A.M. Gilmartin, M.B. Henderson*, T.J.W. Ward, B. Vermeulen
QinetiQ, Cody Technology Park, Farnborough, Hampshire GU14 0LX, United Kingdom
*ALSTOM Power Tech. Centre, Whetstone, Leicester LE8 6LH, United Kingdom

The 2002 Abaqus User Conference, Newport, Rhode Island, USA, May 28-31, 2002

Abstract:
Gas turbine engine combustor manufacturers face the challenge of achieving improved efficiency against the increasingly stringent regulations concerning NOx emissions. Revolutionary changes in design styles will be required with the increased use of high stress concentration features such as effusion cooling holes. Lifetime prediction for new combustor designs will require an estimation of life to first crack and an estimation of the crack propagation life. This paper studies crack propagation in featured low cycle fatigue specimens intended to simulate cooling holes within a combustor liner wall. Based on extensive fatigue crack growth testing of corner notch specimens, linear elastic fracture mechanics crack growth laws have been postulated for the g¢ strengthened, nickel-based superalloy C263 at 300 and 800°C. These laws have been used to predict the growth rates for cracks growing within featured specimens and the results compared with data obtained from experimental testing of specimens with 90° holes. Direct comparison with growth rates obtained from load-controlled fatigue testing of the specimens at 300 and 800°C has shown the growth laws to provide good predictions for the behaviour of the material in the vicinity of the feature. The meshing of the test specimens with elliptical and straight through cracks was performed with the aid of ZENCRACK software, which provides singular elements to a conventional mesh. The 3-D analysis was performed using ABAQUS Standard.