(1. 中國(guó)工程物理研究院 總體工程研究所，綿陽(yáng) 621999；
2. 四川大學(xué) 建筑與環(huán)境學(xué)院，成都 610065)
摘 要: 為描述Ti-6Al-4V(TC4)兩相鈦合金在高應(yīng)變率、高溫載荷條件下的復(fù)雜力學(xué)行為，基于細(xì)觀塑性變形機(jī)理和位錯(cuò)動(dòng)力學(xué)理論，從細(xì)觀尺度構(gòu)建一種兩相鈦合金粘塑性本構(gòu)模型，并闡釋各本構(gòu)參數(shù)與微結(jié)構(gòu)特征量之間的關(guān)聯(lián)及其表征的物理意義。為確定本構(gòu)參數(shù)并提高參數(shù)的識(shí)別效率與精度，提出一種基于拉丁超立方抽樣、Spearman秩相關(guān)分析的參數(shù)敏感度整體分析方法，并在參數(shù)敏感度分析結(jié)果和基本遺傳算法的基礎(chǔ)上，建立基于改進(jìn)小生境算法、可疑峰值點(diǎn)判斷策略和局域精確搜索技術(shù)的改進(jìn)遺傳算法，得到了TC4兩相鈦合金的本構(gòu)參數(shù)。采用應(yīng)力補(bǔ)償更新算法，通過(guò)顯式用戶子程序接口VUMAT將兩相鈦合金本構(gòu)模型嵌入ABAQUS有限元軟件中，實(shí)現(xiàn)了鈦合金在高應(yīng)變率、高溫條件下動(dòng)態(tài)本構(gòu)行為的數(shù)值模擬。對(duì)比模擬結(jié)果與實(shí)驗(yàn)數(shù)據(jù)發(fā)現(xiàn)，所構(gòu)建的本構(gòu)模型描述材料高應(yīng)變率條件下力學(xué)行為的準(zhǔn)確性優(yōu)于Johnson-Cook模型的。
關(guān)鍵字: Ti-6Al-4V；本構(gòu)模型；位錯(cuò)動(dòng)力學(xué)；VUMAT用戶子程序
（1. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621999, China;
2. College of Architecture and Environment, Sichuan University, Chengdu 610065, China）
Abstract:A new physically-based constitutive model of dual-phase Ti-6Al-4V alloy (TC4) was developed based on the microscopic mechanism of plastic deformation and the theory of thermally activated dislocation motion. The relationships among constitutive parameters and microstructure characteristics, as well as the physical meanings were illustrated. In order to determine the constitutive parameters and improve the efficiency and precision of parameters identification, an overall analysis method of parameter sensitivity based on Latin Hypercube Sampling (LHS) method and spearman rank correlation method was presented. Furthermore, the constitutive parameters of the material were determined by a global genetic algorithm composed of an improved niche genetic algorithm, a global peak determination strategy and local accurate searching techniques. By adopting a stress compensation updating algorithm, a subroutine VUAMT of the proposed constitutive model of dual-phase titanium alloy was programmed on plat of ABAQUS/Explicit. Then finite element simulation of dynamic responses of TC4 alloy under loading conditions of high strain rate and high temperature was investigated. The comparison results indicate that the proposed model is more suitable and accurately to describe the mechanical behavior of material subjected to high strain rate than Johnson-Cook model.
Key words: Ti-6Al-4V; constitutive model; dislocation dynamics; VUMAT user subroutine
