Numerical simulation of initiation and crack growth on cast valve body

• Published in: Engineering failure analysis 2020-11, Vol.117, p.104793, Article 104793
• Main Authors: Galić, Ivica, Vučković, Krešimir, Tonković, Zdenko, Čular, Ivan
• Format: Article
• Language: English
• Subjects: Crack growth; Initiation; Stress intensity factor; Valve body; XFEM
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2020.104793

•Fatigue analysis of valve bodies DN100 and DN50.•Crack initiation on a valve body according to Basquin-Coffin-Manson equation.•Stress intensity factor estimation with eXtended Finite Element Method (XFEM).•Cycles for crack growth across the valve body thickness.•The engineering and the true stress–strain diagrams and cycle fatigue behaviour of GP240GH steel. Global industry depends of the different type of valves, such as globe valves which are used for precise flow regulation. Since most of the power plants rely on performance of globe valves, it is necessary that valves function without interruption. In this paper, the main part of the globe valve, valve body, is investigated. Simulation of crack initiation and its growth in a wall of valve body is carried out. Required number of cycles for crack initiation is estimated according to Basquin-Coffin-Manson equation. Afterwards, stress intensity factor is estimated through eXtended Finite Element Method (XFEM) and required number of cycles for crack growth across the valve body thickness is calculated according to Paris’ law. The aforementioned method is validated on the results from the available literature by employing relatively simple shapes such as steel pipe with integrated flaw. Subsequently, the method is used on a relatively complex geometry, as is the valve body. The obtained results indicate lack of brittle fracture in a valve body. In other words, the results imply occurrence of Leakage Before Brake (LBB). This is utterly important for power plant industries, since it ensures the proper reaction of the user and possibly avoids possible catastrophic consequences for personnel and the equipment located in the proximity of the valve.