Yielding and Flow of Sand in Triaxial Compression: Parts II and III

1967 ◽  
Vol 4 (4) ◽  
pp. 376-397 ◽  
Author(s):  
H B Poorooshasb ◽  
I Holubec ◽  
A N Sherbourne
Keyword(s):  
Plastic Strain ◽  
Experimental Evidence ◽  
Potential Function ◽  
Triaxial Compression ◽  
Strain Increment ◽  
Flow Rule ◽  
Plastic Strain Increment ◽  
Yield Loci

In Part I,* based on experimental evidence, the existence of a potential function to define the gradient of the plastic strain increment vector was proved. The study is continued in Part II by defining the term yielding, a discussion of the form of the yield loci and a presentation of the “flow rule.”

Non-Coaxial Plasticity Constitutive Modeling of Sands

2013 ◽  
Vol 684 ◽  
pp. 150-153 ◽  
Author(s):  
Ping Hu ◽  
Mao Song Huang ◽  
Deng Gao Wu
Keyword(s):  
Plastic Strain ◽  
Constitutive Model ◽  
Principal Stress ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Strain Increment ◽  
Stress Axis ◽  
Shear Tests ◽  
Plastic Strain Increment ◽  
Principal Axes

Classical coaxial plasticity constitutive models implicate an inevitable limitation that directions for principal stress and that for principal plastic strain increment are always coaxial. They are not capable of simulating non-coaxial phenomena during the rotation of principal stress axis. In this paper, a three-dimensional, non-coaxial plasticity constitutive model for sands with a modification of Lade angle dependent shape function is introduced to describe the non-coaxial behavior under principal axes rotation. A series of numerical simulations of hollow cylindrical torsional shear tests are performed. The results show that the proposed constitutive model can predict the variations of principal plastic strain increment directions with principal stress directions reasonably.

scholarly journals Large-Scale Triaxial Tests on Dilatancy Characteristics of Lean Cemented Sand and Gravel

2021 ◽  
Vol 9 ◽  
Author(s):  
Hang Yu ◽  
Xue-mei Shen ◽  
Yu-chen Ye ◽  
Jie Yang ◽  
Chen-hui Zhu
Keyword(s):  
Plastic Strain ◽  
Strain Increment ◽  
Triaxial Tests ◽  
Volume Strain ◽  
Triaxial Loading ◽  
Cemented Sand ◽  
Plastic Strain Increment ◽  
Loading And Unloading ◽  
Sand And Gravel ◽  
Increment Ratio

The dilatancy equation, which describes the plastic strain increment ratio and its dependence on the stress state, is an important component of the elastoplastic constitutive model of geotechnical materials. In order to reveal their differences of the dilatancy value determined by the total volume strain increment ratio and the real value of lean cemented sand and gravel (LCSG) materials, in this study, a series of triaxial compression tests, equiaxial loading and unloading tests, and triaxial loading and unloading tests are conducted under different cement contents and confining pressures. The results reveal that hysteretic loops appear in the stress–strain curves of equiaxial loading and unloading tests, and triaxial loading and unloading tests and that the elastic strain is an important component of the total strain. The hysteretic loop size increases with an increase in the stress level or consolidation stress, whereas the shape remains unchanged. Furthermore, with an increase in the cement content, the dilatancy value determined by the total volume strain increment ratio becomes smaller than that determined by the plastic strain increment ratio, and the influence of the elastic deformation cannot be ignored. Thus, in practical engineering scenarios, especially in the calculation of LCSG dam structures, the dilatancy equation of LCSG materials should be expressed by the plastic strain increment ratio, rather than the total volume strain increment rati.

A yield equation for rock

1986 ◽  
Vol 23 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Paul Michelis ◽  
E. T. Brown
Keyword(s):  
Plastic Strain ◽  
Work Hardening ◽  
Triaxial Compression ◽  
Flow Rule ◽  
Work Softening ◽  
Strain Behaviour ◽  
Strain Invariant ◽  
Energy Dissipated ◽  
Extensive Experimental Data ◽  
Work Done

A yield equation for isotropic, homogeneous, geotechnical materials has been developed and applied to the work-softening and work-hardening behaviour of granular rocks. The development of this yield equation was based on a comparison of the work done and the energy dissipated within a sample undergoing yield in triaxial compression. The formulation takes into account friction and dilatancy and also an experimental observation leading to the derivation of a nonassociated flow rule. The analysis of extensive experimental data indicates that the flow rule is consistent for work-softening and -hardening behaviour, and validates the application of the incremental theory of plasticity to the irrecoverable strain behaviour of rocks in which the predominant mode of deformation is cataclastic. The yield equation, which is expressed in terms of readily indentifiable material parameters, predicts yield strength or strength at a given value of plastic strain invariant, and relates stress and strain increments at yield. Key words: rocks, yield, plastic strain, work softening, work hardening, energy, dilatancy, nonassociated flow.

