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1
Content available remote Projekt mikrozrywarki do statycznych badań wytrzymałościowych
EN
This paper presents the micro-tensile machine construction designed for static strength tests, especially for carrying out the static tensile test, adapted to automatic measurements control and recording. It is a response to the increased industrial use of small components that require tensile machines with small but accurate measuring ranges of force and displacement, not only to determine material properties, but also as a quality control tool.
2
Content available remote Experimental Research on Technical Fabric of the Forest Opera Roof in Sopot
EN
The experimental analysis of the technical fabric Valmex is presented. The study involves uniaxial tensile, cyclic, rheological and biaxial tests. Some of the main differencies between two types of the analysed material have been identified. Mechanical properties of the textile have been modeled by the viscoelastic standard model with quite good effect.
3
Content available remote Viscoplastic Models for a Magnetorheological Damper
EN
This work presents the Bodner-Partom and Perzyna constitutive law to describe a dynamic behaviour of magnetorheological damper. Those laws usually used for metals, are presented here for shear stresses to express viscoplastic properties of MR fluid. We determine parameters for fluid in the damper prototype that are required for the Bodner-Partom and Perzyna models. Experimental results are later compared with numerical results.
4
Content available remote MR Fluid Analysis in a Magnetorheological Damper
EN
The main focus of this paper is the analysis of MR fluid in the damper during work. The impact of the temperature, the current intensity, the shear rate on the shear stress in MR fluid in the prototype damper during work has been described. For the investigation, a prototype of the MR damper has been manufactured and tested.
EN
This paper presents an approach to describe a dynamic behaviour of magnetorheological damper by the Bodner-Partom constitutive law. The B-P equations usually used for metals are presented for shear stresses to express viscoplastic proprieties of MR fluid. Material parameters for the B-P law for fluid in the LORD RD 1005-3 damper are determined. Experimental results are compared with numerical results.
6
Content available remote Rheological Properties of Technical Fabric
EN
This work presents a brief results comparison of two different attempts at the nonlinear characteristics of the same textile "Panama", manufactured by Sattler Company (Germany). On the basis of uniaxial tension and creep-recovery laboratory tests the rheological properties of technical fabric were identified. To describe material's nonlinear behaviour in its inelastic range constitutive relations of viscoplasticity and viscoelasticity were applied. The same procedure of the parameters identification, using the least squares method in the Levenberg-Marquardt variant, was conducted in each theory. Calculations were carried out for warp and weft threads individually, that is in two perpendicular directions of the material's weaving. Identification results were verified and compared to the experiments. Both nonlinear model representations advantageously approximate the tests' data of the examined technical fabric.
EN
This paper presents an approach to describe the dynamic behaviour of a magnetorheological (MR) damper by the Bodner-Partom (B-P) constitutive equations. The B-P equations usually used for metal materials are presented for shear stresses to express viscoplastic proprieties of a MR fluid. The material parameters for the LORD RD 1005-3 damper are determined. The experimental results are shown and are compared with the numerical results.
EN
The paper presents three methods of damage parameters identification in viscous flow conditions. Constitutive relations including damage are used according to the Chaboche and Lemaitre concept. The authors propose also their own modifications of identification algorithm. All algorithms are compared in the identification process for aluminum alloys.
9
Content available remote On Finite Element Modelling of Architectural Fabrics for Ganging Roofs
EN
This paper deals with the constitutive modelling and identification of coated woven fabrics properties. The authors give brief characterization of the constitutive models used for the material modelling and discuss in details the fundamental equations of the dense net model. The special identification method of the non-linear elastic properties of the coated fabric is presented. The material parameters are determined on the base of uniaxial tensile tests in the warp and weft directions. For the identification process, techniques using the least squares method are applied. Additionally, the results of the uniaxial tension tests are compared with biaxial tension tests.
