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Koichi Hashiguchi - One of the best experts on this subject based on the ideXlab platform.
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extended tangential subloading Surface Model for general loading behavior of soils application to nonproportional loadings
Soils and Foundations, 2006Co-Authors: Hideki Setouchi, Koichi Hashiguchi, Takeshi Shikanai, Takashi OkayasuAbstract:ABSTRACT The conventional elastoplastic Model premising that the interior of yield Surface is a purely elastic domain is incapable of describing the plastic deformation by the rate of stress inside the yield Surface. Thus, it is inapplicable to the description of cyclic loading behavior. Besides, the traditional elastoplastic Model is independent of the stress rate component tangential to the yield Surface. Therefore, it predicts an unrealistically high stiffness modulus for nonproportional loading process deviating significantly from proportional one. The extended tangential-subloading Surface Model proposed by Hashiguchi and Tsutsumi (2001) would be capable of describing the cyclic loading behavior and the inelastic strain rate induced by the stress rate component tangential to the subloading Surface. In this article, the extended tangential-subloading Surface Model is applied to the prediction of deformation behavior of sands subjected to various loading ranging from proportional to cyclic nonproportional loading. The validity is verified by comparing with the various test data. Then, it is revealed that the incorporation of the strain rate due to the stress rate component tangential to the subloading Surface is of importance for the description of nonproportional loading behavior.
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localized necking analysis by the subloading Surface Model with tangential strain rate and anisotropy
International Journal of Plasticity, 2004Co-Authors: Koichi Hashiguchi, Alexander Y ProtasovAbstract:Abstract A rational approach to the localized necking problem was given by Storen and Rice [J. Mech. Phys. Solids 23 (1975) 421] but this approach is limited to the description of monotonic loading behavior near a proportional loading of the isotropic, rigid-plastic materials with von Mises yield Surface. In this article it is extended so as to be applicable to the arbitrary loading behavior of elastoplastic materials with an arbitrary yield Surface by introducing the subloading Surface Model with the tangential-stress rate effect [Met. Mater. 4 (1998) 652; Int. J. Plasticity 17 (2001) 117]. The localized necking condition under biaxial stretching of a uniform and homogeneous thin sheet subjected to biaxial stretching in the plane stress state is formulated in such a way that elastic deformation and compressibility are allowed. Based on this condition, the localized necking for metals is analyzed showing the forming limit diagrams (FLDs). It becomes clear that not only the tangential-strain rate but also the inherent/induced anisotropy due to the kinematic hardening intensely influence the onset of localized necking.
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plane strain bifurcation analysis of soils by the tangential subloading Surface Model
International Journal of Solids and Structures, 2004Co-Authors: Mehdi Khojastehpour, Koichi HashiguchiAbstract:Abstract The tangential–subloading Surface Model can describe the normal-plastic strain rate due to the rate of stress inside the yield Surface and the tangential-plastic strain rate due to the stress rate component tangential to the subloading Surface. The localized and diffuse bifurcation modes of the rectangular soil specimen subjected to plane strain loading under the undrained conditions are analyzed by adopting the tangential–subloading Surface Model, exhibiting the characteristic regimes of the governing equations (elliptic, hyperbolic and parabolic) in this article. Further, the conditions for shear band formation, shear band inclination, diffuse bifurcation modes, and the long and short wavelength limit of diffuse modes are discussed in relation to material properties and the state of stress, i.e. the stress-ratio and the normal-yield ratio. The tangential-plastic strain rate makes the inception of bifurcation modes easier in not only normal-yield, but also subyield states.
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shear band formation analysis in soils by the subloading Surface Model with tangential stress rate effect
International Journal of Plasticity, 2003Co-Authors: Koichi Hashiguchi, Seiichiro TsutsumiAbstract:Abstract The generalized elastoplastic constitutive equation for soils is proposed based on the subloading Surface Model extended so as to describe the dependence of both the magnitude and the direction of inelastic stretching on the stress rate tangential to the subloading Surface [Int J Plasticity 17 (2001) 117]. It would be applicable to the analysis of deformation of soils in both normal-yield and subyield states for not only lower but also higher stress ratio than that in the critical state. Then, the shear band formation in the rectangular specimen subjected to the biaxial compression under the undrained plane strain condition is analyzed by the generalized equation, and thus the condition for shear band formation and the shear band inclination are discussed in relation to material properties and the state of stress, i.e. the stress-ratio and the normal-yield ratio. These results reveal that the tangential stretching term makes easy to fulfill the necessary condition of shear band formation for not only normal-yield but also subyield states, and further the formation is affected by the material parameter prescribing the approaching degree of the stress to the normal-yield state.
