Surface SH Waves Research Articles

Principal Stress Measurement by Propagation Velocity Estimation at No Stress Using Surface Anisotropy in Surface SH Wave Acoustoelasticity

Principal Stress Measurement by Propagation Velocity Estimation at No Stress Using Surface Anisotropy in Surface SH Wave Acoustoelasticity

Nonlinear surface SH waves in a half-space covered by an irregular layer

Nonlinear surface SH waves in a half-space covered by an irregular layer

Reduction of temperature influence in stress measurement using surface SH‐wave acoustoelasticity

AbstractStress measurements are required to prevent collapse accidents of structures. Surface SH‐wave acoustoelasticity can measure principal stress difference nondestructively and easily. Currently, surface SH‐wave acoustoelasticity can measure with high precision using a T‐type surface SH‐wave sensor in ideal environments such as in the laboratory. However, in actual environments, it cannot be measured with high precision due to change in the temperature of the specimen. In this paper, temperature dependence of surface SH‐wave acoustoelastic constants was verified to investigate the influence of specimen temperature on surface SH‐wave acoustoelasticity. In addition, the measuring system of surface SH‐wave acoustoelasticity using a cross T‐type surface SH‐wave sensor to reduce the influence of specimen temperature was developed.

Reduction of Temperature Influence in Stress Measurement Using Surface SH-wave Acoustoelasticity

Reduction of Temperature Influence in Stress Measurement Using Surface SH-wave Acoustoelasticity

Influence of Subsurface Inhomogeneity on the Propagation of SH Waves in Isotropic Materials

It is shown that, within the framework of a linear nonlocal continual theory of elasticity taking into account the relationship between the strain fields and local displacements of masses, it is possible to describe the process of propagation of antiplane surface shear waves (SH waves) in an isotropic half space. These surface SH waves are not predicted by the classical theory of elasticity. The indicated surface waves may propagate in the half space if the problem is posed within the framework of elasticity theory, which takes into account the tensor character of the local displacements of masses. The stress-strain state of this continuum is characterized by the strain tensor and the tensor of induced mass density, which are independent quantities.

Application of Surface SH-wave Acoustoelasticity for Axial Stress Measurement of Railroad Long Rail

Application of Surface SH-wave Acoustoelasticity for Axial Stress Measurement of Railroad Long Rail

Measurement of Surface SH-Wave Velocities Generated on the Surface of Japanese Cypress Column

Polyetherimide resin wedge transducers were used to generate a shear wave that was obliquely incident relative to the surface of a Japanese cypress column for measuring the surface SH-wave velocity. As the inter-transducer distance increased, the propagation time increased and the am-plitude became smaller. The propagation time and the amplitude were significantly correlated with the inter-transducer distance. The SH-wave velocity ranged from 1270 m/s to 1496 m/s. Surface SH-wave velocity was lower in the central part of the column and higher in the outer part. Velocity was negatively correlated with moisture content at 1% of significance level. These results suggest the accomplishment of the first target for applying the surface SH-wave acoustoelastic technique to nondestructive evaluation of drying stress in wood.

Shear surface waves at the interface of two magneto‐electro‐elastic media

PurposeThe purpose of this paper is to investigate the problem of the existence and propagation of a surface SH wave at the interface of two magneto‐electro‐elastic half‐spaces.Design/methodology/approachEquations of motions for magneto‐electro‐elastic materials have been used with coupling between mechanical, electric and magnetic fields. The problem is solved for four different sets of boundary conditions.FindingsThe results show that, for appropriate choice of material parameters, a non dispersive surface wave can propagate at the interface of these media. The existence condition is easier to satisfy for an electrically closed contact or no electromagnetic contact between two half‐spaces. The existence conditions can be easily satisfied for all four sets of boundary conditions if the two half‐spaces have their main symmetry axis, both parallel to the interface and perpendicular to the propagation direction, directed in the opposite directions. In this case the SH surface wave can always propagate if the two media are identical.Originality/valueThe magneto‐electric coupling effect has extensive applications, for example in electronic packaging, acoustic devices and medical ultrasonic imaging. The results of this paper give better understanding of the effects of the boundary conditions on the propagation of SH surface waves in magneto‐electro‐elastic materials.

