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Wyszukujesz frazę "Strain" wg kryterium: Temat


Tytuł:
Strain distributions in group IV and III-V semiconductor quantum dots
Autorzy:
Wijewardena Gamalath, K. A. I. L.
Fernando, M.A.I.P.
Powiązania:
https://bibliotekanauki.pl/articles/411953.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
quantum dot
strain distribution
hydrostatic strain
biaxial strain
Opis:
A theoretical model was developed using GreenˇŚs function with an anisotropic elastic tensor to study the strain distribution in and around three dimensional semiconductor pyramidal quantum dots formed from group IV and III-V material systems namely, Ge on Si, InAs on GaAs and InP on AlP. A larger positive strain in normal direction which tends to zero beyond 6nm was observed for all three types while the strains parallel to the substrate were negative. For all the three types of quantum dots hydrostatic strain and biaxial strain along x and z directions were not linear but described a curve with a maximum positive value near the base of the quantum dot. The hydrostatic strain in x-direction is mostly confined within the quantum dot and practically goes to zero outside the edges of the quantum dot. For all the three types, the maximum hydrostatic and biaxial strains occur in x-direction around �{1nm and around 2nm in z-direction. The negative strain in x-direction although realtively weak penetrate more deeper to the substrate than hydrostatic strain.The group IV substrate gave larger hydrostatic and biaxial strains than the group III-V semiconductor combinations and InAs /GaAs was the most stable. The results indicated that the movements of atoms due to the lattice mismatch were strong for group III-V.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 2; 36-48
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Srain-concentration factor of internally pressurized thick-walled cylinders
Autorzy:
Tlilan, H. M.
Jawarneh, A. M.
Jawarneh, A.
Tarawneh, M.
Rababah, M.
Smadi, O. A.
Powiązania:
https://bibliotekanauki.pl/articles/264499.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
odkształcenie
naczynia
stres
vessels
stress
strain
strain concentration
Opis:
This study introduces a new definition of the strain-concentration factor (SNCF) of thick walled internally pressurized cylinders. The stress state has been considered in this new definition; i.e. triaxial and biaxial stress states for closed and open ends, respectively. Primarily, the curvature effect of the strain concentration has been studied here. To this end, the inner radius of the employed cylinders has been changed from 0.5 to 50.8 mm. On the other hand, the thickness has been kept constant at 16.7 mm. Moreover, the thickness has been fragmented to 37 elements to study the thickness effect for each case. The results show that the tangential (hoop) strain regularly spread over the whole thickness. It has been revealed that the maximum value of the tangential strain occurs on the inner surface of the cylinder. In particular, it rapidly decreases from a maximum value on the inner surface to reach its minimum value on the outer surface, which is nearly equal to the average value of hoop strain through the thickness. The results also demonstrate that tangential strain values decrease with the increase of the inner radius for any thickness. It is clear that the rate of decrease of the hoop strain changes abruptly with decreasing the inner radius of the cylinder. This led to localization of the strain concentration on the inner surface of the cylinder due to curvature, making the values of the strain concentration factor very high on the inner surface of the cylinder. In addition, the strain concentration factor decreases through the thickness of the cylinder from the inner to outer surfaces, and the rate of the decrease is increasing with a decreasing inner radius of the cylinder. The current results introduce the serious effect of the curvature on the strain concentration even if there are no irregularities in the cylinder.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 143-159
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Estimation of Fatigue Crack Initiation Life of H62 Brass
Autorzy:
Zheng, M.
Zhang, S.
Peng, Xiao Jian
Wang, Yi
Powiązania:
https://bibliotekanauki.pl/articles/2048866.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
strain energy density
fatigue damage strain
theoretical strain fatigue limit
fatigue crack initiation
life prediction
Opis:
In the present paper, the excavation of the energetic approach that estimates the fatigue crack initiation life of metal is conducted for H62 brass. The benefit of the energetic approach is the division of the actual applied strain range Δε into two parts, that is, a damage strain range Δεd that induces fatigue damage within the metal, and an undamaged strain range Δεc, which does not produce fatigue damage of the metal and corresponds to theoretical strain fatigue limit. The brightness of this approach is that the undamaged strain range Δεc can be estimated by the fundamental conventional parameters of metal in tensile test. The result indicated that the fatigue crack initiation life of H62 brass can be estimated by this approach successfully.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 31-35
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Diffraction Strain Sensor Prepared by Interference Lithography
Autorzy:
Zabila, Y.
