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    Wyświetlanie 1-19 z 19
    Tytuł:
    FEM simulation of the tube rolling process in Diescher’s mill
    Autorzy:
    Pater, Z.
    Tofil, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/102656.pdf
    Data publikacji:
    2014
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    tube rolling
    FEM
    state of stress and strain
    Opis:
    This paper deals with the issue of numerical modelling of the piercing process of a thick–walled bush in a two-rolled skew rolling mill, equipped with guiding devices of Diescher’s type. After a short characteristic of the subject matter, the developed geometric model of the process was discussed, with taking kinematics of tools movement and thermal phenomena present in metal during forming into consideration. Next, the results of calculations were presented in a form of fields of strain, damage criterion and temperature. Distributions of force parameters acting on particular tools during the process of bush rolling were also given.
    Źródło:
    Advances in Science and Technology. Research Journal; 2014, 8, 22; 51-55
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Riveting process simulation - upsetting of the mushroom rivet
    Autorzy:
    Szymczyk, E.
    Jachimowicz, J.
    Sławiński, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/244023.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    riveted joint
    mushroom rivet
    FEM local model
    stress and strain fields
    Źródło:
    Journal of KONES; 2008, 15, 2; 493-502
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies on stress and strain state in cold orbital forging a AlMgSi alloy flange pin
    Badania stanu naprężenia i odkształcenia w prasowaniu obwiedniowym sworznia z kołnierzem ze stopu AlMgSi
    Autorzy:
    Samołyk, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/353363.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    orbital forging
    stress and strain state
    aluminium alloy
    FEM
    experiment
    prasowanie obwiedniowe
    stan naprężenia i odkształcenia
    stop aluminium
    eksperyment
    Opis:
    The orbital forging is one of the metal forming processes which enables the manufacture of products through worm or cold working. A characteristic feature of this technological process is the use of a special wobbling motion of one of the tools in order to reduce the required forming force. This is particularly advantageous during the formation of products in the shape of a disc or a flange pin. Unfortunately, typical constraints of cold orbital forging are: uncontrolled buckling, loss of shape stability (“mushroom effect”) and cracks. They depend on the technological parameters of the process and their cause can be explained on the basis of e.g. workpiece stress state analysis, which is a difficult task due to the complexity of orbital forging process. The article discusses the issues of stress and strain in cold orbital forged parts of the flange pin type, made of AlMgSi aluminum alloy. The results of the presented FEM simulation, verified experimentally, explain the influence of the theoretical aspects of this process on its implementation conditions. It is assumed that orbital forging is performed on the PXW-100A press and the numerical model takes into account all possible variants of the process. Debate boils down to discussing the stress and strain state (e.g. analyzing the stress and strain rate fields) occurring in the workpiece in the context of chosen technological parameters and constrains of orbital forging process.
    Prasowanie obwiedniowe jest jedną z technologii obróbki plastycznej, która umożliwia wytwarzanie wyrobów poprzez ich kształtowanie na zimno lub ciepło. Wyroby prasowane obwiedniowo charakteryzują się stosunkowo dużą jakością powierzchni oraz małą tolerancją wymiarową Charakterystyczną oechą tego procesu technologicznego jest zastosowanie specjalnego ruchu wahającego jednego z narzędzi w celu obniżenia wymaganej siły kształtowania. Szczególnie korzystne jest to podczas kształtowania wyrobów typu tarcza lub sworzeń z kołnierzem Typowymi ograniczeniami prasowania obwiedniowego są nie- kontrolowane wyboczenie. utrata stateczności kształtu oraz pęknięcia. Zależą one od parametrów technologicznych procesu, a ich przyczynę można wyjaśnić na podstawie np. analizy stanu naprężenia panującego w wyprasoe. Z uwagi na złożony charakter prasowania obwiedniowego jest to zadanie trudne. W artykule omówiono zagadnienia stanu naprężenia i odkształcenia w prasowaniu obwiedniowym części typu sworzeń z kołnierzem, która jest wykonana ze stopu aluminium AlMgSi. Przedstawione wyniki symulacji, zweryfikowanej doświadczalnie, wyjaśniają znaczenie aspektów teoretycznych tego procesu na jego warunki realizacji Zakłada się. że prasowanie obwiedniowe jest realizowane na prasie PXW-I00A, a model numeryczny uwzględnia wszystkie możliwe warianty realizacji procesu na tej maszynie. Dyskusja sprowadza się do omówienie stanu naprężenia i odkształcenia (analizując prędkość odkształcenia) panującego w wyprasce w kontekście wybranych parametrów technologicznych i ograniczeń procesu prasowania obwiedniowego.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 4; 1183-1189
