scholarly journals An extended super/subloading surface model for soft rock considering structure degradation

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258813
Author(s):  
Kai Cui ◽  
Bin Hu ◽  
Aneng Cui ◽  
Jing Li ◽  
Erjian Wei ◽  
...  
Keyword(s):  
Yield Surface ◽  
Soft Rock ◽  
Yield Function ◽  
Surface Shape ◽  
Surface Model ◽  
Test Results ◽  
Structure Degradation ◽  
Proposed Model ◽  
Comparison Results ◽  
Cam Clay

The strain-softening and dilatancy behavior of soft rock is affected by the loading history and the development of structure. This study regards soft rock as a structured and overconsolidated soil and develops a new elastoplastic model based on the classical super yield surface Cam-clay model. The proposed model is capable of capturing the effect of yield surface shape on the mechanical behavior of soft rock by introducing a new yield function. The proposed model is validated against the triaxial test results on different types of soft rocks under drained condition. The comparison results indicate that the proposed model is suitable for describing the constitutive behavior of soft rock.

A Generalized Anisotropic Hardening Rule Based on the Mroz Multi-Yield-Surface Model

2008 ◽  
Author(s):  
K. S. Choi ◽  
J. Pan
Keyword(s):  
Cyclic Loading ◽  
Yield Surface ◽  
Kinematic Hardening ◽  
Constitutive Relations ◽  
Yield Function ◽  
Surface Model ◽  
Loading Conditions ◽  
Anisotropic Hardening ◽  
Hardening Rule ◽  
Strain Data

In this paper, a generalized anisotropic hardening rule based on the Mroz multi-yield-surface model is derived. The evolution equation for the active yield surface is obtained by considering the continuous expansion of the active yield surface during the unloading/reloading process. The incremental constitutive relation based on the associated flow rule is then derived for a general yield function. As a special case, detailed incremental constitutive relations are derived for the Mises yield function. The closed-form solutions for one-dimensional stress-plastic strain curves are also derived and plotted for the Mises materials under cyclic loading conditions. The stress-plastic strain curves show closed hysteresis loops under uniaxial cyclic loading conditions and the Masing hypothesis is applicable. A user material subroutine based on the Mises yield function, the anisotropic hardening rule and the constitutive relations was then written and implemented into ABAQUS. Computations were conducted for a simple plane strain finite element model under uniaxial monotonic and cyclic loading conditions based on the anisotropic hardening rule and the isotropic and nonlinear kinematic hardening rules of ABAQUS. The results indicate that the plastic response of the material follows the intended input stress-strain data for the anisotropic hardening rule whereas the plastic response depends upon the input strain ranges of the stress-strain data for the nonlinear kinematic hardening rule.

A Consistent Criterion for Diffuse Necking in Sheet Metals Using Hill’s 1979 Yield Surface

1998 ◽  
Vol 120 (2) ◽  
pp. 177-182 ◽  
Author(s):  
S. K. Esche ◽  
R. Shivpuri
Keyword(s):  
Plastic Deformation ◽  
Yield Surface ◽  
Shape Factor ◽  
Biaxial Tension ◽  
Yield Function ◽  
Surface Shape ◽  
Principal Strain ◽  
Sheet Metals ◽  
Diffuse Necking ◽  
Anisotropic Yield Function

A review of some existing criteria for diffuse necking in sheet metals is given and their limitations are discussed. The introduction into production of new sheet materials whose plastic deformation is impossible to be modeled using Hill’s 1948 anisotropic yield function necessitates improvements of these existing criteria to accurately describe their necking behavior. In this paper, a generalization of the existing diffuse necking criteria for materials describable by Case IV of Hill’s 1979 anisotropic yield function is presented. The proposed criterion is consistent with the previous criteria. It predicts a significant effect of Hill’s 1979 yield surface shape factor on the critical principal strain in the range of negative minor strains while in the range of biaxial tension this influence is small.

Unified Three-Dimensional Revision of Modified Cam Clay Model

2007 ◽  
Vol 340-341 ◽  
pp. 1267-1272
Author(s):  
Hang Zhou Li ◽  
Hong Jian Liao ◽  
Kyoji Sassa ◽  
Gong Hui Wang
Keyword(s):  
Three Dimensional ◽  
Yield Function ◽  
Triaxial Tests ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
True Triaxial ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Stress States ◽  
Cam Clay

According to unified strength parameters obtained from unified strength theory, the slope of critical state line is modified to reflect critical states of different geomaterials under general stress states. Yield function that can consider the effect of the third deviatoricic invariant is proposed, and an elasto-plastic constitutive model is established by adopting non-associated flow rules; furthermore, methods of overcoming singular points on the yield surface are discussed. The proposed model is verified by true triaxial tests of clay, and results show that the model can well predict stress-strain relationships.

An Elastoplastic Model for Coarse Grained Soils Obeying Lade's Dilatancy Rule

2013 ◽  
Vol 850-851 ◽  
pp. 381-386
Author(s):  
Jin Wang ◽  
Jiao Na Li ◽  
Sheng Zhu
Keyword(s):  
Potential Function ◽  
Yield Surface ◽  
Large Scale ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Surface Model ◽  
Test Results ◽  
Elastoplastic Model ◽  
Plastic Potential ◽  
Plastic Potential Function

This paper discussed the mechanism of dilatancy in coarse grained soils. Large-scale triaxial tests were also conducted to study the dilatancy law of coarse grained soils. Based on the results of the previous studies, it is found that plastic potential function proposed by Lade can fit the test results well. Lades dilatancy rule was then applied to a practical two-yield-surface model. Elastoplastic formula of the two-yield-surface model was also deduced in detail. The new model was verified with several groups of different materials. Results showed that this model could predict the behaviors of coarse grained soils well.

