Officials at the University of Notre Dame’s Turbomachinery Laboratory (NDTL), South Bend, Indiana, USA, Norsk Titanium, Plattsburgh, New York, USA, Pratt & Whitney, East Hartford, Connecticut, USA, and Turbocam International, Barrington, New Hampshire, USA, have announced that the second phase of testing is now underway for a metal additively manufactured integrally bladed rotor (IBR).
Building on initial testing completed in 2018, this next phase examines the dynamic properties of the IBR. Manufactured using Norsk Titanium’s Rapid Plasma Deposition™ (RPD™) process, the IBR is being inspected to the same quality specifications used in Pratt & Whitney’s current turbomachinery components.
The tests are being conducted at NDTL’s turbomachinery test facility in South Bend, Indiana. After completion of initial testing, where the IBR was said to have met 100% of all design, speed and pressure ratio test points, the current test programme looks at low and high cycle fatigue characteristics of the IBR. Testing will include multiple acceleration/deceleration cycles and investigate synchronous vibration effects on the additively manufactured blades.
The testing was preceded by a manufacturing qualities evaluation performed by Turbocam. The evaluation found no evidence of alpha case, or residual stress concentrations, that would cause distortions typically found in parts produced by Additive Manufacturing. Additionally, Turbocam reportedly confirmed Norsk’s RPD material to be well-suited to traditional milling operations, and as stable as Ti6-4 forgings.
The ultimate goal of this effort is said to be to develop the Additive Manufacturing specifications needed to deliver the complex, heavily-loaded components for turbomachinery applications, while providing the cost and schedule savings that have been proven on Ti 6-4 airframe components. Chet Fuller, Norsk’s Chief Commercial Officer, stated, “Successful completion of this testing will show that additive materials can be used in turbomachinery applications, and paves the way to a full qualification effort.”
The manufacturing and testing effort has been overseen by Pratt & Whitney and is being evaluated for application to future engine developments. “Pratt & Whitney is excited to enter this next phase of testing,” commented Chris Kmetz, Vice President of Engineering, Module Centers, Pratt & Whitney. “Utilising Additive Manufacturing techniques, such as Norsk’s Rapid Plasma Deposition process, allows us to shorten the manufacturing and development schedule for our critical turbomachinery components.”