Fatigue life assessment of the structure with widespread damage exposed to high temperature

Abstract

The exhaust nozzle represents a part of a jet engine which is crucial to its overall performance, since it accelerates the flow of hot gases out of the engine and creates a thrust. During its long service, it is exposed to elevated temperatures and high compressive and hoop stresses, which makes the cracks' occurrence in the exhaust nozzle's inner sleeve almost unavoidable. The aim of this paper is to analyze and numerically estimate the fatigue life of inner sleeve in the presence of widespread damage. When damage is detected, two repair methods are employed: welding of single cracks (manual TIG welding) and the use of welded patches. Using numerical simulations based on extended finite element method (XFEM) and finite element method (FEM), fatigue life of repaired inner sleeves were estimated. Based on the comparison of the results obtained in simulations, it was shown that the repair method with welded patches provides longer fatigue life of widespread damaged nozzle than the other with welding of cracks.