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Basic Concepts
Published in Suresh C. Ameta, Rakshit Ameta, Garima Ameta, Sonochemistry, 2018
Propagation of ultrasonic wave is commonly described in terms of the direction of motion of particles in relation to the direction, in which wave propagates. The longitudinal waves are defined as waves where the motion of particle is parallel to the direction of the wave propagation. On the other hand, shear waves are defined as waves where the motion of particle is perpendicular to the direction of the wave propagation. Both these waves can exist in solids because solids have rigidity to offer resistance to shear as well as compressive loads, unlike liquids and gases. But the shear waves cannot exist in liquid and gaseous medium as they offer no resistance to shear loads in such media.
W
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[general, mechanics] The progressive disturbance propagated in a medium by a periodic vibration of the particles of the medium. Transverse wave motion is that in which the vibration of the particles is perpendicular to the direction of propagation. Longitudinal wave motion is that in which the vibration of the particles is parallel to the direction of propagation (seewave).
Ultrasound
Published in John G Webster, Minimally Invasive Medical Technology, 2016
Sound waves propagate through the air, or any other medium, by exciting molecules and transmitting the energy to adjacent molecules, very much like balls on a pool table pushing each other. Waves that vibrate perpendicular to the traveling direction are called transverse waves and waves that vibrate parallel to the traveling direction are called longitudinal waves. Longitudinal waves create small disturbances on the molecules as they travel into the body, creating zones where the molecules are highly concentrated and others where they are sparse.
Assessment of Laser-Generated Ultrasonic Total Focusing Method for Battery Cell Foil Weld Inspection
Published in Research in Nondestructive Evaluation, 2023
Dmitriy D. Bruder, Megan E. McGovern, Robin James, Teresa J. Rinker, Vineet Gattani
Only two ultrasonic bulk wave modes exist in a solid infinite medium: longitudinal waves and shear waves. Longitudinal waves, sometimes referred to as dilatational or compressional waves, are waves in which the particle motion is in the same direction as the wave propagation. Shear waves, sometimes referred to as transverse waves, have particle motion perpendicular to the direction of wave propagation in the plane of propagation. When boundaries are present in the medium, these bulk waves interact with the boundaries to produce guided waves (if the wavelength is sufficiently long enough to “see” the boundaries, e.g., the wavelength is on the same order as the plate thickness). In other words, the geometry of the sample will impose boundary conditions on the wave propagation, resulting in guided wave modes. One commonly known example of a guided wave is the surface acoustic wave (SAW), or Rayleigh wave where the boundary condition is that of the stress-free surface. Rayleigh waves propagate close to the surface of the body with the amplitude of wave motion decreasing with depth. This results in an elliptical particle motion that only exists~3 wavelengths below the surface and, for solids, travels at a velocity slightly below the shear wave velocity [18].
Partial Discharge Detection and Localization in Power Transformers based on Acoustic Emission: Theory, Methods, and Recent Trends
Published in IETE Technical Review, 2021
Viral B. Rathod, Ganesh B. Kumbhar, Bhavesh R. Bhalja
AE waves based on their direction of propagation are classified as, Longitudinal waves (Pressure waves): These waves consist of alternate compression and rarefaction forces in the direction of propagation. In these waves, particles vibrate along the direction of propagation. They can propagate through all mediums – solids, liquids, and gases.Transverse waves (Shear waves): In these waves, particles vibrate perpendicular to the direction of propagation. They can propagate through solids but not through liquids and gases.Surface waves (Raleigh-Lamb waves): In these waves, the particle moves in the elliptical path near the surface of the material. They are the complex form of longitudinal and transverse waves.
Structural health assessment techniques for in-service timber poles
Published in Structure and Infrastructure Engineering, 2023
Sahan Bandara, Pathmanathan Rajeev, Emad Gad
The stress wave propagation technique is a non-destructive testing method based on the transmission and reflection of a generated stress wave in a structure generated by the application of an external force to the structure. The induced stresses by the applied force transmit to the other points in the body simultaneously with the incident stress wave. Stress waves can be categorised as body waves and surface waves. The body waves consist of compression (longitudinal) and shear (transverse) waves. A longitudinal wave is associated with the propagation of normal stress parallel to the direction of particle motion and a transverse wave is related to the shear stress, where the particle motion is perpendicular to the direction of wave propagation.