The Experts below are selected from a list of 94698 Experts worldwide ranked by ideXlab platform
Zhen Zhang - One of the best experts on this subject based on the ideXlab platform.
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triaxial behavior of granular material under complex loading path by a new numerical true triaxial engine
Advanced Powder Technology, 2019Co-Authors: Xiaoliang Wang, Zhen ZhangAbstract:Abstract A new numerical true triaxial engine based on discrete element method accounting for rolling resistance contact is developed. By this engine, we have simulated mechanical behavior of granular materials under complex Stress loading path in this study. Stress-strain responses of a kind of typical granular sand under several Stress loading path in meridian and deviatoric Stress Space are provided. The results show that the three dimensional effects like the intermediate principal Stress play an important role in the modeling processes. Theoretical analysis in strength characteristic implies the strength criteria with three parameters such as unified strength criterion and van Eekelen strength criterion are capable of describing cohesionless granular material behaviors in three dimensional Stress states. Moreover, the case study for Chende sand further demonstrates the numerical true triaxial engine, is a potential tool. As compared to conventional triaxial compression test, this new developed apparatus could be widely used to “measure” elastic-plastic behavior in three dimensional Stress Space for finite element analysis in geotechnical problems.
Toshihiko Kuwabara - One of the best experts on this subject based on the ideXlab platform.
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effect of biaxial work hardening modeling for sheet metals on the accuracy of forming limit analyses using the marciniak kuczynski approach
2015Co-Authors: Tomoyuki Hakoyama, Toshihiko KuwabaraAbstract:A servo-controlled tension-internal pressure testing machine with an optical 3D deformation analysis system (ARAMIS\(^\circledR \), GOM) was used to measure the multiaxial plastic deformation behavior of a high-strength steel sheet with a tensile strength of 590 MPa for a strain range from initial yield to fracture. Tubular specimens were fabricated by roller bending and laser welding the as-received flat sheet materials. Many linear Stress paths in the first quadrant of the Stress Space were applied to the tubular specimens to measure the forming limit curve (FLC), forming limit Stress curve (FLSC), and forming limit plastic work per unit volume (FLPW) of the as-received sheet material in addition to the contours of plastic work and the directions of the plastic strain rates. Differential hardening behavior was observed; the shapes of the work contours constructed in the principal Stress Space changed with an increase in plastic work. The observed differential hardening behavior was approximated by changing the material parameters and the exponent of the Yld2000-2d yield function as functions of the reference plastic strain. Marciniak-Kuczynski-type forming limit analyses were performed using both the differential hardening model and isotropic hardening models based on the Yld2000-2d yield function. It was found that the material model that is capable of reproducing both the work contours and the directions of the plastic strain rates measured for a strain range close to the fracture limit can give a more effective constitutive model for accurately predicting the FLC, FLSC, and FLPW.
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biaxial tensile test of high strength steel sheet for large plastic strain range
Key Engineering Materials, 2012Co-Authors: Tomoyuki Hakoyama, Toshihiko KuwabaraAbstract:Deformation behavior of high strength steel with a tensile strength of 590 MPa under biaxial tension was investigated for a work equivalent plastic strain range of 0.002 0.16. The test material was bent and laser welded to fabricate a tubular specimen with an inner diameter of 44.6mm and wall thickness of 1.2 mm. Using a servo-controlled tension-internal pressure testing machine, many linear Stress paths in the first quadrant of Stress Space were applied to the tubular specimens. Moreover, biaxial tensile tests using a cruciform specimen were performed to precisely measure the deformation behavior of the test material for a small strain range following initial yielding. True Stress-true plastic strain curves, contours of plastic work in Stress Space and the directions of plastic strain rates were measured and compared with those calculated using selected yield functions. The plastic deformation behavior up to an equivalent plastic strain of 0.16 was successfully measured. The Yld2000-2d yield function most closely predicts the general work contour trends and the directions of plastic strain rates of the test material.
