Analysis of crack on the labyrinth part of the gas turbine engine

Abstract

The main objective of this study is to analyze the crack developed in the Labyrinth seal of a gas turbine engine and to determine the number of cycles required for the crack to grow to various lengths. Here, ANSYS Mechanical APDL is the tool to carry out the crack analysis. The crack is modelled and analyzed according to the principles of Linear Elastic Fracture Mechanics (LEFM) theory by Griffith and Paris law because of the negligible plasticity found at the crack tip. Here, the model is analyzed with and without the crack for the temperature and stress profile. The stress intensity factor is obtained using the ANSYS software. The information is derived from the graph of crack propagation rate as a function of stress intensity factor of Haynes 25 material which was used to analytically determine the number of cycles the labyrinth seal could sustain. The maximum and minimum temperatures were 1132 °C and 250 °C over a span of 10 mm length, which was the region of interest. The maximum thermal stress generated was around 1430 MPa at crack tip region for full crack model. The stress intensity factor was obtained was found to be 18.7 MPa√mm. The crack propagation rate was calculated analytically over a range of 2–4 mm with an increment of 0.5 mm. The number of cycles required for the crack to propagate over the successive 0.5 mm intervals was 97, 82, 71 and 63 cycles respectively.