Wyniki wyszukiwania - BazTech

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

|

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

Possibilities of the Manufacturing and Simulation of the Load on a Customised Mouthguard Used in Combat Sports

Szarek Arkadiusz, Paszta Piotr

Fibres & Textiles in Eastern Europe

|

2020

|

Vol. 28, no. 2 (140)

110--118

EN

The article presents an assessment of the state of stress and deformation of a personalised tooth protector, taking into account various types of elastomer materials that allow optimal protection of the teeth in contact combat sports. The load characteristics of the personalised protector, perfectly adhering to all, even clearly protruding from the anatomical line of teeth, were calculated using ANSYS 18 software. Numerical simulations of different elastomer materials were compared. Assessment of the state of stress and deformation of the protector allowed to demonstrate the legitimacy of protecting teeth with a personalised tooth protector and to increase the safety of the teeth and soft tissues of the oral cavity in contact combat sports. Based on a dental impression and plaster casting of the jaw made using an eviXscan 3D scanner, its model was digitalised. CAx techniques were used to design a mouthguard. Furthermore, a control code was generated and transmitted to a CNC milling machine to make a mouthguard fitted to the user’s teeth.

PL

W artykule przedstawiono możliwości zaprojektowania spersonalizowanego ochraniacza zębów używanego w kontaktowych sportach walki. Na podstawie pobranego wycisku stomatologicznego i wykonanego gipsowego odlewu szczęki przy pomocy skanera eviXscan 3D został zdigitalizowany jej model. Za pomocą technik CAx zaprojektowano ochraniacz. Następnie na tej podstawie został wygenerowany i przesłany do frezarki CNC kod sterujący. Na frezarce został wykonany ochraniacz dopasowany do zębów. Wykorzystując oprogramowanie ANSYS 18 przedstawiono również przykład obciążeń ochraniacza, ciosami bokserskimi zadawanymi w żuchwę. Omówione zostały znane modele fenomenologiczne opisujące gęstość energii odkształceń materiału hiperelastycznego. Zaproponowana metoda daje możliwość lepszego dopasowania ochraniacza z dowolnie wybranego polimeru, wyższą biokompatybilność ze względu na mniejszą zawartość resztkowego monomeru i eliminuje niedogodności w powszechniej stosowanych elementach z tworzyw termoplastycznych oraz niedopasowanie wynikające ze skurczu materiału.

3

Tests on the Mechanical Properties of Polymers in the Aspect of an Attempt to Determine the Parameters of the Mooney-Rivlin Hyperelastic Model

Śliwa-Wieczorek Klaudia, Zając Bogusław, Kozik Tomasz

Civil and Environmental Engineering Reports

|

2020

|

Vol. 30, no. 2

1--14

EN

The article presents testing of the mechanical properties of SIKA® polymer adhesives of the type PBM, PMM, PM, and PSM in the aspect of an attempt to determine the parameters of the Mooney-Rivlin hyperelastic model. The article contains a literature review on developed models for hyperelastic materials as well as a description of the author’s own results obtained in monaxial tensile and monaxial compression tests conducted on oars and cylindrical samples, respectively. Furthermore, the results of modeling of Mooney-Rivlin hyperelastic model parameters are shown in relation to the value of average parameters for polymers after both a week and a month-and-a-half of ripening.

4

Nonlinear composites structural analysis with viscoelastic fibers

Sinaceur Amal, Sahli Ahmed, Sahli Sara

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 2

158--169

EN

This paper presents a formulation for material and geometrical nonlinear analysis of composite materials by immersion of truss finite elements into triangular 2D solid ones using a novel formulation of the finite element method based on positions. This positional formulation uses the shape functions to approximate some quantities defined in the Nonlinear Theory of Elasticity and proposes to describe the specific strain energy and the potential of the external loads as function of nodal positions which are set from a deformation function. Because the nodal positions have current values in each node, this method naturally considers the geometric nonlinearities while the nonlinear relationships between stress and strain may be considered by a pure nonlinear elastic theory called hyperelasticity which allows to obtain linearised constitutive laws in its variational form. This formulation should be able to include both viscoelastic and active behavior, as well as to allow the consideration of nonlinear relations between stresses and deformations. It is common to adopt hyperelastic constitutive laws. Few are the works that use the strategy of approaching the problem such as fibers immersed in a matrix. The immersion of fibers in the matrix makes it possible to include both a viscoelastic behavior in a simple and direct way. The examples are simple cases, some of them even with analytical solutions, mainly for validation purposes of the presented formulations. By modeling a structure, the examples show the potentialities of the concepts and proposed formulations.

5

Changing the philosophy of organization management in the times of e-economy

Bieńkowska J., Sikorski Cz.