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post localization analysis by the subloading Surface Model with tangential stress rate effect
Materials Science Research International, 2001Co-Authors: Koichi Hashiguchi, Alexander Y Protasov, Takashi OkayasuAbstract:Various constitutive Models have been applied to the analyses of localized deformation of solids. However, most of them fall within the framework of the conventional plasticity premising that the interior of yield Surface is an elastic domain and obeys the plastic potential theory in which the plastic stretching is independent of the stress rate component tangential to the yield Surface. Therefore, they predict a stiff elastic response until the stress reaches the yield state and further a stiff elastoplastic response after yielding. On the other hand, the subloading Surface Model falling within the unconventional plasticity would be only the Model capable of describing pertinently the plastic deformation induced by the rate of stress within the yield Surface in general loading process including the unloading, reloading and inverse loading. Further, the numerical calculation by this Model is quite efficient disusing the special algorism, e.g. the mean normal method and the radial return method in order to make the stress lie just on the yield Surface in the plastic loading process since it contains the controlling function to make the stress approach automatically the yield Surface in the plastic loading process. Further, this Model is recently extended so as to describe the tangential stress rate effect, i.e. the inelastic deformation induced by the stress rate component tangential to the subloading Surface. In this article the post-localized deformation of metal due to the shear band formation is analyzed by the finite element method incorporating the subloading Surface Model with the tangential stress rate effect. Thus, the influence of the tangential stress rate effect on the shear band formation is discussed exhibiting several examples of the deformation patterns.
Rolf H Reichle - One of the best experts on this subject based on the ideXlab platform.
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Catchment-averaged Soil Moisture and Runoff Output from the NASA GEOS Catchment Land Surface Model
2018Co-Authors: Rolf H Reichle, Wade CrowAbstract:Overview:Matlab file containing 1) daily-averaged Surface soil moisture ("SM_daily_sz"), 2) daily-averaged root-zone soil moisture ("SM_daily_rz"), 3) daily-total Surface runoff ("srun_daily") and 4) daily-total baseflow runoff ("bf_daily") generated by the NASA Goddard Earth Observing System (GEOS) Catchment land Surface Model (CLSM) for 16 medium-scale (2000 to 10,000 km2) hydrologic basins within the south-central United States. For more information on the GEOS-CLSM simulations see Section 2a of the following article:Reichle, R. et al., Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements. Journal of Hydrometeorology, 18, 2621–2645, doi:10.1175/JHM-D-17-0063.1, 2017.Timing notes: Day 1 = 31 March 2015Day 793 = 1 May 2017Day is 0 to 23:59 UTCData units:Soil moisture is given in daily-averaged volumetric soil moisture (m3/m3)Runoff is given in total mm/day.Spatial domain:For spatial details on the basins see Table 1 and Figure 1 in:Crow, W.T., Chen, F., Reichle, R.H., and Liu, Q. L Band Microwave Remote Sensing and Land Data Assimilation Improve the Representation of Prestorm Soil Moisture Conditions for Hydrologic Forecasting. Geophysical Research Letters, 44(11), 5495–5503, doi:10.1002/2017GL073642, 2017.Contact: Wade.Crow@ars.usda.gov
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assimilation of grace terrestrial water storage data into a land Surface Model results for the mississippi river basin
Journal of Hydrometeorology, 2008Co-Authors: Benjamin F Zaitchik, Matthew Rodell, Rolf H ReichleAbstract:Abstract Assimilation of data from the Gravity Recovery and Climate Experiment (GRACE) system of satellites yielded improved simulation of water storage and fluxes in the Mississippi River basin, as evaluated against independent measurements. The authors assimilated GRACE-derived monthly terrestrial water storage (TWS) anomalies for each of the four major subbasins of the Mississippi into the Catchment Land Surface Model (CLSM) using an ensemble Kalman smoother from January 2003 to May 2006. Compared with the open-loop CLSM simulation, assimilation estimates of groundwater variability exhibited enhanced skill with respect to measured groundwater in all four subbasins. Assimilation also significantly increased the correlation between simulated TWS and gauged river flow for all four subbasins and for the Mississippi River itself. In addition, Model performance was evaluated for eight smaller watersheds within the Mississippi basin, all of which are smaller than the scale of GRACE observations. In seven of e...
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global assimilation of satellite Surface soil moisture retrievals into the nasa catchment land Surface Model
Geophysical Research Letters, 2005Co-Authors: Rolf H Reichle, Randal D KosterAbstract:[1] Global retrievals of Surface soil moisture from the Scanning Multichannel Microwave Radiometer for the period 1979–87 are assimilated into the NASA Catchment land Surface Model as it is driven with Surface meteorological data derived from observations. Validation against ground-based measurements in Eurasia and North America from the Global Soil Moisture Data Bank demonstrates a long assumed (but rarely proven) property of soil moisture fields derived from data assimilation – that the assimilation product is superior to either satellite data or Model data alone. An analysis of the innovations reveals that the filter is only partially operating within its underlying assumptions and offers clues how spatially distributed Model error parameters could further enhance filter performance.
Takashi Okayasu - One of the best experts on this subject based on the ideXlab platform.
