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Journal articles on the topic "Deformation mechanism maps"
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Greenwood, G. W. "Deformation mechanism maps and microstructural influences." Materials Science and Engineering: A 410-411 (November 2005): 12–15. http://dx.doi.org/10.1016/j.msea.2005.08.098.
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Rybacki, Erik, and Georg Dresen. "Deformation mechanism maps for feldspar rocks." Tectonophysics 382, no. 3-4 (April 2004): 173–87. http://dx.doi.org/10.1016/j.tecto.2004.01.006.
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Hou, Qing Yu, and Jing Tao Wang. "Deformation Mechanism in the Mg-Gd-Y Alloys Predicted by Deformation Mechanism Maps." Advanced Materials Research 146-147 (October 2010): 225–32. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.225.
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Deformation mechanism maps at 0-883 K and shear strain rate of 10-10-10+6 s-1 were built from available rate equations for deformation mechanisms in pure magnesium or magnesium alloys. It can be found that the grain size has little effect on the fields of plasticity and phonon or electron drag, though it has important influence on the fields of power-law creep, diffusion creep, and Harper-Dorn creep in the maps within the present range of temperature, strain rate, and grain size. A larger grain size is helpful to increase the field range of power-law creep but decrease that of diffusion creep when the grain size is smaller than ~204 μm. Harper-Dorn creep dominates the deformation competed to diffusion creep in the grain size range of ~204-255 μm. The maps include only plasticity, phonon or electron drag, and power-law creep when the grain size is higher than ~255 μm, then the grain size has little influence on the maps. Comparison between the reported data for the Mg-Gd-Y alloys and the maps built from available rate equations, it can be conclude that the maps are an effective tool to predict or achieve a comprehensive understanding of the deformation behavior of the Mg-Gd-Y alloys and to classify systematically their discrepancies in the deformation mechanism. However, differences exist in the deformation mechanisms of the alloys observed by the reported data and that predicted by the maps. Therefore, refinement of the maps from the viewpoint of mechanical twining, DRX, and adiabatic shear are necessary.
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Kim, W. J., and H. T. Jeong. "Construction of processing maps combined with deformation mechanism maps using creep deformation equations." Journal of Materials Research and Technology 9, no. 6 (November 2020): 13434–49. http://dx.doi.org/10.1016/j.jmrt.2020.09.023.
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Misra, A., M. Verdier, H. Kung, J. D. Embury, and J. P. Hirth. "Deformation mechanism maps for polycrystalline metallic multiplayers." Scripta Materialia 41, no. 9 (October 1999): 973–79. http://dx.doi.org/10.1016/s1359-6462(99)00239-0.
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Lee, I. G., and A. K. Ghosh. "High Temperature Deformation Mechanism Maps of NiAl." Materials Science Forum 449-452 (March 2004): 57–60. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.57.
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In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.
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Misra, A., M. Verdier, H. Kung, J. D. Embury, and J. P. Hirth. "Erratum deformation mechanism maps for polycrystalline metallic multilayers." Scripta Materialia 42, no. 2 (December 1999): 219. http://dx.doi.org/10.1016/s1359-6462(99)00413-3.
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Langdon, Terence G. "Deformation mechanism maps for applications at high temperatures." Ceramics International 11, no. 4 (October 1985): 141. http://dx.doi.org/10.1016/0272-8842(85)90165-8.
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Wang, Jian N., and T. G. Nieh. "Incorporation of peierls stress into deformation mechanism maps." Scripta Metallurgica et Materialia 33, no. 4 (August 1995): 633–38. http://dx.doi.org/10.1016/0956-716x(95)00230-s.
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Xie, De-Gang, Rong-Rong Zhang, Zhi-Yu Nie, Jing Li, Evan Ma, Ju Li, and Zhi-Wei Shan. "Deformation mechanism maps for sub-micron sized aluminum." Acta Materialia 188 (April 2020): 570–78. http://dx.doi.org/10.1016/j.actamat.2020.02.013.
Full textDissertations / Theses on the topic "Deformation mechanism maps"
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Ahmad, Z. B. "Deformation mechanism maps for polymers." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383036.
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Mirmasoudi, Sara. "High Temperature Transient Creep Analysis of Metals." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1452693927.
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Codeglia, Daniela. "Development of an acoustic emission waveguide-based system for monitoring of rock slope deformation mechanisms." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/33500.
