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1

Bio inspired salamander robot with Pneu-Net Soft actuators – design and walking gait analysis

Natarajan Elango, Chia Kwang Y., Faudzi Ahmad Athif Mohd, Lim Wei Hong, Ang Chun Kit, Jafaari Ali

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

|

Vol. 69, nr 3

art. no. e137055

EN

The research was attempted to mimic the locomotion of the salamander, which is found to be one of the main animals from an evolutionary point of view. The design of the limb and body was started with the parametric studies of pneumatic network (Pneu-Net). Pneu-Net is a pneumatically operated soft actuator that bends when compressed fluid is passed inside the chamber. Finite Element Analysis software, ANSYS, was used to evaluate the height of the chamber, number of chambers and the gap between chambers for both limb and body of the soft mechanism. The parameters were decided based on the force generated by the soft actuators. The assembly of the salamander robot was then exported to MATLAB for simulating the locomotion of the robot in a physical environment. Sine-based controller was used to simulate the robot model and the fastest locomotion of the salamander robot was identified at 1 Hz frequency, 0.3 second of signal delay for limb actuator and negative π phase difference for every contralateral side of the limbs. Shin-Etsu KE-1603, a hyper elastic material, was used to build the salamander robot and a series of experiments were conducted to record the bending angle, the respective generated force in soft actuators and the gait speed of the robot. The developed salamander robot was able to walk at 0.06774 m/s, following an almost identical pattern to the simulation.

2

Decoupled homogenization of hyperelastic composite with carbon black inclusion

Poręba-Sebastjan Martyna, Kuś Wacław

Computer Methods in Materials Science

|

2020

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Vol. 20, No. 1

14--21

EN

The goal of the paper is to present the application of decoupled homogenization method to the modeling of hyperelastic composite with inclusions. The method presented in the paper is illustrated by numerical analysis of a trunk door seal. The decoupled homogenization method was used to find macroscale properties of hyperelastic material. The method allows for the determination of the equivalent properties of a composite material based on its structure and the results of numerical experiments. Unlike the coupled method, the results are not transferred in every iteration between scales during computations which leads to lower calculation costs. The analyzed micro model consisted of a hyperelastic matrix and stiff inclusions in the form of spheres of carbon black material. The decoupled procedure uses evolutionary algorithm to obtain macro model material properties. The finite element method is used during analyses of micro scale models.

PL

Celem pracy było zastosowanie metody homogenizacji niesprzężonej do modelowania hipersprężystego kompozytu z wtrąceniami. Metodę przedstawioną w pracy ilustruje analiza numeryczna uszczelki drzwi. Metodę homogenizacji niesprzężonej zastosowano w celu określenia makroskopowych właściwości materiału hipersprężystego. Metoda pozwala wyznaczyć równoważne właściwości materiału kompozytowego na podstawie jego struktury i wyników eksperymentów numerycznych prowadzonych w skali mikro. W przeciwieństwie do metody sprzężonej wyniki nie są przenoszone w każdej iteracji między skalami, co prowadzi do obniżenia kosztów obliczeń. Analizowany mikro model składał się z osnowy z materiału hipersprężystego oraz sztywnych wtrąceń sadzy. Metoda niesprzężona wykorzystuje algorytm ewolucyjny, aby uzyskać właściwości materiału makro. Do analiz numerycznych użyto metody elementów skończonych.

3

Reduction of mechanical wave propagation in a wall made of concrete blocks with rubber filling - a numerical analysis

Major Maciej

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2019

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Z. 25 (175)

162-167

EN

The paper presents a numerical analysis of the propagation of a disturbance in the form of a mechanical wave caused by a concentrated force applied perpendicular to the plane of the wall fragment analyzed in the work. Numerical tests were carried out on a numerical model of concrete blocks with rubber filling and on hollow concrete blocks, as a reference model. The impact of using concrete-rubber hollow bricks on effective stress values obtained in two time steps was assessed. Stress distributions are presented graphically in two perpendicular cross-sections of the wall (vertical and transverse) at the location of the application of the declared concentrated load. The results obtained are summarized in the table. The rubber used as the filling was modeled as Zahorski's hyperelastic material. A numerical analysis was performed in the ADINA program.

