Observation of the dispersion behavior of surface acoustic waves in a wedge waveguide by laser ultrasonics

1992 ◽  
Vol 61 (25) ◽  
pp. 2970-2972 ◽  
Author(s):  
X. Jia ◽  
M. de Billy
Keyword(s):  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Ultrasonics ◽  
Dispersion Behavior

Laser ultrasonic monitoring of reversible/irreversible modification of a real crack under photothermal loading

2020 ◽  
pp. 147592172091516
Author(s):  
Chen-Yin Ni ◽  
Jin-Chao LV ◽  
Yue-Ying Zhang ◽  
Hai-Yan He ◽  
Xi-Feng Xia ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Crack Detection ◽  
Optical Measurement ◽  
Mode Conversion ◽  
Surface Acoustic Waves ◽  
Equilibrium Temperature ◽  
Laser Ultrasonics ◽  
Loading Cycle ◽  
Detection Techniques ◽  
Significant Difference

We study the responses of laser-generated acoustic waves to localized reversible/irreversible modifications of microscopic asperities on crack surfaces during crack closure, which is an essential process in nonlinear photoacoustic/photothermal crack detection techniques. Our laser ultrasonics technique involves optical measurement of the transmission and mode conversion of the laser-generated surface acoustic waves caused by the crack. Reversible/irreversible modifications of asperities can be achieved via non-contact photothermal loading of the crack. Three photothermal loading cycles were realized in individual succession and were monitored using the laser ultrasonics technique at various experimental locations along the crack. In our experiments, each photothermal loading cycle includes multiple successive subcycles, in which the material is first heated and then cooled to its equilibrium temperature, thereby initiating local closing, followed by opening of the crack. Each subcycle is monitored twice using the laser ultrasonics technique, once each at the end of heating and cooling. Furthermore, each successive subcycle is accomplished at a higher power of heating laser than that of the previous subcycle. Significant differences in the peak-to-peak amplitude of the surface skimming longitudinal acoustic wave, which is excited by mode conversion of the Rayleigh wave by the crack, are revealed during the first cycle of photothermal loading. These differences clearly indicate a partial irreversibility of the mechanical processes occurring in the crack surfaces during subcycles of the first cycle. In a larger temporal scale, irreversible modification of crack surfaces is observed from the significant difference between the experimental results of the first photothermal loading cycle and the subsequent two cycles, whereas a reversible response of the crack surface to thermoelastic loading is observed from the similarity of the measurements accumulated during the two subsequent cycles.

Surface Acoustic Wave Band Gaps and Phononic Structures on Thin Solid Plates

2005 ◽  
Author(s):  
Xinya Zhang ◽  
Ted Jackson ◽  
Emmanuel Lafound ◽  
Pierre Deymier ◽  
Jerome Vasseur
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Acoustic Waves ◽  
Phononic Crystal ◽  
Surface Acoustic Waves ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Laser Ultrasonics ◽  
Thin Plates ◽  
Wave Band

Novel phononic crystal structures on thin plates for material science applications in ultrasonic range (~ MHz) are described. Phononic crystals are created by a periodic arrangement of two or more materials displaying a strong contrast in their elastic properties and density. Because of the artificial periodic elastic structures of phononic crystals, there can exist frequency ranges in which waves cannot propagate, giving rise to phononic band gaps which are analogous to photonic band gaps for electromagnetic waves in the well-documented photonic crystals. In the past decades, the phononic structures and acoustic band gaps based on bulk materials have been researched in length. However few investigations have been performed on phononic structures on thin plates to form surface acoustic wave band gaps. In this presentation, we report a new approach: patterning two dimensional membranes to form phononic crystals, searching for specific acoustic transport properties and surface acoustic waves band gaps through a series of deliberate designs and experimental characterizations. The proposed phononic crystals are numerically simulated through a three-dimensional plane wave expansion (PWE) method and experimentally characterized by a laser ultrasonics instrument that has been developed in our laboratory.

LASER ULTRASONICS FOR DETECTION OF ELASTIC NONLINEARITY USING COLLINEAR MIXING OF SURFACE ACOUSTIC WAVES

2010 ◽  
Author(s):  
S. D. Sharpies ◽  
T. Stratoudaki ◽  
R. J. Ellwood ◽  
I. J. Collison ◽  
M. Clark ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Ultrasonics ◽  
Elastic Nonlinearity

Surface Acoustic Waves on a Sphere –Analysis of Propagation Using Laser Ultrasonics–

2001 ◽  
Vol 40 (Part 1, No. 5B) ◽  
pp. 3623-3627 ◽  
Author(s):  
Satoru Ishikawa ◽  
Hideo Cho ◽  
Kazushi Yamanaka ◽  
Noritaka Nakaso ◽  
Yusuke Tsukahara
Keyword(s):  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Ultrasonics

scholarly journals Nondestructive testing of thin films using surface acoustic waves and laser ultrasonics

2018 ◽  
Author(s):  
Frédéric Jenot ◽  
Sabrina Fourez ◽  
Mohammadi Ouaftouh ◽  
Marc Duquennoy
Keyword(s):  
Thin Films ◽  
Nondestructive Testing ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Ultrasonics

scholarly journals Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

2018 ◽  
Vol 8 (10) ◽  
pp. 1991 ◽  
Author(s):  
Rikesh Patel ◽  
Matthias Hirsch ◽  
Paul Dryburgh ◽  
Don Pieris ◽  
Samuel Achamfuo-Yeboah ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Ultrasonics ◽  
Structural Defects ◽  
Spatially Resolved ◽  
Acoustic Spectroscopy ◽  
Material Texture ◽  
Ultrasound Inspection ◽  
Non Destructive

Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. However, the current class of AM systems produce parts that contain structural defects (e.g., cracks and pores) which is not compatible with certification in high value industries. The probable complexity of an AM design increases the difficulty of using many non-destructive evaluation (NDE) techniques to inspect AM parts—however, a unique opportunity exists to interrogate a part during production using a rapid surface based technique. Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound inspection technique used to image material microstructure of metals and alloys. SRAS generates and detects `controlled’ surface acoustic waves (SAWs) using lasers, which makes it a non-contact and non-destructive technique. The technique is also sensitive to surface and subsurface voids. Work until now has been on imaging the texture information of selective laser melted (SLM) parts once prepared (i.e., polished with R a < 0 . 1 μ m)—the challenge for performing laser ultrasonics in-process is measuring waves on the rough surfaces present on as-deposited parts. This paper presents the results of a prototype SRAS system, developed using the rough surface ultrasound detector known as speckle knife edge detector (SKED)—texture images using this setup of an as-deposited Ti64 SLM sample, with a surface roughness of S a ≈ 6 μ m, were obtained.

Characterization of RF Sputtered ZnO Piezoelectric Films Using Transmission Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 86-87
Author(s):  
Kemining W. Yeh ◽  
Richard S. Muller ◽  
Wei-Kuo Wu ◽  
Jack Washburn
Keyword(s):  
Integrated Circuit ◽  
Acoustic Waves ◽  
New Technology ◽  
Surface Acoustic Waves ◽  
Electromechanical Properties ◽  
Leading Role ◽  
Saw Devices ◽  
Transmission Electron ◽  
High Degree

Considerable and continuing interest has been shown in the thin film transducer fabrication for surface acoustic waves (SAW) in the past few years. Due to the high degree of miniaturization, compatibility with silicon integrated circuit technology, simplicity and ease of design, this new technology has played an important role in the design of new devices for communications and signal processing. Among the commonly used piezoelectric thin films, ZnO generally yields superior electromechanical properties and is expected to play a leading role in the development of SAW devices.

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