中文摘要：

为了研究高温条件下高强度螺栓预紧力的松弛特性，螺栓材料分别选用40Cr合金钢和Ti-6Al-4V钛合金。应用ABAQUS有限元软件建立装配体模型，定义了材料的本构模型和装配体各部件之间的接触，分析了常温预紧力状态下及高温条件下螺栓的受力及变形。分析结果表明，在高温条件下，Ti-6Al—4V钛合金预紧力松弛现象明显好于40Cr合金钢，Ti-6Al-4V钛合金高强度螺栓比40Cr合金钢螺栓拥有更高的强度和更好的延展性。得出的结论可为高温条件下高强度螺栓的材料选用提供理论依据。

英文摘要：

In order to study the preload relaxation of high strength bohs, 40Cr steel and Ti -6Al -4V Ti are used separately as the boh materials. The assembly model is built by using ABAQUS finite element software. The material constitutive model and the contact between each part of the assembly body are defined. The stress and deformation of the bolt under preload condition are analyzed at normal temperature and high temperature. The results show that under high temperature conditions, the preload relaxation of Ti -6Al -4V alloy is significantly better than that of 40Cr steel, and the bolt made of Ti -6Al -4V alloy has higher strength and better ductility than that of 40Cr steel bolt. The conclusion can provide a reasonable theoretical basis for the material selection of high strength bolt at high temperature.