PL

Przedstawiono analizę numeryczną propagacji zaburzenia w postaci fali mechanicznej wywołanej oddziaływaniem, które stanowiła wymuszająca siła skupiona, przyłożona prostopadle do płaszczyzny analizowanego w pracy fragmentu muru. Badania numeryczne przeprowadzono, wykonując model numeryczny z pustaków betonowych z wypełnieniem gumowym oraz z samych pustaków betonowych, z których mur stanowił model referencyjny. Oceniono wpływ zastosowania pustaków betonowo-gumowych na wartości naprężeń efektywnych uzyskanych w dwóch krokach czasowych. Rozkłady naprężeń przedstawiono graficznie w dwóch prostopadłych względem siebie przekrojach muru (pionowym i poprzecznym) w miejscu przyłożenia deklarowanego oddziaływania skupionego. Uzyskane wyniki zestawiono w tabeli. Gumę użytą jako wypełnienie zamodelowano jako hipersprężysty materiał Zahorskiego. Analizę numeryczną wykonano w programie ADINA.

4

The determination of mechanical properties of prosthetic liners through experimental and constitutive modelling approaches

Łagan S., Liber-Kneć A.

Technical Transactions

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2018

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Vol. 115, iss. 3

197--209

EN

The aim of the study was the estimation of the ability of hyperelastic material models for the fitting of experimental data obtained in the tensile testing of silicone liners used in lower-limb prosthetics. Three groups of liners were analysed: I – silicone liner, II – part of the liner in which the silicone has a fabric reinforcement, III – silicone liner with an outer covering material. Both longitudinal and circumferential samples were taken. The Neo-Hookean, Mooney-Rivlin and Ogden parameters of constitutive models of hyperelastic materials were calculated.

PL

Celem badań była ocena przydatności modeli materiałów hipersprężystych do dopasowania danych doświadczalnych uzyskanych w próbie rozciągania dla silikonowych linerów ortopedycznych stosowanych w protezach dolnych. Przeanalizowano trzy grupy: I – liner silikonowy, II – liner silikonowy z wewnętrznym wzmocnieniem, III – liner silikonowy z zewnętrznym wzmocnieniem. Wyróżniono dwa kierunki pobrania próbek: podłużny i obwodowy. Zidentyfikowano parametry określonych funkcji modeli konstytutywnych materiałów hipersprężystych: Neo-Hookean’a, Mooney-Rivlin’a i Ogden’a.

5

Experimental and numerical investigation of lead-rubber dampers in chevron concentrically braced frames

Zeynali K., Saeed Monir H., Mirzai N. M., Hu J. W.

Archives of Civil and Mechanical Engineering

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2018

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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.

6

Experimental testing and constitutive modeling of the mechanical properties of the swine skin tissue

Łagan S. D., Liber-Kneć A.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 2

93--102

EN

The aim of the study was an estimation of the possibility of using hyperelastic material models to fit experimental data obtained in the tensile test for the swine skin tissue. Methods: The uniaxial tensile tests of samples taken from the abdomen and back of a pig was carried out. The mechanical properties of the skin such as the mean Young’s modulus, the mean maximum stress and the mean maximum elongation were calculated. The experimental data have been used to identify the parameters in specific strain-energy functions given in seven constitutive models of hyperelastic materials: neo-Hookean, Mooney–Rivlin, Ogden, Yeoh, Martins, Humphrey and Veronda–Westmann. An analysis of errors in fitting of theoretical and experimental data was done. Results: Comparison of load –displacement curves for the back and abdomen regions of skin taken showed a different scope of both the mean maximum loading forces and the mean maximum elongation. Samples which have been prepared from the abdominal area had lower values of the mean maximum load compared to samples from the spine area. The reverse trend was observed during the analysis of the values of elongation. An analysis of the accuracy of model fitting to the experimental data showed that, the least accurate were the model of neo- -Hookean, model of Mooney–Rivlin for the abdominal region and model of Veronda–Westmann for the spine region. Conclusions: An analysis of seven hyperelastic material models showed good correlations between the experimental and the theoretical data for five models.

