Detection of microtexture regions in titanium turbine engine disks using process compensated resonance testing: A modeling study

Titanium alloys used by the aerospace industry, like Ti-64 or Ti-6242, with Microtexture Regions (MTR’s) have been shown to exhibit significantly reduced dwell fatigue lifetimes. Over the last several decades, these titanium alloys have been used for critical components such as turbine engine disks, which are then susceptible to failure well below their expected service life. Current Nondestructive Inspection (NDE) methods are time consuming and can miss MTR’s. Process Compensated Resonance Testing (PCRT) is a fast and accurate full-body NDE method that has been proposed for the detection of MTR’s in titanium turbine engine disks. PCRT excites a part’s resonance frequencies and correlates the resonance spectrum to the part’s material and/or damage state. Turbine engine disks with MTR’s will have different resonance spectra than fully isotropic disks. Both the MTR’s geometric parameters (i.e. size, location, and orientation) and the microstructural parameters (i.e. degree of crystal alignment and orientation) will influence the magnitude and pattern of changes in the resonance spectrum. Using a Monte-Carlo approach, this work developed Finite Element Method (FEM) model population of disks with and without MTR’s. These populations were analyzed to predict the effects of MTR parameter variation on resonance spectra and evaluate PCRT sensitivity to MTR’s in the presence of normal geometric and material property variation. The feasibility of detecting MTR’s in titanium turbine engine disks using PCRT methods is presented and discussed.