Determination of the anelastic modulus for several metals

Alexopoulos, P.; Cho, C.W.; Hu, Chong; Li, Che‐Yu

doi:10.1016/0001-6160(81)90138-3

Cited by 18 publications

(7 citation statements)

References 5 publications

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“…8) in which C h00 is the average dislocation contrast factor for the (h00) reflection, q is a parameter that depends on the edge or screw character of dislocations and H 2 ¼ (h 2 k 2 þ h 2 l 2 þ k 2 l 2 )/(h 2 þ k 2 þ l 2 ) 2 . The value of C h00 and theoretical values of q, for either edge or screw dislocations, can be determined based on the elastic constants of the material and the active slip systems, and are therefore known values [12,32].…”

Section: Discussionmentioning

confidence: 99%

“…After plastic deformation and during unloading, the mobile dislocations move in the reverse direction, so similar mechanisms as those occurring in the pre-yield regime (with an increased dislocation density) are expected to reverse the anelastic strain, and lead to the springback phenomenon. Anelastic strain, as it is defined here, is related to the dislocations' subcritical bowing during loading and reversible bowing during unloading [8,9], which are essentially time independent at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Quantification of dislocation structures from anelastic deformation behaviour

2016

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a b s t r a c tThe pre-yield deformation behaviour (i.e., at stresses below the yield stress) of two materials, pure iron and a low-alloy steel, and its anelastic nature are analysed at room temperature, before and after the dislocation structures are varied by plastic deformation. It is shown, based on tensile experiments, that this behaviour can be explained by limited reversible glide of dislocations without essential changes in the dislocation structure. Moreover, a physically-based model that characterises the dislocation structure by two variables, the dislocation density and the effective dislocation segment length, is used to quantitatively describe this deformation behaviour. The model validity is further evaluated by comparison with dislocation densities from X-Ray Diffraction measurements.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantification of dislocation structures from anelastic deformation behaviour

2016

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“…They used a free-free beam resonant method to measure the anelasticity at a frequency of 17 kHz. Alexopoulos et al (5) measured the anelastic modulus for several metals, including aluminium, austenitic stainless steel and pressure vessel steel. T%ey measurdhysteresis loops using a high-precision tensile test arrangement, and their values for strain hysteresis are in the order of 50 microstrain at maximum stresses as high as the yield stresses.…”

Section: Theorymentioning

confidence: 99%

Mechanical Hysteresis in Force Transducers Manufactured from Precipitation-Hardened Stainless Steel

Allgeier

Evans

1995

Proceedings of the Institution of Mechanical Engineers, Part C:

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A non-linear, anelastic stress-strain relationship, hereafter called mechanical hysteresis, which leads to a signiJ5cant error in the output signal of electrical resistance strain gauge force transducers, has been confirmed to be a general phenomena in precipitation-hardened stainless steels. The mechanism of mechanical hysteresis has been found to be due to the material behaviour; nevertheless, the design of the force transducer and details of the electrical resistance strain gauges could imposefurther minor eflects on the size of the error. Some of the secondary influencing factors Vor example loading and mounting details) have been eliminated in the course of the investigation.Using a specially developed heat treatment process, it has been possible to substantially reduce the hysteresis error, which in turn improves the force transducer accuracy.

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“…The results reported in this article are from an experimental program designed to determine if the quality of the mechanical data obtainable from presently available high-pressure deformation apparatus is sufficient to permit inelastic flow laws which incorporate deformation history dependence to be evaluated for geological materials at elevated confining pressures. The description of inelastic deformation developed by Hart and coworkers (describing successive developments [e.g., Hart, 1970Hart, , 1976Hart et al, 1975;Li, 1981;Korhonen et al, 1987]) was chosen for investigation. This description has been applied successfully to the results of room pressure experiments on a wide range of metals, ceramics, and simple ionic solids.…”

Section: Introductionmentioning

confidence: 99%

“…This may be determined from stress dip tests [e.g., Nir et al, 1977] or, as described here, from constant displacement rate tests at stresses below the yield point [e.g.,Alexopoulos et al, 1981]. The initial part of (e(0, o) curve generated in constant displacement rate tests is commonly divided with increasing stress into (1) a linear elastic part upto the elastic limit, (2) a linear anelastic part between the elastic and anelastic limits, (3) a nonlinear microplastic part between the anelastic limit and the macroscopic yield point, and (4) a macroplastic part beyond the macroscopic yield stress[Alexopoulos et al, 1981]. The microplastic region (which is accounted for only in refined versions of Hart's model [e.g., Jackson et al, 1981]) accommodates the small amount of permanent strain that accumulates prior to macroscopic yielding.…”

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confidence: 99%

The application of Hart's state variable description of inelastic deformation to Carrara marble at T < 450°C

Covey-Crump¹

1994

J. Geophys. Res.

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An attempt has been made to determine if the material parameters in constitutive equations for inelastic deformation which fully accommodate the deformation history dependence of inelastic properties can be evaluated with sufficient accuracy at elevated confining pressures for such equations to be of interest in characterizing geological materials. Accordingly, a large number of constant displacement rate and load relaxation experiments (or variants thereof) have been conducted on Carrara marble at 200 MPa confining pressure in the temperature range 120 to 400°C, and the results have been interpreted in terms of Hart's state variable description of inelastic deformation. The observed mechanical behavior conforms to Hart's description, with a changeover at about 250°C from deformation rate controlled by dislocation glide controlled processes (as represented by concave upward () load relaxation curves), to rate control by strongly thermally activated processes (as represented by concave downward relaxation curves). All relaxation curves generated at a given temperature may be superposed by a translation in fixed direction in the () plane. This defines a master relaxation curve which represents what any individual relaxation curve would look like if it could be determined over a sufficiently wide range of strain rates. For Concave downward relaxation curves the master curve extends over 9 orders of magnitude of strain rate and, in consequence, substantially eases the problem of extrapolating the laboratory data to geological strain rates. The success of Hart's description in accounting for the mechanical behavior means that it is possible to avoid the steady state approximation both in the experimental evaluation of inelastic flow laws and in the application of those flow laws in geophysical modeling problems. Moreover, it provides a simple method of quantifying the mechanical state of a material and thereby is of potential significance for the problem of correlating microstructural observations with mechanical properties.

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Determination of the anelastic modulus for several metals

Cited by 18 publications

References 5 publications

Quantification of dislocation structures from anelastic deformation behaviour

Quantification of dislocation structures from anelastic deformation behaviour

Mechanical Hysteresis in Force Transducers Manufactured from Precipitation-Hardened Stainless Steel

The application of Hart's state variable description of inelastic deformation to Carrara marble at T < 450°C

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