7

Elastic constants influence on the L4-L5-S1 annuli fibrosus behavior, a probabilistic finite element analysis

Jaramillo H. E., Garcia J. J.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 4

3--12

EN

A probabilistic finite element (FE) analysis of the L4-L5 and L5-S1 human annulus fibrosus (AF) was conducted to obtain a better understanding of the biomechanics of the AF and to quantify its influence on the range of motion (ROM) of the L4-L5 and L5-S1 segments. Methods: The FE models were composed of the AF and the upper and lower endplates. The AF was represented as a continuous material composed of a hyperelastic isotropic Yeoh matrix reinforced with two families of fibers described with an exponential energy function. The caudal endplate was fully restricted and 8 Nm pure moment was applied to the cranial endplate in flexion, extension, lateral flexion and axial rotation. The mechanical constants were determined randomly based on a normal distribution and average values reported. Results: Results of the 576 models show that the ROM was more sensitive to the initial stiffness of the fibers rather than to the stiffening coefficient represented in the exponential function. The ROM was more sensitive to the input variables in extension, flexion, axial rotation and lateral bending. The analysis showed an increased probability for the L5-S1 ROM to be higher in flexion, extension and axial rotation, and smaller in lateral flexion, with respect to the L4-L5 ROM. Conclusions: An equation was proposed to obtain the ROM as a function of the elastic constants of the fibers and it may be used to facilitate the calibration process of the human spine segments and to understand the influence of each elastic constant on the ROM.

8

A strain energy density theory for mixed mode crack propagation in rubber-like materials

Boulenouar A., Benseddiq N., Merzoug M., Benamara N., Mazari M.

Journal of Theoretical and Applied Mechanics

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2016

|

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.

9

Ekologiczny kompozyt ścienny betonowo-gumowy

Major M., Major I.

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

|

2016

|

nr 1(17)

61--66

PL

Przedstawiono analizę numeryczną wpływu impulsu siły działającej na ścianę wykonaną z bloczków betonowych z gumowymi wkładkami. Bloczek betonowy ma zatopione w trakcie realizacji procesu technologicznego wkładki gumowe o odpowiednio dobranym kształcie. Dzięki temu ściana posiada właściwości umożliwiające redukcję impulsu siły działającej prostopadle do jej powierzchni. Impuls siły powoduje powstanie fal mechanicznych, których propagację można zaobserwować, analizując rozkład naprężeń w przekroju poprzecznym ściany. Mierząc wartości naprężeń na powierzchniach czołowych rozpatrywanego modelu ściany, można ocenić skuteczność zastosowanego rozwiązania w porównaniu do ściany bez gumowych wkładek. Analizę numeryczną wykonano w programie ADINA.

EN

Paper presents numerical analysis considering the influence of dynamical force perpendicularly acting on the wall made of concrete blocks with rubber inserts. Concrete blocks during production technology process have rubber inserts with properly adapted shape. According to that, wall properties allow to reduce acting to the wall surface dynamic force impulse. By measuring the stress values on the surface of the analysed wall structure model with rubber inserts, the effectiveness of proposed solution can be examined comparing to the wall made of concrete blocks. Numerical analysis was performed using ADINA software.

10

Patient-specific hemodynamics and stress-strain state of cerebral aneurysms

Ivanov D., Dol A., Polienko A.

