(1. 北京科技大學(xué) 機(jī)械工程學(xué)院，北京100083；2. 哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，哈爾濱 150001)
摘 要: 通過真空退火處理得到具有不同β相含量的TA15板材，并對其進(jìn)行室溫單軸拉伸試驗(yàn)，獲得不同β相含量板材的真應(yīng)力-應(yīng)變曲線，并采用Bridgman公式對頸縮階段應(yīng)力進(jìn)行了修正。結(jié)果表明：隨著β相含量的增加，拉伸斷裂應(yīng)變明顯增大。分別考慮α與β相室溫變形行為，基于連續(xù)損傷力學(xué)建立了一套耦合位錯(cuò)密度和微觀損傷的單軸拉伸本構(gòu)模型。通過不同β相含量試樣的應(yīng)力-應(yīng)變曲線，采用遺傳算法確定本構(gòu)方程常數(shù)。利用β相含量為18.63%和20.04%的試樣的應(yīng)力-應(yīng)變曲線對所建模型進(jìn)行驗(yàn)證，計(jì)算值與試驗(yàn)值吻合較好。
關(guān)鍵字: TA15鈦合金；塑性損傷；位錯(cuò)密度；本構(gòu)模型；遺傳算法
（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
