Numerical analysis of the impact effect of foreign bodies on a steam strainer in a steam turbine valve

An in-service steam strainer was found to have failed in a steam turbine valve due to the impact of a foreign body. Thus, a Finite element (FE) model was built to study the impact effect of a foreign body on a steam strainer. A Johnson-Cook strength model and its failure model were used to describe the impact-induced failure of the film and deformation of the support in the strainer. The effects of the impact location, shape, mass and speed of the foreign body on the failure of the strainer were investigated. The possible locations of micro-cracks in the film were determined. The FE results indicated that impact by an exfoliated metal part (with small mass, sharp edges and high speed hitting the film close to the rib) is likely to cause failure of the film and large deformation of the support.