Showing papers on "Deformation (meteorology) published in 1991"
934 citations
TL;DR: In this article, a method was described to determine contact stresses and deformation using a combination of the finite element method and a surface integral form of the Bousinesq solution.
Abstract: A method is described to determine contact stresses and deformation using a combination of the finite element method and a surface integral form of the Bousinesq solution. Numerical examples of contacting hypoid gears are presented.
249 citations
241 citations
TL;DR: In this paper, the ground-state properties of the heavy nuclei were analyzed in the three-dimentional deformation space {βλ, γ = 2, 4, 6}.
232 citations
TL;DR: In this paper, a first order diffraction analysis of an optical interferometer, Coherent Gradient Sensor (CGS), for measuring surface gradients is presented, which has potential for the study of deformation fields near a quasi-statically or dynamically growing crack.
Abstract: A first order diffraction analysis of an optical interferometer, Coherent Gradient Sensor (CGS), for measuring surface gradients is presented. Its applicability in the field of fracture mechanics is demonstrated by quantitatively measuring the gradients of out-of-plane displacements around a crack tip in a three point bent fracture specimen under static loading. This method has potential for the study of deformation fields near a quasi-statically or dynamically growing crack.
163 citations
TL;DR: In this article, a mechanism for uplift at Campi Flegrei in which a sudden connection is established between a deep, hot, high-pressure fluid reservoir and a shallow, relatively cold, low-pressure aquifer is proposed.
152 citations
01 Feb 1991
TL;DR: In this paper, the authors evaluate information on the permanent deformation characteristics of asphalt-aggregate mixtures, with an emphasis on laboratory test techniques for measuring mixture resistance to permanent deformations.
Abstract: This report evaluates information on the permanent deformation characteristics of asphalt-aggregate mixtures, with an emphasis on laboratory test techniques for measuring mixture resistance to permanent deformation, and on methods for prediction of permanent deformation (rutting) in the upper asphalt bound layers of pavements. Factors influencing the amount of rutting are summarized. The laboratory test methds associated with the predictive methodologies that are evaluated include: unaixial and creep tests; uniaxial and triaxial and repeated load test; triaxial dynamic tests; diametral tests, creep and repeated load tests; hollow cylinder tests, combined axial and torsional loading; simple shear tests, unconfined and confined; and wheel-track tests. From these evaluations, specific test methodologies are ranked in order of preference.
141 citations
TL;DR: In this article, a three-point-bend bimaterial specimen with a relatively large stiffness mismatch between the two materials is studied and a recently developed optical method of coherent gradient sensing (CGS) is used to map crack-tip deformation fields.
Abstract: The paper presents a preliminary experimental investigation of crack-tip deformation fields near quasistatically and dynamically growing cracks in bimaterial interfaces. A three-point-bend bimaterial specimen with a relatively large stiffness mismatch between the two materials is studied. A recently developed optical method of coherent gradient sensing (CGS) is used to map crack-tip deformation fields.
124 citations
116 citations
TL;DR: The concept of q-deformation of Hopf algebras has been introduced by Manin this article, where the Hopf algebra resulting from such a qdeformation, being in general neither commutative nor cocommutative, is not in fact still associated with a Lie group or algebra.
TL;DR: In this paper, the authors reviewed several recent results achieved at Northwestern University in the problem of size effects and nonlocal concepts for concrete and other brittle heterogeneous materials, and presented a new method for calculating the load-deflection curves of fracture specimens or structures with time-dependent crack g1'owth and viscoelastic material behavior.
Abstract: The lecture reviews several recent results achieved at Northwestern University in the problem of size effects and nonlocal concepts for concrete and other brittle heterogeneous materials, and presents a new method for calculating the load-deflection curves of fracture specimens or structures with time-dependent crack g1'owth and viscoelastic material behavior. The results reviewed deal with the size effect law in fracture and its exploitation for determining material fl'actu1oe chamcteristics, statistical generalization of the size effect law with a nonlinear reformulation of Weibull's weakest-link theory, determination of the size dependence of the fracture energy determined by w01'k-of-fracture method, nonlocal models for smeared cracking and damage, microstructural determination of the nonlocal material properties and fracture process zone behavior, size effect in fatigue fracture of concrete, and use of the size effect for determining the fracture properties of high-strength concrete.
