We investigate the three-dimensional （3D） scattering problem of an incident plane shear horizontal wave by a partly through-thickness hole in an isotropic plate, in which the Lamb wave modes are also included due to...We investigate the three-dimensional （3D） scattering problem of an incident plane shear horizontal wave by a partly through-thickness hole in an isotropic plate, in which the Lamb wave modes are also included due to the mode conversions by the scattering obstacle in the 3D problem. An analytical model is presented such that the wave fields are expanded in all of propagating and evanescent SH modes and Lamb modes, and the scattered far-fields of three fundamental guided wave modes are analyzed numerically for different sizes of the holes and frequencies. The numerical results are verified by comparing with those obtained by using the approximate Poisson/Mindlin plate model for small hole radius and low frequency. It is also found that the scattering patterns are different from those of the SO wave incidence. Our work is useful for quantitative evaluation of the plate-like structure by ultrasonic guided waves.展开更多
In recent years,shear horizontal(SH)waves are being paid more and more attention to in structural health monitoring as it has only one displacement component.In this paper,a unidirectional SH wave transducer based on ...In recent years,shear horizontal(SH)waves are being paid more and more attention to in structural health monitoring as it has only one displacement component.In this paper,a unidirectional SH wave transducer based on phase-controlled antiparallel thickness-shear(d15)piezoelectric strips(APS)is proposed.Here two pairs of identical APS were used each of which is a bidirectional SH wave transducer.By setting the interval between the two pairs of APS as 1/4 wavelength and the excitation delay between them as 1/4 period of the central operating frequency,unidirectional SH waves can be excited.Both finite element simulations and experiments were performed to validate the proposed design.Results show that SH0 waves were successfully excited only along one direction and those along the unwanted directions were suppressed very well.The proposed unidirectional SH wave transducer is very helpful to study the fundamentals and applications of SH waves.展开更多
The dispersion behavior of the shear horizontal （SH） waves in the coupled structure consisting of a piezomagnetic substrate and an orthorhombic piezoelectric layer is investigated with different cut orientations. Th...The dispersion behavior of the shear horizontal （SH） waves in the coupled structure consisting of a piezomagnetic substrate and an orthorhombic piezoelectric layer is investigated with different cut orientations. The surface of the piezoelectric layer is mechanically free, electrically shorted, or open, while the surface of the piezomagnetic substrate is mechanically free, magnetically open, or shorted. The dispersion relations are derived for four electromagnetic boundary conditions. The dispersion characteristics are graphically illustrated for the layered structure with the PMN-PT layer perfectly bonded on the CoFe2O4 substrate. The effects of the PMN-PT cut orientations, the electromagnetic boundary conditions, and the thickness ratio of the layer to the substrate on the dispersion behavior are analyzed and discussed in detail. The results show that, （i） the effect of the cut orientation on the dispersion curves is very obvious, （ii） the electrical boundary conditions of the PMN-PT layer dominate the propagation feature of the SH waves, and （iii） the thickness ratio has a significant effect on the phase velocity when the wave number is small. The results of the present paper can provide valuable theoretical references to the applications of piezoelectric/piezomagnectic structure in acoustic wave devices.展开更多
For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspectio...For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspection area without blind zones.In comparison with Lamb waves,the shear horizontal(SH)wave is more promising because its fundamental mode is non-dispersive.In this work,we proposed an omni-directional SH wave piezoelec trie t ransducer(OSH-PT)based on a radially poled d24-mode PZT ring.Eoth the finite element simulations and experiments were carried out to demonstrate its performance in generating and receiving SH°wave.Results showed that the radially poled OSH-PT could generate single-mode SHo wave and receive SHo wave only over a wide frequency range from 70 to 200 kHz.The obtained signal-to-noise ratio can reach up to 26 dB in generation and 24 dB in reception.The omni-directivity of this OSH-PT is also very good with the deviation only about 6%in both generation and reception of SHo wave.Considering its easy fabrication,low cost and superior performances,this proposed OSH-PT may promote the applications of SHo wave-based inspection in structural health monitoring and nondestructive testing.展开更多
The present study deals with the propagation of a polarized shear horizontal(SH)wave in a pre-stressed piezoelectric cylinder circumscribed by a self-reinforced cylinder.The interface of the two media is assumed mecha...The present study deals with the propagation of a polarized shear horizontal(SH)wave in a pre-stressed piezoelectric cylinder circumscribed by a self-reinforced cylinder.The interface of the two media is assumed mechanically imperfect.For obtaining the dispersion relation,the mathematical formulation has been developed and solved by an analytical treatment.The effects of various parameters,i.e.,the thickness ratio,the imperfect interface,the initial stress,the reinforcement,and the piezoelectric and dielectric constants,on the dispersion curve are observed prominently.The dispersion curves for different modes have been also plotted.The consequences of the study may be used for achieving optimum efficiency of acoustic wave devices.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11474195,11274226,51478258 and 51405287
文摘We investigate the three-dimensional （3D） scattering problem of an incident plane shear horizontal wave by a partly through-thickness hole in an isotropic plate, in which the Lamb wave modes are also included due to the mode conversions by the scattering obstacle in the 3D problem. An analytical model is presented such that the wave fields are expanded in all of propagating and evanescent SH modes and Lamb modes, and the scattered far-fields of three fundamental guided wave modes are analyzed numerically for different sizes of the holes and frequencies. The numerical results are verified by comparing with those obtained by using the approximate Poisson/Mindlin plate model for small hole radius and low frequency. It is also found that the scattering patterns are different from those of the SO wave incidence. Our work is useful for quantitative evaluation of the plate-like structure by ultrasonic guided waves.