Acta of Bioengineering and Biomechanics

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2016

|

Vol. 18, no. 2

9--17

EN

Purpose: Approximately 5% of the adult population has one or more cerebral aneurysm. Aneurysms are one of the most dangerous cerebral vascular pathologies. Aneurysm rupture leads to a subarachnoid hemorrhage with a very high mortality rate of 45–50%. Despite the high importance of this disease there are no criteria for assessing the probability of aneurysm rupture. Moreover, mechanisms of aneurysm development and rupture are not fully understood until now. Methods: Biomechanical and numerical computer simulations allow us to estimate the behavior of vessels in normal state and under pathological conditions as well as to make a prediction of their postoperative state. Biomechanical studies may help clinicians to find and investigate mechanical factors which are responsible for the initiation, growth and rupture of the cerebral aneurysms. Results: In this work, biomechanical and numerical modeling of healthy and pathological cerebral arteries was conducted. Patient-specific models of the basilar and posterior cerebral arteries and patient-specific boundary conditions at the inlet were used in numerical simulations. A comparative analysis of the three vascular wall models (rigid, perfectly elastic, hyperelastic) was performed. Blood flow and stress-strain state of the two posterior cerebral artery aneurysm models was compared. Conclusions: Numerical simulations revealed that hyperelastic material most adequately and realistically describes the behavior of the cerebral vascular walls. The size and shape of the aneurysm have a significant impact on the blood flow through the affected vessel and on the effective stress distribution in the aneurysm dome. It was shown that large aneurysm is more likely to rupture than small aneurysm.

11

Numerical, experimental and analytical study on MRE used for vibrating pile hammer efficiency improvement

Kwietniewski M., Miedzińska D., Nguyen H. P., Gieleta R., Osiński J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 73, nr 2

151--156

EN

Purpose: of this paper is a research on Vibratory Pile Hammer (VPH) efficiency improvement with the use of Magnetorheological Elastomer (MRE) controlled with external magnetic field. Design/methodology/approach: The analytical equations are made to describe physical dependence of MRE on VPH work. To describe elastomer properties reduced polynomial model proposed by Oon H. Yeoh was used. The shear tests for Magnetorheological Elastomer of two with different volume of carbonyl-iron particles and its influence on elastomer pillow implemented in VPH were carried out. Tests were carried out in external magnetic field and without it. Numerical analyses were conducted with the use of MSC Software applying Finite Elements Method (FEM). The FE model was built on the experimental boundary conditions. Findings: MRE significantly changes elastic properties under applied magnetic field, what can be used to stiffness and damping properties of the construction control. Research limitations/implications: In further analyses, the test results will be used for the evaluation and selection of MRE regulation system. Practical implications: The presented results were used in modification of Vibratory Pile Hammer to improve its efficiency and a maintain device in resonance. Originality/value: The new application of the phenomenon of MRE stiffness change caused by the variable external magnetic field will allow to keep the mechanical system in resonance.

12

Modeling of human circle of Willis with and without aneurisms

Ivanov D., Dol A., Pavlova O., Aristambekova A.

Acta of Bioengineering and Biomechanics

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2014

|

Vol. 16, no. 2

121--129

EN

Purpose: This paper includes results of the first stage of research aimed at the development of recommendations for physicians in order to help them to choose a particular type of cerebral arteries aneurysms treatment. Methods: Recent studies show that the majority of aneurysms develop as a result of hemodynamic and degenerative lesions of the vascular wall. Obviously, such wall damage can be studied using the methods of continuum mechanics and numerical simulations. Biomechanical modelling allows us to study hemodynamic parameters and stress-strain state of these arteries in health and disease, and to formulate practical recommendations for the necessity and reasonable selection of a particular type of cerebral arteries aneurysm treatment. Results: At this stage the realistic geometric models of arterial circle of Willis were built for its normal state and in the presence of aneurysms. The ultrasound analysis of circle of Willis was conducted in order to obtain blood flow parameters and the boundary conditions for carotid and vertebral arteries. Also, the mechanical properties of these arteries were investigated and constants of the Mooney–Rivlin strain energy function were obtained. Conclusions: Thus, the boundary problem describing the behaviour of human Willis circle arteries was stated. Further, this problem will be solved numerically using the finite element method. The numerical results will be analyzed from the point of view of the influence of the mechanical factors on the emergence, growth and rupture of circle of Willis aneurysms.

