Fatigue crack growth in a structure exposed to high temperature

Abstract

The exhaust nozzle, made of titanium, is the part of a jet engine where the final expansion of the hot gas from the turbine occurs and where the speed of the exhaust gas is further increased to create thrust. During the work, it is exposed to elevated temperatures and compressive and hoop stresses, which makes the cracks' occurrence in the exhaust nozzle's inner sleeve unavoidable, making repairs during maintenance necessary. In this study, crack growth in the repaired inner sleeve was analyzed. The aim of the study was to evaluate the fatigue life of the damaged inner sleeve when a new method of repair is applied and to compare obtained number of cycles with the number observed in the maintenance workshop after the old method of repair was used. Developing the numerical model and conducting simulations using the extended finite element method (XFEM) and finite element method (FEM), it was concluded that a new type of repair should be used to provide longer fatigue life of the damaged exhaust nozzle.