Horeglad, P.
Krupiński, M.
Zarzycki, A.
Perzanowski, M.
Maximenko, A.
Marszałek, M.
Powiązania:
https://bibliotekanauki.pl/articles/1030666.pdf
Data publikacji:
2018-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
Strain
direct laser interference patterning
optical strain sensor
diffraction grating
Poisson ratio
Kapton
flexible
optical strain gauge
Opis:
An optical strain sensor was developed for use in stretchable electronics. It consists of a diffraction grating formed directly on the examined surface illuminated by a laser beam which creates interference pattern. This pattern can then be used to determine axial and lateral strains for a uniaxial stress states. Direct laser interference patterning was employed as a fast processing tool for the preparation of micro- and sub-microgratings. Two coherent beams of Nd:YAG laser with 532 nm wavelength and pulse duration of 10 ns were used to selectively remove material from the irradiated sample surface. This technique creates periodic pattern on the metallized surface of polymeric substrates. New sensors formed by direct laser interference patterning method were able to resolve higher order diffraction maxima, which would be of benefit for strain measurement application. Experimental setup for tensile tests was composed of laser probe, the sensor element, and CCD camera. To extract strain values, we analysed acquired interference pattern images in real time software, developed with LabVIEW environment. This kind of contactless strain sensor is suitable for examination of stretchable electronics component for which conventional tensile tests are either not acceptable or can interfere with its normal operation.
Źródło:
Acta Physica Polonica A; 2018, 133, 2; 309-312
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical and Ultrasonographic Model of the Left Ventricle : in Vitro Studies
Autorzy:
Olszewski, R.
Trawiński, Z.
Wójcik, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/176705.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
left ventricle
echocardiography
speckle modeling
ultrasound phantoms
strain
strain rate
Opis:
The main objective of this study is to develop an echocardiographic model of the left ventricular and numerical modeling of the speckles- markers tracking in the ultrasound (ultrasonographic) imaging of the left ventricle. The work is aimed at the creation of controlled and mobile environment that enables to examine the relationships between left ventricular wall deformations and visualizations of these states in the form of echocardiographic imaging and relations between the dynamically changing distributions of tissue markers of studied structures.
Źródło:
Archives of Acoustics; 2012, 37, 4; 583-595
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical-Experimental Research on Some Parameters of Hip and Knee Endoprostheses, Determining Value and Form of Contact Stress Between their Elements
Autorzy:
Nabrdalik, Marcin
Sobociński, Michał
Powiązania:
https://bibliotekanauki.pl/articles/2048862.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
endoprosthesis
stress
strain
FEM
Opis:
The paper presents Finite Elements Method numerical analysis of strength of friction pairs most often used in hip and knee joints alloplasty. Analytic solutions are to indicate and define the areas where damages or premature wear of cooperating elements may occur. Analytical-experimental research states complete and thorough analysis. Accurate technical simulation of the joints of the human motor system, is difficult to conduct due to high level of complexity of human bio-bearings. All attempts to simulate the work of human joints, lead only to an approximate reflection of real human joint motion. To properly face the above problems, along with numerical analysis, there have been conducted empirical tests on the simulator of knee joint endoprosthesis.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 277-282
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of the strain distribution underneath the surface of polyethylene flat and spherical inserts with metal sled
Autorzy:
Nabrdalik, M.
Powiązania:
https://bibliotekanauki.pl/articles/122836.pdf
Data publikacji:
2014
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
strain
endoprosthesis
odkształcenie
endoproteza
Opis:
Most of the mechanical failures in alloplasty are caused by material fatigue. To cut down the risk of it, we can either increase the fatigue resistance of the material or decrease the load strain. All presented numerical calculations allow to draw quality conclusions concerning the influence of some parameters of endoprostheses on the values of stress and strain that are formed in polyethylene inserts.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2014, 13, 4; 97-102
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of plastic strain localization on the basis of strain and temperature fields
Analiza lokalizacji odkształcenia plastycznego na podstawie pola odkształceń i pola temperatury
Autorzy:
Maj, M.
Oliferuk, W.
