(1. 北京科技大学 机械工程学院，北京100083；2. 哈尔滨工业大学 材料科学与工程学院，哈尔滨 150001)
摘 要: 通过真空退火处理得到具有不同β相含量的TA15板材，并对其进行室温单轴拉伸试验，获得不同β相含量板材的真应力-应变曲线，并采用Bridgman公式对颈缩阶段应力进行了修正。结果表明：随着β相含量的增加，拉伸断裂应变明显增大。分别考虑α与β相室温变形行为，基于连续损伤力学建立了一套耦合位错密度和微观损伤的单轴拉伸本构模型。通过不同β相含量试样的应力-应变曲线，采用遗传算法确定本构方程常数。利用β相含量为18.63%和20.04%的试样的应力-应变曲线对所建模型进行验证，计算值与试验值吻合较好。
关键字: TA15钛合金；塑性损伤；位错密度；本构模型；遗传算法
（1. School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China）
Abstract:The sheet specimens of TA15 sheet with different volume fractions of β phase were obtained by vacuum annealing. Then, the stress-strain curves of sheet with different volume fractions of β phase were obtained by tensile test at room temperature, and the true stress after necking was corrected through the well-known Bridgman equations. The results indicate that the tensile strength increases slightly with the volume fraction of β phase. With increasing volume fraction of β phase, the fracture strain increases significantly. Considering the flow behavior of two phases, respectively, a set of constitutive equations coupling dislocation density and damage based on the continuum damage mechanics were developed. The model constants were determined using genetic optimization algorithm (GA). The stress-strain curves of the sheet with 18.63% and 20.04% β phase were used to evaluate the proposed model. The good agreements between the experimental and computed results are obtained.
Key words: TA15 Ti alloy; ductile damage; dislocation density; constitutive model; genetic algorithm