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanical response at peri-implant mandibular bone for variation of pore characteristics of implants: A Finite Element Study
    Autorzy:
    Sarkar, Sulagna
    Sahu, Tikeshwar Prasad
    Datta, Arijit
    Chandra, Nimesh
    Chakraborty, Arindam
    Datta, Pallab
    Majumder, Santanu
    Chowdhury, Amit Roy
    Powiązania:
    https://bibliotekanauki.pl/articles/307131.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    implant stomatologiczny
    uszczelnianie
    FEM
    porous dental implant
    pore size
    percentage porosity
    bone-implant interface
    finite element analysis
    stress and strain
    Opis:
    In this paper, the mechanical response of generic dental implants having calculated porosities with varying pore-sizes has been evaluated. The purpose of this study was to compare the developed stress-strain of designed porous implants (i.e., stress at the implant and strain at the peri-implant bone) with that of the non-porous implant. Methods: 3D model of a mandible was prepared from CT scan data and nine generic dental implant models have been designed having 10%, 20%, and 30% porosity with 500, 700, and 900 micron pore size along with a non-porous model for carrying out FE analyses. First, failure analyses of implants, under a biting force of 250 N have been performed. Next, the remaining implants have been further evaluated under average compressive chewing load of 100 N, for mechanical responses at bone-implant interface. Results: Von Mises strain at the peri-implant mandibular bone increases with the increase in percentage porosity of the implant material and maximum implant stress remained much below the yield stress level. Conclusion: Implant stiffness and compressive strength vary as a function of porosity and pore size. Strain obtained on the peri-implant bone is sufficient enough to facilitate better bone growth with the 700 micron pore size and 30% porosity, thus reducing the effect of stress shielding.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 2; 83-93
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modele globalne i lokalne MES w analizie struktur lotniczych na przykładzie fragmentu skrzydła samolotu PZL M28 Skytruck
    Global and local FE models for aircraft structures analyses based on example of the PLZ M28 Skytruck airplanes wing part
    Autorzy:
    Jachimowicz, J.
    Szymczyk, E.
    Sławiński, G.
    Derewońko, A.
    Wronicz, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/208840.pdf
    Data publikacji:
    2010
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    struktury lotnicze
    połączenie nitowe
    proces zakuwania
    modele MES
    pola naprężeń resztkowych
    riveted joint
    mushroom rivet
    FEM local models
    stress and strain fields
    Opis:
    W niniejszym artykule na wstępie przedstawiono globalne analizy statyczne MES struktury fragmentu skrzydła samolotu PZL M28 Skytruck. W dalszej części pracy zamieszczono kolejno modele lokalne o różnym stopniu szczegółowości, umożliwiające analizy MES obszarów konstrukcji skrzydła z uwzględnieniem połączeń nitowych, analizy poszczególnych szwów nitowych, a w końcu analizy pojedynczych nitów. Omawiane modele lokalne poza warunkami brzegowymi wynikającymi z modeli globalnych i obciążeniami ogólnymi samolotu uwzględniają wybrane czynniki materiałowe i technologiczne oraz ich wpływ na stan przemieszczeń i naprężeń wokół nitu. Na końcu artykułu przedstawiono symulację procesu nitowania nitu grzybkowego w wyniku której uzyskano rozkład naprężeń resztkowych wokół nitu.W analizach wykorzystano systemy MSC Nastran, Marc i Ansys, a zakres analiz obejmował materiały sprężysto-plastyczne oraz sformułowania dużych przemieszczeń i odkształceń, a także wielopłaszczyznowy kontakt powierzchniowy.
    The paper deals with the analysis of residual stress and strain fields in a riveted joint. This stage of study concerns improving the fatigue performance of riveted joints in an airframe. Riveting, particularly in aviation, is a traditional but still commonly used method of joining sheet metal components. Aircraft structures are thin-walled ones, with coverings made of thin sheets stiffened by stringers, frames or ribs. Sheets are typically assembled by multiple rivet or bolt joints. Rivets and bolts are also used to joint sheets and stiffeners. Therefore fatigue resistance of the aircraft structure depends on tens of thousands or even hundreds of thousands rivet joints, which are used to build it. Global and local numerical models of the joint are considered with regard to the aim introduced in the paper. Numerical FE simulations of upsetting process are carried out using the NASTRAN and MARC code. Three-dimensional numerical models are used to determine the resulting stress and strain fields at the mushroom rivet and around the hole. This type of a problem requires the use of contact between the elements assembled and non-linear geometric and elasto-plastic multilinear material models to simulate behaviour of the rivet and sheets. The influence of the squeezing force on strain and stress states is studied. A certain solution to the problem connected with non-uniform stress distribution in the rivet hole is proposed and analysed.