Powiązania:
https://bibliotekanauki.pl/articles/356157.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
plastic strain localization
strain field
temperature field
infrared thermography
heat transfer
Opis:
In the present paper the onset of plastic strain localization was determined using two independent methods based on strain and temperature field analysis. The strain field was obtained from markers displacement recorded using visible light camera. In the same time, on the other side of the specimen, the temperature field was determined by means of infrared camera. The objective of this work was to specify the conditions when the non-uniform temperature distribution can be properly used as the indicator of plastic strain localization. In order to attain the objective an analysis of strain and temperature fields for different deformation rates were performed. It has been shown, that for given experimental conditions, the displacement rate 2000 mm/min is a threshold, above which the non-uniform temperature distribution can be used as the indicator of plastic strain localization.
W niniejszej pracy początek lokalizacji odkształcenia plastycznego wyznaczono przy użyciu dwóch niezależnych metod bazujących na analizie pola odkształceń i pola temperatury. Pole odkształceń wyznaczono na podstawie przemieszczeń markerów zarejestrowanych przy użyciu kamery w świetle widzialnym. Jednocześnie, na przeciwległej powierzchni próbki wyznaczano pole temperatury przy użyciu kamery podczerwieni. Celem niniejszej pracy było określenie warunków, w których niejednorodny rozkład temperatury może być użyty, jako wskaźnik lokalizacji odkształcenia plastycznego. Aby osiągnąć postawiony cel, przeprowadzono analizę pola odkształceń i pola temperatury dla różnych prędkości deformacji. Pokazano, ze dla zadanych warunków eksperymentu, prędkość przemieszczenia 2000 mm/min, stanowi próg, powyżej którego niejednorodne pole temperatury może być używane, jako wskaźnik lokalizacji odkształcenia plastycznego.
Źródło:
Archives of Metallurgy and Materials; 2012, 57, 4; 1111-1116
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strain Measurements in Free Tube Hydroforming Process
Autorzy:
Sadłowska, H.
Morawiński, Ł.
Jasiński, C.
Powiązania:
https://bibliotekanauki.pl/articles/351278.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
strain measurement
hydroforming
stereovision
Opis:
The paper presents a method of measuring deformations of cylindrical samples on the testing machine for free tube hydroforming experiments. During experiments a sample made of a thin-walled metal tube is expanded by the internal pressure of the working liquid and additionally subjected to axial compression. This results in a considerable circumferential deformation of the tube and its shortening. Analysis of the load cases and their impact on the deformations can be helpful in determining e.g. tube material properties or general limiting conditions in the tube hydroforming process. In connection with the above, the value of deformations and knowledge of their course during experiment has become one of the most important problems related to the issue described above.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 1; 257-263
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Work stress among workers of a Moroccan company
Autorzy:
Arji, Samira
Elhaddadi, Mounia
Touhami Ahami, Ahmed Omar
Ziri, Rabea
Powiązania:
https://bibliotekanauki.pl/articles/29519209.pdf
Data publikacji:
2023-03-18
Wydawca:
Fundacja Edukacji Medycznej, Promocji Zdrowia, Sztuki i Kultury Ars Medica
Tematy:
work stress
iso-strain
job-strain
decision latitude
psychological demand
social support
Opis:
Work stress or job-strain and iso-strain are perceived when there is a conflict between the demands placed on a person and their resources to cope with them. They have negative effects on worker health, and organizational productivity and performance. Our study consists of evaluating work stress and its components. 102 workers of different functions (senior managers, supervisors, technicians and executing workers) volunteered and were invited to complete anonymously the Karasek questionnaire (JCQ). The analysis of the results showed a significant prevalence of iso-strain and job-strain. Thus, low decision latitude and high psychological demands are the most widespread stress factors. These results show the need to disseminate information and prevention programs against work stress to managers and staff to ensure the effective performance of a company.
Źródło:
Acta Neuropsychologica; 2023, 21(1); 33-42
1730-7503
2084-4298
Pojawia się w:
Acta Neuropsychologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tensometryczne pomiary odkształceń w poszczególnych warstwach laminatów wzmacnianych włóknami aramidowymi
Strain gauges measurements in particular laminate layers reinforced by aramid fibers
Autorzy:
Schmidt, S.
Jaros, W.
Żółkiewski, S.
Powiązania:
https://bibliotekanauki.pl/articles/408969.pdf
Data publikacji:
2010
Wydawca:
Politechnika Śląska
Tematy:
laminat
tensometria oporowa
włókno aramidowe
odkształcenia
laminate
strain gauge transducer
aramid fibres
strain
Opis:
W niniejszej pracy porównano dwie metody badawcze elementów kompozytowych, stosowanych w badaniach wytrzymałościowych. W pierwszej metodzie - doświadczalnej, wykorzystano tensometry oporowe oraz wzmacniacz tensometryczny niemieckiej firmy Hottinger Baldwin Messtechnik MGCPlus AB22A i oprogramowanie Catman. Natomiast do badań modelowych wykorzystano zaawansowany program graficzny Unigraphics NX 7.
