Load relaxation studies of four alkali halides

Lerner, I.; Chiang, S. W.; Kohlstedt, D. L.

doi:10.1016/0001-6160(79)90136-6

Cited by 27 publications

(6 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In load relaxation, the mechanical energy stored in the testing apparatus is allowed to dissipate through the relaxation of the specimen [Hart, 1967;Holbrook et al, 1982]; if the apparatus is stiff, this dissipation occurs at nominally constant strain for the specimen: without accumulating plastic strain, the deformation-induced microstructure cannot evolve. Using the load-relaxation approach, Hart's [1970Hart's [ , 1976 model has been amply demonstrated to describe dislocation rheology for metals [e.g., Hart and Solomon, 1973] and for nonmetals both ionic [e.g., Lerner et al, 1979;Covey-Crump, 1998;Stone et al, 2004] and covalent [e.g., Chiang and Kohlstedt, 1985].…”

Section: Introductionmentioning

confidence: 99%

Load relaxation of olivine single crystals

2016

View full text Add to dashboard Cite

Single crystals of ferromagnesian olivine (San Carlos, AZ, peridot; ~Fo88‐90) have been deformed in both uniaxial creep and load relaxation under conditions of ambient pressure, T = 1500°C and pnormalO2 = 10−10 atm; creep stresses were in the range 40 ≤ σ1 (MPa) ≤ 220. The crystals were oriented such that the applied stress was parallel to [011]c, which promotes single slip on the slowest slip system in olivine, (010)[001]. The creep rates at steady state match well the results of earlier investigators, as does the stress sensitivity (a power law exponent of n = 3.6). Dislocation microstructures, including spatial distribution of low‐angle (subgrain) boundaries, additionally confirm previous investigations. Inverted primary creep (an accelerating strain rate with an increase in stress) was observed. Load relaxation, however, produced a singular response—a single hardness curve—regardless of the magnitude of creep stress or total accumulated strain preceding relaxation. The log stress versus log strain rate data from load‐relaxation and creep experiments overlap to within experimental error. The load‐relaxation behavior is distinctly different than that described for other crystalline solids, where the flow stress is affected strongly by work hardening such that a family of distinct hardness curves is generated, which are related by a scaling function. The response of olivine for the conditions studied, we argue, indicates flow that is rate limited by dislocation glide, reflecting specifically a high intrinsic lattice resistance (Peierls stress).

show abstract

Section: Introductionmentioning

confidence: 99%

Load relaxation of olivine single crystals

2016

View full text Add to dashboard Cite

show abstract

“…The constants for rock salt are listed in Table 1. Data do exist for single crystal halide from the work done by Lerner et al (1979), Lerner & Kohlstedt (1981) and Stone et al (2004); however, this was not included in this study due to the anisotropy seen in single crystals.…”

Section: Resultsmentioning

confidence: 99%

Application of the Bammann inelasticity internal state variable constitutive model to geological materials

Sherburn¹,

Horstemeyer

Bammann

et al. 2011

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YWe describe how the Bammann internal state variable (ISV) constitutive approach, which has proven highly successful in modelling deformation processes in metals, can be applied with great benefit to silicate rocks and other geological materials in modelling their deformation dynamics. In its essence, ISV theory provides a constitutive framework to account for changing history states that arise from inelastic dissipative microstructural evolution of a polycrystalline solid. In this paper, we restrict our attention to a Bammann ISV elastic-viscoplastic model with temperature and strain rate dependence and use isotropic hardening and anisotropic hardening as our two ISVs. We show the Bammann model captures the inelastic behaviour of olivine aggregates (with and without water), lherzolite (with and without water), Carrara marble and rock salt using some experimental data found in the literature. These examples illustrate that when more experimental stress-strain data are gathered on other rock materials, much more realistic numerical simulation of rock behaviour becomes feasible. Though not available in the literature, we outline a set of experiments to obtain unique Bammann ISV model constants.

show abstract

“…Given that this has been accomplished, eq. The formalism just described has been used by several authors to interpret the mechanical behaviour of both metals and alloys [2][3][4][5][6] and ionic crystals [7,8], mainly for load-relaxation experiments. In fact, if the increment in the plastic strain is negligible during each relaxation run and no recovery is present, logz-log~ stress-relaxation curves are obtained, at essentially constant hardness (see eqs.…”

mentioning

confidence: 99%

“…(16) and (17)). Moreover, it was found in several materials [4][5][6][7] that the loga-log ~ relaxation curves, at different hardness, are related by scaling. This means that any one of the log a-log can be superposed onto any of the others by translating (h log a, 5 log ~) in such a way that the overlapping segments of each curve match within experimental error.…”

mentioning

confidence: 99%

On the plastic equation of state with one structure variable

Povolo

Fontelos

1991

Il Nuovo Cimento D

View full text Add to dashboard Cite

Summary. --The general expression for a plastic equation of state with one structure variable and with a scaling relationship is presented. It is demonstrated that this equation can be written, in general, in terms of stress, plastic strain rate and a function of plastic strain. Finally, the results are compared with previous formulations of the problem presented in the literature to show that they are particular cases of the general formalism presented.PACS 46.20 -Continuum mechanics.1. -Introduction.Hart [1] has developed the concept of the mechanical equation of state, based on the following arguments: ,(Of the three deformation variables z, ~ and ~, where z is the applied stress, s the plastic strain-rate and ~ the plastic strain, the two that are uniquely indicative of the mechanical state of the specimen are the first two, ~ and ~. If the imposed strain-rate ~ is stated, the corresponding stress z to produce ~ is a measure of the current state of the mechanical strength of the specimen. In fact, the mechanical state of the specimen at any instant is fully specified by the set of all possible pairs of values of ~ and ~ of which it is immediately capable. The situation is completely different with the plastic strain. Even when an arbitrary reference state is chosen, the plastic deformation depends on the actual deformation path rather than only on (*) The authors of this paper have agreed to not receive the proofs for correction.

show abstract

Load relaxation studies of four alkali halides

Cited by 27 publications

References 7 publications

Load relaxation of olivine single crystals

Load relaxation of olivine single crystals

Application of the Bammann inelasticity internal state variable constitutive model to geological materials

On the plastic equation of state with one structure variable

Contact Info

Product

Resources

About