Implementation of heterodyne effect in SHM and talking SHM systems

• US 10,191,013 B2
• Filed: 05/11/2017
• Issued: 01/29/2019
• Est. Priority Date: 05/11/2017
• Status: Active Grant

• Current Assignee: The Florida International University Board of Trustees (State University System of Florida)
• Original Assignee: The Florida International University Board of Trustees (State University System of Florida)
• Inventors: Tansel, Ibrahim, Senyurek, Volkan, Unal, Muhammed, Baghalian, Amin, Tashakori, Shervin
• Primary Examiner(s): Chapman, Jr., John
• Application Number:
  US15/592,438
• Publication Number:
  US 20180328892A1
• Time in Patent Office: 628 Days
• Field of Search: 73579
• CPC Class Codes: G01N 2291/02491 Materials with nonlinear acoustic properties
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/262 by electronic orientation or focusing, e.g. with phased arrays phased arrays per se G10K11/34
• CPC Class Codes: G01N 29/4445 Classification of defects
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

Systems and methods for implementation of the heterodyne effect in structural health monitoring (SHM) systems are provided. A system or method can include propagating a first signal with a first frequency and a second signal with a second frequency through a subject structure, and analyzing the output response to determine if a third frequency has been created, according to the heterodyne effect.

Claims

1. A method for a structural health monitoring system, the method comprising:

connecting a first signal generator to a first actuator;

connecting a second signal generator to a second actuator;

connecting the first actuator and the second actuator to a subject structure;

generating, by the first signal generator a first signal with a first frequency, and exciting the first actuator with the first signal;

generating, by the second signal generator, a second signal with a second frequency, and exciting the second actuator with the second signal;

retrieving an output signal from the subject structure; and

analyzing the output signal of a sensor to determine whether a structural defect exists by determining whether a third frequency has been created,

the third frequency being equal to the absolute value of the result of the subtraction of the second frequency from the first frequency,

a verbal message being embedded into the first signal, which is set to the first frequency, and the second signal being set to the first frequency.

2. A method for a structural health monitoring system, the method comprising:

connecting a first signal generator to a first actuator;

connecting a second signal generator to a second actuator;

connecting the first actuator and the second actuator to a subject structure;

generating, by the first signal generator a first signal with a first frequency, and exciting the first actuator with the first signal;

generating, by the second signal generator a second signal with a second frequency and exciting the second actuator with the second signal;

retrieving an output signal from the subject structure; and

analyzing the output signal of a sensor to determine whether a structural defect exists by determining whether a third frequency has been created,

the second signal comprising a sweep frequency within a second frequency range, the lowest frequency of the second frequency range being higher than 20 kHz,

the first signal comprising a sweep frequency within a first frequency range the lowest frequency of the first frequency range being higher than 20 kHz, and

the third frequency being equal to the absolute value the result of the subtraction of the second frequency from the first frequency at a given time while the first and second frequencies vary during the sweep.

3. A method for a structural health monitoring system, the method comprising:

connecting a first signal generator to a first actuator;

connecting a second signal generator to a second actuator;

connecting the first actuator and the second actuator to a subject structure;

generating, by the first signal generator a first signal with a first frequency, and exciting the first actuator with the first signal;

generating, by the second signal generator, a second signal with a second frequency, and exciting the second actuator with the second signal;

retrieving an output signal from the subject structure; and

analyzing the output signal of a sensor to determine whether a structural defect exists by determining whether a third frequency has been created,

the third frequency being equal to the absolute value of the result of the subtraction of the second frequency from the first frequency,

the third frequency being within a range of from 20 Hz to 20 kHz,

an amplitude of the created vibrations being satisfactory to create an audible sound, and

the structural defect thereby being understood without any sensor.

4. A method for a structural health monitoring system, the method comprising:

connecting a first signal generator to a first actuator;

connecting a second signal generator to a second actuator;

connecting the first actuator and the second actuator to a subject structure;

generating, by the first signal generator a first signal with a first frequency, and exciting the first actuator with the first signal;

generating, by the second signal generator, a second signal with a second frequency, and exciting the second actuator with the second signal;

retrieving an output signal from the subject structure; and

analyzing the output signal of a sensor to determine whether a structural defect exists by determining whether a third frequency has been created,

the third frequency being equal to the absolute value of the result of the subtraction of the second frequency from the first frequency,

the first signal comprising a single frequency that is higher than 20 kHz,

the second signal comprising a single frequency that is higher than 20 kHz and being different than the frequency of the first signal,

the first signal and the second signal being discontinuous signals, and emission of the second signal being delayed until after emission of the first signal by a predetermined amount of time,

the third frequency being within a range of from 20 Hz to 20 kHz, and an amplitude of the created vibrations being satisfactory to create an audible sound, the structural defect thereby being understood without any sensor.