This paper presents deformations tests of particular layers of laminates reinforced with Kevlar material. In order to carry out the examination a sample made of four layers of above mentioned material was created. For measuring the deformation, the strain gauges were used. They were placed between layers of the laminate during its manufacture. On the basis of obtained results Young's modulus of the sample was determined.
Źródło:
Wybrane Problemy Inżynierskie; 2010, 1; 98-100
2083-1021
Pojawia się w:
Wybrane Problemy Inżynierskie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Landing gear dynamic tests with strain gages
Autorzy:
Sobieszek, A.
Paprzycki, I.
Tywoniuk, A.
Powiązania:
https://bibliotekanauki.pl/articles/245070.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
landing gear test
dynamic test
load measurement
strain gage instrumentation
strain gage installation
Opis:
Strain gage sensing is widely used method for measurements conducted during dynamic tests. This article describes electrical resistance strain gages performing force measurement during the tests of main and nose landing gear of medium-lift civil aircraft. It is the most common method used for measuring mechanical properties like force, pressure, stress, strain, etc. Strain gages were installed in selected areas of the Drop Test Stand. The paper presents advantages of strain gage measuring method in regards to commercially available, ready-made force sensors. Furthermore, it describes the process of selecting strain gage and load cell measurement systems (bridge, half bridge, quarter bridge) and its influence on the test results. What is more the technological process is presented, taking into account the strain gage installation adhesive technology and sensor protection against external conditions, performance of the measurement system and connection to the data acquisition system. Continuing with the process description of calibrating a load cell system for measuring the occurring forces. The article is summed up with an analysis of the problems which arise during the installation and measurement process using strain gages, and includes a description of advantages and disadvantages that occur while applying strain gages while preforming force measurement.
Źródło:
Journal of KONES; 2015, 22, 3; 221-227
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Long-distance Running and its Effects on Cardiorespiratory Adaptation and Physiological Strain in Marathon Runners
Autorzy:
Przybyła, Katarzyna
Żebrowska, Aleksandra
Posmysz, Anna
Manowska, Beata
Pokora, Ilona
Żak, Agata
Powiązania:
https://bibliotekanauki.pl/articles/1054890.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
marathon
physiological strain index
spirometry
Opis:
Popularity of long-distance running has increased as well as number of female and male marathon runners. Whilst research into physiological characteristics of endurance trained athletes has significantly increased there are only few studies on the risk factors for respiratory failure in marathon runners. Therefore, the aim of the study was to evaluate the differences in respiratory function and the physiological strain in the response to exercise stress in marathon runners. Twenty three subjects (aged 36.1 ±11.6 years) participated in a marathon running. Prior to the run and after its completion, body mass and composition, spirometry and body temperature were measured. Based on pre- and post-run temperature and changes in heart rate, the physiological strain index (PSI) was calculated. Long-distance running significantly decreased the temperature of body surfaces (p < 0.05); no significant effects were observed regarding aural canal temperature and physiological strain index (PSI). Compared to resting values, post-marathon spirometry revealed a significant decrease in post-marathon forced expiratory volume (p < 0.05), peak expiratory flow (p < 0.05) and maximal expiratory flow values (p < 0.05). In conclusion, the long-distance running results in functional changes within the respiratory system which may limit the adaptive potential and decrease exercise tolerance.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2016, 13, 1; 81-87
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena przydatności szczepów drożdży wyizolowanych z kefirów do syntezy polimerów zewnątrzkomórkowych
Evaluate the ability of the yeast strains isolated from kefir for the synthesis of extracellular polymers
Autorzy:
Gientka, I.
Madejska, A.
