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

摘要

This paper presents the results of finite elementrnbased stress and fracture mechanics analysesrncarried out on the compressor disc of a jetrnengine using two and three dimensional models.rnA total of ninety finite element models of therncompressor disc were prepared, out of which 81rnwere two dimensional models and 9 were threerndimensional. All models were prepared andrnanalysed for the uncracked discs, discs withrnvarious numbers of cracks emanating fromrnneighbouring bolt holes as well as for a discrnwith two cracks emanating from the same boltrnhole. It was established that the primaryrnfracture critical location in the compressor discrnwas the bolt hole surface closest to the discrncentre and the secondary fracture criticalrnlocation was the bolt hole surface closest to therndisc rim.rnPlastic zone size measurements ahead ofrntips in service-induced cracks were carried outrnusing a microhardness technique and thesernvalues were used to estimate the stress intensityrnfactors as a function of crack size. Quantitativernfractography results were also used to estimaternthe stress intensity factors. There was a goodrnagreement between numerical calculations andrnexperimental data.