Management

|

2017

|

Vol. 21, no. 2

7--19

EN

The paper highlights the fundamental changes in the way of thinking in science and the management practice caused by the transition from the era of industrial civilization to the information civilization. These include the change in the subject of management, i.e. the transition from the management of the organization to the management of joint projects; from the requirement of flexibility from own resources to the ability to use external resources and the departure from the methodological rationality of a decision to the material rationality. The change of management philosophy is particularly evident in the electronic market which sets a new and interesting research area, due to its cognitive appeal resulting from different conditions in comparison to the traditional market, and due to the high dynamics of development. The article is theoretical and its purpose is cognitive. Its subject is a fragment of the author’s concept of the evolution of management in the organizational space. It presents the synthesis of observations on the transformations of the essence of management. To undertake such a research task is motivated by the argument that one of the tasks of management science is to visualize the changes that take place within it, in order to induce the revision of anchored old cognitive patterns inadequate to reality and replace them with new, described by an appropriate conceptual apparatus.

PL

W artykule zwrócono uwagę na zasadnicze zmiany sposobu myślenia w nauce i praktyce zarządzania spowodowane przejściem z epoki cywilizacji przemysłowej do cywilizacji informacyjnej. Należy do nich zaliczyć zmianę przedmiotu zarządzania, czyli przejście od zarządzania organizacją do zarządzania wspólnymi projektami; od wymagania elastyczności od własnych zasobów do umiejętności korzystania z zasobów obcych oraz odchodzenie od racjonalności metodologicznej decyzji na rzecz racjonalności rzeczowej. Zmiana filozofii zarządzania jest szczególnie widoczna na rynku elektronicznym, który wyznacza nowy i interesujący obszar badawczy ze względu na jego atrakcyjność poznawczą wynikająca z odmiennych uwarunkowań w porównaniu z rynkiem tradycyjnym, i jak ze względu na wysoką dynamikę rozwoju. Artykuł ma charakter teoretyczny, a jego cel jest poznawczy. Podjęta w nim tematyka stanowi fragment autorskiej koncepcji ewolucji zarządzania w przestrzeni organizacyjnej. Przedstawia syntezę obserwacji na temat przeobrażeń istoty zarządzania. Podjęcie takiego zadania badawczego umotywowane zostało argumentem, że jednym z zadań nauki o zarządzaniu jest obrazowanie przemian jakie zachodzą w jej obrębie, w celu skłonienia do rewizji zakotwiczonych starych schematów poznawczych nieadekwatnych do rzeczywistości oraz zastąpienia ich nowymi, opisywanymi odpowiednią aparaturą pojęciową.

6

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

|

2017

|

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.

7

Hyperflexibility. A feature of e-commerce organisations

Bieńkowska J., Sikorski C.

Management

|

2016

|

Vol. 20, no. 2

209--222

EN

The paper is sacrificed analysis of conditions organizational activity on e-commerce business and desired ways of management. Organizations on e-commerce business must be hyper-flexible because of stormy environment and high level of competition. Hyperflexibility means ability to creating new organizational forms so as to realization of different projects collaboration with other organizations and utilizing strange resources. The main condition of Hyperflexibility is pragmatic organizational culture and such its attributes as confidence, tolerance and fluent identity.

PL

Opracowanie poświęcone jest analizie warunków funkcjonowania organizacji na rynku e-commerce i związanym z tym sposobem zarządzania. Ze względu na burzliwość otoczenia i wysoki stopień konkurencyjności, organizacje na rynku e-commerce cechować musi hiperelastyczność. Hiperelastyczność polega na łatwości tworzenia nowych form organizacyjnych dla realizacji różnych projektów we współpracy z innymi organizacjami i wykorzystywaniu obcych zasobów. Głównym warunkiem hiperelastyczności jest pragmatyczna kultura organizacyjna oparta na zaufaniu, tolerancji i płynnej tożsamości.

8

Corneal hyper-viscoelastic model: derivations, experiments, and simulations

Su P., Yang Y., Song Y

Acta of Bioengineering and Biomechanics

|

2015

|

Vol. 17, no. 2

73--84

EN

Purpose: The aim of this study is to propose a method to construct corneal biomechanical model which is the foundation for simulation of corneal microsurgery. Methods: Corneal material has two significant characteristics: hyperelastic and viscoelastic. Firstly, Mooney–Rivlin hyperelastic model of cornea obtained based on stored-energy function can be simplified as a linear equation with two unknown parameters. Then, modified Maxwell viscoelastic model of the cornea, whose analytical form is consistent with the generalized Prony-series model, is proposed from the perspective of material mechanics. Results: Parameters of the model are determined by the uniaxial tensile tests and the stress-relaxation tests. Corneal material properties are simulated to verify the hyper-viscoelastic model and measure the effectiveness of the model in the finite element simulation. On this basis, an in vivo model of the corneal is built. And the simulation of extrusion in vivo cornea shows that the force is roughly nonlinearly increasing with displacement, and it is consistent with the results obtained by extrusion experiment of in vivo cornea. Conlusions: This paper derives a corneal hyper-viscoelastic model to describe the material properties more accurately, and explains the mathematical method for determination of the model parameters. The model is an effective biomechanical model, which can be directly used for simulation of trephine and suture in keratoplasty. Although the corneal hyper-viscoelastic model is taken as the object of study, the method has certain adaptability in biomechanical research of ophthalmology.

9

A finite element implementation of Knowles stored-energy function: theory, coding and applications

Suchocki C.

