Development of Stress Enhanced Ultrasonic Compressor Blade Inspection Equipment.
SOUTHWEST RESEARCH INST SAN ANTONIO TEX DEPT OF INSTRUMENTATION RESEARCH
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Background research leading to the concept of the stress enhanced ultrasonic surface wave inspection of compressor blades is reviewed. Basically, the approach consists of applying a tension stress to the region being examined ultrasonically which opens tightly closed fatigue cracks so that the interfaces become good ultrasonic reflectors. Procedures for the development of small fatigue cracks in T53 compressor blades and results obtained with experimental ultrasonic transducers are described. Incorporation of the method into an automatic apparatus for inspecting T53 first and second stage compressor blades with the blades still installed in the engine was accomplished. Design features are described which include push-button operation of the overall system, self-checking circuits, automatic placement of transducer arrays on the convex and concave sides of the blades, automatic signature analysis with and without tension stress, discrimination between flaws, pits, foreign object damage, scratches and fatigue cracks automatic indexing from blade to blade and counting of blades, etc. Inspection results are indicated by illumination of alpha-numeric displays andor direct recording. Author
- Electric Power Production and Distribution