Waves shear

The austenitic and, hence, anisotropic V-butt weld is embedded in isotropic steel it has a width of 10 mm at its baseline and a height of 30 mm. If a notch is present, it has a width of 1 mm and a height of 15 mm it is located at the right-hand side of the V-butt weld. The simulated transducer is a commercial 45°-shear wave probe (MWB45-2E). The parameters varied during the simulations are ... 

Figure 9 Slowness diagram At the interface between isotropic steel and a V-bntt weld with 10° inclination and perpendicular grain orientation the incident 45° (with regard to the sample top surface) shea.r wave will split into two quasi shear waves qSV and qSV( 2.)...

Splitting into two quasi shear waves If the transducer is coupling to the isotropic steel the incident shear wave may split into two independent quasi shear vertical wave-... 

Using now the phase matching condition, it can be seen that besides the quasi shear wave (qSV) which is obtained as usual, a second quasi shear wave (qSV(2)) results from the upper quasi shear wave part. Since the direction of the group velocity vector points downwards this wave is able to propagate and can be seen in the snapshot (see Fig. 10) if a is properly adjusted, i.e. is pointing upwards as in Fig. 2. 

Figure 1 shows the ultrasonic testing configuration used for detecting OSD. The ultrasonic focused probe is placed at an angle (18.9°) such that OSD are insonified by mode converted 45° shear waves. 

For defect sizing by TOED, use of L waves involves a penalty in resolution of almost a factor of two at a given frequency because of difference in velocity as compared to shear waves and use of SV waves runs into difficulties because of the mode conversion problems. Further, problems due to couplant thickness variations, surface roughness affects, beam skewing and distortion problems in anisotropic welds can also be expected. On the contrary, SH waves are not affected... 

The transmission coefficient Cl (Qj,t), considering transient (broadband) sources, is time-dependent and therefore accounts for the possible pulse deformation in the refraction process. It also takes account of the quantity actually computed in the solid (displacement, velocity potential,...) and the possible mode-conversion into shear waves and is given by... 

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... 

In the case of shear waves probes, we can do nothing else but using a steel blocks with holes at different depths (see figure 4a). The automatic system is described further. 

A piezo-composite consists of a piezoelectric active phase and a passive plastic phase [2]. In the 1-3-configuration adopted in our case, piezoelectric rods parallely aligned in thickness direction are imbedded in a three-dimensional plastic matrix (Fig. 1). The distance between the rods has to be chosen inferior to the half wave length of the shear wave in the matrix material ensuring that the whole compound is vibrating as a quasi-homogeneous material. 

The test range was adjusted to 100mm in shear wave by the use of STB-N1 Calibration Block. 

A shear wave transducer with the height H, and the width W on the wedge and at the angle a, transmitted shear waves, at the frequency f and perpendicular to the paper. The limited plane SH Waves were transmitted to the test surface. The height H of the transducer was considered by dividing it into N pieces. On the test surface in the areafW XHl), the transducer vibrated perpendicular to the paper where Hl=H/cos , the... 

Is the recorded signal a delayed compression wave or the shear wave ... 

Special contact transducers having wedges providing incidence angles for specific appHcations are used widely in industry. For example, normal incidence is used in tests for laminations within sheets, and for sheet or plate thickness where the back surface of the test material parallels, to within perhaps 10°, the front surface. Shear wave transducers typically used for weld examination have 45°, 60°, or 70° inspection (refracted) angles. To locate discontinuities, the transducers may be moved back and forth over selected surface areas until the angled search beam approaches normal incidence on the... 

Ultrasonic Properties. Vitreous sihca of high purity, such as the synthetic type, has an unusually low attenuation of high frequency ultrasonic waves. The loss, is a linear function of frequency, up to the 30—40 MHz region and can be expressed a.s A = Bf, where B = 0.26 dB-MHz/m for shear waves and 0.16 dB-MHz/m for compressional waves (168). 

Vibratory Shear-Enhanced Membranes The vibratory shearenhancing process (VSEP) is j ist starting commerciahzation by Logic International, Emeryville, CA. It employs the nse of intense sinnsiodal shear waves to ensnre that the membrane snrfaces remain ac tive and clean of sohd matter. The application of this technology wonld be in the pnrification of wastewater (Ref. 2). 

Figure 3.6. Experimental configuration for introducing simultaneous compression and shear waves in a specimen.

Thus, by using two VISARs, and by monitoring two beams at 6, both the longitudinal velocity and the shear-wave velocity can be determined simultaneously by solving the above two equations. With a lens delay leg VISAR (Amery, 1976), a precision in determining F(t) to 2% can be achieved. The longitudinal and transverse particle velocity profiles obtained in a study of aluminum are indicated in Fig. 3.12. 

Koller, L.R. and G.R. Fowles (1979), Simultaneous Generation and Measurement of Longitudinal and Shear Waves in Shock Compressed Media, in High Pressure Science and Technology, vol. 2, (edited by K.D. Timmerhaus and M.S. Barber), Plenum, New York, pp. 927-934. 

The parameters for the model were originally evaluated for oil shale, a material for which substantial fracture stress and fragment size data depending on strain rate were available (see Fig. 8.11). In the case of a less well-characterized brittle material, the parameters may be inferred from the shear-wave velocity and a dynamic fracture or spall stress at a known strain rate. In particular, is approximately one-third the shear-wave velocity, m has been shown to be about 6 for various brittle materials (Grady and Lipkin, 1980), and k can then be determined from a known dynamic fracture stress using an analytic solution of (8.65), (8.66) and (8.68) in one dimension for constant strain rate. 

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