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Forming Limit Stresses of Sheet Metal under Proportional and Combined Loadings
AIP Conference Proceedings, 2005Co-Authors: Kengo Yoshida, Toshihiko Kuwabara, Mitsutoshi KurodaAbstract:The effects of changing strain paths on forming limit Stresses of sheet metals are investigated using the Marciniak‐Kuczynski model. Forming limits are analyzed for proportional loading and two types of combined loadings: combined loading which includes unloading between the first and second loadings and that which includes an abrupt strain path change without unloading between the first and second loadings. The forming limit Stress curves in Stress Space calculated for the combined loading with unloading are in good agreement with those calculated for the proportional loading, while the forming limit curves in strain Space are strongly dependent on the strain paths. The forming limit Stresses calculated for combined loading with an abrupt strain path change, however, do not coincide with those calculated for proportional loading. The strain path dependence of the forming limit Stresses is discussed in detail.
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measurement and analysis of yield locus and work hardening characteristics of steel sheets wtih different r values
Acta Materialia, 2002Co-Authors: Toshihiko Kuwabara, Albert Van Bael, Eiji IizukaAbstract:Abstract Biaxial tensile experiments of six kinds of steel sheet with different r-values are carried out using a servo-controlled biaxial tensile testing machine. Successive contours of plastic work in the biaxial Stress Space and the plastic strain rate vectors are precisely measured for linear loading paths. The measured data are compared with the theoretical predictions based on the Taylor–Bishop–Hill model with the full constraints and relaxed constraints assumptions using the experimentally determined crystallographic textures. Comparisons with the Hill quadratic and Hosford yield criteria are also made. It is found that (1) the TBH model with the full constraints assumption is superior to that with the relaxed constraints assumption in predicting the plastic deformation characteristics of steel sheets; (2) The Hosford yield criterion is an effective phenomenological model for predicting the plastic deformation characteristics of steel sheets.
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measurement and analysis of differential work hardening in cold rolled steel sheet under biaxial tension
Journal of Materials Processing Technology, 1998Co-Authors: Toshihiko Kuwabara, Satoshi Ikeda, Kensuke KurodaAbstract:Abstract Biaxial tensile tests of cold-rolled steel sheet were carried out using newly designed cruciform specimens. The specimens were deformed under linear loading paths in a servo-controlled biaxial tensile testing machine. The maximum equivalent strain attained was 0.04. Plastic orthotropy remained coaxial with the principal Stresses throughout every experiment. However, the successive contours of plastic work in biaxial Stress Space changed their shapes progressively, exemplifying a phenomenon which has been termed differential work hardening by Hill and Hutchinson (Trans. ASME J. Appl. Mech. 59 (1992) 1) and by Hill et al. (Int. J. Solids Struct. 31 (1994) 2999). The geometry of the entire family of the work contours was compared with the yield loci calculated from several existing yield criteria. Hill’s quadratic yield criterion overestimated the measured work contours; in particular, in the neighborhood of balanced biaxial tension, the discrepancy was large, while the other yield criteria described the behavior of the work contours well. The only yield criterion that could describe the general trends of the work contours as well as the in-plane r -value distribution with good accuracy was Gotoh’s biquadratic yield criterion. Moreover, it was observed that the components of an increment of logarithmic plastic strain are proportional to the components of the associated normal to the current work contour in Stress Space. Accordingly, it appears that the work contours act instantaneously as plastic potentials, at least under linear loading paths.
Sanjay Nimbalkar - One of the best experts on this subject based on the ideXlab platform.