13

Propagacja płaskiej fali przyspieszenia w cienkim czterosegmentowym pręcie wykonanym z materiałów Murnaghana

Major M., Major I., Różycka J.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

|

2012

|

z. 59, nr 3/II

389-396

PL

Celem niniejszej pracy jest omówienie przybliżonego zachowania propagacji fal nieciągłości w cienkim pręcie segmentowym o powoli zmieniającym się przekroju poprzecznym (Rys.1). Zagadnienie to w ośrodkach ciągłych stanowi bazę do prowadzenia badań mających na celu szersze poznanie nieliniowych materiałów hipersprężystych. W pracy, zgodnie z przyjętymi założeniami omawiana jest fala słabej nieciągłości, inaczej fala przyśpieszenia (padająca, transmitowana i odbita) propagująca wzdłuż długości przyjętego pręta. Do rozważań przyjęto ściśliwy materiał hipersprężysty określony potencjałem Murnaghana. Zagadnienie propagacji fal w przypadku pręta o zmiennym przekroju poprzecznym zostało przedstawione i omówione szczegółowo w pracach [1] A. Jeffrey’a oraz [2] A. Jeffrey’a i R.P. Gilbert’a, z których wynika m.in., że natężenie fali przyśpieszenia opisuje równanie Bernouliego dla ośrodka o potencjale sprężystym sigma(p) spełniającym warunek sigma3/sigma p3=0, gdzie p jest gradientem przemieszczenia. Niniejsza praca ma na celu omówienie zachowania propagującej się fali przyśpieszenia przechodzącej przez kolejne powierzchnie rozdziału segmentów pręta, przy założeniu powierzchni poprzecznej opisanej funkcją wykładniczą kolejno: rosnącą i malejącą.

EN

The purpose of the present paper is to discuss the issue of discontinuity waves propagation in a segmental rod of slowly varying cross-section area. In the paper, in accordance with the assumptions, the wave of weak discontinuity or acceleration wave (incident, transmitted and reflected) propagating along the length the rod adopted is discussed. The propagation of acceleration waves assumed in the compressible elastic material is determined by Murnaghan’s potential. Numerical analysis was carried out in order to discuss the behaviour of acceleration wave propagating through the subsequent surfaces of the layers contact segment rod, assuming the lateral surface of the exponential function described successively as descending and ascending.

14

Potencjał Murnaghana dla ciała hipersprężystego : wybrane informacje i przykład obliczeniowy propagacji fali przyspieszenia w pręcie

Major M., Major I.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

|

2012

|

Z. 18 (168)

174--181

PL

Przedstawiono podstawowe informacje dotyczące materiałów hipersprężystych. Omówiono powierzchnię nieciągłości, podając wzór na prędkość propagacji powierzchni oraz omówiono falę słabej nieciągłości. Do analizy numerycznej przyjęto pręt o wolno zmieniającym się przekroju poprzecznym opisany potencjałem Murnaghana. Zamodelowano funkcję opisującą przekrój poprzeczny i wykonano obliczenia propagacji fali przyspieszenia w pręcie wykonanym ze stali. Analiza numeryczna wykazała, że wraz ze wzrostem przekroju pręta intensywność propagującej się fali przyspieszenia maleje.

EN

The paper presents basic information about the hyperelastic materials. Discussed the surface of discontinuity, giving the formula for the speed of propagation of surface and also were discussed waves of weak discontinuities. For numerical analysis assumed rod with slowly changing cross-section, described by Murnaghan potential. Modeled the function describing the cross-section and calculated the acceleration wave propagation speed in a stainless rod. Numerical analysis proves that if the cross-section of the rod grows, the intensity of propagating wave decreases.

15

Simulation of Energy Dissipation During Impacts with Hyperelastic Elements

Osiński J., Rumianek P.

