NJDOT Research

NJ #
Detection of Damage Precursors in Steel Components for Life-Cycle Assessments

The early identification of damage of fracture-critical members is of the outmost importance in the maintenance of a safe bridge infrastructure. A new Non-Destructive Evaluation method that gives an early warning of accumulating damage is been formulated herein. The Vibro-Acoustic Modulation method utilizes nonlinear interactions of a high frequency ultrasonic wave with a low frequency modulating vibration in the presence of various flaws such as fatigue and stress-corrosion cracks. The growth of a flaw in time is correlated with an increase in a parameter called the Modulation Index which is defined in the spectral domain as the ratio of the side-band spectral components formed at frequencies around the amplitude of the carrier. The new method is shown capable of detecting damage in simple during cyclic loading. An experimental set-up has been fabricated that can be taken to the field for farther developments of the new NDE method.
For more information, see Experimental Nonlinear Vibro-Modulation Testing System FN-Scan® User’s Guide.

Performing Organization
Stevens Institute of Technology
Key Word(s)
Vibro-Acoustic Modulation, Acoustic Methods, Damage Detection, Fatigue, Fracture

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