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Hundreds of thousands of landslides occur every year around the world impacting on people's lives. Monitoring techniques able to foresee imminent collapse and provide a warning in time useful for action to be taken are essential for risk reduction and disaster prevention. Acoustic emission (AE) is generated in soil and rock materials by rearrangement of particles during displacement or increasing damage in the microstructure preceding a collapse; therefore AE is appropriate for estimation of slope deformation. To overcome the high attenuation that characterise geological materials and thus to be able to monitor AE activity, a system called Slope ALARMS that makes use of a waveguide to transmit AE waves from a deforming zone to a piezoelectric transducer was developed. The system quantifies acoustic activity as Ring Down Count (RDC) rates. In soil applications RDC rates have been correlated with the rate of deformation, however, the application to rock slopes poses new challenges over the significance of the measured AE trends, requiring new interpretation strategies. In order to develop new approaches to interpret acoustic emission rates measured within rock slopes, the system was installed at two trial sites in Italy and Austria. RDC rates from these sites, which have been measured over 6 and 2.5 years respectively, are analysed and clear and recurring trends were identified. The comparison of AE trends with response from a series of traditional instruments available at the sites allowed correlation with changes in external slope loading and internal stress changes. AE signatures from the limestone slope at the Italian site have been identified as generated in response to variations in the groundwater level and snow loading. At the conglomerate slope in Austria, AE signatures include the detachment of small boulders from the slope surface caused by the succession of freeze-thaw cycles during winter time. Consideration was also given to laboratory testing of specific system elements and field experiments. A framework towards strategies to interpret measured acoustic emission trends is provided for the use of the system within rock slopes.
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Henriksson, Marielle. "Cellulose Nanofibril Networks and Composites : Preparation, Structure and Properties." Doctoral thesis, Stockholm : Fiber- och polymerteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4610.
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HUME, COLIN DAVID. "Numerical Validation and Refinement of Empirical Rock Mass Modulus Estimation." Thesis, 2011. http://hdl.handle.net/1974/6740.
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A sound understanding of rock mass characteristics is critical for the engineering prediction of tunnel stability and deformation both during construction and post-excavation. The rock mass modulus of deformation is a necessary input parameter for many numerical analysis methods to describe the constitutive behavior of a rock mass. Tests for determining this parameter directly by in situ test methods are inherently difficult, time consuming and expensive, and these challenges are more problematic when dealing with tunnels in weaker, softer rock masses where errors in modulus (stiffness) estimation have a profound impact on closure predictions. In addition, rock masses with modest structure can be candidate sites for highly sensitive structures such as nuclear waste repository tunnels. For these generally stiffer rock masses, the correct modulus assessment is essential for prediction of thermal response during the service life of the tunnel.
Numerous empirical relationships based on rock mass classification schemes have been developed to determine rock mass deformation modulus in response to these issues. The empirical relationship provided by Hoek & Diederichs (2006) based on Geological Strength Index (GSI) has been determined from a database of in situ test data describing a wide range of rock masses with GSI values greater than 25 and less than 80. Within this range of applications there is a large variation in measured values compared to the predicted relationship and predictive uncertainty at low GSI values. In this research, a practical range of rock mass quality, as defined by GSI, including "Blocky\Disturbed\Seamy" rock masses, "Very Blocky" and relatively competent rock masses are analyzed using discretely fractured numerical models. In particular the focus is on tunnel response. Tunnel closure in these simulations is compared to predictions based on modulus estimates. The proposed refinement to the Generalized Hoek-Diederichs relationship is made on the basis of these simulations for tunnelling applications.Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2011-09-20 22:34:06.642
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Maji, Vidya Bhushan. "Strength And Deformation Behaviour Of Jointed Rocks : An Equivalent Continuum Model." Thesis, 2007. http://hdl.handle.net/2005/545.
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Most rock masses encountered in civil and mining engineering projects contain pre-existing discontinuities. These discontinuities weaken the rock masses to an extent, which depends very much on the size of engineering structure relation to discontinuity spacing. The strength and deformability of rock mass is controlled not only by the intact portion of rock, but by the characteristic of the joints that break up the mass, particularly their pattern and their orientation with respect to the in-situ stresses. In considering the effect of joints, the discrete approach emerged as an efficient tool and advocated since 1970s (Cundall, 1971). However, the numerical approach with modelling the joints explicitly has the limitation of computational complexity for modelling large-scale problems with extremely large number of joints. As an alternative to this limitation, the equivalent continuum approach models the jointed rock masses as a continuum with the equivalent properties that represent implicitly the effects of the joints.
Several numerical methods have been developed by various researchers to model jointed rock masses as equivalent continuum, using various techniques. However, the existing equivalent continuum models are complicated and need more input data from experimental or field testing in order to carry out the analysis. Present approach attempts to use statistical relations, which are simple and obtained after analyzing a large data from the literature on laboratory test results of jointed rock masses. Systematic investigations were done including laboratory experiments to develop the methodologies to determine the equivalent material properties of rock mass and their stress-strain behaviour, using a hyperbolic approach (Duncan and Chang, 1970). Present study covers the development of equivalent continuum model for rock mass right from developing statistical correlations to find out equivalent material properties based on experimental results, to the implementation of the model in FLAC3D for 3-dimensional applications and subsequently verification leading to real field application involving jointed rocks.