    Źródło:
    Biuletyn Wojskowej Akademii Technicznej; 2010, 59, 1; 35-59
    1234-5865
    Pojawia się w:
    Biuletyn Wojskowej Akademii Technicznej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of stress-strain state of vehicles’ metal structures elements
    Autorzy:
    Hrevtsev, O.
    Selivanova, N.
    Popovych, P.
    Poberezhny, L.
    Rudyak, Yu.
    Shevchuk, O.
    Poberezhna, L.
    Ivanova, A.
    Skyba, O.
    Shashkevych, O.
    Hrytsanchuk, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2201126.pdf
    Data publikacji:
    2022
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    thermomechanical stress
    disk brakes durability
    stress and strain state
    vehicle reliability
    braking distance
    naprężenia termomechaniczne
    trwałość hamulców tarczowych
    stan naprężenia i odkształcenia
    niezawodność pojazdu
    droga hamowania
    Opis:
    Purpose: Develop a method for determining and evaluating the stress-strain state, in particular the distribution of thermomechanical stresses in the materials of individual rotating parts of vehicles. Design/methodology/approach: The proposed method is based on the principle of gradual approximations of the solution when the boundary conditions are satisfied on the curvilinear limiting surfaces of the disk body. Findings: The proposed method of determining and estimating the distribution of thermomechanical stresses in the disk material makes it possible to take into account the variable geometry: thickness and presence of a hole in the central part of the disk, also correctly determine stress strain state at any point of unevenly heated rotating axial body. Research limitations/implications: The work uses generally accepted assumptions and limitations for thermomechanical calculations. Originality/value: It is proved that in real disks the stress-strain state is spatial, and the well-known method based on the hypotheses of the plane-stress state does not provide the possibility of calculating the values of stresses in the thickness of the disk. The obtained results can be used as a basis for improving the methodology of auto technical examination of road accidents. In addition, they can be taken into account by design engineers of car brake systems.
    Źródło:
    Archives of Materials Science and Engineering; 2022, 113, 2; 77--85
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelling of stresses and strains in two-layer combined materials at their formation
    Autorzy:
    Koloskova, G. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/379456.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    computational material science and mechanics
    multi-layer combined material
    stress and strain modelling
    calendering method
    komputerowa nauka o materiałach
    wielowarstwowy materiał łączony
    modelowanie naprężeń i odkształceń
    Opis:
    Purpose: The aim of the represented study was to model the behaviour of two-layer combined material during its manufacturing. Design/methodology/approach: The model of material layers joining by means of calender method is built in LS-DYNA software on the basis of finite element method. Using the developed model the study of stress and strain condition changes is carried out. Numerical modelling was carried out for two types of two-layer combined materials in similar conditions. First combination was of high-density polyethylene top layer and aluminium foil bottom layer. Second combination was of high-density polyethylene top layer and low- density polyethylene bottom layer. Joining materials had equal thicknesses. Findings: During formation of two-layer combined materials the primary strain always occurs at the bottom plate of the bottom layer. However, the maximum plastic strain will be represented for the layer with lower elastic modulus value. At the point of the highest loading applied to the two-layer combined material the elasticity condition is changed to the plasticity one and the yield process is registered. Practical implications: Multi-layer combined materials are some of the most advanced types of materials. The quality of the joining of the layers, the strains and the stresses arising in their manufacturing process are the main causes of low interlayer strength. It leads to easy exfoliation and destruction of the material. The results of the study may be used to improve the quality of multi-layer combined materials. Originality/value: For the first time the model was developed for the determination of strains and stresses arising during the formation of multi-layer combined materials by means of calendering method. The calculations of the stresses and strains distribution dynamics for two-layer combined materials are represented for polymer-metal and polymer-polymer layers combinations. The results of the study may be of interest to specialists in the field of multi-layer combined materials designing and manufacturing.