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isotropic kinematic hardening model for coarse granular soils capturing particle breakage and cyclic loading under triaxial Stress Space
Canadian Geotechnical Journal, 2016Co-Authors: Qingsheng Chen, J P Carter, Buddhima Indraratna, Sanjay NimbalkarAbstract:In this paper, a simple but comprehensive cyclic Stress–strain model that incorporates particle breakage for granular soils including ballast and rockfill has been proposed on the basis of bounding surface plasticity theory within a critical state framework. Particle breakage and its effects are captured by a critical state line that is translated in voids ratio–Stress Space according to the dissipated energy (plastic work), through a hyperbolic function. A comprehensive equation related to particle breakage is proposed for the Stress–dilatancy relationship to capture the complex dilatancy of granular soils. By extending Masing’s rule to bounding surface plasticity theory and introducing a generalized homological centre, a combined isotropic–kinematic hardening rule and a mapping rule have been established to simulate more realistically the response of gravelly soils under cyclic loading. The applicability and accuracy of this model are demonstrated by comparing its predictions with experimental results f...
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isotropic kinematic hardening model for coarse granular soils capturing particle breakage and cyclic loading under triaxial Stress Space
Canadian Geotechnical Journal, 2016Co-Authors: Qingsheng Chen, J P Carter, Buddhima Indraratna, Sanjay NimbalkarAbstract:In this paper, a simple but comprehensive cyclic Stress–strain model that incorporates particle breakage for granular soils including ballast and rockfill has been proposed on the basis of bounding...
Xiaoliang Wang - One of the best experts on this subject based on the ideXlab platform.
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triaxial behavior of granular material under complex loading path by a new numerical true triaxial engine
Advanced Powder Technology, 2019Co-Authors: Xiaoliang Wang, Zhen ZhangAbstract:Abstract A new numerical true triaxial engine based on discrete element method accounting for rolling resistance contact is developed. By this engine, we have simulated mechanical behavior of granular materials under complex Stress loading path in this study. Stress-strain responses of a kind of typical granular sand under several Stress loading path in meridian and deviatoric Stress Space are provided. The results show that the three dimensional effects like the intermediate principal Stress play an important role in the modeling processes. Theoretical analysis in strength characteristic implies the strength criteria with three parameters such as unified strength criterion and van Eekelen strength criterion are capable of describing cohesionless granular material behaviors in three dimensional Stress states. Moreover, the case study for Chende sand further demonstrates the numerical true triaxial engine, is a potential tool. As compared to conventional triaxial compression test, this new developed apparatus could be widely used to “measure” elastic-plastic behavior in three dimensional Stress Space for finite element analysis in geotechnical problems.
P Van Houtte - One of the best experts on this subject based on the ideXlab platform.
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multi level modelling of mechanical anisotropy of commercial pure aluminium plate crystal plasticity models advanced yield functions and parameter identification
International Journal of Plasticity, 2015Co-Authors: Kai Zhang, Bjorn Holmedal, Odd Sture Hopperstad, Stephane Dumoulin, Jerzy Gawad, Albert Van Bael, P Van HoutteAbstract:Abstract The mechanical anisotropy of an AA1050 aluminium plate is studied by the use of five crystal plasticity models and two advanced yield functions. In-plane uniaxial tension properties of the plate were predicted by the full-constraint Taylor model, the advanced Lamel model (Van Houtte et al., 2005) and a modified version of this model (Manik and Holmedal, 2013), the viscoplastic self-consistent model and a crystal plasticity finite element method (CPFEM). Results are compared with data from tensile tests at every 15° from the rolling direction (RD) to the transverse direction (TD) in the plate. Furthermore, all the models, except CPFEM, were used to provide Stress points in the five-dimensional deviatoric Stress Space at yielding for 201 plastic strain-rate directions. The Facet yield surface was calibrated using these 201 Stress points and compared to in-plane yield loci and the planar anisotropy which were calculated by the crystal plasticity models. The anisotropic yield function Yld2004-18p (Barlat et al., 2005) was calibrated by three methods: using uniaxial tension data, using the 201 virtual yield points in Stress Space, and using a combination of experimental data and virtual yield points (i.e. a hybrid method). Optimal yield-surface exponents were found for each of the crystal plasticity models, based on calibration to calculated Stress points at yielding for a random texture, and used in the latter two calibration methods. It is found that the last hybrid calibration method can capture the experimental results and at the same time ensure a good fit to the anisotropy in the full Stress Space predicted by the crystal plasticity models.
