Identification of the model of nonlinear viscoelasticity of filled polymer materials in millisecond time range

Bykov, Dmitry A.; Казаков, А. В.; Коновалов, Д. Н.; Mel’nikov, V. P.; Осавчук, А. Н.; Peleshko, V. A.

doi:10.3103/s0025654412060052

Cited by 7 publications

(12 citation statements)

References 7 publications

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“…The linear model correctly describes the active segment of loading but significantly overestimates the speed of the hammer reverse motion or, in other words, overstimates the material rigidity on the passive segment of loading. A similar result was obtained in [17] (for a different HFPM). Moreover, the linear model leads to the same results for the first and successive equal loadings if the interval between them significantly exceeds the greatest τ n in the functionR(t).…”

Section: Axial Shock Compressionsupporting

confidence: 87%

“…The scheme of finite-element modeling of the process of the hammer fall on the specimen was described in detail in [17]. The axially symmetric dynamic problem of viscoelasticity in geometrically nonlinear statement was solved using a simplified version of model (2.1)-(2.6), where…”

Section: Axial Shock Compressionmentioning

confidence: 99%

“…The other coefficientsR 1 ,R 2 , andR 3 are determined from the condition of the best description of the experimental dependence v(t) on the active segment (i.e., before the moment of beginning of the reverse motion of the hammer at which the function v(t) changes its sign) in the first loading of the specimen d1. The genetic algorithm for minimizing the discrepancy (for details, see [17]) is used to obtain several setsR 1 ,R 2 ,R 3 , which are close to the valuesR 1 =R 2 =R 3 = 0.2 MPa and are taken as the solution of the problem of identification of the functionR(t).…”

Section: Axial Shock Compressionmentioning

confidence: 99%

“…In [16], the tensor generalization of the model [15] was carried out (in incremental form) and a method for solving the initial boundaryvalue problems was proposed, implemented in software, and tested by finite-element computations of geometrically nonlinear deformation and local fracture of bodies with strongly inhomogeneous stress state. The dynamical version of the model [15] was used in [17] to solve the problem of shock compression for a cylinder. A generalization of the model [15] to the loading processes with long rests and the change of the deformation direction was presented in [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…A generalization of the model [15] to the loading processes with long rests and the change of the deformation direction was presented in [18,19]. One possible application of the theory [15][16][17][18][19] can be the study of conjugate problems of modeling of intraballistic characteristics of solid-propellant rocket engines, because the solid propellant is in fact a HFPM. In such problems, the accuracy of the predicted result is mainly determined by the reliability of the mechanical model used to calculate the charge strain state at the beginning and during the operation of the engine [20].…”

Section: Introductionmentioning

confidence: 99%

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Law of damage accumulation and fracture criteria in highly filled polymer materials

et al. 2014

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We present the results of a large series of experiments aimed at the study of laws of damage accumulation and fracture in highly filled polymer materials under loading conditions of various types: monotone, repeated, low-and high-cycle, with varying type of stress state, dynamic (in general, more than 50 programs implemented on specimens from one lot of material). The data obtained in these test allow one to make conclusions about the constitutive role of the attained maximum of strain intensity when estimating the accumulated damage in the process of uniaxial tension by various programs (in particular, an additional cyclic deformation below the preliminary attained strain maximum does not affect the limit values of strain and stress in the subsequent active extension), about the strong influence of the stress state on the deformation and fracture, about the specific features of the nonlinear behavior of the material under the shock loading conditions and its influence on the repeated deformation. All tests are described (with an accuracy acceptable in practical calculations, both with respect to stresses and strains in the process of loading and at the moment of fracture) in the framework of the same model of nonlinear viscoelasticity with the same set of constants. The constants of the proposed model are calculated according to a relatively simple algorithm by using the results of standard uniaxial tension tests with constant values of the strain rate and hydrostatic pressure (each test for 2-3 levels of these parameters chosen from the ranges proposed in applications, each loading lasts until the fracture occurs, and one of the tests contains an intermediate interval of total loading and repeated loading) and one axial shock compression test if there are dynamic problems in the applications. The model is based on the use of the criterion fracture parameter which, in the class of proportional loading processes, is the sum of partial increments of the strain intensity on active segments of the process (where the strain intensity is at its historical maximum) with the form of the stress state and the intensity of strain rates taken into account.

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Section: Axial Shock Compressionsupporting

confidence: 87%

Section: Axial Shock Compressionmentioning

confidence: 99%

Section: Axial Shock Compressionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Law of damage accumulation and fracture criteria in highly filled polymer materials

et al. 2014

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Identification of the relaxation kernel in diffusion processes and viscoelasticity with memory via deconvolution

Pandolfi

2016

Math Methods in App Sciences

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We present an algorithm for the identification of the relaxation kernel in the theory of diffusion systems with memory (or of viscoelasticity), which is linear, in the sense that we propose a linear Volterra integral equation of convolution type whose solution is the relaxation kernel. The algorithm is based on the observation of the flux through a part of the boundary of a body. The identification of the relaxation kernel is ill posed, as we should expect from an inverse problem. In fact, we shall see that it is mildly ill posed, precisely as the deconvolution problem which has to be solved in the algorithm we propose. Copyright © 2016 John Wiley & Sons, Ltd.

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Dynamical Algorithms for Identification Problems

Pandolfi

2021

Systems With Persistent Memory

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Identification of the model of nonlinear viscoelasticity of filled polymer materials in millisecond time range

Cited by 7 publications

References 7 publications

Law of damage accumulation and fracture criteria in highly filled polymer materials

Law of damage accumulation and fracture criteria in highly filled polymer materials

Identification of the relaxation kernel in diffusion processes and viscoelasticity with memory via deconvolution

Dynamical Algorithms for Identification Problems

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