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Showing papers by "Osama M. Mukdadi published in 2001"


Journal ArticleDOI
TL;DR: This work explores exact and approximate analysis methods of ultrasonic guided wave propagation in thin layers, explicitly dealing with orthotropic symmetry and propagation off-axis with respect to the manufacturing direction and theoretical predictions are presented for other guided wave modes.
Abstract: The elastic properties of many materials in sheet or plate form can be approximated with orthotropic symmetry. In many sheet material manufacturing industries (e.g., the paper industry), manufacturers desire knowledge of certain anisotropic elastic properties in the sheet for handling and quality issues. Ultrasonic wave propagation in plate materials forms a method to determine the anisotropic elastic properties in a nondestructive manner. This work explores exact and approximate analysis methods of ultrasonic guided wave propagation in thin layers, explicitly dealing with orthotropic symmetry and propagation off-axis with respect to the manufacturing direction. Recent advances in full-field ultrasonic imaging methods, based on dynamic holography, allow simultaneous measurement of the plate wave motion in all planar directions within a single image. Results from this laser ultrasonic imaging approach are presented that record the lowest anti-symmetric (flexural) mode wavefront in a single image without scanning. Specific numerical predictions for flexural wave propagation in two distinctly different types of paper are presented and compared with direct imaging measurements. Very good agreement is obtained for the lowest anti-symmetric plate mode using paper properties independently determined by a third party. Complete determination of the elastic modulus tensor for orthotropic layers requires measurement of other modes in addition to the lowest anti-symmetric. Theoretical predictions are presented for other guided wave modes [extensional (S), flexural (A), and shear-horizontal (SH)] in orthotropic plates with emphasis on propagation in all planar directions. It is shown that there are significant changes in the dispersion characterization of these modes at certain frequencies (including off-axis mode coupling) that can be exploited to measure additional in-plane elastic moduli of thin layers. At present, the sensitivity of the imaging measurement approach limits experimental investigation to relatively large amplitudes easily produced by flexural wave motion (>0.1 nm). Extension of the measurement range and application to other plate wave modes are in progress and shall be reported in future work.

15 citations


Proceedings ArticleDOI
07 Jun 2001
TL;DR: In this paper, an exact and approximate theoretical analysis of the wavelengths of plate wave mode propagation in all planar directions for the dispersive antisymmetric Lamb wave mode are compared with measurements from a laser ultrasonic imaging approach that records the out of plane ultrasonic motion over a large area in a single frame without scanning.
Abstract: Exact and approximate theoretical analysis of the wavelengths of plate wave mode propagation in all planar directions for the dispersive antisymmetric Lamb wave mode are compared with measurements from a laser ultrasonic imaging approach that records the out of plane ultrasonic motion over a large area in a single frame without scanning. Good agreement is demonstrated, based on independent determination of the elastic constants, for two different types of paper.

1 citations