Методики идентификации нелинейной модели типа Максвелла для реономных материалов по кривым обратной ползучестистатья
Статья опубликована в журнале из списка RSCI Web of Science
Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 11 апреля 2019 г.
Аннотация:А.V. Khokhlov. Identification techniques for the nonlinear Maxwell-type viscoelastoplastic model using creep recovery curves
**************************************************
SUMMARY
A physically nonlinear Maxwell-type constitutive relation for non-aging rheonomic materials is studied analytically to elucidate the set of basic rheological phenomena that it simulates, to indicate its application field, to reveal necessary phenomenological restrictions on two material functions of the relation and to develop identification techniques and ways of fitting. General properties of creep and recovery curves produced by the model with arbitrary material functions are analyzed in uni-axial case and an effective identification technique is developed based on a set of creep and recovery tests at various stress levels. The explicit formulas are derived to evaluate the material functions values at arbitrarily chosen points in stress domain via minimal set of measured magnitudes of strain. The identification technique enables direct and separate evaluation of the material functions values at a mesh points via test data without error accumulation. The technique doesn’t need any prescribed forms of approximations and any type of least square deviation minimization to determine its parameters, it doesn’t require to solve a set of non-linear equations and to use iteration or recurrent procedures.
In the case of materials exhibiting creep rate power dependence on stress, a specific rapid procedure is developed for the model identification in the class of power material functions. In this case only two creep recovery tests and four measured magnitudes of strain are needed to determine four parameters through the explicit expressions. A number of additional applicability indicators are found for the power model employing characteristic features of test stress-strain curves.
Keywords: viscoplasticity, viscoelasticity, physical non-linearity, creep rate, plastic strain, applicability indicators, identification, superplasticity, polymers