Machine Dynamics Research

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2012

|

Vol. 36, No. 2

64-75

EN

The aim of this article is to analyze the possibility of energy dissipation during the impact a pedestrian by a vehicle. The energy created during the impact will be dissipated by element of protection made of a hyperdeformable material. Energy intensive structures are able to take over the kinematic energy during impact, which is equivalent to the work of their destruction (crushing, breaking). This has the effect of increasing pedestrian safety during the accident to fulfillment of the regulation of the European Parliament and Council Regulation (WE) No 78/2009 of 14 January 2009 with all amendments. Ensuring the safety and reduce pedestrian injuries during an accident is very important. Presented in work method of analysis of polyurethane materials, hyperdeformable with using the Finite Element Method can demonstrate how important it is to conduct researches to increase security. Exercising studies of materials using the FEM can verify used materials, and thus, drawing conclusions and present proposals for the use of new materials with improved properties. To describe the properties of the foam will be used previously known theories: hyperelstic materials and properties of elastic-plastic materials, including volumetric plastic deformations. The results of experimental studies will enable determine the model of to the foam and use it in calculations using the Finite Element Method of ABAQUS system. Explicit calculation of the dynamic module of the ABAQUS system is used to simulate impact of a bumper with protective element in the under-bumper beam to the pedestrian, will be analyzed the degree of energy dissipation. Simulation will allow an assessment of the effectiveness pedestrian protection - the operation of protection element.

16

Application of Modified Ogden’s Model for Describing Features of Composites with Gas Phase

Osiński J., Rumianek P.

Machine Dynamics Research

|

2012

|

Vol. 36, No. 2

76-83

EN

In modem technology, more widely are used the composites with the gas phase - porous structures with pores closed, filled the gas. Can find here polymeric materials: EPP polyurethanes used in automobile bumpers, CELLASTO polyurethane in suspension systems. To the same group may also include gazars - composites reinforced by gas, and thus structure, in which the gas in the closed pores is subjected to initial pressure. Gazars are made as the structure of metal, usually copper, carbon dioxide or a mixture of gases. The aim of this work is to develop methods of describing the properties of such materials based on knowledge of: basic materials, technologies (gas pressure formed during foaming) using the theory of hyperplastic materials, in particular using Ogden’s model and its modifications. The resulting description can be used for the applicability of hyperelstic models, and therefore in the whole range of deformation of the polymer-based composites and elastic composites of metals (not included plasticity). Verification of the method is carried out through the execution of experimental EPP foam polyurethane derived from car bumpers, enabling a better understanding of materials and will be able to better modify structures, and thus, improve the mechanical properties.

17

Preliminary numerical analysis of selected phenomena occurring in a rail fastening system

Szurgott P., Bernyś K.

Journal of KONES

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2012

|

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.

18

Numerical analysis of a shaped rail pad under selected static load

Szurgott P., Gotowicki P., Niezgoda T.

Journal of KONES

|

2012

|

Vol. 19, No. 1

407-414

EN

Numerical analysis of selected type of the polyurethane rail pad is presented in the paper. A shaped pad with cylindrical-shaped elements in its working section was selected as a representative for the computational simulation. Analysis reflected the experimental test according to the valid standard. The test included loading of the vertical force perpendicular to the foot of the rail. Such test allows determining the static stiffness of the pad. The Mooney - Rivlin material model was selected in the current study. Necessary experimental tests including a uniaxial compression and tension were conducted to provide material constants for the hyperelastic material model applied for the FE model. Simplified FE models of the considered rail pad and the rail were developed. Rounded corners and edges of the cylindrical-shaped elements were omitted, since their modelling required a significant density of the FE mesh. Vertical force perpendicular to the foot of the rail was declared as nodal force distributed evenly along the edges of the selected finite element models Non-linear static analysis was performed using MSC.Marc software with large displacements and deformations taken into consideration. The obtained results allowed estimating deformations and the state of stress in a highly deformed rail pad. The static stiffness of the pad was defined as secant stiffness based on the vertical force - deflection curve.

19

Analiza rozkładu energii odkształcenia z uwzględnieniem tarcia powierzchniowego w pierścieniu wykonanym z materiału o właściwościach hiperelastycznych

Wegner T., Kokot M.

Biuletyn Wojskowej Akademii Technicznej

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2012

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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.

20

Jednoosiowy stan naprężeń w hipersprężystym materiale Zahorskiego oraz Mooneya-Rivlina i neo-Hookeana : porównanie

Major M., Major I., Kwiatkowski T.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2011

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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.