Experimental work carried out to study the strength and deformation characteristics of jointed rock by using standard laboratory tests on cylindrical specimens of plaster of Paris by introducing artificial joints. The objective was to derive the compressive strength and elastic modulus of rock mass as a function of intact rock strength/modulus and joint factor. The obtained experimental results and developed relations were compared with the previous experimental data on jointed rocks. Further, a failure criterion as proposed by Ramamurthy (1993) has been validated from these experimental results of intact and jointed rock specimens. Empirical relationships similar to Ramamurthy’s relations are established for the prediction of rock mass strength and were compared with proposed equation by Ramamurthy (1993) and are found comparable. However, the equations by Ramamurthy were based on different variety of rocks and therefore recommended for further use and were used in numerical models.
For efficient application to the field problems the equivalent continuum model is implemented in the program Fast Lagrangian analysis of continua (FLAC3D). The model was rigorously validated by simulating jointed rock specimens. Element tests were conducted for both uniaxial and triaxial cases and then compared with the respective experimental results. The numerical test program includes laboratory tested cylindrical rock specimens of different rock types, from plaster of Paris representing soft rock to granite representing very hard rock. The results of the equivalent continuum modelling were also compared with explicit modelling results where joints were incorporated in the model as interfaces. To represent highly discontinuous system, the laboratory investigation on block jointed specimens of gypsum plaster (Brown and Trollope, 1970) was modelled numerically using equivalent continuum approach.
To extend the applicability of the model to field applications, investigation were done by undertaking numerical modelling of two case studies underground caverns, one Nathpa Jhakri hydroelectric power cavern in Himachal Pradesh, India, and the other one Shiobara hydroelectric power cavern in Japan. This study verifies the efficiency of the present approach in estimating ground movement and stress distribution around the excavations in jointed rock masses. The modelling results were also compared with six other computation models as presented by Horii et al. (1999) for the Shiobara power house cavern. An attempt has also been made to numerically model the support system for the cavern and investigate the efficiency of reinforcements using FLAC3D. The model was also used for analyzing large scale slope in jointed rocks using the equivalent continuum model by undertaking numerical modelling of Anji bridge abutment slopes, in Jammu and Kashmir, India. Slope stability analysis is done using equivalent continuum approach for both, the original profiles as well as with the pier loads on cut profiles. Attempt was also made to exhibit the shear strength dependency of the strain though the hyperbolic stress- strain model. The shear strain developed in the slope increases with reducing the shear strength. The relationship between the shear strength reduction ratio ‘R’ and axial strain ‘ε’, for different values of failure ratio ‘Rf’ was studied and it was observed that, the value of ‘ε’ increases, as the value of ‘R’ increases especially it increases rapidly when the value ‘R’ approaches certain critical value, which varies with the value of ‘Rf’. This critical value of R is known as the critical shear strength reduction factor Rc and is highly sensitive to the confining stress. As the value of Rf increases, representing a transition from linear elastic nature to nonlinear nature, the value of critical shear strength reduction ratio also decreases. Relationship between the critical shear strength reduction ratio and the safety factor were examined to elucidate their physical meaning. It was observed that at critical value of the shear strength reduction ratio, a well defined failure shear zone developed from the toe to the crest of the slope.
Intelligent models using ANNs were also developed to predict the elastic modulus of jointed rocks as an alternative to empirical equations and without predefining a mathematical model to correlate the properties.
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Garaga, Arunakumari. "Factors Affecting The Static And Dynamic Response Of Jointed Rock Masses." Thesis, 2008. http://hdl.handle.net/2005/772.
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Infrastructure is developing at an extremely fast pace which includes construction of metros, underground storage places, railway bridges, caverns and tunnels. Very often these structures are found in or on the rock masses. Rock masses are seldom found in nature without joints or discontinuities. Jointed rocks are characterized by the presence of inherent discontinuities of varied sizes with different orientations and intensities, which can have significant effect on their mechanical response. Constructions involving jointed rocks often become challenging jobs for Civil Engineers as the instability of slopes or excavations in these jointed rocks poses serious concerns, sometimes leading to the failure of structures built on them. Experimental investigations on jointed rock masses are not always feasible and pose formidable problems to the engineers. Apart from the technical difficulties of extracting undisturbed rock samples, it is very expensive and time consuming to conduct the experiments on jointed rock masses of huge dimensions. The most popular methods of evaluating the rock mass behaviour are the Numerical methods. In this thesis, numerical modelling of jointed rock masses is carried out using computer program FLAC (Fast Lagrangian Analysis of Continua).