Viscoplastic Simulation of Rate Dependent behavior of the Taipei Silty Clay

2012 ◽  
Vol 28 (3) ◽  
pp. 543-553
Author(s):  
C.-K. Chin ◽  
C.-Y. Ou
Keyword(s):  
Yield Surface ◽  
High Stress ◽  
Constitutive Models ◽  
Silty Clay ◽  
Test Results ◽  
Creep Failure ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Proposed Model ◽  
High Stress Level

AbstractThe objective of this study was to derive e an anisotropic viscoplastic rate dependent constitutive model. The model was derived on the basis of the viscoplastic theory proposed by Kutter and Sathialingam and the yield surface function suggested by Wheeler et al. The adopted yield surface function was more consistent with the yield surface of the Taipei silty clay, compared with the existing constitutive models. The model was confirmed able to simulate the undrained stress strain response for the K0-consolidated undrained compression and extension tests. The model was also used to simulate the isotropic consolidated and K0-consolidated undrained creep test. Results show that the predicted strain from the proposed model was close to the test data. Especially the model is able to predict the tertiary creep failure when the soil is subject to high stress level.

Numerical Prediction of Spar Motions Considering Top Tension Riser Stiffness

2004 ◽  
Author(s):  
Cheng-Yo Chen ◽  
Prahoro Nurtjahyo
Keyword(s):  
Gulf Of Mexico ◽  
Model Test ◽  
Pitch Angle ◽  
Motion Prediction ◽  
Test Results ◽  
Proposed Model ◽  
Comparison Results ◽  
Truss Spar ◽  
Righting Moment ◽  
Delta Model

Spar motions are often predicted without explicitly considering the stiffness effect of the buoyancy can of top tension risers (TTRs). This may result from the inability of most motion prediction programs to take this effect into consideration. The forces exerted by the TTR buoyancy can on the spar provide a net beneficial righting moment. Hence, neglecting the effect of TTR stiffness could produce excessive predicted spar motions, particularly maximum pitch angle. The derived spar configurations based on such predicted motions are likely to be conservative and not optimal. This paper proposes a simple “Linearized P-Delta” model to account for the effect of TTR stiffness on spar motions. The predicted motions using the proposed model are compared with the model test results for a production truss spar in the Gulf of Mexico. The comparison results indicate that the proposed model is quite rigorous and correlates reasonably well with the model test results.

Anisotropic Distortional Yield Model

1990 ◽  
Vol 57 (3) ◽  
pp. 537-547 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Mehrdad Foroozesh
Keyword(s):  
Fourth Order ◽  
Yield Surface ◽  
Large Strain ◽  
Small Strain ◽  
Surface Model ◽  
Yield Model ◽  
Proposed Model ◽  
Anisotropy Tensor ◽  
Subsequent Yield Surface ◽  
Uniform Expansion

A yield surface model is proposed in this work which may be adapted to both small strain and large strain offset definitions of yielding. The proposed anisotropic distortional yield model is capable of translation, uniform expansion or contraction, as well as distortion of the subsequent yield surface. Two versions of the proposed model are introduced through variations in fourth-order anisotropy tensor M of the yield surface. Experimental observations by Phillips and co-workers (1973, 1974, 1977, 1979, 1985), Helling et al. (1986), and Stout et al. (1985) are taken into consideration in the development of the proposed model. The corresponding fourth-order elastoplastic stiffness matrix is formulated and specific examples are given.

Modelling the rate-sensitive characteristics of the Gloucester foundation soil

1998 ◽  
Vol 35 (5) ◽  
pp. 769-789 ◽  
Author(s):  
Sean D Hinchberger ◽  
R Kerry Rowe
Keyword(s):  
Yield Surface ◽  
Field Performance ◽  
Element Model ◽  
Triaxial Tests ◽  
Surface Model ◽  
Test Results ◽  
Foundation Soil ◽  
Sensitive Characteristics ◽  
Test Embankment

Stages 1 (1967) and 2 (1982) of the Gloucester test embankment are studied using a fully coupled finite-element model. The rate-sensitive characteristics of the foundation soil are modelled using an elastoviscoplastic constitutive equation based on the elliptical cap yield surface and Perzyna's overstress theory of viscoplasticity. The aspect ratio of the yield surface for the Gloucester foundation soil is estimated using conventional laboratory shear and consolidation test results. Calculated and measured behaviour during consolidated isotropically undrained triaxial tests and long-term Rowe cell consolidation tests are compared and the ability of the model to describe the measured behaviour of stages 1 and 2 of the Gloucester test embankment is studied. This paper explores the implications of modelling the residual or restructured properties of the Gloucester foundation soil and demonstrates the ability of a single elastoviscoplastic yield-surface model to describe the undrained and drained response of the Gloucester foundation soil during laboratory and field loading conditions.Key words: elliptical cap, rate sensitive, elastoviscoplasticity, embankment settlements, pore pressures, field performance.

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