(1. 浙江吉利汽车研究院有限公司，宁波 315000；
2. 北京交通大学 机械与电子控制工程学院，北京 100044)
摘 要: 对车用6061-T5铝合金材料进行了拉伸和剪切力学试验研究，获取了不同应变下与挤压方向成不同角度的屈服应力和各向异性系数，分析了材料的各向异性特征；并在此基础之上，使用Hill1948和Karafillis-Boyce (K-B)两种各向异性塑性模型对材料进行了标定研究，发现两种屈服准则能够对特定应变下的单拉屈服应力进行较好的预测，但标定的方程系数随不同塑性应变发生明显变化，因此，为了揭示标定的屈服准则系数随塑性应变的变化规律以便完整描述铝合金的硬化特性，将上述两种屈服准则的系数表达成塑性应变的函数关系式，使得改进后的模型能够准确地描述6061-T5铝合金断裂前的完整力学特征。
关键字: 6061-T5铝合金型材；屈服行为；硬化特性；各向异性；屈服准则
（1. Zhejiang Geely Automobile Research Institute Co., Ltd., Ningbo 315000, China;
2.School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China）
Abstract:The uniaxial and shear tests were conducted on 6061-T5 aluminum alloy extruded profiles which were widely used in the vehicle components. The yield stress and anisotropic coefficient at different strains and angles with extrusion direction were obtained and its anisotropic behavior were represented. Furthermore, two plastic criteria, Hill1948 and Karafillis and Boyce (K-B), were adopted to describe the material plastic behavior and the coefficients of the plastic models were calibrated. The results show that these two plastic criteria can predict the tension yield stress at specific strains fairly well, whereas, the coefficient values change largely with plastic strain. Therefore, the changing law of the coefficients with plastic stain was investigated and the hardening characteristics were completely described, the coefficients of the plastic criteria were expressed as functions of plastic strain and the corresponding plastic criterion were revised, and the results illustrates that the improved plastic criterion can describe the complete plastic and hardening behavior of the material prior to fracture.
Key words: 6061-T5 aluminum alloy extruded profiles; plastic behavior; hardening characteristics; anisotropy; yield criterion
