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Three dimensional scattering of elastic waves by surface corrosion pits
N DT Abstracts 44707
Blake,
RJ.; Bond, LJ’.
43595 Lord, W.; You, Z.; Lusk, M. Numerical predictions of surface wave phenomena for ultrasonic NDE Proceedings of the IEEE 1988 Ultrasonics Symposium, Chicago (United States), 2-5 Oct. 1988, Vol. 2. pp. 1065-1068 Edited by B.R. McAvoy. IEEE (1989). ISSN 0090-5607.
Rayleigh wave scattering from surface features: wedges and down-steps Ultrasonics, Vol. 28, No. 4, pp. 214-228 (Jul. 1990) ‘I’& development of a Rayleigh wave based method of sizing surface defects has been hampered by the lack of a theory to describethe scattering problem. A new mixed finite element-finite difference model, which provides accurate and stable nulmerical solutions for faceted scattering geometries, has been developed. This paper presentsan outline of the model and details of the interaction of Rayleigh waves with wedges and angled down-steps.
Finite element analysis formulation has been developed for the simulation of ultrasonic nondestructive evaluation phenomena which includes the effects of finite aperture transducersand anisotropic material properties. This paper is an extension of this basic work and describeshow the finite element formulation can be used to predict not only longitudinal and shear wave propagation, but also the interaction of surface waves with cracks in materials.
44684 Fellinger. F.; Lungenberg, K.J. Numerical techniques for elastic wave propagation and scattering Proceedings of the IUTAM Symposium on Elastic Waves and Ultrasonic Nondestructive Evaluation, University of Colorado, Boulder, Colorado (United States), 30 Jul. - 3 Aug. 1989. pp. 8 1-86 Edited by S.K. Datta, J.D. Achenbach and Y.S. Rajapakse. North Holland, (1990). ISBN 0 444 874 852
43383 Khair, K.R.; Datta, S.K.; Shah, A.H. Three dimensional scattering of elastic waves by surface corrosion pits Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 63-70. Plenum Press (1989), ISBN 0 306 43209 9 In this paper we have studied the general three-dimensionalproblem of elastic wave scatteringby surface-breakingcavities of arbitary shapeusing a
Based on an integral formulaltion of the elastodynamic equations of motion - Newton’s and Hooke’s laws - we present a method of descretization resulting in a numlerical scheme to solve these equations within a rectangular grid. The technique is called EFIT for Elastodynamic Finite Integration Technique and compares well with Finite Difference and Finite Element methods.
hybrid method which combines the finite element representation of the interior field with the boundary integral representationof the exterior field. The advantageof the method is that it is suitable for analyzing scatteringby arbitrarily shapedand multiple cavities. In this regard the method is similar to that used where the outside field was representedin terms of multipolar potentials.The details of the present method can be found.
44633 You, Z.; Lord, W. Finite element study of diffraction tomography Proceedings of the IUTAM Symposium on Elastic Waves and Ultrasonic Nondestructive Evaluation, University of Colorado, Boulder, Colorado (United States), 30 Jul. - 3 Aug. 1989. pp. 463-465 Edited by S.K. Datha, J.D. Achenbach and Y.S. Rajapakse. North - Holland, (1990). ISBN 0 444 874 852.
43378 Moore, D.; Ludwig, R.; Lord, W. A 3-D finite element formulation for ultrasonic NDT phenomena Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 103-108. Plenum Press (1989), ISBN 0 306 43209 9
A finite element model for elastic wave propagation in solids has been developed [I .2] which can predict displacementfor all the nodesin the solid at every instant of time in a given time interval. The objective of this research, is to utilize such a numerical model as a test bed for diffraction tomography. This paper gives results which show that the normal component of the displacement on the measurementsurface can be used as the prime data for a diffraction tomographic algorithm derived form the scalar wave equation.
Past research into the numerical modeling of ultrasonic wave propagationand scatteringin 2-D has resulted in an implicit Newmark- type finite element algorithm. In this paper an explicit element-by- element time steppingalgorithm is introduced.The approach is capable of handling very large 2-D grid sizes in excess of 64,000 quadrilateral elements; making a 3-D model feasible. In the following the basic finite element algorithm is presented in conjunction with the principle feature of the novel elemental multiplication strategy.
44404
43377 You, Z.; Lord, W. Finite elements study of elastic wave interaction with cracks Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 109-116. Plenum Press (1989). ISBN 0 306 43209 9
Datta, S.K.; Shah, A.M.