Reflection and refraction from a vertical layer of surface SH waves radiated from a point source on a boundary free of tensions

With the help of the asymptotic boundary layer method, the transformation of an elastic SH-polarized surface wave of whispering gallery type (the so-called Love wave) is analyzed in the case where this wave passes many times through a vertical layer between two half-planes, Bibliography: 6 titles.

The green’s function of sh-polarized surface waves

In this paper, the Green’s function corresponding to surface SH-waves is found. Whispering gallery waves, creeping waves, and waves propagating with a constant transverse velocity in an elastic medium are investigated. Bibliography: 5 titles.

First Evidence of Surface SH-Wave Propagation in Cubic Piezomagnetics

This theoretical work provides with results of characteristics calculation of the ultrasonic surface Zakharenko waves (USZWs) existing in piezomagnetic cubic monocrystals of class m3m that can be readily used for non-destructive testing. The piezomagnetic waves propagate in direction [101] corresponding to relatively easy magnetization for the following piezomagnetics: Galfenol, Terfenol-D, and CoFe2O4 with cubic structures. The phase velocities of the USZW-waves and the coefficient of magnetomechanical coupling (CMMC) K2 were calculated for the crystals. It was found that the coefficient K2 for piezomagnetics with Km2 > 1/3 and Km2 >> 1/3 is about 8% to 9%, where K2 = 2 (VUSZW,o – VUSZW,c)/VUSZW,o and Km2 = h2/(Cμ). Knowledge of piezomagnetic properties of cubic crystals makes possible the use of them in new products utilizing the phenomenon called the magnetoelectric effect. Also, this study is useful for possible application of cubic piezomagnetics in composite structures consisting of piezoelectric and (or) piezomagnetic materials and in the microwave technology. This broadens choice of possible piezomagnetic materials for utilization in various technical devices.

Study on In-Pipe Corrosion Diagnosis System -Corrosion Estimation on Screw Parts Using a Surface SH Probe-

In diagnosing air-conditioning pipe deterioration, it is especially important to inspect screwed parts because their original thickness is thinner than that of straight parts and it is comparatively easy for leakage to occur if there is local internal corrosion. We examined a method of applying an ultrasonic test for the inspection, and proposed a method for detecting internal local corrosions of screwed parts and estimating the size and the position of corrosion with angle probe of surface SH waves. In this paper, we describe the results of experimental analysis on the echo from screwed parts of pipes, and we show the method to detect the internal local corrosion and estimate the size and position by using the edge echo. Finally, we describe the results of tests on artificial corrosion pipes and the limitations of this method.

Non-Contact Ultrasonic Inspection Technology of Fillet Weldments Monitoring

It's not easy to detect the defects in fillet weldment which is widely used in various building structures and power plants just with nondestructive inspection due to its complex geometrical shape and difficult access. But it's easy to detect the cracks on the surface or just below the surface of fillet weldment heel part if surface SH-wave, among ultrasonic wave modes, is applied. The traditional ultrasound inspection using surface SH-wave is usually a contact method using piezoelectric transducer, so it's not suitable for a field application because the reliability of inspection varies depending on field environments such as couplant, contact pressure and pre-process, etc. Therefore, the necessity for non-contact ultrasound inspection is increasing. This study proposes non-contact ultrasound inspection method using EMAT (electro-magnetic acoustic transducer), and presented non-contact ultrasound inspection method for fillet weldment through experimental verification.

Study of the Detection of Fatigue Cracks at Weld Toes by Crack Detection Paint and Surface SH Wave

Study of the Detection of Fatigue Cracks at Weld Toes by Crack Detection Paint and Surface SH Wave

Study on In-Pipe Corrosion Diagnosis System (Corrosion Estimation on Screw Parts Using a Surface SH Probe)

In diagnosing air-conditioning pipe deterioration, it is especially important to inspect screwed parts because their original thickness is thinner than that of straight parts and it is comparatively easy for leakage to occur if there is local internal corrosion. We examined a method of applying an ultrasonic test for the inspection, and proposed a method for detecting internal local corrosions of screwed parts and estimating the size and the position of corrosion with angle probe of surface SH waves. In this paper, we describe results of experimental analysis on the echo from screwed parts of pipes, and we show the method to detect the internal local corrosion and estimate the size and position by using the pipe-end echo. Finally, we describe the results of tests on artificial corrosion pipes and the limitations of this method.

