Determination of elastic parameters in isotropic plates by using acoustic microscopy measurements and an optimization method

• Published in: NDT & E international : independent nondestructive testing and evaluation Vol. 35; no. 8; pp. 493 - 502
• Main Authors: Lematre, M., Benmehrez, Y., Bourse, G., Xu, J.W., Ourak, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-12-2002; Elsevier Science; Elsevier
• Subjects: Acoustical measurements and instrumentation; Acoustics; Cross-disciplinary physics: materials science; rheology; Elastic constants; Engineering Sciences; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Isotropic plates; Kushibiki method; Line-focus acoustic microscopy; Materials science; Materials testing; Measurement and testing methods; Measurement methods and techniques in continuum mechanics of solids; Nondestructive testing: ultrasonic testing, photoacoustic testing; Physics; Simplex method; Solid mechanics; Structural and continuum mechanics; Kushibiki method; Line-focus acoustic microscopy; Elastic constants; Isotropic plates; Simplex method; Elastic constant; Acoustic measurement; Initial value problem; Glass; Surface wave; Aluminium; Numerical method; Experimental study; Leaky wave; Spectral analysis; Plate; Lamb wave; Acoustic microscopy; Spectrum analysis; Isotropic material
• ISSN: 0963-8695; 1879-1174
• DOI: 10.1016/S0963-8695(02)00010-5

The determination of elastic constants in isotropic solids by line focus acoustic (LFA) microscopy is discussed. A velocity corresponding to a global resonance of leaky Lamb waves has been obtained for different frequencies of excitation (
f) from the
V(
z,
f) curves. This fact is analysed by using a Kushibiki spectrum analysis. The elastic constants are determined from the comparison between measured and calculated velocities. The principle is based on the minimization of the summation of the square difference ∑|
V
f
c−
V
f
m|
2 by using an algorithm based on the simplex method. This paper deals with the case of isotropic plates such as glass and aluminium plates. The influence of the initial values of
c
ij
on the final result is discussed in these cases. Experimental velocity profiles are measured on glass and aluminium plates as a function of the frequency varying from 8 to 17
MHz which corresponds to the bandwidth of the used transducer. The problem of geometric
V
G(
z) and measured
V(
z) curves fitting is also discussed.