Ultrasonic nondestructive evaluation: computational methods and experimental measurements Proceedings of the 3rd International Conference on Computational Methods and Experimental Measurements, Porto Carras (Greece), 2-5 Sep. 1986. pp. 433-448. Eidited by G.A. Keramidas and C.A. Brebbia. Springer Verlag, (1986) ISBN 090545 16 I9 In recent years considerable progress has been made on the solution of diffraction of elastic waves by cr,acksand other inhomogeneities. In this
Because of their ability to simulate realistic engineering problems numerical techniques are particularly applicable to NDE fields where energy/defect interactionsare of considerableimportance. It can be said that only numerical approaches naturally combine all the coupled wave phenomena together in one situation with complicated geometries. Finite difference techniques also show promise in modeling the coupled wave phenomenain regular geometries. The finite element method is superior in that it is easier to deal with the awkward geometries suchas complex shaped defects associated with NDE. This paper emphasizes the wave/defect interactions,and both spaceand time discretization problems are discussed.
paper we discuss the various numerical techniques, such as the boundary integral methods, the T-matrix method and the hybrid finite element and eigen-function expansion technique. Numerical results are presented using the latter technique for scattering by cracks or cavities in semi-infinite media and in plates of finite thickness.Comparison of the theoretical results with observationsshows very good agreement.
43944 Bratton, R.L.; Datta, S.K.; Shah, A.H. Scattering of SH waves by cracks and delaminations in a cladded plate Proceedings of the 15th Annual Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (USA), 31 Jul - 5 Aug. 1988. Vol. 8B, pp. 1329-11335.Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1989). ISBN O-306-43209-9.
43374 Kriz, R.D.: Heyliger, P.R. Finite element model of stress wave topology in unidirectional graphite/epoxy: wave velocities and flux deviations Review of Progress in Quantitative Nondestructive Evaluation, Vol SA. Edited by D.C. Thompson and D.E. Chimenti, pp. 141-148. Plenum Press (1989). ISBN 0 306 43209 9 Recently, Ludwig, et. al have demonstratedthe feasibility of numerical sirrulation to simulate stress wave propagation for problems where
In this paper we use a hybrid method to analyze SH wave scatteringin a cladded anisotropic plate. The hybrid method used here combines a finite element representation in a bounded region of the plate with the modal representationin the exterior region. The problem of scatteringby a normal surface-breaking crack in the cladding is studied here. For pure mode SH propagation and scattering it is necessarythat the propagation direction be perpendicularto the crack edgesand coincides with one of the principle axes of the anisotropic material.
materials are either isotropic or only slightly anisotropic. We extend this effort to unidirectional graphite/epoxy which has large variations in elastic properties. For this material the effect of elastic anisotropy on stresswave propagation has been studied both experimentally and analytically and several interesting properties have been predicted and measured: mode transitions,sensitivity of flux deviations to small changesin anisotropy, and shear wave speeds exceeding longitudinal waves. With a FEM we can simulate and study some of these properties most effectively.
253
Blake,
RJ.; Bond, LJ’.
43595 Lord, W.; You, Z.; Lusk, M. Numerical predictions of surface wave phenomena for ultrasonic NDE Proceedings of the IEEE 1988 Ultrasonics Symposium, Chicago (United States), 2-5 Oct. 1988, Vol. 2. pp. 1065-1068 Edited by B.R. McAvoy. IEEE (1989). ISSN 0090-5607.
Rayleigh wave scattering from surface features: wedges and down-steps Ultrasonics, Vol. 28, No. 4, pp. 214-228 (Jul. 1990) ‘I’& development of a Rayleigh wave based method of sizing surface defects has been hampered by the lack of a theory to describethe scattering problem. A new mixed finite element-finite difference model, which provides accurate and stable nulmerical solutions for faceted scattering geometries, has been developed. This paper presentsan outline of the model and details of the interaction of Rayleigh waves with wedges and angled down-steps.
Finite element analysis formulation has been developed for the simulation of ultrasonic nondestructive evaluation phenomena which includes the effects of finite aperture transducersand anisotropic material properties. This paper is an extension of this basic work and describeshow the finite element formulation can be used to predict not only longitudinal and shear wave propagation, but also the interaction of surface waves with cracks in materials.
44684 Fellinger. F.; Lungenberg, K.J. Numerical techniques for elastic wave propagation and scattering Proceedings of the IUTAM Symposium on Elastic Waves and Ultrasonic Nondestructive Evaluation, University of Colorado, Boulder, Colorado (United States), 30 Jul. - 3 Aug. 1989. pp. 8 1-86 Edited by S.K. Datta, J.D. Achenbach and Y.S. Rajapakse. North Holland, (1990). ISBN 0 444 874 852
43383 Khair, K.R.; Datta, S.K.; Shah, A.H. Three dimensional scattering of elastic waves by surface corrosion pits Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 63-70. Plenum Press (1989), ISBN 0 306 43209 9 In this paper we have studied the general three-dimensionalproblem of elastic wave scatteringby surface-breakingcavities of arbitary shapeusing a
Based on an integral formulaltion of the elastodynamic equations of motion - Newton’s and Hooke’s laws - we present a method of descretization resulting in a numlerical scheme to solve these equations within a rectangular grid. The technique is called EFIT for Elastodynamic Finite Integration Technique and compares well with Finite Difference and Finite Element methods.
hybrid method which combines the finite element representation of the interior field with the boundary integral representationof the exterior field. The advantageof the method is that it is suitable for analyzing scatteringby arbitrarily shapedand multiple cavities. In this regard the method is similar to that used where the outside field was representedin terms of multipolar potentials.The details of the present method can be found.
