(1. 浙江吉利汽車研究院有限公司，寧波 315000；
2. 北京交通大學(xué) 機(jī)械與電子控制工程學(xué)院，北京 100044)
摘 要: 對車用6061-T5鋁合金材料進(jìn)行了拉伸和剪切力學(xué)試驗(yàn)研究，獲取了不同應(yīng)變下與擠壓方向成不同角度的屈服應(yīng)力和各向異性系數(shù)，分析了材料的各向異性特征；并在此基礎(chǔ)之上，使用Hill1948和Karafillis-Boyce (K-B)兩種各向異性塑性模型對材料進(jìn)行了標(biāo)定研究，發(fā)現(xiàn)兩種屈服準(zhǔn)則能夠?qū)μ囟☉?yīng)變下的單拉屈服應(yīng)力進(jìn)行較好的預(yù)測，但標(biāo)定的方程系數(shù)隨不同塑性應(yīng)變發(fā)生明顯變化，因此，為了揭示標(biāo)定的屈服準(zhǔn)則系數(shù)隨塑性應(yīng)變的變化規(guī)律以便完整描述鋁合金的硬化特性，將上述兩種屈服準(zhǔn)則的系數(shù)表達(dá)成塑性應(yīng)變的函數(shù)關(guān)系式，使得改進(jìn)后的模型能夠準(zhǔn)確地描述6061-T5鋁合金斷裂前的完整力學(xué)特征。
關(guān)鍵字: 6061-T5鋁合金型材；屈服行為；硬化特性；各向異性；屈服準(zhǔn)則
（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