基金the National Natural Science Foundation of China(Grant 11521202).
文摘In recent years,shear horizontal(SH)waves are being paid more and more attention to in structural health monitoring as it has only one displacement component.In this paper,a unidirectional SH wave transducer based on phase-controlled antiparallel thickness-shear(d15)piezoelectric strips(APS)is proposed.Here two pairs of identical APS were used each of which is a bidirectional SH wave transducer.By setting the interval between the two pairs of APS as 1/4 wavelength and the excitation delay between them as 1/4 period of the central operating frequency,unidirectional SH waves can be excited.Both finite element simulations and experiments were performed to validate the proposed design.Results show that SH0 waves were successfully excited only along one direction and those along the unwanted directions were suppressed very well.The proposed unidirectional SH wave transducer is very helpful to study the fundamentals and applications of SH waves.
基金supported by the National Natural Science Foundation of China(No.11272222)the Key Project of Hebei Provincial Education Department of China(No.ZD2017072)
文摘The dispersion behavior of the shear horizontal （SH） waves in the coupled structure consisting of a piezomagnetic substrate and an orthorhombic piezoelectric layer is investigated with different cut orientations. The surface of the piezoelectric layer is mechanically free, electrically shorted, or open, while the surface of the piezomagnetic substrate is mechanically free, magnetically open, or shorted. The dispersion relations are derived for four electromagnetic boundary conditions. The dispersion characteristics are graphically illustrated for the layered structure with the PMN-PT layer perfectly bonded on the CoFe2O4 substrate. The effects of the PMN-PT cut orientations, the electromagnetic boundary conditions, and the thickness ratio of the layer to the substrate on the dispersion behavior are analyzed and discussed in detail. The results show that, （i） the effect of the cut orientation on the dispersion curves is very obvious, （ii） the electrical boundary conditions of the PMN-PT layer dominate the propagation feature of the SH waves, and （iii） the thickness ratio has a significant effect on the phase velocity when the wave number is small. The results of the present paper can provide valuable theoretical references to the applications of piezoelectric/piezomagnectic structure in acoustic wave devices.
基金the National Natural Science Foundation of China under Grant No.11672003.
文摘For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspection area without blind zones.In comparison with Lamb waves,the shear horizontal(SH)wave is more promising because its fundamental mode is non-dispersive.In this work,we proposed an omni-directional SH wave piezoelec trie t ransducer(OSH-PT)based on a radially poled d24-mode PZT ring.Eoth the finite element simulations and experiments were carried out to demonstrate its performance in generating and receiving SH°wave.Results showed that the radially poled OSH-PT could generate single-mode SHo wave and receive SHo wave only over a wide frequency range from 70 to 200 kHz.The obtained signal-to-noise ratio can reach up to 26 dB in generation and 24 dB in reception.The omni-directivity of this OSH-PT is also very good with the deviation only about 6%in both generation and reception of SHo wave.Considering its easy fabrication,low cost and superior performances,this proposed OSH-PT may promote the applications of SHo wave-based inspection in structural health monitoring and nondestructive testing.
文摘The present study deals with the propagation of a polarized shear horizontal(SH)wave in a pre-stressed piezoelectric cylinder circumscribed by a self-reinforced cylinder.The interface of the two media is assumed mechanically imperfect.For obtaining the dispersion relation,the mathematical formulation has been developed and solved by an analytical treatment.The effects of various parameters,i.e.,the thickness ratio,the imperfect interface,the initial stress,the reinforcement,and the piezoelectric and dielectric constants,on the dispersion curve are observed prominently.The dispersion curves for different modes have been also plotted.The consequences of the study may be used for achieving optimum efficiency of acoustic wave devices.