44633 You, Z.; Lord, W. Finite element study of diffraction tomography Proceedings of the IUTAM Symposium on Elastic Waves and Ultrasonic Nondestructive Evaluation, University of Colorado, Boulder, Colorado (United States), 30 Jul. - 3 Aug. 1989. pp. 463-465 Edited by S.K. Datha, J.D. Achenbach and Y.S. Rajapakse. North - Holland, (1990). ISBN 0 444 874 852.
43378 Moore, D.; Ludwig, R.; Lord, W. A 3-D finite element formulation for ultrasonic NDT phenomena Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 103-108. Plenum Press (1989), ISBN 0 306 43209 9
A finite element model for elastic wave propagation in solids has been developed [I .2] which can predict displacementfor all the nodesin the solid at every instant of time in a given time interval. The objective of this research, is to utilize such a numerical model as a test bed for diffraction tomography. This paper gives results which show that the normal component of the displacement on the measurementsurface can be used as the prime data for a diffraction tomographic algorithm derived form the scalar wave equation.
Past research into the numerical modeling of ultrasonic wave propagationand scatteringin 2-D has resulted in an implicit Newmark- type finite element algorithm. In this paper an explicit element-by- element time steppingalgorithm is introduced.The approach is capable of handling very large 2-D grid sizes in excess of 64,000 quadrilateral elements; making a 3-D model feasible. In the following the basic finite element algorithm is presented in conjunction with the principle feature of the novel elemental multiplication strategy.
44404
43377 You, Z.; Lord, W. Finite elements study of elastic wave interaction with cracks Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 109-116. Plenum Press (1989). ISBN 0 306 43209 9
Datta, S.K.; Shah, A.M.
Ultrasonic nondestructive evaluation: computational methods and experimental measurements Proceedings of the 3rd International Conference on Computational Methods and Experimental Measurements, Porto Carras (Greece), 2-5 Sep. 1986. pp. 433-448. Eidited by G.A. Keramidas and C.A. Brebbia. Springer Verlag, (1986) ISBN 090545 16 I9 In recent years considerable progress has been made on the solution of diffraction of elastic waves by cr,acksand other inhomogeneities. In this
Because of their ability to simulate realistic engineering problems numerical techniques are particularly applicable to NDE fields where energy/defect interactionsare of considerableimportance. It can be said that only numerical approaches naturally combine all the coupled wave phenomena together in one situation with complicated geometries. Finite difference techniques also show promise in modeling the coupled wave phenomenain regular geometries. The finite element method is superior in that it is easier to deal with the awkward geometries suchas complex shaped defects associated with NDE. This paper emphasizes the wave/defect interactions,and both spaceand time discretization problems are discussed.
paper we discuss the various numerical techniques, such as the boundary integral methods, the T-matrix method and the hybrid finite element and eigen-function expansion technique. Numerical results are presented using the latter technique for scattering by cracks or cavities in semi-infinite media and in plates of finite thickness.Comparison of the theoretical results with observationsshows very good agreement.
43944 Bratton, R.L.; Datta, S.K.; Shah, A.H. Scattering of SH waves by cracks and delaminations in a cladded plate Proceedings of the 15th Annual Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (USA), 31 Jul - 5 Aug. 1988. Vol. 8B, pp. 1329-11335.Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1989). ISBN O-306-43209-9.
43374 Kriz, R.D.: Heyliger, P.R. Finite element model of stress wave topology in unidirectional graphite/epoxy: wave velocities and flux deviations Review of Progress in Quantitative Nondestructive Evaluation, Vol SA. Edited by D.C. Thompson and D.E. Chimenti, pp. 141-148. Plenum Press (1989). ISBN 0 306 43209 9 Recently, Ludwig, et. al have demonstratedthe feasibility of numerical sirrulation to simulate stress wave propagation for problems where
In this paper we use a hybrid method to analyze SH wave scatteringin a cladded anisotropic plate. The hybrid method used here combines a finite element representation in a bounded region of the plate with the modal representationin the exterior region. The problem of scatteringby a normal surface-breaking crack in the cladding is studied here. For pure mode SH propagation and scattering it is necessarythat the propagation direction be perpendicularto the crack edgesand coincides with one of the principle axes of the anisotropic material.
materials are either isotropic or only slightly anisotropic. We extend this effort to unidirectional graphite/epoxy which has large variations in elastic properties. For this material the effect of elastic anisotropy on stresswave propagation has been studied both experimentally and analytically and several interesting properties have been predicted and measured: mode transitions,sensitivity of flux deviations to small changesin anisotropy, and shear wave speeds exceeding longitudinal waves. With a FEM we can simulate and study some of these properties most effectively.
253