Eddy current methodology has been shown feasibility of measuring residual stress depth profile in engine materials in a nondestructive way. In general, the changes in an eddy current signal, due to the residual stress variation, are known to be at least an order of magnitude smaller as compared to defect signals. These feasibility measurements were performed in ideal laboratory conditions on controlled samples. In order to extend the eddy current based methodology to engine components, both probe design and instrumentation capability have to be optimized and controlled. This presentation will address the following:

• Probe: size, shape, frequency, bandwidth
• Instrumentation: frequency, phase, cable, thermal stability
• Automated testing: calibration, speed, positioning, environment
• Engine components: part curvature, geometry and edges

Further, it will also provide possible solutions to successfully implement eddy current methodology for residual stress profile measurement. USAF Contract Number: F33615-03-C-5219