Powiązania:
https://bibliotekanauki.pl/articles/807023.pdf
Data publikacji:
2013
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
drozdze
szczepy drozdzy
kefir
izolacja
identyfikacja
przydatnosc do syntezy
polimery zewnatrzkomorkowe
synteza
yeast
yeast strain
strain isolation
strain identification
extracellular polymer
synthesis
Opis:
Celem niniejszej pracy było scharakteryzowanie zdolności do wytwarzania polimerów zewnątrzkomórkowych przez szczepy drożdży kefirowych. Zakres pracy obejmował izolację szczepów drożdży z kefirów, ich identyfikację, badanie ilości wytworzonych EPS i analizę morfologii komórek w czasie 48-godzinnej hodowli wytrząsanych w podłożach YPD oraz YM. Wyizolowano 11 różnych szczepów, wśród których zidentyfikowano: 2 szczepy Candida guilliermondii oraz Candida famata, Candida kefyr, Candida inconspicua, Cryptococcus humicolus, Cryptococcus albidus, Kluyveromyces lactis, Saccharomyces cerevisiae oraz Geotrichum penicillatum. Wszystkie badane drożdże wytworzyły polimery zewnątrzkomórkowe, a ich zawartość w płynach pohodowlanych zależała od rodzaju szczepu i podłoża. Najwięcej polimerów, około 1200 mg w jednym dm3 podłoża YPD, oznaczono po hodowli szczepów Geotrichium penicillatum, Saccharomyces cerevisiae oraz szczepu nr 11. Skład podłoża YM niekorzystnie wpływał na syntezę EPS, ale jednocześnie był przyczyną zwiększonego plonu biomasy wszystkich badanych szczepów. W podłożu YPD uzyskano większą wartość EPS w przeliczeniu na 1 g s.s. biomasy.
The aim of this study was to characterize the ability to produce extracellular polymers by strains of yeast kefi r. The work included the isolation of yeasts from kefi r, their identifi cation, examination of the amounts of EPS and analysis of cell morphology during 48 h shake culture in YPD and YM medias. It was isolated 11 different strains and identifi ed: two strains of Candida guilliermondii and Candida famata, Candida kefyr, Candida inconspicua, Cryptococcus humicolus, Cryptococcus albidus, Kluyveromyces lactis, Saccharomyces cerevisiae and Geotrichum penicillatum. All tested strains produced extracellular polysaccharides and their contents after incubation depend on the type of strain and substrate. About 1200 mg exopolymers in one dm3 of YPD medium were determined after cultivation of strains of Geotrichium penicillatum, Saccharomyces cerevisiae and strain no. 11. The composition of the substrate YM adversely affect the synthesis of EPS but also increased the biomass yield of all the tested strains. Compare to YM medium from 1 g d.m. biomass on YPD medium was more exopolymers obtained.
Źródło:
Zeszyty Problemowe Postępów Nauk Rolniczych; 2013, 574
0084-5477
Pojawia się w:
Zeszyty Problemowe Postępów Nauk Rolniczych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Przygotowanie mianowanych zawiesin szczepów wzorcowych znajdujących zastosowanie w badaniach mikrobiologicznych
Autorzy:
Mysłowska, K.
Bucała-Śladowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/273858.pdf
Data publikacji:
2016
Wydawca:
Roble
Tematy:
szczepy odniesienia
zawiesina szczepu odniesienia
badania mikrobiologiczne
reference strain
reference strain suspension
microbiological testing
Źródło:
LAB Laboratoria, Aparatura, Badania; 2016, 21, 3; 14-18
1427-5619
Pojawia się w:
LAB Laboratoria, Aparatura, Badania
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of production chains as a tool for intelligent manufacturing in metal forming
Autorzy:
Madej, L.
Weglarczyk, S.
Rauch, L.
Pietrzyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/1429427.pdf
Data publikacji:
2008
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
life cycle modelling
strain localization
Opis:
The objective of the paper is demonstration of the role of multi scale modelling in the system, which optimizes the whole production chain. Product exploitation and properties are the key parameters for formulation of the objective function in the optimization problem. Such parameters as fatigue resistance, wear resistance or thermal resistance are crucial for extending the life cycle of products, therefore, theoretical prediction of those parameters is inevitable for the optimization of the manufacturing system. Thus, the main focus in the paper is on description of the idea of multi scale modelling and on presentation of the multi scale model developed by the Authors. This model combines finite element (FE) solution of the macro scale problem with the cellular automata (CA) model of the micro scale phenomena. Simulation of the production chain is the second part of the paper. The chain under consideration is composed of stock heating, cold forging, machining and simulation of exploitation conditions. The correlation between the process parameters and the exploitation properties of the product is demonstrated. Finally, the optimization problem which would be the base of intelligent manufacturing, is formulated.
Źródło:
Journal of Machine Engineering; 2008, 8, 2; 33-42
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of solutions for microseismic focal mechanism estimation
Autorzy:
Wandycz, P.
