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- Boström, Anders E, 1951, et al.
(författare)
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Scattering of elastic waves by a rectangular crack in an anisotropic half-space
- 2003
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Ingår i: Wave Motion. - 0165-2125. ; 38, s. 91-107
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Tidskriftsartikel (refereegranskat)abstract
- The scattering of elastic waves by a rectangular crack in a half-space of arbitrary anisotropy is considered. The application in mind is ultrasonic testing of thick-walled anisotropic components where the crack is close to a planar back surface. The orientation of the crack and the back surface may be arbitrary relative the anisotropy. The scattering problem is formulated as hypersingular integral equation for the crack-opening-displacement (COD) by means of a half-spce Green's tensor. The integral equation is solved by expanding the COD in a double series of Chebyshev functions with the correct behavior along the crack's edges. Insertion inte the integral equation and projection onto the same set of functions result in a linear system of equations for the expansion coefficients appearing in the representation of the COD. The transmitting transducer is modeled by the traction beneath it on the scanning surface and the incident field may then be calculated. An electromechanical reciprocity relation is used to model the receiving transducer. Numerical examples are included which show the influence of the anisotropy and espcially the prexence of a nearby planar back surface.
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- Zhang, Bixing, 1963, et al.
(författare)
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Antiplane shear waves from a piezoelectric strip actuator: exact versus effective boundary condition solutions
- 2004
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Ingår i: Smart Materials and Structures. - 0964-1726 .- 1361-665X. ; 13, s. 161-168
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Tidskriftsartikel (refereegranskat)abstract
- A piezoelectric strip of finite width and thickness is placed on top of an isotropic half-space. It operates in actuator mode and a time harmonic voltage is thus applied across it. The piezoelectric material is of type 6mm oriented so that a 2D antiplane (scalar) problem results. By Fourier series expansions the problem is solved exactly and this result is compared to the case when the piezoelectric strip is replaced by an effective boundary condition, which is derived by series expansions in the thickness coordinate in the piezoelectric strip. At low frequencies the results agree very well and this corresponds to the situation usually found in practice. In general the effective boundary condition should be easier to apply and it is in particular noted that this is the case when using a FEM program where the option of a piezoelectric material is usually not available.
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