[...]
TL;DR: In this paper, it was shown that cusps are dense in Bers' boundary for Teichmuller space, based on an estimate for the algebraic effect of a unit quasiconformal deformation supported in the thin part of a hyperbolic Riemann surface.
Abstract: We show cusps are dense in Bers' boundary for Teichmuller space. The proof rests on an estimate for the algebraic effect of a unit quasiconformal deformation supported in the thin part of a hyperbolic Riemann surface.
TL;DR: In this paper, the surface roughness is modeled with sinusoidal functions of small wavelength compared to the contact zone, and the surface smoothness is modelled with a small wavelength.
Abstract: The surface roughness is modeled with sinusoidal functions of small wavelength compared to the contact zone
01 Jan 1991
TL;DR: In this paper, the relation between deformation mode and β phase stability was investigated using Ti-16V and Ti-7Cr base alloys doped with Sn, Zr and Al as ternary or quaternary additions.
Abstract: The relation between deformation mode and β phase stability was investigated using Ti-16V and Ti-7Cr base alloys doped with Sn, Zr and Al as ternary or quaternary additions. Sn and Al additions change the dominant deformation mode from (332) twinning in the binary alloys to deformation induced martensitic transformation, which is related to the suppression of athermal ω phase transformation by the addition of these elements. The deformation induced martensite has orthorhombic structure (α") or hexagonal structure (α') depending on the alloying element. On the other hand, Zr addition has no significant influence on deformation mode and athermal ω phase transformation, and thus the dominant deformation mode of Zr added alloys is (332) twinning identical to the binary alloys. Discrepancy in deformation mode observed in metastable β titanium alloys can be explained reasonably by considering the present results on the effect of Sn, Zr and Al on the deformation mode.
TL;DR: In this paper, it is suggested that the domino model is an elegant, geometric simplification of the more complete flexural-isostatic solution to fault displacements, which can account well for the uplift/subsidence patterns observed within particular areas of the North Sea rift.
Abstract: Abstract It has been demonstrated previously that the rigid-domino model of extensional faulting can account well for the uplift/subsidence patterns observed within particular areas of the North Sea rift. This model, however, provides an unsatisfactory solution to deformation occurring at the basin margins. It is suggested here that the domino model is an elegant, geometric simplification of the more complete flexural-isostatic solution to fault displacements. Application of a flexural model allows a unified treatment of the basin and its margins. The basin-margins to the North Sea/Mid-Norway rift are all shown to have responded to extensional faulting by experiencing isostatic uplift in the footwalls to the marginal faults. Uplift magnitude varies from a few hundred metres adjacent to small faults to perhaps 5 km adjacent to the largest faults. Uplift patterns can be modelled or predicted by use of the flexural-cantilever basin model. Recognition of marginal uplift throughout the rift means that geometric section balancing techniques, all of which require the footwall to be rigid during extension, are inapplicable as a method for analysis of large, basement faults within the North Sea. Marginal, fault-related uplift is considered to have been a primary source of syn-rift clastic detritus. The precise locus of deposition for material eroded from emergent basin margins will depend on local drainage patterns, but deposition in the hangingwall basin and on the footwall platform may both be anticipated.
TL;DR: In this paper, plane model liners were constructed from pure kaolin and from a mixture of sand, silica flour and bentonite, and their integrity and performance were evaluated on a geotechnical centrifuge at 50 gravities.