Święch, E.
Pasternacki, A.
Powiązania:
https://bibliotekanauki.pl/articles/184552.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
stress condition
strain conditions
subsurface
Opis:
One of the major advantages of microseismic data, recorded during hydraulic fracturing of prospective shale intervals is ability to use both P and S wave in the analysis, not only to determine epicentral locations of events but also to describe source itself. The information about the mechanisms of located microseismic events allows better understanding of in situ stress and strain conditions and the local subsurface geomechanical properties and forces (Kamei et al. 2015). As Duncan stated in his work, a proper characterization of the observed events mechanisms is the key to understand radiation pattern of the signals in the investigated area (Duncan & Eisner 2010). Moreover, an understanding of the nature of the rock failure supports reservoir simulation models and stimulated reservoir volume estimates (Kratz & Thorton 2016). Proper assessment of event strike, dip and rake provides the geometry of the fracture plane assuming double couple focal mechanism, while full moment tensor inversion provides information about shear and tensile nature of the calculated mechanisms. The common method to obtain reliable focal mechanisms of observed microseismic events is decomposing of the full moment tensor. Seismic moment tensor is powerful tool which provides a general mathematical solution of sources that can be used to distinguish between various types of microseismic events. The method comes to reliably estimation of the six independent components of a full moment tensor by lestsquares inversion (Eaton & Forouhideh 2010). The motivation for this analysis was to determine microseismic focal mechanisms based on P – wave peak amplitude, P and S – waves peak amplitudes and S – wave peak amplitude only to estimate the differences and uncertainties between these three different solutions. Furthermore authors decided to check how the mechanisms changes with different geometries of downhole monitoring array. In this study only synthetic data computed in MiVu GeoTomo software using raytracing method and simple layered velocity model were used. The mentioned velocity model was constructed based on well logs data delivered by PGNiG from measurements done in Northern Poland where active exploration of shale gas takes place. In this analysis authors focused only on double couple (DC) and compensated linear vector dipole (CLVD) mechanisms which are two most common types of microseismic focal mechanisms occur during hydraulic fracturing of shale deposits. Performed analysis proved that the best and most consistent results with the lowest uncertainties reflected in the condition number parameter can be obtained by using both P and S peak amplitudes.
Źródło:
Geology, Geophysics and Environment; 2016, 42, 1; 137-138
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction between edge dislocation and inhomogeneity of an arbitrary shape and properties under coupled thermomechanical strains
Autorzy:
Sun, Yang
Li, Ang
Shi, Lan
Liu, Mabao
Powiązania:
https://bibliotekanauki.pl/articles/1839691.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
thermomechanical strain
edge dislocation
inhomogeneity
Opis:
In this work, a general approximate solution for the configurational force between edge dislocation and inhomogeneity of an arbitrary shape and properties with coupled thermo- mechanical loads was developed on the basis of the Eshelby equivalent inclusion theory. The effect of temperature-dependent elastic properties, thermal expansion coefficient and yield strength on the configurational forces was analyzed. Furthermore, the configurational force considered to be the driving force for dislocation migration was innovatively used to investigate the interaction mechanism between graphene and internal defects of a metal.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 1; 121-133
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dydaktyczny system pomiarowy do współpracy z czujnikami tensometrycznymi
Didactic measuremt system for cooperation with strain gauge sensors
Autorzy:
Furmankiewicz, Leszek
Sawicki, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/2031396.pdf
Data publikacji:
2021
Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Tematy:
wzmacniacz tensometryczny
pomiary mostkowe
pomiary tensometryczne
strain gauges amplifier
bridge measurement system
strain gauge measurement
Opis:
W artykule przedstawiono projekt i budowę systemu pomiarowego przystosowanego do współpracy ze stanowiskiem dydaktycznym, znajdującym się na wyposażeniu Laboratorium Przetworników i Systemów Pomiarowych Instytutu Metrologii, Elektroniki i Informatyki Uniwersytetu Zielonogórskiego. Zaproponowany system pozwala na badania tensometrów i układów mostkowych. Składa się on ze stanowiska dydaktycznego, rozbudowanego wzmacniacza tensometrycznego oraz aplikacji na komputer PC, która pozwala na sterowanie tym wzmacniaczem poprzez interfejs szeregowy. Artykuł zawiera: koncepcję systemu pomiarowego, strukturę blokową wzmacniacza, rozwiązania techniczne wybranych bloków funkcjonalnych, wyniki badań torów pomiarowych oraz właściwości aplikacji przeznaczonej do współpracy z urządzeniem.
