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1
Content available A strain energy density theory for mixed mode crack propagation in rubber-like materials
100%
Boulenouar A. , Benseddiq N. , Merzoug M. , Benamara N. , Mazari M.
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tom Vol. 54 nr 4
1417--1431
EN
In this paper, a numerical modeling of crack propagation for rubber-like materials is presented. This technique aims at simulating the crack growth under mixed-mode loading based on the strain energy density approach. At each crack increment length, the kinking angle is evaluated as a function of the minimum strain energy density (MSED) around the crack tip, using the Ansys Parametric Design Language (APDL). In this work, numerical examples are illustrated to demonstrate the effectiveness, robustness and accuracy of the computational algorithm to predict the crack propagation path. The results obtained show that the plan of crack propagation is perpendicular to the direction of the maximum principal stretch. Moreover, in the framework of linear elastic fracture mechanics (LEFM), the minimum values of the density are reached at the points corresponding to the crack propagation direction.
2
Content available Influence of a surface friction on the deformation process of ring made of nonlinear properties material
100%
Wegner T. , Kokot M.
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tom Vol. 17, No. 1
465-478
EN
The paper presents application of an energy-based finite element and a local relaxation method to computer calculation of deformation of a ring made of hyperelastic material. The present study considers a surface friction mechanism. This mechanism is a physical phenomenon counteracting the relative motion of the contacting bodies. Friction causes loss of energy the dissipation of which is a result of wearing out of the bodies' surfaces and heat emission. This directly affects the shape of the deformed body. The above statements are confirmed by the results of computer calculation performed for rubber ring with rectangular cross-section. Rubber is a nearly incompressible material and, therefore, requires application of special mechanical models of the material properties as well as proper calculation methods. Implementation of energy-based finite element and local relaxation method enables studying the ring deformation with consideration of nonlinear properties of rubber and its displacements in the platering contact plane, according to the value of a friction coefficient between rubber and the plate material. Application of energy method resulted in determination of the work of friction forces and the energy density distribution of volumetric and deviatoric strain. It also simplified energy analysis of the surface friction mechanism and influence of the friction coefficient value on the process of the ring deformation.
3
Content available Preliminary numerical analysis of selected phenomena occurring in a rail fastening system
88%
Szurgott P. , Bernyś K.
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tom Vol. 19, No. 4
607-614
EN
The results of numerical analysis of selected phenomena occurring in a rail fastening system were presented in the paper. The study is focused on assessment of the state of displacement and stresses in the rail pad subjected to a moving load. Two finite element models of the considered system were developed. The first one included elementary track segment corresponding to one sleeper. The second FE model consisted of several elementary segments. The number of the track segments was determined independently on the basis of dynamic analysis carried out using LS-DYNA computer code. Essential FE analyses were performed using MSC.Marc/Mentat software. FE model of the elementary segment included 600 mm length rail and a two-side shaped rail pad. The Mooney - Rivlin material model was applied for the polyurethane rail pad. The fastening systems were modelled using spring elements. The vertical and longitudinal spring elements were also applied for the ballast modelling. A case of moving load caused by single vertical force - one axle - was considered in the study. Methodology of moving load simulation in the MSC.Marc software was proposed. The obtained results allowed assessing the total deflection of the rail pad, the state of stress, the load distribution on respective sleepers. Moreover, they gave information about the behaviour of the rail pad under moving load in context of static test described in respective standards.
4
Content available remote Experimental and numerical investigation of lead-rubber dampers in chevron concentrically braced frames
75%
Zeynali K. , Saeed Monir H. , Mirzai N. M. , Hu J. W.
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tom Vol. 18, no. 1
162--178
EN
This paper presents a theoretical and experimental evaluation of the application of lead rubber dampers (LRD) in the chevron bracing of structures. This device consists of a circular lead core with several layers of steel and rubber plates that are sandwiched together. This damper was manufactured at the earthquake engineering laboratory of Urmia University and installed inside a SDOF steel frame. The frame was placed on a shaking table, and its responses under several earthquake excitations were recorded. A 3D finite element model was created for the device, and hyper-elastic properties were determined for the rubber layers. To check the effectiveness of the device in mitigating the responses of multi-story frames, several nonlinear time history analyses were conducted on the structures using three earthquake excitations. The results indicate that significant reductions in the stories’ drift can be achieved by installing lead-rubber dampers in the chevron bracing.
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Content available remote Method and device for in-vivo measurement of elasto-mechanical properties of soft biological tissues
75%
Vuskovic V. , Kauer M. , Dual J. , Bajka M.