The objective of the present study is to study the effect of various joint parameters on the response of jointed rock masses in static as well as seismic shaking conditions. This is achieved through systematic series of numerical simulations of jointed rocks in triaxial compression, in underground openings and in large rock slopes. This thesis is an attempt to study the individual effect of different joint parameters on the rock mass behaviour and to integrate these results to provide useful insight into the behaviour of jointed rock mass under various joint conditions.
In practice, it is almost impossible to explore all of the joint systems or to investigate all their mechanical characteristics and implementing them explicitly in the model. In these cases, the use of the equivalent continuum model to simulate the behaviour of jointed rock masses could be valuable. Hence this approach is mainly used in this thesis. Some numerical simulations with explicitly modelled joints are also presented for comparison with the continuum modelling. The applicability of Artificial Neural Networks for the prediction of stress-strain response of jointed rocks is also explored. Static, pseudo-static and dynamic analyses of a large rock slope in Himalayas is carried out and parametric seismic analysis of rock slope is carried out with varying input shaking, material damping and shear strength parameters.
Results from the numerical studies showed that joint inclination is the most influencing parameter for the jointed rock mass behaviour. Rock masses exhibit lowest strength at critical angle of joint inclination and the deformations around excavations will be highest when the joints are inclined at an angle close to the critical angle. However at very high confining pressures, the influence of joint inclination gets subdued. Under seismic base shaking conditions, the deformations of rock masses largely depend on the acceleration response with time, frequency content and duration rather than the peak amplitude or the magnitude of earthquake. All these aspects are discussed in the light of results from numerical studies presented in this thesis.
Books on the topic "Deformation mechanism maps"
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Mann, Peter. Constrained Hamiltonian Dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198822370.003.0021.
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This chapter focuses on autonomous geometrical mechanics, using the language of symplectic geometry. It discusses manifolds (including Kähler manifolds, Riemannian manifolds and Poisson manifolds), tangent bundles, cotangent bundles, vector fields, the Poincaré–Cartan 1-form and Darboux’s theorem. It covers symplectic transforms, the Marsden–Weinstein symplectic quotient, presymplectic and symplectic 2-forms, almost symplectic structures, symplectic leaves and foliation. It also discusses contact structures, musical isomorphisms and Arnold’s theorem, as well as integral invariants, Nambu structures, the Nambu bracket and the Lagrange bracket. It describes Poisson bi-vector fields, Poisson structures, the Lie–Poisson bracket and the Lie–Poisson reduction, as well as Lie algebra, the Lie bracket and Lie algebra homomorphisms. Other topics include Casimir functions, momentum maps, the Euler–Poincaré equation, fibre derivatives and the geodesic equation. The chapter concludes by looking at deformation quantisation of the Poisson algebra, using the Moyal bracket and C*-algebras to develop a quantum physics.
Book chapters on the topic "Deformation mechanism maps"
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Anand, Lallit, and Sanjay Govindjee. "Balance laws for small deformations." In Continuum Mechanics of Solids, 91–94. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198864721.003.0006.
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For solids it is often a good approximation to assume that the displacement and displacement gradient are small everywhere in the body. In this setting the basic laws for balance of mass, the balance laws for forces and moments, and the two laws of thermodynamics --- the balance of energy and the imbalance of entropy --- take on simpler forms which are derived and discussed in this chapter.
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Dramis, Francesco, and Emanuele Tondi. "Neotectonics." In The Physical Geography of Western Europe. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199277759.003.0011.
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Debate in neotectonics mainly hinges on how far back in time the prefix ‘neo’ should be taken. The term ‘neotectonics’ means, in a first approximation, geologically young, recent or living (active) crustal structures and processes. Some of the many definitions (Angelier 1976; Mercier 1976; Beloussov 1978; Hancock and Williams 1986; Vita-Finzi 1986; Winslow 1986) focus neotectonic studies only on active deformation (late Quaternary–Present) and accept neotectonics as more or less synonymous to active tectonics, while others trace the neotectonic period mainly from the Middle Miocene. It is very difficult to identify a standard time period for defining the beginning of neotectonics, but the present-day opinion is that it depends on the individual characteristics of each geological environment. According to Fourniguet (1987), no time limit is fixed and the field of investigation extends from the present as far back into the past as necessary to understand present or active deformation. The INQUA (International Union for Quaternary Research) Tectonic Commission has accepted the definition of Mörner (1978): ‘Neotectonics is defined as any earth movements or deformations of the geodetic reference level, their mechanisms, their geological origin, their implications for various practical purposes and their future extrapolations.’ Pavlides (1989) proposed a definition along the following lines: ‘Neotectonics is the study of young tectonic events (deformation of upper crust), which have occurred or are still occurring in a given region after its final orogeny (at least for recent orogenies) or more precisely after its last significant reorganization.’ When western Europe is considered, a major change in boundary conditions occurred in the Upper Miocene (7 Ma) when the motion of Africa became directed to the north-west (Dewey et al. 1989). Geological, seismological, and geodetic data in the Mediterranean region and in continental Europe show that the relative motion of Africa and Europe is still in this direction. For this reason we think that for the neotectonics of western Europe one cannot go far back in time beyond the Upper Miocene. The study of the state of stress of the lithosphere around the world has recently been attempted within the World Stress Map Project of the International Lithosphere Programme (Zoback 1992).
