Showing papers on "Deformation (meteorology) published in 2004"

Deformation microstructures and textures of some cold rolled Mg alloys

Abstract: Electron Backscatter Diffraction (EBSD) is employed to characterize the deformation microstructures and textures established during the cold rolling of pure Mg, Mg–0.2Ce and Mg–3Al–1Zn (also known as AZ31). The maximum cold rolling reductions achievable in these alloys prior to failure were ∼30, >90 and ∼15%, respectively. The dominant features of the microstructure were twins and shear bands. The frequency of the former decreased while that of the latter increased with rolling reduction. Each alloy displayed a fibre texture in which the c -axis was closely aligned with the sheet normal direction. There was little change to the rolling textures with increasing rolling reduction beyond ∼10%. Much of the deformation appeared to be concentrated in the shear bands. It is speculated that the striking effect of alloying addition on cold rollability can be understood in terms of differences in severity, frequency and lifetime of shear bands.

Seismic versus aseismic deformation in Iran inferred from earthquakes and geodetic data

Abstract: SUMMARY A combined analysis of the geodetic strain-rate field and the strain-rate field deduced from the seismicity allows us to define the style of deformation and to distinguish seismic from aseismic deformation. We perform this analysis in Iran where the present-day tectonics results from the north‐south convergence between the plates of Arabia to the south and Eurasia to the north. The data consist of velocities measured with a GPS network of 28 benchmarks and of instrumental and historical earthquake catalogues. The axes of the seismic strain-rate tensor have similar orientations to those deduced from the GPS velocity field. This indicates that the seismicity can be used to improve GPS information on the style and the orientation of the deformation. Comparison of seismic and geodetic strain rates indicates that highly strained zones experience mainly aseismic deformation in southern Iran and seismic deformation in northern Iran. A large contrast is observed between the Zagros (less than 5 per cent seismic deformation) and the Alborz‐Kopet-Dag regions (more than 30‐100 per cent seismic deformation). The distribution of the seismic/geodetic ratio correlates with the distribution of large earthquakes: intensive, low-magnitude seismicity is observed in the Zagros whereas the largest earthquakes occur in northern Iran. The contrast of seismic deformation between the Zagros and peri-Caspian mountains is confirmed considering 300 or 1000 yr of seismicity rather than 100 or 200 yr.

Verification and modeling of three-stage permanent deformation behavior of asphalt mixes

Abstract: In laboratory testing of asphalt mixtures, the relationship between the number of load repetitions and permanent deformation has been found to include three distinct stages, namely the primary, secondary and tertiary stages. Similar permanent deformation behavior has also been observed in the field accelerated pavement testing data. It is argued that the three-stage permanent deformation behavior is a basic material property and to comprehensively model asphalt layer behavior, it is necessary to develop a model that accurately characterizes this behavior. In this paper, each of the well-known models critically reviewed appears that they are limited to characterizing only the primary stage. Therefore, a new three-stage model is proposed to describe all three stages. Moreover, an algorithm is established to determine the model parameters from typical laboratory data. The algorithm can also be used to identify the transition point between stages, such as flow number. The proposed model and algorithm are demonstrated through laboratory test results. The analysis results match the field performance.

Effect of Stamp Deformation on the Quality of Microcontact Printing: Theory and Experiment

Abstract: Microcontact printing (μCP) is an effective way to generate micrometer- or submicrometer-sized patterns on a variety of substrates. However, the fidelity of the final pattern depends critically on the coupled phenomena of stamp deformation, fluid transfer between surfaces, and the ability of the ink to self-assemble on the substrate. In particular, stamp deformation can produce undesirable effects that limit the practice and precision of μCP. Experimental observations and comparison with theoretical predictions are presented here for three of the most undesirable consequences of stamp deformation: (1) roof collapse of low aspect ratio recesses, (2) buckling of high aspect ratio plates, and (3) lateral sticking of high aspect ratio plates. Stamp behavior was observed visually with an inverted optical microscope while load−displacement data were collected during compression and retraction of stamps. Additionally, a “robotic stamper” was used to deliver ink patterns in precise locations on substrates. These...

The Generalized Method of Cells and High-Fidelity Generalized Method of Cells Micromechanical Models—A Review

Abstract: The models of the generalized method of cells and the recently developed high-fidelity generalized method of cells are reviewed. These two methods are micromechanical theories that are capable of providing the overall behavior of periodic multiphase materials of various types, including thermoelastic, viscoelastic, thermo-inelastic, and electromagnetothermoelastic materials. Both infinitesimal and finite deformation analyses of multiphase composites are discussed.

Deformation induced martensitic transformation in stainless steels

Abstract: Deformation induced martensitic transformation was investigated in metastable austenitic stainless steel. This steel can present a microstructure of austenite (γ), α′ martensite and non magnetic e martensite. Uni-axial tensile test was used for loading at different temperatures below room temperature (from −120 to 20 °C). During the deformation the transformation takes place at certain places in an anisotropic way and texture also develops. Quantitative phase analysis was done by X-ray diffraction (XRD) and magnetic methods while the texture was described by X-ray diffraction using a special inverse pole figure. The quantitative phase analysis has shown that the formation of α′ and e martensite from austenite is the function of deformation rate, and deformation temperature. The transformation of the textured austenite takes place in an anisotropic way and a well defined crystallographic relationship between the parent and α′ martensite phase has been measured.

