Scattering of a Love Wave by the Edge of a Thin Surface Layer

1975 ◽  
Vol 42 (4) ◽  
pp. 842-846 ◽  
Author(s):  
D. A. Simons
Keyword(s):  
Boundary Condition ◽  
Surface Layer ◽  
Reflection Coefficient ◽  
Scattered Field ◽  
Love Wave ◽  
Thin Surface Layer ◽  
Antiplane Strain ◽  
Power Flux ◽  
Power Reflection Coefficient

The antiplane strain problem of the scattering of an incident Love wave by the edge of a thin surface layer is solved. The effect of the layer is represented by a boundary condition applied at the surface of the substrate. In addition, the condition of vanishing traction on the edge of the layer is explicitly enforced. At large distances from the layer’s edge the scattered field is found to consist of a reflected Love wave and a radiated wave. The power flux identity for the problem is derived, and values of the power reflection coefficient are computed. The power flux identity is verified numerically, and the discrepancy which would arise from a failure to satisfy the condition of vanishing traction on the layer’s edge is evaluated.

Features of Wear of Abrasive Grains Depending on Microcuttings Speed of Steels

2016 ◽  
Vol 674 ◽  
pp. 189-194 ◽  
Author(s):  
Margarita A. Skotnikova ◽  
Galina V. Tsvetkova ◽  
Nikolay A. Krylov ◽  
Evgeniy K. Ivanov ◽  
Viktoriy V. Medvedeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
Thin Surface Layer ◽  
Abrasive Grains ◽  
Microscopy Method ◽  
Scanning Electron Microscopy Method ◽  
Electron Microscopy Method ◽  
Scanning Electron ◽  
Alloy Titanium

In this article by the example of two abrasive materials from oxide of aluminum and nitride of boron, the processes developing in a thin surface layer between a grain of abrasive and the material, processed by microcutting with speeds of 40 and 160 m/s, the preforms from armko-iron, steels R18, 45, H18N10T and alloy titanium VT6 are investigated, using the scanning electron microscopy method.

The Photo-Oxidation of Polypropylene Monofilaments

1977 ◽  
Vol 47 (6) ◽  
pp. 423-428 ◽  
Author(s):  
A. Garton ◽  
D. J. Carlsson ◽  
P. Z. Sturgeon ◽  
D. M. Wiles
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Uv Irradiation ◽  
Oxidation Product ◽  
Uv Exposure ◽  
Thin Surface Layer ◽  
Elongation At Break ◽  
Photo Oxidation ◽  
Oriented Samples ◽  
Oriented Polypropylene

The elongation-at-break of highly-oriented polypropylene monofilaments is much less affected by photo-oxidation build-up than undrawn or partially-oriented filaments. This appears to result from the very poor lateral cohesion of the fibril bundles in the highly-oriented filament, limiting restructuring and cracking to a thin surface layer. For less-oriented samples photo-oxidation-induced restructuring of the surface layer results in deep cracks that can propagate under stress, greatly embrittling the sample. Areas of filaments cold drawn by, for example, bending or stretching deteriorate very rapidly on uv irradiation as a result of strain-induced chromophore formation, and fracture occurs first at these points. Oxidation-product levels (either hydroperoxide or carbonyl) are shown to be an unreliable index of the extent of deterioration of mechanical properties resulting from uv exposure.

Effect of Weather, Age, and Cyclic Pressurizations on Structural Performance of Acrylic Plastic Spherical Shells Under External Pressure Loading

1982 ◽  
Vol 104 (2) ◽  
pp. 190-200
Author(s):  
J. D. Stachiw ◽  
R. B. Dolan
Keyword(s):  
Surface Layer ◽  
Critical Pressure ◽  
External Pressure ◽  
Thin Surface Layer ◽  
Ambient Atmosphere ◽  
Plastic Shell ◽  
Spherical Shells ◽  
Acrylic Plastic ◽  
Operational Life ◽  
Physical And Chemical

Weathering, aging, and cyclic application of stresses to acrylic plastic degrades its physical properties. The rate of degradation must be known if the useful life of load-carrying acrylic structures is to be predicted with accuracy. Physical and chemical tests conducted by the authors on thick spherical shells indicate that the weathering affects only a thin surface layer of material, which after 10 years is still less than 0.020 in. thick. Similarly, pollutants in the ambient atmosphere of the pressure chamber affect the surface layer of the spherical shell facing the interior of the chamber. The physical and chemical properties of the thin surface layer affected by weathering differed significantly from those in the middle of 2.5-in.-thick Plexiglas G plate; the decrease in properties was: 40 percent in tensile elongation, 34 percent in flexure strength, 21 percent in tensile strength, and 79 percent in molecular weight. Since the interior body of the thick plastic shell is not affected by weathering or chemical attack and the affected surface layers are very thin, the ability of the shell to carry compressive loads is not significantly diminished after 10 years of service. Only an 11 percent decrease of critical pressure was observed in spherical shells with thickness of 1 in. subjected to 10 years of weathering and 2000 pressure cycles of 8 hour duration each to 30 percent of its original critical pressure. Based on the preceding data it appears safe to extend the operational life from 10 to 20 years of all acrylic plastic spherical shells with bearing surfaces normal to spherical surface designed on the basis of ANSI/ASME PVHO-1 Safety Standard for external pressure service.

Abnormal Structural Strength of Topocomposites

2012 ◽  
Vol 560-561 ◽  
pp. 338-343 ◽  
Author(s):  
Nikolay A. Voronin
Keyword(s):  
Surface Layer ◽  
Bearing Capacity ◽  
Half Space ◽  
Contact Interaction ◽  
Solid Body ◽  
Mechanical Characteristics ◽  
Structural Strength ◽  
Layered Material ◽  
Thin Surface Layer ◽  
Layer Coating

The mechanics of contact interaction of rigid spherical indenter with two-layer elastic - plastic half-space, simulating a surface of a solid body with a thin surface layer is considered. Analytical dependences of critical indentation and bearing capacity on mechanical characteristics of materials of a base and a coating, and as well as that for thickness of top layer (coating) in all region of possible thickness are received and analyzed. Existence of regions of the abnormal structural strength allowing the surface layered material to identify unequivocally as a topocomposite is shown. Theoretical dependences were verified by a final elements method.

PHYSICAL ASPECTS OF THE CONTRACTION HYPOTHESIS OF OROGENESIS

1952 ◽  
Vol 30 (1) ◽  
pp. 14-25 ◽  
Author(s):  
Adrian E. Scheidegger
Keyword(s):  
Surface Layer ◽  
Theoretical Consideration ◽  
Thin Surface Layer ◽  
Depth Curve ◽  
Temperature Depth

Several geophysical arguments important in the theoretical consideration of the contraction hypothesis of orogenesis are analyzed in detail with respect to their physical bases. Specifically, it is shown (a) that a thin surface layer of a sphere will fold in a smaller pattern than a thicker surface layer if the interior shrinks by the same amount; (b) that the speed of cooling of a sphere decreases if some radioactive and hence heat generating material is moved from the surface towards the center (and conversely); and (c) that at the level of no strain of a cooling sphere the temperature–depth curve must be almost straight. Those geological theories in which these considerations are important are indicated.

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