Detection of structural variations in articles using acoustic resonance spectroscopy

A method for determining whether fluid is leaking through a valve seat of a valve when said valve is in a closed condition, comprising:

• generating vibrations having chosen frequencies in a selected frequency range in said valve comprising a valve seat, a disk or plug for forming a fluid seal with the seat, a stem for driving said disk or plug against the seat, and a valve body having an outside surface using an acoustic transmitting transducer disposed in vibrational contact with the outside surface of said valve and driven by a frequency sweep generator;
• receiving resonance vibrations induced in the valve body using an acoustic receiver disposed in vibrational contact with the outside surface of said valve, and converting the received vibrations into electrical voltages;
• receiving the electrical voltages and filtering the electrical voltages using a narrow-band, band-pass tracking filter having a center frequency which tracks selected excitation frequencies in the selected frequency range;
• storing the filtered electrical voltages, whereby an acoustic resonance spectrum of said valve is generated;
• comparing the generated acoustic resonance spectrum of said valve with at least one other acoustic resonance spectrum obtained for said valve in the closed condition thereof;
• and
• determining whether there is a difference between the generated acoustic resonance spectrum and the at least one other acoustic resonance spectrum.

A method for determining whether a vessel similar or identical in appearance to other vessels is similar or identical thereto, and contains similar fluids thereto, comprising:

• generating vibrations having chosen frequencies in a selected frequency range in said vessel from an acoustic transmitting transducer disposed in vibrational communication with the outside surface of said vessel, and driven by a frequency sweep generator;
• receiving resonance vibrations induced in said vessel using an acoustic receiver disposed in vibrational communication with the outside surface of said vessel, and converting the received vibrations into electrical voltages;
• receiving the electrical voltages and filtering the electrical voltages using a narrow-band, band-pass tracking filter having a center frequency which tracks selected excitation frequencies in the selected frequency range;
• storing the filtered electrical voltages, whereby an acoustic resonance spectrum of said vessel is generated;
• comparing the generated resonance spectrum of said vessel with at least one acoustic resonance spectrum obtained for another of said vessels;
• and
• determining whether there is a difference between the generated acoustic resonance spectrum and the at least one other acoustic resonance spectrum.

A method for determining the tightness of sealing flanges, comprising a cover flange and a flange attached to a pipe secured by bolts and nuts or a clamp, for accessing fluids in a vessel, comprising:

• generating vibrations having chosen frequencies in a selected frequency range in said sealing flanges, said nuts and bolts or said clamp, said pipe, and said vessel, using an acoustic transmitting transducer disposed in vibrational communication with an outside surface of said pipe or said vessel and driven by an acoustic frequency sweep generator;
• receiving resonance vibrations induced in said sealing flanges, said nuts and bolts or said clamp, said pipe, and said vessel, combined, using an acoustic receiver disposed in vibrational contact with the outside surface of said pipe or said vessel, and converting the received vibrations into electrical voltages;
• receiving the electrical voltages and filtering the electrical voltages using a narrow-band, band-pass tracking filter having a center frequency which tracks selected excitation frequencies in the selected frequency range;
• storing the filtered electrical voltages, whereby an acoustic resonance spectrum of the combination of said sealing flanges, said nuts and bolts or said clamp, said pipe, and saki vessel, is generated;
• comparing the generated acoustic resonance spectrum that includes the frequency range of the combination of said sealing flanges, said nuts and bolts or said clamp, said pipe, and said vessel, with at least one other acoustic resonance spectrum obtained for the combination of said sealing flanges, said nuts and bolts or said clamp, said pipe, and said vessel;
• and
• determining whether there is a difference between the generated acoustic resonance spectrum and the at least one other acoustic resonance spectrum.