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tom Vol. 8, No. 4
637-654
EN
We present a method to determine elasto--mechanical properties of soft biological tissues, and a device able to perform the required measurements in-vivo. The device permits the controlled application of vacuum to small spots of organic tissue and registers the small deformation caused, during the whole measurement process. Deformation is measured with a vision based technique and the grabbed images are processed in real-time to avoid storage problems. We model biological tissue with a hyperelastic quasilinear viscoelastic material law and determine the unknown material parameters via inverse finite element methods.
6
Content available Analiza rozkładu energii odkształcenia z uwzględnieniem tarcia powierzchniowego w pierścieniu wykonanym z materiału o właściwościach hiperelastycznych
63%
Wegner T. , Kokot M.
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2012
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tom Vol. 61, nr 4
133-151
PL
Rozwój technologii informatycznych pozwolił na wprowadzenie do obliczeń inżynierskich na masową skalę programów wykorzystujących metodę elementów skończonych MES do symulowania zachowania się elementów maszyn, urządzeń mechanicznych oraz zjawisk fizycznych. Głównym problemem ich zastosowania w przypadku analizy tarcia powierzchniowego jest to, że w większości są przeznaczone tylko do obliczeń materiałów o właściwościach liniowych. To zjawisko ma szczególne znaczenie przy obliczeniach materiałów hiperelastycznych, do których należy również guma. Jest ona dzisiaj masowo wykorzystywana w różnych dziedzinach techniki. Zjawisko tarcia ma bezpośredni wpływ na odkształcanie się przedmiotów wykonanych z materiałów hiperelastycznych. Do obliczeń tych materiałów zastosowano metodę energetyczną, wykorzystującą element skończony o nieliniowych właściwościach modelowany energetycznie oraz oryginalny algorytm iteracyjny nazwany metodą relaksacji lokalnej. W artykule przedstawiono zastosowanie metody energetycznej do wyznaczenia odkształceń pierścienia gumowego z uwzględnieniem zjawiska tarcia powierzchniowego. Oprócz otrzymanych deformacji danego elementu przedstawiono również wyniki obliczeń dyssypacji energii spowodowanej pracą sił tarcia oraz rozkłady energii odkształcenia postaciowego i objętościowego w poszczególnych warstwach odkształcanego pierścienia.
EN
The information technology development improved engineering calculations by global spread of finite element method FEM to simulate behaviour of machine elements, mechanical devices and physical phenomena. The main problem of using it in case of superficial friction phenomenon is that in most cases its main purpose is to calculate materials of linear properties. This phenomenon is especially important for calculations of hyperelastic materials which include rubber. Nowadays, it is widely used in technology. Friction directly influences on deformations of objects made from hyperelastic materials. Energy method has been used for materials’ calculations by means of energy-based finite element of non-linear features, and iterative algorithm, named the local relaxation method. This paper presents the application of energy method for rubber ring deformations assignment including the superficial friction phenomena. Besides the observed deformations of examined element, there have been also presented the results of energy dissipation caused by friction forces work and the energy density distribution of volumetric and deviatoric strain in particular layers of the deformed ring.
7
Content available Jednoosiowy stan naprężeń w hipersprężystym materiale Zahorskiego oraz Mooneya-Rivlina i neo-Hookeana : porównanie
44%
Major M. , Major I. , Kwiatkowski T.
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo
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2011
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tom Z. 17 (167)
129-133
PL
W pracy przeprowadzono obliczenia dla jednoosiowego rozciągania w hipersprężystym materiale Zahorskiego. Uzyskane wyniki porównano graficznie z wartościami dla powszechnie stosowanych materiałów Mooneya-Rivlina oraz neo-Hookeana.
EN
In this paper there are calculations for the uniaxial stretch in the hyperelastic Zahorski material. Graphically the results obtained were compared with values for commonly used materials Mooney-Rivlin and neo-Hookean.
8
Content available Gumopochodne materiały hipersprężyste : omówienie i kryteria praktycznego zastosowania
38%
Major M. , Różycka J.
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo
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2011
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tom Z. 17 (167)
134-145
PL
W niniejszej pracy dokonano przeglądu gumopochodnych materiałów hipersprężystych. Podano związki konstytutywne opisujące ich zachowanie oraz kryterium praktycznego zastosowania. Przedstawiono również wybrane programy numeryczne wykorzystujące modele materiałów hipersprężystych.
EN
This paper presents the review of rubberlike hyperelastic materials, their constitutive relations describing their behaviour and the criterion of practical application. It also contains some numerical programs which use hyperelastic materials models.
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