Progress in the processing and fabrication of metal matrix composites (MMC’s) requires appropriate mechanical and non-destructive testing methods. These methods are needed to characterize properties, assess integrity, and predict the life of engine components such as compressor rotors, blades, and vanes. For this paper, we investigated the capabilities and limitations of several state-of-the-art nondestructive evaluation (NDE) technologies in characterizing titanium MMC rings for gas turbine engines. We examined the use of NDE technologies such as x-ray computed tomography, radiography, and ultrasonics in identifying fabrication-related problems that cause defects in components. Acousto-ultrasonics was explored to assess degradation of material mechanical properties by using stress wave factor and ultrasonic velocity measurements before and after the burst testing of the rings.
We concluded that radiography and pulse-echo ultrasonics are viable imaging techniques for fast and complementary evaluation of the rings. Furthermore, acousto-ultrasonics can be useful in a comparative analysis with a standard ring and for intermittent evaluation during the life of the rings. X-ray computed tomography can identify the manufacturing steps resulting in poor quality components, guide machining of components to final dimensions, and lead structural and design engineers to realistic component life-prediction models.