Stand-Off Residual Stress Measurement System (STORMS)

Turbine engines contain disks that rotate at a high-speed and store a significant amount of rotational kinetic energy. In the event of a disk failure, this stored kinetic energy is released, and the result can be catastrophic. In order to ensure optimal reliability, durability, and quality, these disks must undergo rigorous engineering and testing processes. Residual stress is a key characteristic that influences the behavior of engine disks during manufacturing (distortion) and operation (distortion and fatigue). Pre-spin is a mature process that is routinely applied during the machining stage of engine disk manufacturing. The pre-spin process involves rotating (spinning) disk forgings to a specified speed to yield the material. This helps to condition and stabilize the material for subsequent machining and operation (e.g., tip clearance control). The driving mechanism for this manufacturing efficiency improvement is a change in the underlying residual stress in the material (as the material yields during pre-spin the residual stress state is normalized); however, this relationship is not well characterized. More importantly, the residual stress state, which is a key result of the pre-spin process, is not currently monitored, controlled, or documented. This leads to uncertainty in manufacturing and sustainment of engines. This program is aimed at providing technology to nondestructively quantify the residual stress in each eigne disk forging as part of the pre-spin process to enable better decision-making during manufacturing and sustainment of these assets. This program will contribute to Digital Engineering for the USAF Propulsion Enterprise. Most importantly, this program will reduce production (machining) and sustainment (life extension) costs for aircraft engines.