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Cavosie, Aaron J., Christopher L. Kirkland, Steven M. Reddy, Nicholas E. Timms, Cristina Talavera, and Maya R. Pincus. "Extreme plastic deformation and subsequent Pb loss in shocked xenotime from the Vredefort Dome, South Africa." In Large Meteorite Impacts and Planetary Evolution VI. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2550(20).
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ABSTRACT Accessory mineral U-Pb geochronometers are crucial tools for constraining the timing of deformation in a wide range of geological settings. Despite the growing recognition that intragrain age variations within deformed minerals can spatially correlate to zones of microstructural damage, the causal mechanisms of Pb loss are not always evident. Here, we report the first U-Pb data for shock-deformed xenotime, from a detrital grain collected at the Vredefort impact structure in South Africa. Orientation mapping revealed multiple shock features, including pervasive planar deformation bands (PDBs) that accommodate up to 40° of lattice misorientation by <100>{010} slip, and also an ~50-µm-wide intragrain shear zone that contains {112} deformation twin lamellae in two orientations. Twenty-nine in situ secondary ion mass spectrometry (SIMS) U-Pb analyses from all microstructural domains yielded a well-defined discordia with upper-intercept age of 2953 ± 15 Ma (mean square of weighted deviates [MSWD] = 0.57, n = 29, 2σ), consistent with derivation from Kaapvaal craton bedrock. However, the 1754 ± 150 Ma lower concordia intercept age falls between the 2020 Ma Vredefort impact and ca. 1100 Ma Kibaran orogenesis and is not well explained by multiple Pb-loss episodes. The pattern and degree of Pb loss (discordance) correlate with increased [U] but do not correlate to microstructure (twin, PDB) or to crystallinity (band contrast) at the scale of SIMS analysis. Numerical modeling of the Pb-loss history using a concordia-discordia-comparison (CDC) test indicated that the lower concordia age is instead best explained by an alteration episode at ca. 1750 Ma, rather than a multiple Pb-loss history. In this example, the U-Pb system in deformed xenotime does not record a clear signature of impact age resetting; rather, the implied high dislocation density recorded by planar deformation bands and the presence of deformation twins facilitated subsequent Pb loss during a younger event that affected the Witwatersrand basin. Microstructural characterization of xenotime targeted for geochronology provides a new tool for recognizing evidence of deformation and can provide insight into complex age data from highly strained grains, and, as is the case in this study, elucidate previously unrecognized alteration events.
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Ogawa, Yujiro, and Shin’ichi Mori. "Gravitational sliding or tectonic thrusting?: Examples and field recognition in the Miura-Boso subduction zone prism." In Plate Tectonics, Ophiolites, and Societal Significance of Geology: A Celebration of the Career of Eldridge Moores. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2552(10).
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ABSTRACT Discrimination between gravity slides and tectonic fold-and-thrust belts in the geologic record has long been a challenge, as both have similar layer shortening structures resulting from single bed duplication by thrust faults of outcrop to map scales. Outcrops on uplifted benches within the Miocene to Pliocene Misaki accretionary unit of Miura-Boso accretionary prism, Miura Peninsula, central Japan, preserve good examples of various types of bedding duplication and duplex structures with multiple styles of folds. These provide a foundation for discussion of the processes, mechanisms, and tectonic implications of structure formation in shallow parts of accretionary prisms. Careful observation of 2-D or 3-D and time dimensions of attitudes allows discrimination between formative processes. The structures of gravitational slide origin develop under semi-lithified conditions existing before the sediments are incorporated into the prism at the shallow surfaces of the outward, or on the inward slopes of the trench. They are constrained within the intraformational horizons above bedding-parallel detachment faults and are unconformably covered with the superjacent beds, or are intruded by diapiric, sedimentary sill or dike intrusions associated with liquefaction or fluidization under ductile conditions. The directions of vergence are variable. On the other hand, layer shortening structure formed by tectonic deformation within the accretionary prism are characterized by more constant styles and attitudes, and by strong shear features with cataclastic textures. In these structures, the fault surfaces are oblique to the bedding, and the beds are systematically duplicated (i.e., lacking random styles of slump folds), and they are commonly associated with fault-propagation folds. Gravitational slide bodies may be further deformed at deeper levels in the prism by tectonism. Such deformed rocks with both processes constitute the whole accretionary prism at depth, and later may be deformed, exhumed to shallow levels, and exposed at the surface of the trench slope, where they may experience further deformation. These observations are not only applicable in time and space to large-scale thrust-and-fold belts of accretionary prism orogens, but to small-scale examples. If we know the total 3-D geometry of geologic bodies, including the time and scale of deformational stages, we can discriminate between gravitational slide and tectonic formation of each fold-and-thrust belt at the various scales of occurrence.
