NDE for Residual Stress Relaxation

Fatigue lives of rotating engine components are greatly enhanced through application of shot peening and other processes that impart residual compressive stresses to their surfaces. X-ray diffraction measurements, however, confirm that these stresses relax during service. Furthermore, residual stresses may relax rapidly or gradually and can vary by location. This proposal addresses the need for a nondestructive method of measuring and tracking residual stress relaxation with scanning MWM-Arrays. JENTEK’s patented MWM-Arrays have demonstrated capability to measure shot peen quality in nickel alloys and we are confident we can transition a solution for stress relaxation tracking in nickel alloy components, within two years. This proposed program will also address stress relaxation in titanium alloys. JENTEK currently has two active programs that will provide leverage to this program. Under Air Force funding, we are adapting our technology for manufacturing quality assessment of Low Plasticity Burnishing and Laser Shock Processing. Under a separate Air Force program, we are adapting our technology for IBR inspection for cracks and mechanical damage. Scanning MWM-Arrays, already integrated into automated engine disk inspection systems in use at Navy depots, have the potential to provide crack detection and residual stress relaxation tracking with a single inspection.