Deformation in magnetorheological elastomer and elastomer?ferromagnet composite driven by a magnetic field

Abstract: Magnetorheological elastomer (MRE) is a new class of smart materials, whose modulus can be controlled by the applied magnetic field. In this paper, using a white light speckle technique for deformation analysis, we present the real-time dynamic deformation progress (the vector diagram of the displacement or the whole-field quantitative displacement distribution) of the MRE and the elastomer?ferromagnet composite (EFC) while the magnetic field is turned on. The experimental results verify the prediction presented in a recently published paper, (Borcea and Bruno 2001 J.?Mech.?Phys.?Solids 49 2877?919), and reveals some interesting phenomena which will give us a deeper understanding for such smart materials.

Scale dependence and localization of the deformation of Arctic sea ice.

Abstract: A scaling analysis of the deformation of Arctic sea ice over a 3-day time period is performed for scales of 10 to 1000 km. The deformation field is derived from satellite radar data; it allows us to study how a very large solid body---the Arctic sea-ice cover---deforms under the action of heterogeneous forcing winds and ocean currents. The deformation is strongly localized at small scales, and can be characterized as multifractal. This behavior is well known for turbulent flows, and is here also observed for a deforming solid. A multiscaling extrapolation to the meter scale (laboratory scale) shows that, at the 3-day time scale, about $15%$ of the deformation is larger than ${10}^{\ensuremath{-}4}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, implying brittle failure, over $0.2%$ of the total area.

Interaction between long period stacking order phase and deformation twin in rapidly solidified Mg97Zn1Y2 alloy

Abstract: Interaction between long period stacking order (LPSO) phase and { 1 0 1 ¯ 2 } deformation twin in rapidly solidified Mg97Zn1Y2 alloy is investigated. The densely developed LPSO phase prevents the growth of { 1 0 1 ¯ 2 } deformation twin in Mg matrix. On the other hand, the LPSO phase with low density cannot be the resistance of the twinning. The trace of basal plane in such LPSO phase deviates with constant angle of about 3.8° at the twin boundary. This angle is well explained by the atomic movement with shuffling in the formation of { 1 0 1 ¯ 2 } twin. The interfacial microstructure of { 1 0 1 ¯ 2 } deformation twin is also discussed on the basis of high resolution electron microscopy (HREM).

Static Modeling of Linear Object Deformation Based on Differential Geometry

Abstract: We describe the modeling of linear object deformation based on differential geometry and its applications to manipulative operations. A particle-based approach, the finite element method, and the Cosserat theory have been applied to the modeling of linear object deformation. In this paper, we establish an alternative modeling approach based on an extension of differential geometry. First, we extend differential geometry to describe linear object deformation including flexure, torsion, and extension. Secondly, we show computational results to demonstrate the feasibility of the proposed modeling technique, and we compare computational and experimental results to demonstrate the accuracy of the model. Next, we apply the proposed approach to the grasping of a deformable linear object. We propose a disturbance force margin to indicate the stability of the grasping and we describe the computation of the margin using the proposed approach. Finally, we apply the proposed approach to the deformation path planning ...

Method for improving measurement accuracy of a portable coordinate measurement machine

Abstract: A method for improving the measurement accuracy of a portable coordinate measurement machine which comprises an articulated arm having jointed arm segments is presented. This method includes sensing deformation of a portion of the articulated arm when the arm is placed under a load, this deformation causing an error in the measurement made by the CMM, and correcting such error in response to the sensed deformation.

Representative styles of deformation along the Chelungpu fault from the 1999 Chi-Chi (Taiwan) earthquake: Geomorphic characteristics and responses of man-made structures

Abstract: The Chi-Chi earthquake provides dramatic evidence of the damaging effects of surface ground deformation to buildings, lifelines, and other facilities. Much of the building damage is associated with surface faulting and folding along the Chelungpu thrust fault. Our detailed surveying at representative sites along the fault shows that the rupture commonly is a relatively simple 1- to 4-m-high scarp with minor hanging-wall deformation and localized (but severe) uplift, folding, and graben formation along the scarp crest. For individual scarps, the width of deformation is about 10 to 20 times the net vertical displacement. Distributed secondary faulting and folding on the hanging wall occurred as much as 350 m from the primary fault. Near the northern end of the rupture, growth of a pre-existing 1-km-wide late Quaternary anticline produced severe ground rupture along multiple thrusts and backthrusts but only minor tilting between fault strands. The pattern of building damage coincides with the pattern of geologic deformation, with severe damage along large fault scarps and lesser but still significant damage attributable to distributed secondary surface deformation on the hanging wall. Rupture-related building damage on the footwall occurred next to the prerupture fault trace, where the hanging wall bulldozed onto the footwall. The width of this damage zone is related to the local horizontal shortening along the fault and generally is less than 10 m. Building zonation along reverse faults should account for this pattern of surface deformation. In addition, buildings with massive foundations locally influenced the style and location of near-surface deformation, producing variations in fault strike or accentuated secondary deformation on the hanging wall. Manuscript received 15 January 2001.