10
Content available remote Identification of Nonlinear Viscoelastic Properties of the "Panama" Fabric
EN
Technical fabric "Panama", manufactured by Sattler Company (Germany), exhibits some nonlinear behaviour including the viscoelastic effects, during the long-term experiments. On the basis of uniaxial creep-recovery laboratory tests, conducted for five different stress levels from 10% to 50% of the ultimate force declared by the producer, an attempt on the nonlinear viscoelastic identification of the fabric properties was made. The Schapery one-integral model of nonlinear viscoelasticity was applied as the constitutive relation, describing material's behaviour in inelastic range. The power law time function was assumed to represent the transient component of the linear creep compliance. For each stress level the same procedure of the parameters identification was conducted, using the least squares method in the Levenberg-Marquardt variant. As the considered material has two thread families, warp and weft, weaved perpendicularly one to another, calculations were carried out for each thread direction individually. Results of the identification were verified and compared to the experiments' data. Good agreement between the nonlinear model representation and the tests' data of the examined technical fabric was obtained. Some remarks upon further research were included.
11
Content available remote Comparative Analysis of Dynamic Behaviour of an Elasto-Viscoplastic Truss Element
EN
Modeling of dynamic behaviour of elasto-viscoplastic structural elements is studied in the paper. The Chaboche and Bodner-Partom models have been chosen for numerical reasons among different types of existing constitutive laws. The numerical results on the vibration of a truss element illustrate the proposed method.
PL
Praca dotyczy modelowania damicznego zachowania sprężysto-lepkoplastycznych elementów konstrukcji. Spośród różnych typów znanych praw konstytutywnych wybrano ze względów numerycznych modele Chaboche'a i Bodnera-Partoma. Numeryczne przykłady drgań elementu kratowego ilustrują zastosowanie poszczególnych modeli.
EN
In the paper the problem of identification of the material parameters of the elastoviscoplastic constitutive equations is considered. A method based on the uniaxial tension tests for the Bodner - Partom law and two methods (from the tension and cyclic tests) for the Chaboche laws are presented. The parameters for both models for mild steel are directly calculated from the tension tests. Additionally, the numerical simulation of the cyclic loading tests is used for identification of the Chaboche model parameters. Results of the identification are verified in the viscoplastic analysis of vibrations of circular plates.
EN
In this paper some problems of vibrations of a cylindrical panel and circular plates under impulsive loading are considered. Different types of elasto-viscoplastic constitutive equations: the Bodner-Partom, Chaboche and Perzyna models are used. Significant differences in values of the material parameters published in the literature for different types of law are noticed. Influence of proper identification of them is studied on an example of vibrations of a circular plate. It was found that similar dynamic answer of the structure for special constitutive laws could be obtained only when the yield limit function for the wide range of strain rates is similar. Different types of boundary conditions of a cylindrical panel in numerical calculations are studied together with all three types of constitutive models. Results are compared with experiments and numerical solutions published in the literature. Verification of the boundary conditions used for calculations of the panel in the literature is presented.
PL
W pracy omawiane są pewne problemy odpowiedzi dynamicznej otwartej powłoki walcowej i okrągłych płyt poddanych obciążeniom impulsowym. Użyto różnych typów sprężysto lepkoplastycznych praw konstytutywnych: modele Perzyny, Chaboche'a i Bodera-Partoma. Stwierdzono znaczne różnice wartości parametrów materiałowych podanych w literaturze. Wpływ poprawnej ich identyfikacji jest badany na przykładzie drgań płyty okrągłej. Stwierdzono, że podobnej dynamicznej odpowiedzi konstrukcji dla różnych praw można oczekiwać tylko wtedy, gdy uzyskuje się zgodność funkcji granicy sprężystości w szerokim zakresie prędkości odkształceń. Różne typy warunków brzegowych otwartej powłoki walcowej w obliczeniach numerycznych są badane łącznie ze wszystkimi typami modeli konstytutywnych. Wyniki uzyskane z doświadczeń są porównane z wynikami numerycznymi podanymi w literaturze. Przeprowadzono weryfikację użytych w literaturze warunków brzegowych przyjętych do liczenia prezentowanej powłoki.
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