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Идентификация нелинейного определяющего соотношения Работнова по данным испытаний полиэтилена и полипропилена на ползучестьстатья
- Авторы: Стеценко Н.С., Хохлов А.В.
- Журнал: Труды МАИ
- Номер: 103
- Год издания: 2018
- Издательство: Изд-во МАИ
- Местоположение издательства: М.
- Первая страница: 1
- Последняя страница: 23
- Аннотация: The calibration technique for the Rabotnov non-linear (quasi-linear) constitutive equation is developed using a set of creep curves of the material under uni-axial loading. The constitutive equation describes rheonomic materials behavior and generalizes the linear integral relationship of viscoelasticity with an arbitrary creep function by introducing the second material function. We propose to construct isochronous creep curves using the test data, to approximate them by a number of special families of functions depending on 4-7 parameters and to select the most suitable family (the one yielding the smallest value of the relative quadratic deviation from the experimental points). As a rule, such families of functions could be chosen which permit the analytic inversion of the constitutive equation, which enable not to resort to an approximate treatment procedure and to reduce the identification error. Next a "basic" isochronous curve should be selected (its choice is related to the choice of the characteristic time scale for the test under study), and a nonlinearity function is found from it. Then, taking into account the specific features of the experimental data, the type of approximation of the creep function is chosen and its parameters are found (using the nonlinearity function found before ). The advantages of the identification technique are discussed in comparison with the traditional one. In particular, the procedure for quantitative estimation of fulfillment of the similarity condition for experimental isochronous creep curves (the necessary condition for the relation applicability) is proposed. The identification procedure was applied to polyethylene and polypropylene creep tests. High-density polyethylenes are widely used for manufacturing of water and gas supply pipes and other products, so the study of their mechanical characteristics and modeling of their behavior is of great interest. Verification of the found material functions was carried out using the creep curves that did not participate in the identification procedure, stress-strain curves with constant rate and multi-step creep tests. It is shown that the technique developed herein describes the experimental data well
- Добавил в систему: Хохлов Андрей Владимирович