Chemical bleaching indicates episodes of fluid flow in deformation bands in sandstone

Abstract: Jurassic sandstones on the Colorado Plateau have been variably bleached through interaction with hydrocarbon-bearing solutions or other reducing agents. Deformation bands in the Navajo Sandstone have a variety of colors in comparison with the host rock color that indicate the timing of bleaching relative to deformation-band formation. White deformation bands in red sandstone indicate that deformation bands were likely permeable at an early dilatant stage in their development history. Field characteristics, petrography, bulk rock chemistry, clay mineralogy, and geochemical modeling show that bleached deformation bands experienced an episode of chemical reduction where fluids removed some iron and left the remaining iron as pyrite and magnetite. Mass-balance calculations show that as much as 10 kg of chemically reducing fluid per 100 g of rock (1500 pore volumes of fluid) are necessary to remove 0.1 wt.% iron from a deformation band. These large pore volumes suggest that moving, reducing solutions regionally bleached the sandstone white, and bleached deformation bands resulted where deformation bands provided localized fluid access to unbleached, red sandstone during an initial dilatant stage. Alternatively, access of reducing soil solutions may be provided by gravity-driven, unsaturated flow in arid to semiarid vadose zones. Color and chemical composition is a valuable index to the pathway and timing of hydrocarbon movement through both host rocks and deformation bands.

Synchrotron Ultrasmall-Angle X-ray Scattering Studies on Tensile Deformation of Poly(1-butene)

Abstract: Real-time synchrotron ultrasmall-angle X-ray scattering measurements were performed during the tensile deformation of crystalline phase I poly(1-butene) (P1B). For comparison, high-density polyethy...

The origin of tectonic fabrics in “undeformed” clays: The early stages of deformation in extensional sedimentary basins

Abstract: [1] An integrated approach was used to detect tectonic effects in apparently undeformed fine-grained clay sediments filling extensional basins in Southern Italy. Results from low and high field anisotropy of magnetic susceptibility and mineral fabric, deduced by neutron texture analysis, show penetrative deformation on a grain-scale. The well-defined tectonic magnetic lineation is parallel to the stretching direction and located at the intersection of the basal planes of phyllosilicates, forming grain-scale folds and crenulations. This spatial configuration reflects basin scale deformation processes and suggests the existence of a nearly uniaxial stress field during the incipient extensional phases. The integrated approach of magnetic and mineral fabric investigations is a valid tool to detect grain scale and regional deformation pattern in weakly deformed extensional basins, where macroscopic evidence of deformation is not visible.

Currency processing system with fitness detection

Abstract: A currency handling system comprising a fitness detector. The fitness detector comprising a thickness detector, a limpness detector, a soil detector or a combination thereof. The thickness detector comprising an upper roller displaceable in a predetermined arc by a note passing between the upper roller and a lower roller. The limpness detector comprising a single driven crackle roller comprising an elongated central bulge and two outer bulges, wherein the central bulge is in conforming relation to a flexible belt. Sheet metal guides further facilitate note deformation and sound production.

An InSAR-based survey of volcanic deformation in the southern Andes

Abstract: We use Interferometric Synthetic Aperture Radar (InSAR) to search for surface deformation in the southern Andes (40°S–46°S and 49°S–53°S) associated with magmatic processes. Although the available data are not optimal, we can constrain the amount of volcanic deformation at about 27 Holocene volcanoes between the years 1993–1999. We detect inflation of Cerro Hudson volcano following its 1991 eruption, and use spherical and non-spherical models to constrain the source of deformation to be between 4 and 8 km below sea level. We measure the rate of deformation to be about 5 cm/year in the radar line-of-sight, and infer that the maximum deformation could exceed 10 cm/year in the center of the caldera. Within the errors of the measurements, the rate of deformation is constant from 1993–1998 (10–30 × 10^6 m^3/year). At this rate, 100–200 years is required to accumulate the volume of material erupted in 1991.

Estimation of Seismic Demands on Isolators Based on Nonlinear Analysis

Abstract: A procedure based on rigorous nonlinear analysis that estimates the deformation and force of an isolator due to strong ground motion is presented. The procedure offers an alternative to the iterative equivalent-linear methods used by current U.S. building codes. The governing equation is reduced to a form such that the median normalized deformation of the system due to an ensemble of ground motions with a given corner period \IT\dd\N is found to depend on only two parameters: the natural period, defined from the postyield stiffness, and the normalized strength, or strength normalized by peak ground velocity. The dispersion of normalized deformation for an ensemble of ground motions is shown to be small, implying that the median normalized deformation is a meaningful estimate of response. The simple trends shown by the median normalized deformation led to the development of suitable design equations for isolator deformation. These design equations reflect a 13% increase when the excitation includes two lateral components of ground motion instead of just one component. For comparison, deformations estimated by the equivalent-linear method are unconservative by up to 50% compared to those found from the more accurate nonlinear spectrum, and building codes include at most a 4.4% increase for a second component.