基于三维理论的TC4ELI钛合金疲劳裂纹扩展研究  

Fatigue crack growth of TC4ELI titanium alloy based on three-dimensional theory

作　　者：吴连生 于培师 韦朋余[2] 郭鑫 赵军华 王连 WU Lian-sheng;YU Pei-shi;WEI Peng-yu;GUO Xin;ZHAO Jun-hua;WANG Lian(Jiangnan Key Laboratory of Advanced Food Manufacturing Equipment and Technology,Jiangnan University,Wuxi 214122,China;China Ship Scientific Research Center,Wuxi 214082,China)

机构地区：[1]江南大学江苏省食品先进制造装备技术重点实验室,江苏无锡214122 [2]中国船舶科学研究中心,江苏无锡214082

出　　处：《船舶力学》2022年第9期1354-1362,共9页Journal of Ship Mechanics

基　　金：国家自然科学基金资助项目(11972171);江苏省杰出青年基金资助项目(BK20180031);中国博士后科学基金资助项目(2018M630513)。

摘　　要：TC4ELI钛合金以其优异的力学和抗腐蚀性能广泛应用于深海耐压结构。在深海交变载荷作用下,钛合金结构的初始微缺陷易发生疲劳扩展,进而会导致灾难性破坏。因此,耐压结构逐渐采用损伤容限设计理念来保证安全。然而,传统的二维损伤容限设计理念过于保守,不利于三维深海耐压结构的轻量化设计。本文对TC4ELI钛合金的疲劳裂纹扩展进行了系统研究,发现在二维理论框架内材料的裂纹扩展速率依赖于试件厚度和应力比。而基于三维断裂理论,同种材料裂纹扩展速率与厚度和应力比无关。在此基础上,将得到的材料常数用于裂纹扩展模拟,实现了不同试件厚度和载荷下的疲劳寿命与裂纹尺寸的准确预测。Owing to the outstanding mechanical property and corrosion resistance,the TC4ELI titanium alloy is widely used to fabricate various pressure-resistant structures of deep diving equipment.During the in-service period,the intrinsic defects in titanium alloy usually propagate under fatigue loadings,which may lead to high risk of unstable failure.Therefore,the damage tolerance design is gradually adopted for the deep diving equipment to guarantee the long-term safety.However,the existing damage tolerance design principle is based on two-dimensional fracture theory,which is conservative for lightweight design of deep diving equipment.In this paper,the fatigue crack growth of TC4ELI is systematically tested,in which the obtained results show a significant dependence on both the specimen thickness and stress ratio based on the two-dimensional fracture theory.To overcome the shortcomings,the three-dimensional fracture theory is adopted to improve the understanding and processing of the test data,leading to the thickness and stress ratio independent fatigue crack growth rate as the true material constants.Then the life and length of fatigue cracks in specimens with different thicknesses under various fatigue loadings are successfully predicted based on the obtained material constants in combination with three-dimensional fracture theory.

关 键 词：钛合金 损伤容限 三维裂纹扩展 模拟 

分 类 号：TG146.2[一般工业技术—材料科学与工程]