APPARATUS FOR WIRELESSLY DIAGNOSING STRUCTURE USING NONLINEAR ULTRASONIC MODULATION TECHNIQUE AND DIAGNOSIS METHOD FOR ASSURING SAFETY USING SAME

摘要

A method for diagnosing a structure to assure the safety thereof according to the present invention includes the steps of: making the structure vibrate by applying all signals of different frequencies; converting the responses of the structure elicited by the vibration into digital signals; generating primary modulation signals by synchronizing and demodulating the digital signals rid of the harmonics and the linear response of the signals of different frequencies; generating a first sideband spectrogram by combining the primary modulation signals corresponding with frequencies, the primary modulation signals being extracted by continuously changing the frequencies of the signals; and judging whether the structure is fissured based on the first sideband spectrogram, precisely detecting a flaw in spite of the very small power of the ultrasonic wave applied to the structure compared to the conventional technology, thus decreasing the power consumption.