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1
Content available remote Analysis of special granular structures response on the external loading
EN
This paper concerns problems related to complex response of Special Granular Structures (SGS) on applied external loading. Typical experimental results acquired from uniaxial compression tests are presented. For the most part influences of underpressure and strain rate are discussed. Universal dependencies between determined Young modulus values and underpressures and proof stresses vs. underpressures are introduced. Finally complex behavior of SGS is analyzed basing on experimentally obtained surfaces: E=f(V,p) and k=(V,p).
PL
Niniejsza praca jest kolejnym etapem rozważań dotyczących struktur "semiinteligentnych", zbudowanych na bazie materiałów granulowanych. Omówiono możliwość zastosowania typowych równań konstytutywnych, zbudowanych dla metali do opisu zachowania granulowanych konglomeratów poza zakresem ich sprężystych odkształceń. Dwa typowe modele lepkoplastyczne (Bodnera-Partoma oraz Chaboche'a) zostały zidentyfikowane na podstawie otrzymanych wyników badań eksperymentalnych.
EN
Presented work is the next stage of considerations related to innovative semi-inteligent structures composed on the basis of granular materials. Loose granular material is initially placed in a hermetic plastomer envelope, where in the next step so called "underpressure" is generated. Such a treatment causes a nonlinear increase of "intermolecular" friction forces and in consequences to visible stiffening of the whole structure. In the paper typical experimental results carried on cylindrical samples of special granular structures are presented. Application of typical viscoplastic models for metals to description of special granular structures behavior over elastic range of deformations is discussed. Two typical viscoplastic constitutive models (Bodner-Partom and Chaboche) have been identified basing on acquired experimental data. Conducted numerical simulations confirmed correctness of the models response.
3
Content available remote Rheological Model Proposition for Granular Structures in Special Conditions
EN
The present work mainly focuses on modeling of the mechanical properties of Special Granular Structures (SGS). SGS are structures composed on the basis of loose granular materials encapsulated in a hermetic space. Initially such a material behaves like a traditional plastic mass. When the internal pressure is pumped out of the system, what was baggy bulk transforms into solid (semisolid) state. In some aspects SGS are comparable to MR fluids. Typical rheological model, describing MR fluids and devices working on the basis of it, is adopted to describe cyclic loading experimental results of specially performed SGS testing specimen. In the final part of the paper some numerical results are presented.
EN
This work concerns the results of the experimental research of a magneto-rheological damper. Using a special testing stand and a damper prototype with exchangeable piston, a set of damping characteristics were obtained. Experimental results where compared with computer simulations. Results have been discussed and presented in suitable figures. The comparison of damper characteristics has been made. General problems related to the impact of selected constructional and operating parameters have been introduced.
5
EN
In presented paper a new proposition of granular structure, composed on the basis of granular materials placed in hermetic space with underpressure, as a damping material for vibrated steel beam has been described. Three different types of laboratory tests have been described: fundamental strength properties of granular testing specimen, bending of granular beam and damping of the steel beam vibrations using special granular structures. Obtained results revealed that the behavior of such a structure could be easily controlled by underpressure parameter. Also damping characteristics of vibrated steel beam could be controlled by changing internal underpressure value.
PL
W artykule zaprezentowano zastosowanie struktury, zbudowanej na bazie luźnego granulatu umieszczonego w szczelnej przestrzeni z podciśnieniem, do tłumienia drgań belki stalowej. Omówiono trzy typy badań eksperymentalnych: podstawowe badania wytrzymałościowe próbki struktury granulowanej, badania zginania belek granulowanych oraz badania tłumienia drgań belki stalowej za pomocą wspomnianych materiałów. Wyniki przeprowadzonych eksperymentów jednoznacznie potwierdzają możliwość wpływania na parametry fizyczne granulowanych konglomeratów za pomocą parametru podciśnienia i tym samym na postacie charakterystyk tłumienia drgań swobodnych belki stalowej.
EN
Presented paper is an initial probe of adaptation of the new "smart" structures, built on the basis of a loose material, encapsulated in a thigh sleeve, where in the next stage, so called underpressure has been generated, for the active (semi-active) damping of vibrations.
PL
Głównym celem niniejszej pracy jest oszacowanie wpływu zastosowanego granulatu na wielkości naprężeń lepkich, będących skutkiem rozciągania specjalnie przygotowanych próbek struktur, utworzonych z materiałów granulowanych, umieszczonych w szczelnej przestrzeni z podciśnieniem.
EN
The main objective of a currently discussed paper is evaluation of applied granular material kind on values of a viscous stress which is resulting from deformation (elongation) of specially performed granular specimens, built basing on a loose material enclosed in a tight space with underpressure.
EN
Presented work concerns problems connected with a new "smart material". It is a granular structure, built basing on a loose material, placed in a tight encapsulation, where in a next stage so called underpressure has been generated. The main aim of this paper is to establish the general dependence between grain's material and an elastic range of deformations (proof stress), in uniaxial experiments, of specially performed granular samples, for a wide range of applied underpressure values.
EN
Presented work concerns problems connected with a new "smart structure". It is a granular structure, built basing on a loose material, placed in a tight encapsulation, where in a next stage so called underpressure has been generated. The main objective of this paper is to establish the general dependence between grain's material and stiffness (Young modulus) values, for a wide range of applied underpressures.
EN
Presented paper concerns problems connected with evaluation of the influence of a kind of granular materials on the isotropic hardening function parameters. All presented results are obtained form uniaxial compression probes on specially presented granular specimen.
EN
A new "smart structure", based on granular materials encapsulated in an elastic envelope, is proposed and investigated in the paper. Fundamental mechanical properties of the specially prepared granular testing specimens are described by the viscoplastic constitutive Chaboche's model. The experimental results of uniaxial tests are presented and applied to the identification of parameters of the Chaboche's law. The proposed procedure of material parameters estimation is based on evolutionary algorithms, solving corresponding optimization problem. The efficiency of the approach and the quality of the results are discussed.
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