scholarly journals Two-Dimensional FDTD Inverse-Scattering Scheme for Determination of Near-Surface Material Properties at Microwave Frequencies

2004 ◽  
Vol 52 (9) ◽  
pp. 2366-2373 ◽  
Author(s):  
M. Popovic ◽  
A. Taflove
Keyword(s):  
Inverse Scattering ◽  
Material Properties ◽  
Surface Material ◽  
Two Dimensional ◽  
Near Surface ◽  
Microwave Frequencies

Edge magnetoplasmons in single two‐dimensional electron disks at microwave frequencies: Determination of the lateral depletion length

1995 ◽  
Vol 66 (17) ◽  
pp. 2271-2273 ◽  
Author(s):  
C. Dahl ◽  
S. Manus ◽  
J. P. Kotthaus ◽  
H. Nickel ◽  
W. Schlapp
Keyword(s):  
Two Dimensional ◽  
Dimensional Electron ◽  
Microwave Frequencies

Nanomechanical Properties of Aluminum 390-T6 Rough Surfaces Undergoing Tribological Testing

2004 ◽  
Vol 126 (3) ◽  
pp. 573-582 ◽  
Author(s):  
Shaun R. Pergande ◽  
Andreas A. Polycarpou ◽  
Thomas F. Conry
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Bulk Material ◽  
Normal Load ◽  
Effective Elastic Modulus ◽  
Surface Microstructure ◽  
Surface Material ◽  
Surface Layers ◽  
Near Surface ◽  
Nanomechanical Properties

The nanoindentation technique was used to quantify nano-scale changes in material properties (effective elastic modulus and hardness) of Al390-T6 samples that have undergone tribological testing under a protocol in a high-pressure tribometer where the applied normal load was step-wise increased until failure by scuffing occurred. The test was highly repeatable, so additional tests were run to three intermediate fractions of the total-time-to-scuffing-failure, which provided data on the progressive wear of the surfaces preparatory to reaching the scuffed condition. The samples were engineering surfaces with significant surface roughness, nonhomogeneous surface microstructure and unknown, nonuniform surface layers. This study demonstrated that nanomechanical techniques can be extended to characterize the material properties of rough engineering surfaces. For the samples subjected to tribological testing, the material at the surface, and to approximately 60 nm below the surface, exhibited significantly higher hardness than the bulk material. Also, progressive wear of the surfaces resulted in a corresponding weakening of the near-surface material below the surface to a depth of 60 nm, while the hardness of material below the 60 nm depth remained relatively unchanged. The hardness data for the scuffed samples showed a large amount of scatter in the data, indicating that the surface is not homogeneous and that the protective surface layer is removed, at least at some points on the surface.

On Interface Crack Growth in Composite Plates

1992 ◽  
Vol 59 (3) ◽  
pp. 530-538 ◽  
Author(s):  
K.-F. Nilsson ◽  
B. Stora˚kers
Keyword(s):  
Crack Growth ◽  
Material Properties ◽  
Composite Structures ◽  
Plate Theory ◽  
Beam Theory ◽  
Composite Plates ◽  
Crack Advance ◽  
Two Dimensional ◽  
Singular Stress

Analysis of fracture growth, and in particular at interfaces, is pertinent not only to load-carrying members in composite structures but also as regards, e.g., adhesive joints, thin films, and coatings. Ordinarily linear fracture mechanics then constitutes the common tool to solve two-dimensional problems occasionally based on beam theory. In the present more general effort, an analysis is first carried out for determination of the energy release rate at general loading of multilayered plates with local crack advance either at interfaces or parallel to such. The procedure is accomplished for arbitrary hyperelastic material properties within von Karman plate theory and the results are expressed by aid of an Eshelby energy momentum tensor. By a feasible superposition it is then shown that the original nonlinear plate problem may be reduced to that of an equivalent beam in case of linear material properties. As a consequence of the so-established principle, the magnitude of mode-dependent singular stress amplitude factors is then directly determinable from earlier two-dimensional linear beam solutions for isotropic and anisotropic bimaterials and relevant at determination of cohesive and adhesive fracture. The procedure is illustrated by an analysis of combined buckling and crack growth of a delaminated plate having a nontrivial crack contour.

Inverse scattering of surface waves: A new look at surface Consistency

Geophysics ◽  
1994 ◽  
Vol 59 (6) ◽  
pp. 963-972 ◽  
Author(s):  
Bastian Blonk ◽  
Gérard C. Herman
Keyword(s):  
Inverse Scattering ◽  
Seismic Data ◽  
Scattering Theory ◽  
Synthetic Data ◽  
Surface Scattering ◽  
Frequency Filtering ◽  
Near Surface ◽  
Scattering Model ◽  
Static Corrections

A method is presented for eliminating near‐surface scattered noise from seismic data. Starting from an appropriately chosen background model, a surface‐consistent scattering model is determined using linearized elastodynamic inverse scattering theory. This scattering model does not necessarily equal the actual scatterer distribution, but it enables one to calculate, approximately, the near‐surface scattered part of the data. The method honors at least some of the complexity of the near‐surface scattering process and can be applied in cases where traditional methods, like wavenumber‐frequency filtering techniques and methods for static corrections, are ineffective. From a number of tests on synthetic data, we conclude that the method is rather robust; its main sensitivity is because of errors in the determination of the background Rayleigh‐wave velocity.

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