Longitudinal wave

Another example shows a 4 MHz longitudinal wave probe WSY70-4 normally used for testing of coarse grained austenitic material. In this application a high pulse amplitude is... 

By means of the pair SI/El a longitudinal wave travels parallel to the object surface. 

The figures 9 and 10 show the A-Scans of these two steps. Figure 9 presents the velocity measurement of the longitudinal wave parallel to the surface in the first step and figure 10 presents the A-Scan of the thickness measurement in the second step. 

Therefore, we may say that head wave is the excited shear wave when longitudinal wave is spreading along boundaries. This is the head wave which we often call. In Fig.3 the wavefront of head wave is indicated by AB. The biggest circular arc AC in Fig.3 is the wavefront of longitudinal wave. The small arrow beside the circular line indicates the direction of displacement after the wavefront arrives and the written character 8 nearby indicates its... 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

Fig. 2 shows the CFRP-sandwich specimen and the transducer mounted on the scanner. Fig. 23 presents a C-scan of the specimen as first interesting result. Only the defects visible from the outside are indicated. The distance between transducer and specimen was smaller than the focal length, so that the angle of incidence at the edge of the sound beam converts the longitudinal waves to Rayleigh-waves in the specimen. These waves provide a very sharp image of the surface. This method opens the possibility for a non-contact acoustic microscope. 

For exciting the surface waves the traditional method of transforming of the longitudinal wave by the plastic wedge is used. The scheme of surface waves excitation is shown in fig. 1. In particular, it is ascertained that the intensity of the excitation of the surface wave is determined by the position of the extreme point of the exit of the acoustic beam relatively to the front meniscus of the contact liquid. The investigations have shown, that under the... 

For example, at a frequency of 1 MHz, the effect of ultrasound in water of surface tension 73 dyn-cm and density 1 g-cm- is to produce longitudinal waves of about 12 pm. The resulting mean droplet diameter (D) is given by Equation 19.2. 

T. Leon-Salamanca and D. E. Bray, "Ultrasonic Measurement Of Residual Stress In Steels Using Critically Refracted Longitudinal Waves (L j )," R j". NDE 6(4) 1995 (in press). 

The lower the value of the more likely it is that S is positive indicating a thermodynamic tendency for the process to occur. Longitudinal wave theory has been appHed to the defoamer spreading process as in equation 5 where P is the penetration depth of a spreading droplet of initial radius R, viscosity Tj, and density p. 

Attenuation occurs because the tensile release, which is traveling at an elastic longitudinal wave speed, Q, overtakes the tensile front traveling at a plastic wave speed Cp < Q. Assuming a pulse as shown in Fig. 8.10 with a stress rate in the tensile front and tensile release of a and b, respectively, an approximate analysis shows that the peak will decay by an amount... 

Lui, D.T., Longitudinal Wave Propagation in an Elastic-Plastic Medium, Lockheed Missiles and Space Company Technical Report LAC-MSC-2-60-64-39, Sunnyvale, CA, September 1964. 

The best of all methods of measuring E is to measure the velocity of sound in the material. The velocity of longitudinal waves, v, depends on Young s modulus and the density, p ... 

Sound waves are propagated in a gas as longitudinal waves of speed vs ... 

In planar waves the amplitude A(r) = Aq is a constant. All particles situated within a plane normal to the wave vector move at the same time. Longitudinal waves are planar waves where the displacements are parallel to the wave vector (v and c are colinear). Longitudinal waves can propagate in every material media. These are compression or dilatation waves. In transverse waves, v and c are orthogonal. Transverse waves do not propagate in fluids. 

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