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|Jazyk zpracování závěrečné práce:||anglický jazyk|
Části práce s odloženým zveřejněním:
|Název práce:||Rheology. Visco-Elastic and Visco-Elasto-Plastic Modelling |
|Abstrakt:||This habilitation thesis deals with rheology. It presents recent investigation results in this field. Theoretical aspects of rheology are introduced, viscoelasticity with all needed theoretical aspects is elaborated in more detail. The explanation proceeds from the very basic phenomena through more complex ones up to the practical utilization. The interconnections among particular phenomena are provided. Though the rheological materials behave non-linearly, the rheologists found and still are looking for more tools for describing their behaviour as precisely as possible. It is demonstrated in the thesis that each rheological material as soft material or Non-Newtonian _uid can be represented by a rheological model. This model consists of basic elements (atomic members) arranged in some geometric con_guration. Several members of each type can be involved in the model. This con_guration together with physical relations of atomic members then determines uniquely global constitutive relation, i.e. relation between the deformation and stress of entire model. Nevertheless, it is a very hard task to contrive of the well matching model to some type of material. The _rst question is, how the con_guration should look like and the second one, even if the con_guration is given, what are the material properties of the elementary members. And for this sake the deeper investigation in the viscoelasticity theory arose. Let us recall that linear viscoelasticity is supposed where the principle of superposition is valid. These investigations revealed very nice connection among particular phenomena and target in practical utilization.
As an example of important phenomena, the time dependent material characteristics which are gained during the creep and relaxation tests, can be mentioned . They enable further categorizing of viscoelastic materials.
For the sake of explicit expression of the physical relations, the hereditary integrals are employed.
Time relaxation and time retardation spectra are related to some speci_c con_guration which are tied up reciprocally with roots of characteristic equation related to the linear ordinary di_erential equation that stands as the constitutive equation within the particular load test. These retardation and relaxation time spectra then appear in Prony series. As the Prony coe_cients can be stipulated during lab test, we can say that the Prony series is the connection between theory and lab measurements. A lot of utilization is recorded in polymer science and material science at all.
As a very practical tool alongside the viscoelastic handling the conditional sti_ness has been approved. For more complex rheological model, where the establishing of the base constitutive relation need a lot of tedious work, the algoritmization of computation is very e_ective, we can say algoritmization is inevitable.
Alongside the thesis, applications either elaborated or just brie_y mentioned, are added as to document of some theoretical items. Plasticity with brief theory employing the variation inequalities, together with an application is involved.
|Klíčová slova:||Rheological model, conditional stiffness, constitutive equations|
|–||Závěrečná práce (přílohy závěrečné práce) neomezeně|
|–||Posudky závěrečné práce neomezeně|