Principal Stress Rotation: A Missing Parameter

Arthur, J. R. F.; C., Juan I. Rodriguez del; Dunstan, T.; Chua, Ken S.

doi:10.1061/ajgeb6.0000946

Cited by 85 publications

(13 citation statements)

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“…Drescher & de Josselin de Jong (1972) carried out an experimental micro-mechanical study using a photoelastic disc assembly as a two-dimensional analogue of granular media and presented further experimental evidence for non-coaxiality. In addition, other researchers have also observed that the direction of the principal stress deviates from that of the principal strain increment under rotation of the principal stress axes (Arthur et al 1980;Gutierrez et al 1991;Joer et al 1998). These all point to the fact that the plastic behaviour of granular material is generally non-coaxial when subjected to stress rotations.…”

Section: Introductionmentioning

confidence: 90%

On a class of non-coaxial plasticity models for granular soils

Yuan

2005

Proc. R. Soc. A.

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The non-coaxiality of the directions of principal stresses and principal plastic strain rates in granular soils under stress rotations has long been observed and recognized in soil tests using both simple shear and hollow cylinder apparatuses. A few constitutive theories have also been proposed in the literature to account for the effect of stress rotations and the subsequent non-coaxial soil behaviour, particularly in the context of shear band analysis. However, the lack of corresponding general numerical methods makes it difficult to investigate the influence of non-coaxial stress–strain behaviour on the results of geotechnical boundary value problems. This paper presents a numerical evaluation of a class of non-coaxial, elastic–plastic models that are developed by combining the conventional plastic potential theory and the double shearing theory. The general non-coaxial constitutive theories are first formulated and then a finite element implementation of the theories is carried out. To evaluate the non-coaxial theories, the problem of simple shear of soils is chosen to investigate the predicted behaviour of soils under simple shear loading conditions where the axes of principal stresses rotate. In particular, the influence of initial stress states and the degree of non-coaxiality are examined. It is found that the numerical results predicted using the non-coaxial model are in general agreement with the experimental observations reported in the literature.

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Section: Introductionmentioning

confidence: 90%

On a class of non-coaxial plasticity models for granular soils

Yuan

2005

Proc. R. Soc. A.

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“…The fabric tensor and load-carrying direction are combined to define dilatancy state lines, from which a state parameter called the dilatancy state parameter is derived to quantify the void cell system's contracting and dilation strain trends [38,44]. These strain trends have been studied in a variety of anisotropic critical state theory models [45], with the results indicating that dilatancy is significantly impacted by the direction of the load, with the stress and volume change being analyzed in principal stress trajectories [46,47].…”

Section: Introductionmentioning

confidence: 99%

Flexural Models for Vacuum-Packed Particles as a Variable-Stiffness Mechanism in Smart Structures

et al. 2022

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Vacuum-packed particle (VPP) systems have been recently used in the development of smart structures due to their ability to actively change material stiffness through the mechanism of granular jamming. By altering the strength of the vacuum pressure applied to the particles, the material can be proportionally and reversibly transitioned from a liquidlike low-stiffness state to a stiff state. The ability to control material stiffness in this way opens up different possibilities for the design of morphing and smart structures by allowing them to soften during deformation to reduce actuation energy requirements and to then stiffen once the desired shape has been achieved to provide a zero-energy holding mechanism. The following research describes two useful models that predict the mechanical response of VPP beams under flexural loading. Firstly, four-point bending tests with digital image correlation strain mapping are performed in order to measure the axial and transverse strains in a bending beam made from vacuum-packed particles. The test results show a nonlinear mechanical response, including a change in beam thickness with deformation, that motivated an analytical model of the structure incorporating a nonlinear material stress model based on the Mohr-Coulomb failure envelope. In addition, finite-element simulations are implemented using a Johnson-Cook model extension to predict the response under loading of three-dimensional beam elements at different vacuum pressure levels. Lastly, the models are compared to the experimental results, indicating good agreement. Both methods are shown to be useful for predicting the variation of stiffness of vacuum-packed particle beams.

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“…Soil is often subjected to 3D loading involving changes in both principal stress value and orientation under natural and engineering conditions. However, due to limitations in testing capability, the mechanical behaviour of soil is often evaluated under grossly simplified conditions, where the principal stress orientation is fixed in triaxial tests [Nakata et al, 1998] or rotated in a fixed plane in hollow cylinder torsional (HCT) shear tests [Arthur et al, 1980]. While these type of tests have provided valuable information for the advancement of soil mechanics, the representativeness of such an approach for real world 3D conditions needs to be assessed.…”

Section: Introductionmentioning

confidence: 99%

Response of granular material under combined principal stress value and orientation change in 3D space

He¹,

Xue²,

Wang³

et al. 2022

Open Geomechanics

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Laboratory tests on soil adopt simplified stress paths compared to real world counterparts due to mechanical limitations. This study investigates the deformation of granular material under combined principal stress value and orientation change in full 3D space using the discrete element method. Such stress paths are achieved by applying a 3D force line boundary condition on spherical granular material samples. Continuous cyclic tests with stress paths restricted in a fixed plane and in full 3D space, simulating a bidirectional seismic stress path, are both conducted. The importance of taking both principal stress value and orientation change into consideration is highlighted. In the tests, the greatest deformation is observed under pure stress orientation change, while the smallest deformation is observed when the principal stress axes are fixed. The change of stress value and orientation in 3D is also shown to result in deformations different to those within a fixed plane. The origins of these differences are found to be associated with difference in shear modulus, dilatancy, and noncoaxiality at the macroscale, and particle contact and fabric anisotropy at the microscale.

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Principal Stress Rotation: A Missing Parameter

Cited by 85 publications

References 0 publications

On a class of non-coaxial plasticity models for granular soils

On a class of non-coaxial plasticity models for granular soils

Flexural Models for Vacuum-Packed Particles as a Variable-Stiffness Mechanism in Smart Structures

Response of granular material under combined principal stress value and orientation change in 3D space

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