The paper presents an extended structure and construction of a measurement system for cooperation with the training stand located in the laboratory of the Institute of Electrical Metrology, Electronics and Computer Science, of the University of Zielona Góra. The measurement system allows testing of strain gauges and bridge systems. The system consists of three independent components: the training stand, an advanced strain gauges amplifier and a server. The training stand allows to determine the sensors characteristics as a function of a metal bar deflection and allows to study the influence of the temperature on the work of the strain gauges. The advanced strain gauges amplifier is a multifunctional device, capable of measuring differential voltage, resistance, current and temperature. The precision operational amplifiers and reference voltage sources used during the construction of the instrumentation amplifier allowed to obtain the accuracy of the measurement at a level close to the average class of measuring equipment. The modular structure of the system enables the construction of various measurement systems, where it is necessary to measure voltage, current, resistance or temperature.
Źródło:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2021, 73; 17-22
1425-5766
2353-1290
Pojawia się w:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Functional behavior of pseudoelastic niti alloy under variable amplitude loading
Autorzy:
Iasnii, Volodymyr
Yasniy, Petro
Lapusta, Yuri
Yasniy, Oleg
Dyvdyk, Oleksandr
Powiązania:
https://bibliotekanauki.pl/articles/1837926.pdf
Data publikacji:
2020
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
pseudoelastic alloy
NiTi alloy
functional fatigue
variable amplitude loading
strain range
residual strain
dissipation energy
Opis:
Cyclic loading of superelastic NiTi shape memory alloy (SMA) causes forward and reverse austenite–martensіte transfor-mations, and also increases the volume of stabilized martensite. This appears in the change of stress-strain curve form, the decrease of dissipation energy, and increase of residual strain, that is, named transformation ratcheting. In real structures, the SMA components in most cases are under the action of variable amplitude loading. Therefore, it is obvious that the loading history will influence the functional fatigue. In the present work, the effect of stress ratio on the functional properties of superelastic NiTi shape memory alloy under variable amplitude loading sequence with two blocks was investigated. The studies were carried out under the uniaxial tension of cy-lindrical specimens under load-full unload and load-part unload. The change of residual strain, strain range, dissipation, and cumulative dissipation energy density of NiTi alloy related to load sequences are discussed. Under both stress ratios, the residual strain in NiTi alloy is increased depending on the number of loading cycles on the high loading block that is similar to the tests at constant stress or strain amplitude. An unusual effect of NiTi alloy residual strain reduction with the number cycles is found at a lower block loading. There was revealed the effect of residual strain reduction of NiTi alloy on the number of loading cycles on the lower amplitude block. The amount of decrement of the residual strain during a low loading block is approximately equal to the reversible part of the residual strain due to the stabilized martensite. The decrease of the residual strain during the low loading block is approximately equal to the reversible part of residual strain due to the stabilized martensite. A good correlation of the effective Young’s modulus for both load blocks with residual strain, which is a measure of the volume of irreversible martensite, is observed.
Źródło:
Acta Mechanica et Automatica; 2020, 14, 3; 154-160
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Filler Surface Modification on Static and Dynamic Mechanical Responses of Rice Husk Reinforced Linear Low-Density Polyethylene Composites
Autorzy:
Omar, Mohd Firdaus
Al Bakri Abdullah, Mohd Mustafa
Ting, Sam Sung
Jeż, Bartłomiej
Nabiałek, Marcin
Md Akil, Hazizan
Zulkepli, Nik Noriman
Abd Rahim, Shayfull Zamree
Azmi, Azida
Powiązania:
https://bibliotekanauki.pl/articles/2106572.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silane coupling agents
strain rate
universal testing machine
split Hopkinson pressure bar
strain rate sensitivity
Opis:
Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s-1, 0.01 s-1 and 0.1 s-1) and dynamic loading rates (650 s-1, 900 s-1 and 1100 s-1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 2; 507--519
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Локальная устой чйвость плоскйх многограннйков сетчатых куполов
Local stability of flat polyhedrons of mesh domes
Autorzy:
ДРАГАН, В. И.
ГЛУШКО, К. К
Powiązania:
https://bibliotekanauki.pl/articles/1203945.pdf
Data publikacji:
2016
Wydawca:
Centrum Rzeczoznawstwa Budowlanego Sp. z o.o.