    Źródło:
    Archives of Materials Science and Engineering; 2019, 97, 1/2; 12-19
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermoelastic strain and stress fields due to a spherical inclusion in an elastic half-space
    Autorzy:
    Singh, K.
    Muwal, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/281796.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    uncoupled thermoelasticity
    strain and stress fields
    potential functions
    spherical inclusion
    Opis:
    In this paper, closed form analytical expressions for thermoelastic strain and stress components due to a spherical inclusion in an elastic half-space are obtained. These expressions are derived in the context of steady-state uncoupled thermoelasticity using thermoelastic displacement potential functions. The thermal strain and stress fields are generated due to differences in the coefficients of linear thermal expansion between a subregion and the surrounding material. The strain and stress components for exterior points of the spherical inclusion are same as those of the center of dilatation. Variations of strain and stress components for exterior and interior points of the spherical inclusion are shown graphically.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1369-1380
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geokinematics of Central Europe: new insights from CERGOP-2/Environment Project
    Autorzy:
    Caporali, A.
    Becker, M.
    Fejes, I.
    Gerhatova, L.
    Ghitau, D.
    Grenerczy, G.
    Hefty, J.
    Medac, D.
    Milev, G.
    Mojzes, M.
    Mulic, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/224596.pdf
    Data publikacji:
    2007
    Wydawca:
    Politechnika Warszawska. Wydział Geodezji i Kartografii
    Tematy:
    GPS
    geodezja
    geodynamika w Europie Centralnej
    tektonika w Europie Centralnej
    naprężenia i odształcenia w Europie Środkowej
    GPS Geodesy
    Central European Geodynamics
    Central European Tectonics
    Stress and Strain in Central Europe
    Opis:
    The CERGOP2 project funded by the European Union from 2003 to 2006 under the 5th Framework Programme benefits from repeated measurements of the coordinates of epoch and permanent GPS stations forming the CEGRN network in Central Europe, starting 1994. We report on the results of the systematic processing of the available data up to 2005. The analysis work has yielded the velocities of some 60 sites, covering a variety of Central European tectonic provinces, from the Adria indenter to the Tauern window, the Pannonian basin, the Vrancea Seismic Zone and the Carpathian Mountains. The estimated velocities define kinematical patterns which outline, with varying spatial resolution depending on the station density and history, the present day tectonic flow in Central Europe.The CEGRN data show that the majority of active contraction originating from the Eurasia Nubia plate boundary and the microplate between them is taken up primarily in the Eastern Alps, the Dinarides, and the Pannonian Basin. After removal from the ITRF2000 velocities of a rigid rotation accounting for the mean motion of stable Europe, the residual velocities have random orientations with 0.3 mm/yr scatter. This Iow figure provides an upper estimate for the level of rigidity of the European Platform. A 2.3 mm/yr north-south oriented convergence rate is implied by our data between Adria and the Southern Alps, and a narrow - -60 km wide- contraction zone in the Southern Alps is identified, consistently with earlier results. An eastward extrusion north of the contraction zone corresponds with the extension of the Tauern Window. In the southeastern boundary of the microplate, 4-4.5 mm/yr motion of Adria decreases to -1 mm/yr through the microplate, its boundary, and the Dinarides mountain range towards the southwestern part of the Pannonian Basin. Our data suggest that if the Pannonian Basin is subject to deformation, then it is most likely to be compressional than extensional. We conclude that compression and associated contraction due to the Adria collision with the Alps and the Dinarides is likely to fade away in the Western and Northern Carpathians, where our velocities and strain rates show no significant deformation.
