热力耦合作用下阀门高温结构蠕变疲劳损伤研究

Creep fatigue damage of high-temperature structure of valve under thermal-mechanical interaction

在运行过程中,高温阀门同时经历高温高压、长时稳定载荷和短时交变载荷的作用,蠕变损伤和疲劳损伤同时存在,但目前针对高温阀门多工况蠕变损伤、疲劳损伤和蠕变疲劳耦合的研究还较少。为此,建立了钠快冷堆调节阀阀体有限元模型,对蠕变、疲劳以及蠕变疲劳损伤进行了计算与安全性评估。首先,采用ANSYS有限元分析软件,结合多工况稳态以及瞬态热力耦合的方法,对高温核电阀门的阀体进行了数值模拟计算;然后,使用蠕变本构方程对高温阀门阀体进行了蠕变分析;最后,以ASME规范的线性累积损伤理论为判据,对高温调节阀阀体进行了蠕变、疲劳以及蠕变疲劳交互损伤安全性评定。研究结果表明:在13种瞬态工况以及4种稳态工况产生的热力耦合作用下,阀体出口处均产生了较高的应力,经分析得出扭矩是造成阀体出口处应力高的主要因素;通过数值计算得出了循环变载荷造成阀体产生的疲劳损伤为0.001 8,而长时间处于高温环境中的蠕变损伤为0.1,由此得出了高温阀门受到蠕变破坏的可能性高于疲劳破坏;该研究结果可为第四代高温核电阀门的分析与设计提供理论基础和技术方案。

In the operation process,high-temperature valves simultaneously experience high temperature and high pressure,long-time steady load and short-time alternating load,creep damage and fatigue damage at the same time,but the current research on creep damage,fatigue damage and creep-fatigue coupling of high-temperature valves for multiple working conditions is still relatively small.For this purpose,a finite element model of the sodium fast-cooled reactor regulator valve body was developed to calculate and evaluate the creep,fatigue,and creep fatigue damage for safety.Firstly,ANSYS finite element analysis software was employed to numerically simulate the valve body by incorporating multi-case steady-state and transient thermal coupling methods.Then,the creep analysis of the valve body was performed using the creep constitutive equation.Finally,the linear cumulative damage theory of ASME code was used as a criterion to evaluate the safety of creep,fatigue,and creep-fatigue interaction damage of the high temperature control valve body.The research results show that high stresses are generated at the valve outlet under the thermal coupling effect of 13 transient conditions and 4 steady-state conditions,and the analysis shows that the torque is the main factor causing high stresses at the valve outlet.The fatigue damage caused by cyclic variable load on the valve body is 0.0018,while the creep damage in a high temperature environment for a long time is 0.1.The study concludes that the high temperature valve is more likely to be damaged by creep than fatigue damage.The research provides the theoretical basis and technical solutions for the analysis and design of fourth-generation high-temperature nuclear power valves.