Conference papers on the topic "Deformation mechanism maps"
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Vega, Ricardo, Jaime A. Cano, and Calvin M. Stewart. "Development of “Material Specific” Creep Continuum Damage Mechanics-Based Constitutive Equations." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21677.
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Abstract The objective of this study is to introduce a method for creating “material specific” creep continuum damage mechanics-based constitutive models. Herein, material specific is defined as a constitutive model based on the mechanism-informed minimum creep strain rate (MCSR) equations found in deformation mechanism maps and calibrated to available material data. The material specific models are created by finding the best MCSR model for a dataset. Once the best MCSR model is found, the Monkman Grant inverse relationship between the MCSR and rupture time is employed to derive a rupture equation. The equations are substituted into continuum damage mechanics-based creep strain rate and damage evolution equations to furnish predictions of creep deformation and damage. Material specific modeling allows for the derivation of creep constitutive models that can better the material behavior specific to the available data of a material. The material specific framework is also advantageous since it has a systematic framework that moves from finding the best MCSR model, to rupture time, to damage evolution and, creep strain rate. Data for Alloy P91 was evaluated and a material specific constitutive model derived. The material specific model was able to accurately predict the MCSR, creep deformation, damage, and rupture of alloy P91.
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Mayeur, J. R., D. L. McDowell, and R. W. Neu. "Effect of Crystallographic Texture on Deformation Fields in Fretting Contacts." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63536.
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Fretting contacts in the partial slip regime are simulated by a finite element model of a rigid cylinder on an elastic-crystal viscoplastic half-space. The half-space is modeled as duplex Ti-6Al-4V, a polycrystalline metal alloy consisting of equiaxed primary alpha grains and secondary lamellar alpha+beta grains. Various realistic 3-D crystallographic textures are considered. The deformation fields generated by fretting are quantified in terms of cumulative effective plastic strain distributions and plastic strain maps. The results clearly demonstrate the importance of the various sources of microstructural heterogeneity in the surface layers. The main sources of microstructural heterogeneity include the distribution of phases, slip system strength anisotropy, and crystallographic texture. In basal textured materials with fretting on the edge, the plastic strain is more evenly distributed in the subsurface regions than in other textured cases. This is explained by the greater number of grains able to deform by soft slip modes and the symmetry of this type of texture relative to the fretting orientation. Transverse and basal/transverse textures result in more heterogeneously-distributed plastic strain with strain often concentrated in narrow vein-like structures with maximum accumulation near alpha/alpha+beta grain boundaries. Elastic shakedown is more difficult to achieve in the later case. Ratcheting is the primary mechanism for cyclic plastic strain accumulation.
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Luan, B. F., R. S. Qiu, Z. Zhou, K. L. Murty, J. Zhou, and Q. Liu. "Characterization of Hot Deformation Behavior of Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr Using Processing Map." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15186.
