The possibility of reiterated plastic flow at the overall unloading of an elastoplastic medium

Буренин, А. В.; Kovtanyuk, L. V.; Polonik, Marina V.

doi:10.1134/1.1342452

Cited by 24 publications

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“…It is well known [1][2][3][4][5] that, in the unloading process, the plastic flow can arise at a significant level of the loading pressure p. Here we consider the case without such an effect; i.e., in the unloading process there remain two domains, the domain r 0 ≤ r ≤ r 1 (t 1 ) = r 1 = const, where the accumulated irreversible strains remain unchanged, and the domain r 1 ≤ r ≤ R 0 , where there are no irreversible strains.…”

Section: Unloading Processmentioning

confidence: 99%

“…One-dimensional problems on the onset of residual stress fields near degenerate medium inhomogeneities were earlier considered in [1][2][3][4][5]. The paper [2], where the same problem is actually considered in the framework of the Prandtl-Reuss model of elastoplastic medium, i.e., without taking into account the viscous properties of the medium, is most closely related to the present publication.…”

Section: Introductionmentioning

confidence: 99%

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Irreversible deformation with subsequent unloading of a spherical viscoelastoplastic layer

2014

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Analytic solutions are obtained for a sequence of one-dimensional quasistatic problems describing viscoelastic deformation processes in the material of a hollow ball and the plastic flow nucleation and evolution processes occurring in the ball as the pressure on the outer boundary increases. The unloading process under slow removal of the loading pressure is considered as well. The stress fields and the elastic and plastic strain fields in the spherical layer material, the law of motion of the elastoplastic boundary, and the residual stress level and distribution are computed. It is assumed that at the stage preceding the plastic flow the material obeys the viscoelastic Voigt model and the loading surface is determined by the von Mises plastic flow condition.

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Section: Unloading Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Irreversible deformation with subsequent unloading of a spherical viscoelastoplastic layer

2014

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“…Актуальность данной задачи обусловлена обнаруженным на опыте эффектом существенного повышения эксплуатационных характеристик металла при интенсивном всестороннем сжатии образцов [1] «залечивания» микродефектов сплошности. Попытки смоделировать процесс залечивания микропоры в металле делались неоднократно, в том числе и на основе модели больших упругопластических деформаций [2], обладающей эффектом приспосабливаемости к периодическим нагружениям по циклу «нагрузка -разгрузка» [3].…”

Section: Introductionunclassified

The Loading Parameters Calculation of a Hollow Sphere at the Large Elastocreep Deformations

Murashkin¹

2014

MMI

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Предложена модель больших упругоползучих деформаций. Разделение тензора полных деформаций альманси определяется уравнениями изменения обратимой и необратимой его составляющих. Рассмотрено сферически симметричное деформирование полого шара в процессе установившейся ползучести. Получена разрешающая система уравнений рассматриваемой краевой задачи. Предложен способ определения нагружающего усилия вызывающего заданное деформированное состояние. По заданным законам изменения поля перемещений построены функции внешнего нагружающего усилия.

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“…The monotonic function h(t), defined for t t 1 , is such that h(t 1 ) = 0 and h(t) > 0. In the case where p 1 is large enough, the unloading process can initiate new plastic flow [4] because the stress state on the boundary of the defect reaches the loading surface (1.5) under tensile internal forces [σ θθ = 2K at r = s(t)]. Let us consider this in a more general case.…”

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confidence: 96%

On the Residual Stresses in the Vicinity of a Cylindrical Discontinuity in a Viscoelastoplastic Material

Буренин

Kovtanyuk

Murashkin

2006

J Appl Mech Tech Phys

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The one-dimensional deformation of a material and subsequent unloading in the vicinity of a single cylindrical discontinuity is calculated using the theory of large viscoelastoplastic strains. Emphasis is on the formation of a residual stress field during the loading-unloading process and the effect of the viscous properties of the material on the level and distribution of these stresses. A comparison is performed with results of solution of the corresponding problem using the theory of large elastoplastic strains.Introduction. The formation of a residual stress field in the vicinity of a cylindrical discontinuity has been previously considered for the model of large elastoplastic strains [1]. It turned out that the assumption of an ideal nature of plastic flow and allowance for only the elastic properties of the material during its deformation before plastic flow and during unloading are responsible for the adjustability of the defect to cyclic loads. In other words, irreversible strains near the defect are not accumulated with increase in the number of cycles, and residual stresses in its vicinity remain unchanged after each unloading. It is obvious that allowance for the viscous properties of the material during its irreversible deformation leads to the deceleration of plastic flow and, hence, to the development of a discontinuity. The rate of discontinuity development is the main factor that determines the fatigue strength of the article working under cyclic loads. The manifestation of viscous properties in the deformation stage preceding plastic flow or in the unloading stage is less obvious. Below, we consider exactly this case, assuming, as in [1], that the plastic flow is ideal. We note that the displacements of points of the medium being deformed in the vicinity of the discontinuity are commensurable with the defect size; therefore the assumption of small strains cannot be used. In the vicinity of the discontinuity they are always larger.1. Basic Modeling Relations. One of the goals of the present study is to compare the results obtained with the results of solution of the problem in question for the model of an ideal elastoplastic medium. As noted above, this problem is considered in [1] using the model of large elastoplastic strains proposed in [2]. Therefore, the given mathematical model is chosen as the basis for the construction of further modeling relations. In [2], the splitting of the total Almansi strains d ij into the reversible component e ij and irreversible component p ij is based on the requirement that the components of the latter vary during unloading in a similar manner as in the case of rigid body motion. Therefore, we define the components of the total Almansi strains using the equations of their transfer [3]: dp ij dt = ε p ij − ε p ik p kj − p ik ε p kj + r ik p kj − p ik r kj ,

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The possibility of reiterated plastic flow at the overall unloading of an elastoplastic medium

Cited by 24 publications

References 0 publications

Irreversible deformation with subsequent unloading of a spherical viscoelastoplastic layer

Irreversible deformation with subsequent unloading of a spherical viscoelastoplastic layer

The Loading Parameters Calculation of a Hollow Sphere at the Large Elastocreep Deformations

On the Residual Stresses in the Vicinity of a Cylindrical Discontinuity in a Viscoelastoplastic Material

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