Applications for quantification and modeling of the residual stress and cold work outside of NASA are significant. Non-NASA applications are much the same as those listed above. Engine OEM's and their suppliers can use the predictive tools developed in this program to thoroughly understand how residual stresses and cold work change during the life cycle disks. Furthermore, the OEMs can use the measurement and modeling tools to develop more robust surface enhancement processes that remain stable at high temperatures and stresses, producing higher fatigue strengths, and safer longer lasting performance. The proposed development program will provide the following for NASA applications: ¬∑ A multi-functional modeling tool to be used in NASA's Aviation Safety Program to provide longer lasting and safer compressor and turbine disk operation. ¬∑ A means of measuring residual stress and cold work depth distributions simultaneously in critical high stress regions of disks. ¬∑ A software tool that will allow for accurate assessment of the change in residual stress and cold working of disks providing a predictive capability of determining the remaining life of a part. ¬∑ A means of developing surface enhancement processes that can produce the optimal compressive residual stress and cold working for maximum residual stress stability through the life of the part. ¬∑ The model will allow for NASA engineers to understand the full stress state of the disk (applied + residual) as a function of life for a much more accurate interpretation of fatigue life. ¬∑ This development will ultimately assist NASA in achieving their goal of safer and more reliable operation of legacy and new production aircraft.