    Źródło:
    Reports on Geodesy; 2007, z. 2/83; 7-46
    0867-3179
    Pojawia się w:
    Reports on Geodesy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analytical solution of mixed boundary value problems using the displacement potential approach for the case of plane stress and plane strain conditions
    Autorzy:
    Deb Nath, S. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/266247.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    rozwiązanie analityczne
    naprężenie płaskie
    odkształcenie
    wartość graniczna
    analytical solution
    displacement potential approach
    plane stress and plane strain conditions
    mixed boundary value problems
    Opis:
    Two elastic plate problems made of duralumin are solved analytically using the displacement potential approach for the case of plane strain and plane stress conditions. Firstly, a one end fixed plate is considered in which the rest of the edges are stiffened and a uniform load is applied to the opposite end of the fixed end. Secondly, a plate is considered in which all of the edges are stiffened and a uniform tension is applied at its both ends. Solutions to both of the problems are presented for the case of plane stress and plane strain conditions. The effects of plane stress and plane strain conditions on the solutions are explained. In the case of stiffening of the edges of the plate, the shape of the plate does not change abruptly, which is clearly observed in both of the cases. For the plane strain condition, the plates become stiffer in the loading direction as compared to the plane stress condition. For the plane strain condition, there is a significant variation of the normal stress component, σzz at different sections of the plate. The graphical results, clearly identify the critical regions of the plate for the case of the plane stress and plane strain condition.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2017, 22, 2; 269-291
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Numerical and Experimental Analysis of Ballizing Process of Steel Tubes
    Autorzy:
    Dyl, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/356697.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    numerical analysis
    strain and stress state
    burnishing (surface plastic forming)
    ballizing process
    steel tubes
    Opis:
    This paper presents chosen results of experimental and numerical research of ballizing process of the steel tubes. Ballizing process is a method of burnishing technology of an internal diameter by precisely forcing a ball through a slightly undersized premachined tubes. Ballizing process is a fast, low-cost process for sizing and finishing tubes. It consists of pressing a slightly oversized ball through an unfinished tube to quickly bring the hole to desired size. The ball is typically made from a very hard material such as tungsten carbide or bearing steel. Ballizing process is by cold surface plastic forming of the surface structure, thereby leaving a layer of harder material and reducing its roughness. After theoretical and experimental analysis it was determined that the smaller the diameter of the balls, the bigger intensity of stress and strain and strain rate. The paper presents influence of ballizing process on the strain and stress state and on the surface roughness reduction rate of the steel tubes.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 2A; 807-814
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Influence of Technological Conditions of the Process of Cogging in Flat Dies on the Quality of Two-Phase Titanium Alloys
    Autorzy:
    Dyja, H.
    Tukibay, A. A.
    Mashekov, S. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/354341.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cogging
    flat die
    stress-strain state
    effective stresses and strains
    tilting
    reduction
    Opis:
    To create a rational technology of cogging process and to determinate the optimal values of the angles of tilt and single reduction the stress-strain state (SSS) of the blank during cogging in the flat dies was analyzed. By using the finite element method and program MSC.SuperForge quantitative data are obtained and the basic patterns of distribution of SSS, the temperature during the simulation of tilting in flat dies with different angles of tilting and the amount of reduction were established. Sustainable experimental-industrial technology of forging of two-phase titanium alloys was developed and tested.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 2A; 671-676
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Drained Against Undrained Behaviour of Sand
    Autorzy:
    Sawicki, A.
    Świdziński, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/241226.pdf
    Data publikacji:
    2007
    Wydawca:
    Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
    Tematy:
    granular soils
    stress-strain characteristics
    instability line
    dilative and contractive behaviour
    static liquefaction
    Opis:
    The incremental constitutive equations describing the pre-failure deformations of sand are presented. These equations were calibrated on the basis of extensive experimental data, obtained from investigations performed in a triaxial apparatus. Incremental equations were calibrated separately for initially contractive and dilative soil samples. Then, they were applied to predict the undrained behaviour of saturated soil samples. In the case of contractive soils, the constitutive equations describe the effective stress paths leading to the static liquefaction. In the case of dilative soils, the effective stress path is different, as the mean effective stress initially decreases, and after passing the instability line, it starts to increase, asymptotically reaching the failure envelope. Theoretical predictions of undrained behaviour are supported by experimental data. The original feature of this paper is that one can predict the undrained behaviour of saturated granular soils on the basis of stress-strain characteristics of the same soil but dry or tested in drained conditions.
    Źródło:
    Archives of Hydro-Engineering and Environmental Mechanics; 2007, 54, 3; 207-222
    1231-3726
    Pojawia się w:
    Archives of Hydro-Engineering and Environmental Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biomechanical Loads and Subjective Stress Exposure to Lumber Graders in Sawmill Industry
    Autorzy:
    Jones, T.
    Kumar, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/90791.pdf
    Data publikacji:
    2011
    Wydawca:
    Centralny Instytut Ochrony Pracy
    Tematy:
    job analysis
    lumber graders
    wood product manufacturing
    repetitive strain
    upper extremity
    physical and psychophysical stress
    Opis:
    The aim of this study was to determine biomechanical loads and subjective stresses on lumber graders and associated morbidity in a high risk and repetitive sawmill occupation. The exposures of all 29 male sawmill worker volunteers were recorded. Motion and posture were studied with electrogoniometers, muscle loads were recorded with surface electromyography, and psychophysical stresses were assessed with subjective responses. Fifty-nine percent of the participants reported greater than moderate discomfort in their taskdominant upper extremity. Job performance required an average range of motion of 44º, 21º, and 52º in flexion/extension, radial/ulnar deviations, and pronation/supination respectively. It also required an average of 9% maximum voluntary contraction force and was repeated an average of 34 times/min. This repetitive exertion over an 8-h shift was deemed to be a significant risk factor associated with prevalent upper extremity morbidity.
