高强度钢锥柱耐压结构焊接残余应力及其对疲劳强度影响的研究

Welding residual stress and its effects on fatigue strength of high-strength steel cone-cylinder pressure structures

高强度钢锥柱耐压结构在服役过程中不断下潜和上浮,可能会使高强度钢锥柱耐压结构产生疲劳破坏。而锥柱耐压结构通常采用高强度钢建造,在焊接完成过后,锥柱耐压结构焊缝附近会存在较大的残余应力,残余应力的存在对高强度钢锥柱耐压结构的疲劳强度和安全性能可能会产生不利的影响。因此,非常有必要研究焊接残余应力及其变化对高强度钢锥柱耐压结构疲劳强度的影响。本文以高强度钢锥柱耐压结构为研究对象,首先基于热弹塑性理论的数值模拟方法研究焊接残余应力分布规律,然后进行高强度钢锥柱耐压结构疲劳寿命研究。结果表明:由于内压试验及上下潜浮运动的影响,锥柱耐压壳结构的疲劳破坏有可能发生在凸锥内表面;内表面焊接残余应力的消除可延长疲劳寿命。

High-strength steel cone-cylinder pressure structures may suffer fatigue damage due to continual submergence and floatation during service.The cone-cylinder pressure structures are usually constructed with high-strength steel.After the welding is completed,there is a large welding residual stress near the weld seam of cone-cylinder pressure structures,which may affect the fatigue strength and safety performance of high-strength steel cone-cylinder pressure structures.Therefore,it is necessary to study the influence of welding residual stress and its variation on the fatigue strength of high-strength steel cone-cylinder pressure structures.In this paper,a high-strength steel cone-cylinder pressure structure was taken as the research object.Firstly,the distribution of welding residual stress was studied with numerical simulation method based on thermal elastic-plastic theory.Then,the fatigue life of the high-strength steel cone-cylinder pressure structure was studied.The results show that the fatigue failure of a cone-cylinder pressure shell structure may occur on the inner surface of the convex cone due to the influence of internal pressure test and submergence and floatation.The elimination of welding residual stress on the inner surface may increase the fatigue life.