INVESTIGATION OF APPLYING INTERFEROMETRIC HOLOGRAPHY TO TURBINE BLADE STRESS ANALYSIS.

The primary results of a research investigation to determine the feasibility of applying interferometric holography to turbine blade stress analysis are reported and may be briefly summarized as follows: (1) It has been demonstrated that the strain at the surface of a turbine blade, excited in dynamic flexure, can be calculated from interferometric holographic fringe information. (2) Interferometric holography appears to offer some promise in the detection of weaknesses, unusual wear or fatigue in turbine blades, however experimental implementation and fringe interpretation would be a somewhat time consuming process. (3) The introduction of elevated temperatures to the turbine blade stress analysis problem requires the use of pulsed holographic techniques for best results, but otherwise it appears to present no insurmountable problems. (4) Pulsed interferometric holograms of transient and cyclically excited turbine blades have been successfully and readily constructed, demonstrating that the developed pulsed laser system possesses more than sufficient pulse reproducibility, coherence and intensity for recording reflected light holograms. (Author)