Archive of Mechanical Engineering

|

2011

|

Vol. LVIII, nr 3

319-346

EN

This paper contains the full way of implementing a user-defined hyperelastic constitutive model into the finite element method (FEM) through defining an appropriate elasticity tensor. The Knowles stored-energy potential has been chosen to illustrate the implementation, as this particular potential function proved to be very effective in modeling nonlinear elasticity within moderate deformations. Thus, the Knowles stored-energy potential allows for appropriate modeling of thermoplastics, resins, polymeric composites and living tissues, such as bone for example. The decoupling of volumetric and isochoric behavior within a hyperelastic constitutive equation has been extensively discussed. An analytical elasticity tensor, corresponding to the Knowles stored-energy potential, has been derived. To the best of author's knowledge, this tensor has not been presented in the literature yet. The way of deriving analytical elasticity tensors for hyperelastic materials has been discussed in detail. The analytical elasticity tensor may be further used to develop visco-hyperelastic, nonlinear viscoelastic or viscoplastic constitutive models. A FORTRAN 77 code has been written in order to implement the Knowles hyperelastic model into a FEM system. The performace of the developed code is examined using an exemplary problem.

PL

Praca przedstawia pełną drogę wprowadzania do systemu metody elementów skończonych (MES) równania konstytutywnego hipersprężystości zdefiniowanego przez użytkownika przy użyciu odpowiedniego tensora sztywności. Aby zilustrować metodykę wprowadzania równania konstytutywnego do MES posłużono się modelem materiału hipersprężystego typu Knowlesa, gdyż model ten dobrze opisuje nieliniową sprężystość w zakresie średnich deformacji. Stąd model Knowlesa pozwala na poprawny opis własności mechanicznych polimerów termoplastycznych, żywic, kompozytów polimerowych i niektórych tkanek biologicznych, jak np. tkanka kostna. Przedstawiono podział równania konstytutywnego na część izochoryczną i objętościową. Wyprowadzono analitycznie tensor sztywności odpowiadający modelowi Knowlesa. Tensor ten nie był dotąd prezentowany w literaturze. Omówiono szczegółowo sposób wyprowadzania analitycznych tensorów sztywności dla materiałów hipersprężystych. Wyznaczony tensor sztywności może dalej posłużyć do budowy równań konstytutywnych nieliniowej lepkosprężystości lub lepkoplastyczności. W celu wprowadzenia modelu do systemu MES napisany został program w języku FORTRAN 77. W pracy przedstawiono wyniki z prostej symulacji MES wykonanej z wykorzystaniem napisanego programu.

10

Modeling of pulsating flow in a collapsible wall

Veshkina N., Zbiciński I., Obidowski D.

Inżynieria i Aparatura Chemiczna

|

2010

|

Nr 1

117-118

EN

The paper presents the methodology for verification of Fluid Structure Interaction (FS1) model for silicone pipe reflecting pulsating blood vessel in human body. The 3-term Yeoh model for strain energy density function was used in order to describe nonlinear behavior of siliconc material. To dctcr-:. mine the boundary conditions for CFD simulations our own experimental set-up was designed. A good agreement between simulation and experiment was achieved.

PL

W artykule przedstawiono metodę weryfikacji modelu (FSI) dla silikonowej rurki odzwierciedlającej zachowanie pulsującego naczynia krwionośnego z przepływającą wewnątrz krwią. Przy pomocy trój członowego modelu Yeoha funkcji gęstości energii naprężenia rozważono nieliniowe zachowanie materiału silikonowego. Aby uzyskać warunki brzegowe do symulacji CFD przeprowadzono badania na specjalnie do tego celu zbudowanej aparaturze. Otrzymano dobre dopasowanie danych z symulacji do eksperymentu.

11

Simple shear test in identification of constitutive behaviour of materials submitted to large deformations - hyperelastic materials case

Ziółkowski A.

Engineering Transactions

|

2006

|

Vol. 54, iss. 4

251-269

EN

The present work is directed at evaluation of the simple shear test for identification of constitutive behaviour of materials submitted to large deformations. For that purpose, actual experimental conditions together with theoretical background of the test are analyzed on the example of two hyperelastic material models. Advantages and disadvantages of various strain and stress measures used for presentation of simple shear test (SST) results are analyzed. The most often presented as the only result of "standard" SST proof chart, i.e. shear nominal stress - shear nominal strain (?12(N) - ?/2), characterizes the material energetically in the sense that it reveals its capacity for elastic energy storage dW/V0 = ?12(N) d?. However, it characterizes the constitutive behaviour of the material only partially, since it is equivalent to shear II Piola Krichoff stress - shear Green-Lagrange strain (?21(2) - E21(2)) chart, within the large deformations context. This data alone does not even allow to reconstruct the shear Cauchy stress - shear spatial Hencky strain (?12(0) - e12(0)) chart for the tested material. In order to take full advantage of the constitutive information available from simple shear test, it is highly recommended to extend the experimental methodology of "standard" SST proof in such a way as to determine simultaneously two components (shear and normal) of nominal stress tensor in the same SST proof. Such experimental information allows for subsequent recalculation of non-symmetric nominal stress tensor components into Cauchy stress components.