23rd Congress of International Council of the Aeronautical Sciences, 8-13 September, 2002, Toronto, Canada
Paper ICAS 2002-5.8.3

STRESS INTENSITY FACTOR CALCULATIONS FOR CRACKS EMANATING FROM BOLT HOLES IN A JET ENGINE COMPRESSOR DISC

W. Beres (1), A. K. Koul (2)
(1) IAR/NRC, Canada; (2) Life Prediction Technologies Inc., Ontario, Canada

Keywords: gas turbine engine, life prediction, damage tolerance, stress intensity factor

This paper presents the results of finite element based stress and fracture mechanics analyses carried out on the compressor disc of a jet engine using two and three dimensional models. A total of ninety finite element models of the compressor disc were prepared, out of which 81 were two dimensional models and 9 were three dimensional. All models were prepared and analysed for the uncracked discs, discs with various numbers of cracks emanating from neighbouring bolt holes as well as for a disc with two cracks emanating from the same bolt hole. It was established that the primary fracture critical location in the compressor disc was the bolt hole surface closest to the disc centre and the secondary fracture critical location was the bolt hole surface closest to the disc rim. Plastic zone size measurements ahead of tips in service-induced cracks were carried out using a microhardness technique and these values were used to estimate the stress intensity factors as a function of crack size. Quantitative fractography results were also used to estimate the stress intensity factors. There was a good agreement between numerical calculations and experimental data.

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