Prediction of Crack Initiation in Combustion Chamber Liners

An analytical procedure for predicting the crack initiation life of jet engine combustion chamber liners is presented. Sample calculations using the procedure are made and correlated against representative engine and test rig data. The analysis employs the Strain Range Partitioning Method, proposed by Manson et al., to determine the low cyclic thermal fatigue (LCTF) and creep damage components. A procedure for estimating plastic strain range and creep strain per cycle is presented, and life estimates are made using this in combination with a linear cumulative damage summation of the LCTF and creep damage components.