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Hot deformation characteristics of forged and β-quenched Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr (N18 alloy) in the temperature range 625–950°C and in the strain rate range 0.005–5 s−1 have been studied by uniaxial compression testing of Gleeble 3500. For this study, the approach of processing maps has been adopted and their interpretation done using the Dynamic Materials Model (DMM). Based on a series of true stress-true strain curves on various temperatures and strain rates, the flow stress has been summarized and both the strain rate sensitivity index (m) and deformation activation energy (Q) have been calculated by the constitutive equations that flow stress and the relationship of Z parameter and flow stress have been established subsequently. Furthermore, the efficiency of power dissipation (⬜) given by [2m/(m+1)] and improved by Murty has been plotted as a function of temperature and strain rate to obtain different processing maps at different true strain rates ranging from 0.1–0.7. Subsequently, the microstructures of the specimens after compression testing were characterized by electron channeling contrast (ECC) imaging techniques used an FEI Nova 400 field emission gun scanning electron microscopy (FEG-SEM). The results showed that: (i) The hyperbolic sine constitutive equation can describe the flow stress behavior of zirconium alloy, and the deformation activation energy and flow stress equation were calculated under the different temperature stages which insists that the deformation mechanism is not dynamic recovery. (ii) The hot processing maps and its validation were analyzed, which indicated that the DMM theory was reliable and could be adopted as useful tool for optimizing hot workability of Zr. The optimum parameters for extrusion and hammer forging were revealed on the processing maps of 830–950°C, 0.048–2.141 s−1 and 916–950°C, 2.465–5 s−1. (iii) The microstructure of the ingot exhibits a typical lamellar Widmanstatten structure. Under the different strain rates, the grains formed by dynamic recrystallization existed normally in the central zone of the compression samples while the no uniformity of grain size increased with the increasing of strain rate. Meanwhile, due to the dynamic recrystallization as a thermal activation process, the grains size and uniformity increased with the increasing of temperature. In brief, microstructure analysis showed that continuous dynamic recrystallization and geometric dynamic recrystallization operated concurrently during the isothermal compressive deformation.
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Harsha, S. P., and C. ‘Nat’ Nataraj. "Intermittent Chaotic Dynamics of Rail Axle Supported by Roller Bearings." In ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-87183.
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In this paper, intermittent chaotic analysis of high speed rail axle supported by roller bearings has been analyzed. In the analytical formulation, the contacts between rolling elements and races are considered as nonlinear springs, whose stiffness values are obtained by using Hertzian elastic contact deformation theory. The results show the appearance of instability and chaos in the dynamic response as the speed of the axle-bearing system is changed. Period doubling and mechanism of intermittency have been observed which lead to chaos. The appearance of regions of periodic, sub-harmonic and chaotic behavior is seen to be strongly dependent on the radial clearance. Poincare´ maps, time response and frequency spectra are used to elucidate and to illustrate the diversity of the system behavior.
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Zhang, Xuemin, Fuwei Kang, Haichao Li, Zhiwei Wang, Junling Zhao, and Erjun Guo. "Study on hot processing maps and deformation mechanisms of TC11 titanium alloy." In 2012 7th International Forum on Strategic Technology (IFOST). IEEE, 2012. http://dx.doi.org/10.1109/ifost.2012.6357560.
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Mitsuhara, Masatoshi, Yu Yoshida, Ken-Ichi Ikeda, Hideharu Nakashima, and Takashi Wakai. "Effect of Vanadium and Niobium on Creep Strength in 10% Chromium Steel Analyzed by STEM-EDS." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/creep2007-26746.
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The effect of vanadium and niobium on creep strengthening was studied in 10% chromium steels. Eleven kinds of samples which varied the additive amounts of vanadium and niobium were prepared. From the creep deformation behavior of them, the threshold stresses were estimated. The distribution maps of precipitates were obtained by STEM-EDS. In a steel with added 0.06% vanadium where no particles were observed in the lath, creep strength was slightly increased, indicating that it was not strengthened by a particle hardening effect in the lath. Lump-shaped precipitates and film-shaped precipitates including chromium and vanadium, which were observed on lath boundaries in the steel with added vanadium, are expected to inhibit the lath boundaries from migrating. This inhibition is the mechanism of the improvement in the steel with added vanadium. In the case of steels with added niobium, creep strength was found to be increased by dispersion hardening due to fine precipitates in the lath. The threshold stress was quantitatively estimated depending on the particle spacing. The estimated threshold stress corresponded to the one obtained by the creep deformation behavior. These results revealed that vanadium and niobium each have a role in improving creep strength. In steels with added both vanadium and niobium, the effect on creep strength was expressed by the sum of the effects due to each element, which were the retardation of the lath boundary migrations and the pinning of the dislocations in the lath.
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Ozawa, Yuji, Tatsuya Ishikawa, and Yoichi Takeda. "Characterization of Crack Tip Damage Zone Formation on Alloy 625 During Fatigue Crack Growth at 750°C by Transmission EBSD Method." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3458.
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In order to clarify the mechanism of fatigue crack growth in alloy 625, which is a candidate material for use in advanced ultra supercritical power plants, the crack tip damage zone formation after a crack growth test conducted in high temperature steam was investigated. It was observed that the oxide thickness at the crack tip tended to increase with decreasing cyclic loading frequency. The crack path was a mix of transgranular and intergranular fractures. According to the grain reference orientation deviation (GROD) maps, it was revealed that the density of geometrically necessary dislocations (GNDs) in the matrix along the crack path and ahead of crack tip increased with an increase in the fatigue crack growth rate (FCGR) due to environmental effects. It was observed that (1) mobile dislocations at the crack surface were blocked due to the thick oxide layer, resulting in an increase in the density of GNDs, and (2) an increase in the density of GNDs might induce stress concentration at the crack tip, deformation twinning, and the acceleration of FCGRs.