Abstract: Centrifuge model tests have been performed to study the response of clay barriers subjected to differential deformations. The modes of deformation that have been observed are relevant to those that might occur as the result of differential settlements of waste material leading to deformation of cover liners, or from non-uniform soil strength profiles or the propagation of deep-sited subsidence towards the surface, leading to deformations of the base liner. Plane model liners were constructed both from pure kaolin and from a mixture of sand, silica flour and bentonite. The integrity and performance of these model liners were evaluated on a geotechnical centrifuge at 50 gravities. Physical degradation of the model liners was monitored photographically and their performance as effective hydraulic barriers assessed throughout the deformation process. For all the model liners where no overburden was present, tension cracking of the liner surfaces was observed. These tension cracks were very significant in the ...
TL;DR: In this article, a slip-line field model for orthogonal cutting with chip breaker and flank wear was developed, where the cutting geometry is completely determined by specifying the rake angle, tool-chip interface friction and the chip breaker constraint.
TL;DR: In this article, the deformation behavior under creep conditions of several unreinforced and reinforced binary near-gamma titanium aluminide alloys has been examined, and it has been found that the rate of deformation is strongly dependent on matrix grain size and microstructural stability.
Abstract: The deformation behavior under creep conditions of several unreinforced and participate (TiB2)-reinforced binary near-gamma titanium aluminide alloys has been examined. Material has been produced using both ingot-and powder-processing techniques, yielding material of varying microstructures and grain sizes. It has been found that the rate of deformation is strongly dependent on matrix grain size and microstructural stability. The presence of the dispersed phase dramatically impacts the microstructural character which evolves following isothermal forging, and this has been observed to strongly influence the creep behavior. Constitutive equations which describe the observed behavior indicate that the mechanism of creep deformation is the same for both the reinforced and unreinforced variants and is independent of processing route.
TL;DR: In this article, the deformation behavior of IN738LC in two γ′ morphologies under monotonic loading at elevated temperatures has been studied and mechanisms of dislocation-γ′ precipitate interaction have been identified.
Abstract: Deformation behaviour of IN738LC in two γ′ morphologies under monotonic loading at elevated temperatures has been studied. Mechanisms of dislocation-γ′ precipitate interaction have been identified. Dislocation reactions leading to stacking fault formation within γ′ have been characterized.
TL;DR: In this article, the shape of the free surface of a liquid film flowing down an inclined plane wall over a particle captured on the wall is studied in the asymptotic limit where the size of the particle is much smaller than the film thickness, and the Reynolds number is vanishingly small.
Abstract: The shape of the free surface of a liquid film flowing down an inclined plane wall over a particle captured on the wall is studied in the asymptotic limit where the size of the particle is much smaller than the film thickness, and the Reynolds number is vanishingly small. Using the boundary integral method for Stokes flow, the problem is formulated in terms of a system of four linear integral and differential equations for the elevation of the free surface and the three components of the velocity at the free surface, and is solved using a semi‐iterative method. The results demonstrate that the particle causes a marked deformation of the free surface upstream right before the particle, and a surface corrugation resembling a surface wake downstream behind the particle. The detailed features of the deformation and the disturbance flow are affected strongly by the geometry of the particle, surface tension, and the inclination of the wall.
25 Mar 1991-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The superplastic properties of conventionally cast and rapidly solidified magnesium alloy AZ91 have been studied in this article, and the latter material had by far the best super-plastic performance.
Abstract: The superplastic properties of conventionally cast and rapidly solidified magnesium alloy AZ91 have been studied. The latter material had by far the best superplastic properties, and elongations of at least 1000% were obtained in the temperature range 275–300 °C. Formation of pores during superplastic deformation had an adverse effect on the room-temperature mechanical properties.
TL;DR: A theoretical interpretation of the deformation pattern that develops in vacuum-deposited thin films after being exposed to atmospheric conditions is presented in this article, where a ratio between the characteristic dimensions of a unit cross-section of the debonded, buckled film is obtained by minimizing the strain energy of the displacement surface which is approximated by the product of two sinusoidal curves.