Non-Destructive Inspection for Repaired Integrally Bladed Disk Airfoils

ABSTRACT: Integrally bladed disks (IBDs) are critical components of jet engines that must be replaced at great cost if they experience any damage. The Air Force has begun a push to repair IBDs, rather than replace them, and requires a non-destructive inspection method to confirm there are no structural defects associated with the repair and that the microstructure of the repair has been properly blended with that of the bulk.To address this issue, TRI/Austin will leverage previous research and using a combination of highly focused, non-contacting polyvinylidene floride (PVDF) ultrasonic (UT) transducers and high gain amplifiers to perform ultrasonic backscattering measurements to identify signals corresponding to the grain structure in Ti6Al4V. This will be combined with more traditional UT inspections to identify internal and external structural flaws in the repair.TRI/Austin will team with the University of Texas at Austin for metallurgical expertise and fabrication of Ti6Al4V specimens to demonstrate this technology in Phase I.; BENEFIT: Ultrasonic systems, such as the one proposed in this work, are non-contacting, safe, and are a widely adopted means to perform non-destructive inspections in many industries. The ability to be able to inspect and quantify the surface microstructure (size, shape, micro-texturing, etc.) is invaluable to the end user of a component. In the case of the Air Force, the proposed technology will assist in ensuring better part quality, tighter controls on inspection of repairs, better life predictions for repairs, and better supplier and manufacturing controls, such as fewer unnecessary purchases of replacement integrally bladed disks.Additionally, quantified C-scan images and datasets for any repair will fit neatly into the Air Forces Digital Twin initiatives to digitize inspection records, CAD files, repairs, etc., associated with each individual airframe. Other potential adopters of the final product from this proposal would include any military branch operating turbine powered aircraft engines that is in the process or has made the change from individually installed blades to integrally bladed disks, such as those used on U.S. Army rotary winged aircraft.Development of an ultrasonic based inspection system, such as is required for this SBIR effort, will translate very well to the titanium welding industry, both in terms of microstructural examination, and inspection of structural defects within welds.Civilian uses for titanium welding, and therefore, potential commercial customers for an NDI system such as this range from aerospace, marine, chemical plants, process plants, power generation, oil and gas extraction, medical technology, and sports equipment.