Advanced Ultrasonic Spectroscopy for Improved Inspection of Highly Attenuative Components

In the case of complex material structures, such as highly attenuative and anisotropic materials, multi-layer components or bonded structures, a swept-wave ultrasonic spectroscopy method, UltraSpec®, has proven to be useful where conventional techniques are inadequate. When coupled with specialized data analysis software, this produces a highly sensitive nondestructive inspection technique that can be employed for challenging inspection applications. UltraSpec uses a long-duration, swept-frequency excitation pulse in contrast to the short duration, large amplitude excitation pulses used in traditional ultrasonic methods. The technique offers substantial signal-to-noise improvement and can be efficiently tailored to application-specific frequency ranges to maximize sensitivity and fidelity. Spectral analysis, resonance characteristics and processed time reflections provide the user with more information to assess the structure being inspected. The system also allows for evaluations at different depths or interfaces within a complex stack-up. This is especially useful for bond inspections, porosity detection/quantification, identification of micro-cracking or impact damage in composite materials. The technique has been used to successfully produce material insights that cannot be provided by other methods. This paper will use results from challenging inspections to highlight these unique UltraSpec capabilities and advantages.