    Źródło:
    International Journal of Occupational Safety and Ergonomics; 2011, 17, 1; 87-97
    1080-3548
    Pojawia się w:
    International Journal of Occupational Safety and Ergonomics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physiological strain in the Hungarian mining industry: The impact of physical and psychological factors
    Autorzy:
    Varga, József
    Nagy, Imre
    Szirtes, László
    Pórszász, János
    Powiązania:
    https://bibliotekanauki.pl/articles/2177421.pdf
    Data publikacji:
    2016-06-30
    Wydawca:
    Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
    Tematy:
    work-related complex stress
    physiological strain
    health protection and promotion
    work pulse
    work-related accidents
    workplace illumination
    Opis:
    Objectives The objectives of these investigations completed on workplaces in the Hungarian mining industry were to characterize the physiological strain of workers by means of work pulse and to examine the effects of work-related psychological factors. Material and Methods Continuous heart rate (HR) recording was completed on 71 miners over a total of 794 shifts between 1987 and 1992 in mining plants of the Hungarian mining industry using a 6-channel recorder – Bioport (ZAK, Germany). The work processes were simultaneously documented by video recording along with drawing up the traditional ergonomic workday schedule. All workers passed health evaluation for fitness for work. The effects of different psychological factors (simulated danger, “instrument stress,” presence of managers, and effect of prior involvement in accidents as well as different mining technologies and work place illumination) on the work pulse were evaluated. The statistical analysis was completed using SPSS software (version 13.0, SPSS Inc., USA). Results The work-related physiological strain differed between work places with different mining technologies in groups of 12–18 workers. The work pulse was lowest in bauxite mining (ΔHR = 22±8.9 bpm) and highest in drift drilling in dead rock with electric drilling machine (ΔHR = 30±6.9 bpm). During sham alarm situation the work pulse was significantly higher than during normal activities with the same physical task (ΔHR = 36.7±4.8 bpm vs. 25.8±1.6 bpm, p < 0.001). When work was performed under different psychological stress, the work pulse was consistently higher, while improving the work place illumination decreased the physiological strain appreciably (ΔHR (median, 25–75 percentiles) = 23, 20–26 bmp vs. 28, 25–31.3 bpm, p < 0.001). Conclusions Recording the heart rate during whole-shift work along with the work conditions gives reliable results and helps isolating factors that contribute to increased strain. The results can be used to implement preventive and health promotion measures.
    Źródło:
    International Journal of Occupational Medicine and Environmental Health; 2016, 29, 4; 597-611
    1232-1087
    1896-494X
    Pojawia się w:
    International Journal of Occupational Medicine and Environmental Health
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on the State of Internal Stress and Strain of TATB-based Polymer Bonded Explosive Using Strain Markers and Cone-Beam Computed Tomography
    Autorzy:
    Dai, B.
    Lan, L.-G.
    Zhang, W.-B.