Subsequent Yield Surfaces for Annealed Mild Steel Under Servo-Controlled Strain and Load Histories: Aging, Normality, Convexity, Corners, Bauschinger and Cross Effects

1975 ◽  
Vol 97 (1) ◽  
pp. 25-32 ◽  
Author(s):  
M. J. Michno ◽  
W. N. Findley
Keyword(s):  
Plastic Strain ◽  
Axial Load ◽  
Kinematic Hardening ◽  
Axial Stress ◽  
Axial Strain ◽  
Small Strain ◽  
Strain Increment ◽  
Limit Curve ◽  
Yield Curves ◽  
Plastic Strain Increment

Initial-yield results on SAE 1017 steel are presented for: four different specimens under combined axial load and twisting moment for servo controlled loading; and six different specimens under various combinations of servo controlled axial strain and shear strain. Subsequent yield curves determined by small strain offset multiple probes on a given specimen are presented covering all four quadrants of axial stress-shear stress space. The resulting families of subsequent yield curves allows conclusions to be drawn concerning the effects of plastic strain and strain aging. All curves were found to be convex and normality of the plastic strain increment vector was obeyed. The response to plastic straining allowed discussion of corner formation, translation, rotation, Bauschinger and cross effects of subsequent yield curves and formation of a limit curve. A comparison is made between the experiments and the Prager kinematic hardening model and the Ziegler modification.

Yielding and Flow of Sand in Triaxial Compression: Part I

1966 ◽  
Vol 3 (4) ◽  
pp. 179-190 ◽  
Author(s):  
H B Poorooshasb ◽  
I Holubec ◽  
A N Sherbourne
Keyword(s):  
Eigenvalue Problems ◽  
Triaxial Compression ◽  
Flow Rule ◽  
Sand Sample ◽  
Triaxial Apparatus ◽  
Plastic Potential ◽  
Constant E ◽  
The Subject ◽  
Yield Loci ◽  
Stress And Deformation

A theoretical and experimental study of the nature of deformation of a sand sample when tested in the triaxial apparatus is presented. The medium is shown to be elastic-strain hardening plastic but does not conform to certain rules usually adopted in the classical theory of plasticity. Experimental verification of an earlier suggestion by Poorooshasb (1961) leads to a proof of the existence of a potential function, known as the plastic potential, of the form Ψ(σ, e) the parameters σ representing the stress and e the voids ratio. The plastic potential curves defined by Ψ = constant, e = constant, trace a family of geometrically similar curves when plotted in a stress space. The yield loci, on the other hand, are found to be independent of voids ratio and are only functions of the ratio of the second invariant of the stress deviation tensor to the first invariant of the stress tensor. It is noted, therefore, that the plastic potential and yield surface are not coincidental. This defies the normality condition and in this respect the medium's behaviour appears to deviate from that of a classical plastic body. Although the scope of the study is limited, being applicable only to stress conditions provided in a triaxial compression test, extensions are made to incorporate stress and strain in their more general form. This is done to stimulate further research on the subject, although a fair amount of evidence is available to support, qualitatively at least, the validity of the propositions made. The paper is concluded by presenting the flow rule for the medium and discussing the application of the theory presented to the solution of equilibrium and eigenvalue problems involving stress and deformation.

Subsequent Yield Surfaces for Annealed Mild Steel Under Dead-Weight Loading: Aging, Normality, Convexity, Corners, Bauschinger, and Cross Effects

1974 ◽  
Vol 96 (1) ◽  
pp. 56-64 ◽  
Author(s):  
M. J. Michno ◽  
W. N. Findley
Keyword(s):  
Plastic Strain ◽  
Strain Aging ◽  
Strain Increment ◽  
Plastic Range ◽  
Dead Weight ◽  
Yield Curves ◽  
Plastic Strain Increment ◽  
Multiple Probe ◽  
Sharp Corners ◽  
Tubular Specimens

After initial yielding of one to five percent small-offset multiple-probe yield curves were determined under combined axial-torsion loading for six tubular specimens. Subsequent yield curves were obtained following either strain aging or loading into the plastic range. Aging and plastic straining usually resulted in smooth, convex yield curves. Occasionally well-rounded blunt corners were formed under combined tension and torsion. Subsequent curves underwent translation and changes in shape. Plastic strain increment vectors from zigzag loadings supported well-rounded blunt (not sharp) corners. Normality of plastic strain increment vectors was observed.

Plastic strain increment in low-carbon steel

2020 ◽  
Author(s):  
Y. V. Li ◽  
A. M. Nikonova ◽  
S. A. Barannikova
Keyword(s):  
Carbon Steel ◽  
Plastic Strain ◽  
Low Carbon Steel ◽  
Strain Increment ◽  
Low Carbon ◽  
Plastic Strain Increment
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