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extended tangential subloading Surface Model for general loading behavior of soils application to nonproportional loadings
Soils and Foundations, 2006Co-Authors: Hideki Setouchi, Koichi Hashiguchi, Takeshi Shikanai, Takashi OkayasuAbstract:ABSTRACT The conventional elastoplastic Model premising that the interior of yield Surface is a purely elastic domain is incapable of describing the plastic deformation by the rate of stress inside the yield Surface. Thus, it is inapplicable to the description of cyclic loading behavior. Besides, the traditional elastoplastic Model is independent of the stress rate component tangential to the yield Surface. Therefore, it predicts an unrealistically high stiffness modulus for nonproportional loading process deviating significantly from proportional one. The extended tangential-subloading Surface Model proposed by Hashiguchi and Tsutsumi (2001) would be capable of describing the cyclic loading behavior and the inelastic strain rate induced by the stress rate component tangential to the subloading Surface. In this article, the extended tangential-subloading Surface Model is applied to the prediction of deformation behavior of sands subjected to various loading ranging from proportional to cyclic nonproportional loading. The validity is verified by comparing with the various test data. Then, it is revealed that the incorporation of the strain rate due to the stress rate component tangential to the subloading Surface is of importance for the description of nonproportional loading behavior.
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post localization analysis by the subloading Surface Model with tangential stress rate effect
Materials Science Research International, 2001Co-Authors: Koichi Hashiguchi, Alexander Y Protasov, Takashi OkayasuAbstract:Various constitutive Models have been applied to the analyses of localized deformation of solids. However, most of them fall within the framework of the conventional plasticity premising that the interior of yield Surface is an elastic domain and obeys the plastic potential theory in which the plastic stretching is independent of the stress rate component tangential to the yield Surface. Therefore, they predict a stiff elastic response until the stress reaches the yield state and further a stiff elastoplastic response after yielding. On the other hand, the subloading Surface Model falling within the unconventional plasticity would be only the Model capable of describing pertinently the plastic deformation induced by the rate of stress within the yield Surface in general loading process including the unloading, reloading and inverse loading. Further, the numerical calculation by this Model is quite efficient disusing the special algorism, e.g. the mean normal method and the radial return method in order to make the stress lie just on the yield Surface in the plastic loading process since it contains the controlling function to make the stress approach automatically the yield Surface in the plastic loading process. Further, this Model is recently extended so as to describe the tangential stress rate effect, i.e. the inelastic deformation induced by the stress rate component tangential to the subloading Surface. In this article the post-localized deformation of metal due to the shear band formation is analyzed by the finite element method incorporating the subloading Surface Model with the tangential stress rate effect. Thus, the influence of the tangential stress rate effect on the shear band formation is discussed exhibiting several examples of the deformation patterns.
N Atsushi - One of the best experts on this subject based on the ideXlab platform.
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a new Surface Model based on a fibre bundle of 1 parameter groups
International Conference on Multimedia and Expo, 2004Co-Authors: Jinhui Chao, Jongdae Kim, N AtsushiAbstract:A new fibre bundle Surface Model is proposed for 3D object Modeling. This fibre bundle Model, consisting of local direct product of a base curve and a fibre curve, is able to represent arbitrary Surfaces. In particular, the fibre bundle of 1-parameter groups, i.e. with fibres as 1-parameter groups are efficient in both synthesis and recognition. Indeed, the 1-parameter groups can be uniquely determined by finite, e.g. six invariants of their Lie algebras. Besides, the Surfaces can be quickly generated by elementary functions without numerical integration errors. This Model is also expected to be useful in object-based 3D image coding.
Guoqi Zhang - One of the best experts on this subject based on the ideXlab platform.
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Reliability Assessment of Light-Emitting Diode Packages With Both Luminous Flux Response Surface Model and Spectral Power Distribution Method
IEEE Access, 2019Co-Authors: Wei Chen, Bin Pu, Cheng Qian, Guoqi ZhangAbstract:The inherent luminous characteristics and stability of LED packages during the operation period are highly dependent on their junction temperatures and driving currents. In this paper, the luminous flux of LED packages operated under a wide range of driving currents and junction temperatures are investigated to develop a luminous flux response Surface Model. The coefficients of the proposed Model are further extracted to compare the luminous efficacy decay mechanisms of LED packages with different packaging structures. Furthermore, a spectral power distribution (SPD) method Modeled by the Gaussian function is proposed to analyze the long-term degradation mechanisms of all selected LED packages. The results of this study show that: (1) The luminous flux of phosphor converted white LED decreases to accompany with the increase of junction temperature, while that of bare blue LED die keeps relatively stable; (2) The proposed general luminous flux response Surface Model can be used to predict the luminous flux of LEDs with different packaging technologies accurately, and it can be known from the proposed Model that the influences of driving current and temperature on LED chip and phosphor vary with different packaging structures; and (3) The driving current and temperature dependent sensitivities and degradation mechanisms of LED packages can be investigated by using both the luminous flux response Surface Model and the spectral power distribution method.