    Tian, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/358613.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    technology of materials
    testing and analysis
    compression molding
    polymer bonded explosive
    stress state
    strain ellipsoid
    X-ray tomography
    Opis:
    Precise measurement of the inner structural strain of polymer bonded explosive (PBXs) granules during compression molding is highly desirable in order to investigate the inner stress distribution field and its underlying generation mechanism, with the aim of improving the stress distribution uniformity. In this contribution, TATB-based (1,3,5-triamino-2,4,6-trinitrobenzene) PBX granules were formulated and the stress-strain state of the PBX granules during the warm molding process was analyzed. Strain markers were implanted at different locations and the deformation characteristics and regularity of the embedded spherical strain markers were obtained by X-ray micro-tomography. Thus the local strain states at different locations could be obtained, and the local stress state could be deduced. The results showed that axisymmetric deformation occurred in all of the strain markers, where the flat strain ellipsoids were mainly compressed uni-axially. In the central region, the stress was mainly in an axial direction, and the shear force was small. Not only axial stresses, but also large shear stresses in the surrounding region of the cylindrical grains were present. The stress gradient in the central region was greater than that in the surrounding region. The stress was greater in the surrounding region because this region was squeezed by the mold. The maximum strain degree was 44.8% larger than the minimum strain degree. The local stress increment in each region was quantified. The stress increments of the three axes were in the range 14.2-19.5 MPa. This study examined the feasibility of evaluating the inner stress–strain state of PBX granules in a quantitative manner, which is significant in determining the inner strain and stress distribution in PBX granules during the molding process.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 3; 688-707
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design Analysis of Closed Vessel for Power Cartridge Testing
    Autorzy:
    Parate, Bhupesh Ambadas
    Chandel, Sunil
    Shekhar, Himanshu
    Powiązania:
    https://bibliotekanauki.pl/articles/403278.pdf
    Data publikacji:
    2019
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    closed vessel
    design analysis
    disruptor
    factor of safety
    finite element method (FEM)
    internal pressure
    power cartridge
    stress
    strain and water-jet disruptor
    Opis:
    This paper discusses the design analysis of closed vessel (CV) for power cartridge application in water-jet disruptor. In this article, various design theories are presented in which the vessel is subjected to internal pressure. CV is a kind of pressure vessel utilized to evaluate the performance of power cartridge used for water-jet application. It is a test vessel which generates pressure - time profile by burning the propellant. Energy derived from burning of the propellant of power cartridge aids in neutralizing Improvised Devices (IED's). This energy creates high water-jet plume in the disruptor. In order to evaluate various performance parameters of the cartridge, CV design plays a vital role in the research and development activities, including, development, life trials, production, lot proof trials and life extension / life revision trials. CV is one of the methodologies / techniques from which energy generated is measured in terms of the maximum pressure (Pmax) and the time to maximum pressure (TPmax). This paper also discusses about various design aspects using the finite element method (FEM) and their comparative results with different design theories. In the light of these theoretical, numerical, and experimental works, it was recommended that octahedral stress theory or van Mises theory should be used for vessel design. This satisfies the designer requirements. FEM analysis tool helps in reducing time & development cost.
    Źródło:
    Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2019, 10, 1 (35); 25-48
    2081-5891
    Pojawia się w:
    Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling of Post-Failure Behavior of the Rock Mass and its Effect on the Stress-Deformation State in the Vicinity of a Mining Excavation
    Autorzy:
    Marczak, Halina
    Powiązania:
    https://bibliotekanauki.pl/articles/102059.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    rock mass model
    modeling of excavations
    strain and displacement
    stress analysis
    elastic-plastic model with strain-softening
    Mohr-Coulomb criterion
    inelastic zones
    model masy skalnej
    modelowanie wykopów
    odkształcenie i przemieszczenie
    analiza naprężenia
    model sprężysto-plastyczny z miękkim odkształceniem
    kryterium Mohra Coulomba
    strefy nieelastyczne
    Opis:
    The study investigated the impact of post-failure properties of the rock mass on the stress-deformation state in the vicinity of the underground excavation and the pressure exerted on the support. An analytical solution to the problem was presented, including the creation of inelastic zones in the vicinity of the excavation: ideal-plastic zone with residual strength and plastic zone with mild decrease of rock medium strength and taking into account the dilatancy. The analysis of the obtained dependencies was carried out using geotechnical parameters characterizing the Carboniferous rock mass of a hard coal mine. The influence of the plastic zone was determined with a mild decrease in strength to the state of stress, deformation and pressure on the rock mass support. The results of the considerations were compared with the solution, which omitted the softening of the rock mass and the solution based on the model of the elastic-plastic-brittle medium. The results of the analysis broaden the knowledge on the behavior of the rock medium in the vicinity of the excavation. The obtained solution can be further developed in order to enable its practical application, especially under the conditions in which the behavior of the rock medium in the vicinity of the excavation well reflects the elastic-plastic model with a gentle drop in the strength of the rock material.
    Źródło:
    Advances in Science and Technology. Research Journal; 2019, 13, 2; 130-140
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of effective sealing units for oil and gas equipment in the oil and gas production system
    Opracowanie skutecznych zespołów uszczelniających dla urządzeń naftowych w systemie wydobywczym ropy i gazu
    Autorzy:
    Hasanov, Ilman I.
    Guliyev, Agali A.
