Ultrasonic Resonance Measurements of Sound Velocity in Thin Composite Laminates

Wave impedance inversion method of the objective layer between the casing and the formation is brought forward utilizing compound reflection coefficients within the resonant transmission window of the casing in frequency domain. Calculation formula for wave impedance of the objective layer is obtained by main values of the inverse tangent function of phase‐shift at two neighboring frequencies and the corresponding integral character of phase‐shift is denoted as the convergent criterion of the inversion. To solve the uncertainty of acoustic source waveforms and compound reflection coefficients caused by ultrasonic transducer that is affected by the temperature and the pressure in down‐hole, the theoretical method of extracting acoustic source waveforms and compound reflection coefficients from in situ ultrasonic echoes are studied. With the treatment of the synthetic data, the effects of the changes in the known acoustic and geometrical parameters on wave impedance inversion results of the objective layer are investigated. The validity of the inversion method is verified by the good agreement between wave impedance images and the realistic status after the wave impedance images of the measured data in two scaling wells are obtained. The inversion and image of wave impedance of the objective layer using the realistic data of an oil field are carried out.

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“…5b) are obtained utilizing Eq. (12). The frequencies shown in Fig.5 is the start frequencies with the frequency interval of 3kHz.…”

Section: The Formula For Calculating Wave Impedance In the Form Of Thmentioning

confidence: 99%

Wave Impedance Inversion Method and Image Examples of the Objective Layer Between the Casing and the Formation

Yao

Wang

et al. 2005

Chinese J. Geophys.

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“…where d is the film thickness, and ρ is the density [9]. Thus, the C 33 was determined to be 7.7 GPa.…”

Section: A Vertical Incident Measurementmentioning

confidence: 99%

“…The reflection coefficient includes the information of waves, such as bulk waves and guided waves. From the reflection coefficient of the wave transmitted vertically to the surface of the thin plate, the longitudinal wave velocity can be obtained [8], [9]. When the reflection coefficient is measured as the incident angle is changed, the magnitude has minimum points caused by the excitation of leaky Lamb waves.…”

Section: Introductionmentioning

confidence: 99%

Determination of the orthotropic elastic constants of thin PET film by an ultrasonic micro-spectrometer

Okabe

Takeda

Yanaka

et al. 1999

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The elastic constants of a thin polyethylene terephthalate (PET) film, whose thickness was 12 mum, were determined from the acoustic reflection coefficients. The reflection coefficients were measured by an ultrasonic micro-spectrometer (UMSM), and all of the elastic constants were obtained through the fitting of a theory to the dip points of the magnitude of the reflection constants where leaky Lamb waves were excited. As a result, the film was found to be an orthotropic material, and the observed elastic constants were consistent with those measured by tensile tests. Besides, the in-plane shear modulus was found to be much larger than the out-of-plane shear moduli. Then, the reflection coefficients were calculated using the obtained stiffness matrix. The calculated values reproduced not only the dip points but also the change in magnitude of measured reflection coefficients depending on the frequency and the incident angle. These agreements suggest that the stiffness matrix components were determined accurately.

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“…The error in Q12 affects the value of v12 more than it does the values of Ev E2 and v23, because of the large value of Q11 as seen in eqs. (6). …”

Section: Results and Conclusionmentioning

confidence: 99%

48418 Nondestructive determination of elastic constants of composite materials

1994

NDT & E International

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Ultrasonic Resonance Measurements of Sound Velocity in Thin Composite Laminates

Cited by 24 publications

References 2 publications

Wave Impedance Inversion Method and Image Examples of the Objective Layer Between the Casing and the Formation

Wave Impedance Inversion Method and Image Examples of the Objective Layer Between the Casing and the Formation

Determination of the orthotropic elastic constants of thin PET film by an ultrasonic micro-spectrometer

48418 Nondestructive determination of elastic constants of composite materials

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