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Johnston, Dennis C., and Thomas G. Hrncir. "Using In-Line Inspection to Address Deformations Containing Near-Neutral pH Stress Corrosion Cracking." In 2002 4th International Pipeline Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ipc2002-27063.
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Marathon Ashland Pipe Line LLC (MAPL) experienced a pipeline release on January 27, 2000 from cracking in a bottom-side shallow deformation. The crack that caused the release was determined to have propagated due to corrosion fatigue that progressed from an area of near-neutral pH stress corrosion cracks. A combination of a transverse field magnetic flux inspection (TFI) tool and a slope-deformation tool were used to inspect the entire pipeline segment for additional injurious deformations that could contain cracks. The TFI tool data were used to differentiate deformations that contained linear indications (typically cracks or corrosion) from deformations that did not. The slope-deformation tool data were used to measure the deformation magnitudes and shapes and to assist with locating the (TFI) deformations that were to be excavated. The pipe conditions necessary for these types of cracking to occur are discussed as well as the findings of the in-line inspection and remediation program. Prior to this release, it was perceived within the industry that constrained shallow deformations were not likely to fail catastrophically. The failure mechanism, particularly from constrained deformations, was normally as a leak. The near-neutral pH stress corrosion cracking phenomenon within deformations was first thought to be a unique event. Based on the investigation program conducted by MAPL, this phenomenon was identified elsewhere within the pipeline system. Based on MAPL’s investigation, pipelines susceptible to or containing slight deformations (typically high D/t ratios) in areas with groundwater containing high levels of dissolved carbon dioxide and coated with materials prone to shielding cathodic protection may be particularly susceptible to the deformation near-neutral pH stress corrosion cracking phenomenon.
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Irmak, Firat, and Ali P. Gordon. "A Framework for Life Prediction of 2.25Cr-1Mo Under Creep and Thermomechanical Fatigue." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76669.
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Low alloy steels are often utilized in components experiencing decades of usage under aggressive operating conditions. Even though there has been remarkable advancement in the development of modern alloys, however, these materials continue to be applied in boilers, heat exchanger tubes, and throttle valve bodies in both turbomachinery and pressure-vessel/piping applications. These steels display excellent resistance to deformation and damage under creep and/or fatigue at moderate temperatures. For example, the material 2.25Cr-1Mo has exceptional balance of ductility, corrosion resistance, and creep strength under temperatures up to 650□C. Both creep and non-isothermal fatigue conditions have been the limiting factor for most 2.25Cr-1Mo components; therefore, a life prediction approach is constructed with the capability of approximating the number of cycles to failure for conditions where the material is experiencing creep and fatigue with thermal cycling. Parameters for the approach are built on regression fits in comparison with a comprehensive experimental database. This database includes low cycle fatigue (LCF), creep fatigue (CF), and thermomechanical fatigue (TMF) experiments. The cumulative damage approach was utilized for the life prediction model where dominant damage maps can be used to determine primary microstructural mechanism associated with failure. Life calculations are facilitated by the usage of a non-interacting creep-plasticity constitutive model capable of representing not only the temperature- and rate-dependence, but also the history-dependence of the material.
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Baik, Andrew D., X. Lucas Lu, Elizabeth M. Hillman, Cheng Dong, and X. Edward Guo. "Pseudo-3D Visualization of Cytoskeletal and Whole-Cell Deformation of MLO-Y4 Osteocytes Under Flow." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19239.
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Osteocytes respond to fluid shear loading by activating various biochemical pathways, mediating a dynamic process of bone formation and resorption. Whole-cell [1] and intracellular deformation [2] may be able to directly activate and modulate relevant biochemical pathways. Most studies on cell deformation have focused only on cell deformation in the plane parallel to the substrate surface. However, height-dependent cell deformation has not been well characterized even though it may contribute greatly to mechanotransduction mechanisms. Traditional techniques to obtain this additional height information of a cell-body include confocal and deconvolution microscopy, which require scanning a z-stack of the cell. However, this inherently limits the timescale under which the deformational information can be visualized. To further investigate this behavior at a high temporal resolution, we propose using a “pseudo-3D” microscopy method to better characterize osteocyte cell behavior. In this study, we present a novel technique that is able to image a single cell simultaneously in two orthogonal planes to obtain real-time images of cell at a millisecond timescale. The objectives of this study were to: (1) visualize actin or microtubule networks with the plasma membrane in two orthogonal planes simultaneously under fluid shear; (2) map out the deformations using digital image correlation; and (3) compare the depth-directional deformation of actin and microtubule networks of osteocytes.