    Powiązania:
    https://bibliotekanauki.pl/articles/31343886.pdf
    Data publikacji:
    2023
    Wydawca:
    Instytut Nafty i Gazu - Państwowy Instytut Badawczy
    Tematy:
    oil and gas equipment
    sealing element
    stress-strain state
    tightness
    self-sealing
    seizing value
    force-deformation
    physical wear
    durability
    urządzenia przemysłu naftowego
    element uszczelniający
    stan naprężenie-odkształcenie
    samouszczelnianie
    wartość zatarcia
    siła
    odkształcenie
    zużycie fizyczne
    trwałość
    Opis:
    The paper presents the results of many years of experience in studying the efficiency of sealing units in the conditions of their operation in the oil and gas production system, as well as the influence of technological parameters that ensure normal operation and protect them from failure due to leakage through the working surface of the seals in the friction zone. In addition, according to the results of practical studies, it has been established that, in order to improve the elastic properties, for example, of cup springs of a direct-flow valve, we calculated heat treatment of the operational values of spring compression for various material thicknesses. The work of the elastic elements of the packer was improved mainly by the design, and the optimal parameters for the development of the elastic element of the packer were determined. The study of the stress-strain state of the sealing element of packers during setting and improving its performance is of both practical and scientific interest. One of the factors that significantly affect operation of pumps is the fluid leakage in valve assemblies in order to identify the effect of the above parameters on tightness based on a preliminary theoretical analysis. Comparison of data during the study showed that the flow rate of work with low viscosities is greater than with high viscosities. The technological processes of hardening the parts of the shut-off assembly of X-mas tree valves, to increase their reliability, are considered. The dependence of the compression force of the spring and its deformation because of geometric parameters of the disk springs has been determined; it has been found that the residual deformation of the disk spring after collapse has a negative effect on tightness. Calculations show that the amount of leakage of the elastic elements in the sealing assembly should not exceed ≤0.309, since the seal at the value of elastic energy deformation provides a self-compacting mode. Thus, the degree of uneven pressing of the seat to the surface of the gate and its regulation to prevent leakage is practically determined.
    Artykuł przedstawia wyniki wieloletnich doświadczeń w badaniu skuteczności zespołów uszczelniających, w warunkach ich pracy w systemie wydobywczym ropy i gazu, jak również wpływ parametrów technologicznych zapewniających ich normalną eksploatację i zabezpieczających je przed awarią spowodowaną wyciekiem przez powierzchnię roboczą uszczelnienia w strefie tarcia. Ponadto, zgodnie z wynikami badań o charakterze praktycznym, ustalono, że aby poprawić właściwości sprężyste, np. sprężyn talerzowych zaworu bezpośredniego przepływu, obliczono obróbkę cieplną wartości eksploatacyjnych ściśnięcia sprężyny dla różnych grubości materiału. Praca elementów sprężystych uszczelniacza została poprawiona głównie dzięki projektowi oraz ustalono optymalne parametry dla budowy elementu sprężystego uszczelniacza. Badania stanu naprężenie-odkształcenie elementu uszczelniającego uszczelniacza w czasie posadowienia oraz poprawa jego działania są interesujące zarówno ze względów praktycznych, jak i naukowych. Jednym z czynników znacząco wpływających na pracę pomp jest wyciek płynu w zespołach zaworów, co pozwoliło na określenie wpływu powyższych parametrów na szczelność w oparciu o wstępną analizę teoretyczną. Porównanie danych w czasie badania wykazało, że prędkość przepływu pracy z niskimi lepkościami jest większa niż z wysokimi lepkościami. Rozważane są procesy technologiczne utwardzania części zespołu odcinającego zaworów choinkowych w celu zwiększenia ich niezawodności. Ustalono zależność siły ściskania sprężyny i jej odkształcenia ze względu na parametry geometryczne sprężyn talerzowych; stwierdzono, że odkształcenie resztkowe sprężyny talerzowej po zgnieceniu ma negatywny wpływ na szczelność. Obliczenia wykazują, że wielkość wycieku elementów sprężystych w zespole uszczelniającym nie powinna przekraczać ≤0,309, gdyż uszczelnienie przy wartości odkształcenia energii sprężystej zapewnia tryb samoczynnego zagęszczania. Tak więc stopień nierównomiernego dociśnięcia gniazda do powierzchni zasuwy i jego regulacja w celu przeciwdziałania wyciekowi został praktycznie określony.
    Źródło:
    Nafta-Gaz; 2023, 79, 7; 464-472
    0867-8871
    Pojawia się w:
    Nafta-Gaz
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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