Study on In-Pipe Corrosion Diagnosis System -Estimation of Corrosion on Screw Parts Using a Surface SH Probe-

Correlating to changes in society’s expectations, there is an increasing demand for the diagnosis of building equipment. Examination and diagnosis of air-conditioning pipes is an important safeguard against unexpected trouble such as pipe leakage. It is particularly important to inspect the screwed parts of pipes because their thickness is thinner than other parts due to the thread. In the past, radiography and endoscopy have been used for the inspection of screwed parts, but radiographic testing must be performed by a licensed technician, and endoscopy requires halting of plant operations. In this paper, we introduce a method for detecting and estimating the size and position of corrosion using ultrasonic testing, surface SH waves. We describe the algorithms used to estimate the corrosion size using the edge echo height, and the corrosion position using a simple numerical echo height model. And finally, we show the results of using the algorithms in experiments on pipes with artificial corrosion.

Study on Detection and Quantitative Evaluation of Fatigue Cracks Using Surface SH Waves(NDE2)

Nondestructive evaluation of a surface slit and a fatigue crack by surface SH waves has been studied. By adjusting incident angle of SH waves probe, surface SH waves passing through the surface region of materials are received. In this study, diffraction of surface SH waves received by double-probe technique was used. Firstly, the specimens introduced surface slit were inspected by surface SH waves. With the results that the amplitude of surface SH waves decreased with the increment of slit depth in the depth over half wavelength of SH waves, but the amplitude is constant in the depth under half wavelength of SH waves. On the other hand, the arrival time of surface SH waves increased with the increment of slit depth in every depth. Furthermore, the changes of the amplitude and the arrival time to the increment of slit depth were calculated based on Fresnel-Kirchhoff diffraction integral. A comparison between the measured values and the calculated ones shows that the change of the arrival time is useful for evaluating surface defect. Secondly, the evaluation method of a fatigue crack in the round bar using the artificial circle osculating fatigue crack was proposed, and the growth behavior of fatigue crack, which initiated at an artificial small hole by rotating-bending fatigue, was evaluated with the change of the arrival time. By applying the evaluation results to Paris' law, the validity of our method was confirmed.

Study on Detection and Quantitative Evaluation of Fatigue Cracks Using Surface SH Waves.

The surface SH waves technique has been used to evaluate the fatigue cracks at the surface of mild steel specimens. By adjusting incident angle of SH wave transducer, surface SH waves passing through the surface region of materials are received. In this study, the diffraction of surface SH waves received by double-probe technique was used. Firstly, the specimens introduced surface slit were inspected. With the results that the amplitude decreased and the propagation time increased with the slit depth. Secondly, the shapes of the fatigue cracks, which initiated at a small drill hole by rotating-bending fatigue, were evaluated with the difference between the propagation time of the inspected plate with crack. Obtained results showed that the evaluated values of crack length and crack depth were good agreement with the measured values. Furthermore, this technique was applied to evaluating the crack growth behavior.

Love waves of SH type in an inhomogeneous transversely isotropic elastic medium

The asymptotics of high-frequency Love waves, which are analogous to transverse surface SH waves, is considered for a special type of anisotropy (transverse isotropy) of elastic media. The wave field is represented as a sum of the space-time (ST) caustic expansion and two additional ST ray series for faster (relative to the transverse surface wave) body waves, decaying exponentially with depth. Near the surface, the coefficients of the ST caustic and ray series, as well as the eikonals of waves, are determined in the form of expansions in a small parameter, which characterizes the proximity of the caustic of the ray field to the surface. With regard for the specific structure of the elasticity tensor of a transversely isotropic medium, the surface is treated as a plane. Interrelations between the parameters of elasticity, which are consistent with the conditions of the positivity of the elastic deformation energy and provide for the origination of the surface waves considered, are obtained.

Experimental study of echo directivity for surface SH wave and SH wave angle probes : Journal of JSNDI, Vol. 45, No. 9 (September 1996) p. 688 Takahashi, Masakazu; Kimura, Katsuyoshi; Hoshino, Mitsuhiro

Experimental study of echo directivity for surface SH wave and SH wave angle probes : Journal of JSNDI, Vol. 45, No. 9 (September 1996) p. 688 Takahashi, Masakazu; Kimura, Katsuyoshi; Hoshino, Mitsuhiro