Tematy:
stress-strain state
fragment
mesh dome
Opis:
The dependences for determining the stress-strain state of a fragment of a mesh dome. These formulas are valid for the case of constant-largest hub load on a mesh dome. Experimentally determined tense and strained state of the dome fragment. The proposed method has a good agreement with the experimental results.
Źródło:
Modern Engineering; 2016, 1; 82-93
2450-5501
Pojawia się w:
Modern Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of a constant state of deformation on the friction coefficient in selected thermoplastics (polymer–steel pair)
Wpływ utrzymywanego stanu odkształcenia wybranych polimerów termoplastycznych na współczynnik tarcia po stali
Autorzy:
Kujawa, M.
Wieleba, W.
Powiązania:
https://bibliotekanauki.pl/articles/190368.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
strain
hardness
tension
odkształcenie
twardość
rozciąganie
Opis:
The effect of tensile deformation on polymer structures and their mechanical properties is described in various papers. However, the majority of articles are focused on high deformation (a few hundred percentiles) at increased temperature. It causes changes in orientation and the crystallinity ratio. The authors of this paper asses the influence of strain (max. 50%) on hardness and the coefficient of friction (polymer–steel A1 couple) for selected polymers. The deformation was conducted at room temperature and maintained during tests. There was a significant reduction (up to 50%) of hardness after deformation, in the case of all examined polymers. In the case of PE-HD, the coefficient of kinetic friction almost doubled its value (89% increase). The reduction of the coefficient of static friction for sliding pairs that include PTFE and PA6 was about 26% (in comparison with non-deformed polymer). For all investigated polymers, hardness increased over time (up to 40% after 24 hours). Coefficients of static and kinetic friction decreased in 24 hours (up to 29% coefficient of static friction and 19% coefficient of kinetic friction). The research shows that a small deformation causes changes in polymer properties. Moreover, these changes appear at room temperature directly after deformation.
Wpływ rozciągania na strukturę polimeru i jego właściwości jest szeroko opisany w literaturze. Jednakże publikacje dotyczące tej tematyki skupiają się na znacznych odkształceniach (kilkaset %) przy podwyższonej temperaturze. Zabieg ten powoduje orientację struktury i zmianę stopnia krystaliczności. Autorzy tej publikacji przebadali wpływ odkształcenia (max. 50%) na twardość i współczynnik tarcia po stali (A1). Próbki były rozciągane w temperaturze pokojowej, a odkształcenie utrzymywano podczas badań. W przypadku wszystkich badanych polimerów zaobserwowano znaczące zmniejszenie twardości po odkształceniu (aż do 50%). Dla pary PE-HD – stal (A1) po odkształceniu polimeru współczynnik tarcia kinetycznego niemalże podwoił swoją wartość (zwiększenie o 89%). Zmniejszenie współczynnika tarcia wynosiło do 26% dla par zawierających PTFE i PA6. Wraz z upływem czasu zwiększała się twardość polimerów (o maksymalnie 40% po 24 godzinach). Wartości współczynników tarcia statycznego i kinetycznego zmniejszyły się maksymalnie o odpowiednio 29% i19%. Badania ukazują, że nawet stosunkowo niewielkie odkształcenie powoduje zmiany właściwości polimeru. Ponadto modyfikacje pojawiają się bezpośrednio po odkształceniu w temperaturze pokojowej.
Źródło:
Tribologia; 2017, 274, 4; 39-45
0208-7774
Pojawia się w:
Tribologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of piezoelectric transducer to glass fiber reinforced composite stiffness
Autorzy:
Rządkowski, W.
Suprynowicz, K
Pyrzanowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/102215.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
piezo material
stiffness
piezoelectric strain sensor
Opis:
The main goal was to determine if transducers based on piezoelectric materials are suitable for strain calculations in thin GFRP specimens. Numerous experimental studies, both physical and numerical, performed by the authors, have shown that there is a huge influence of bonded piezoelectric transducer on the overall stiffness of the measured object. The paper presents tensile test performed on strength machine with Digital Image Correlation strain and deflection observations. Test were compared with FEM models for detailed investigation. The main conclusion is piezoelectric transducers has huge influence on local stiffness of measured object. That is critical especially when they are used as strain sensors, when presence of sensor is influencing to measured results.
Źródło:
Advances in Science and Technology. Research Journal; 2015, 9, 27; 106-111
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł

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