzed. The development of biaxial tensile testing machines for verifying yield criterion was also summarized. Based on the different ductile facture mechanisms of sheet metal, the failure criteria were divided into the macro instability criterion, ductile facture criterion and ductile facture criterion coupled with the damage evolution, which were summarized and elaborated respectively. In addition, with the gradual popularization of microforming technology, the paper also illustrated the application of macro plastic deformation theory in micro-scale and pointed out the deficiencies of phenomenological yield function and failure criterion in micro-scale. Finally, the future research directions of phenomenological yield function and instability model were discussed, and the application prospect of macro plastic deformation theory at microscale was also analyzed.