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Tytuł:
Analysis of lateral vibrations of the axially loaded helical spring
Autorzy:
Michalczyk, K.
Powiązania:
https://bibliotekanauki.pl/articles/279466.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
helical spring vibrations
axially loaded spring
coil spring
Timoshenko equivalent beam
Opis:
It is shown in this paper that the proposed concept by Krużelecki and Życzkowski (1990) of the equivalent rod can be applied in calculations of natural lateral vibrations of springs and that the obtained results will be nearer FEM results than the standard model based on the Timoshenko equivalent beam. The model, created on this base, allows one to calculate natural frequencies of the clamped-clamped spring. It is also shown that models based on the equivalent beam concept, which are easier to apply than the models treating the spring as the spatially curved rod, have only a slightly smaller accuracy. It is also indicated that in the most common practice making of manufacturing end coils of springs, the natural frequencies differ significantly from the frequencies calculated by means of all tested methods. The performed simulations show that differences between the first and the second as well as the third and the fourth natural frequency of the spring are small and, therefore, the axially symmetrical equivalent beam model can be used without a large error. The diagram allowing one to determine whether the desired frequencies are lower or higher than the cut-off frequency is developed for the presented model.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 745-755
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modelling of metal-elastomer spring nonlinear response for low-rate deformations
Autorzy:
Sikora, W.
Michalczyk, K.
Machniewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/386307.pdf
Data publikacji:
2018
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
bergström-boyce model
neidhart’s spring
metal-elastomer spring
FEM
SBR rubber
nonlinear spring
Opis:
Advanced knowledge of mechanical characteristics of metal-elastomer springs is useful in their design process and selection. It can also be used in simulating dynamics of machine where such elements are utilized. Therefore this paper presents a procedure for preparing and executing FEM modelling of a single metal-elastomer spring, also called Neidhart’s spring, for low-rate deformations. Elastomer elements were made of SBR rubber of two hardness values: 50°Sh and 70°Sh. For the description of material behaviour the Bergström-Boyce model has been used.
Źródło:
Acta Mechanica et Automatica; 2018, 12, 1; 31-37
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
REGULAR D-OPTIMAL SPRING BALANCE WEIGHING DESIGNS: CONSTRUCTION
Autorzy:
Ceranka, Bronisław
Powiązania:
https://bibliotekanauki.pl/articles/656991.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
D-optimal design
spring balance weighing design
Opis:
Spring balance weighing design there is the model of experiment in that the result of experiment we can present as linear combination of unknown measurements of objects with factors of this combination equal to zero or one. In the paper we consider such designs under the basic assumption that the errors of measurements are uncorrelated and they have different variances, that means the measurements are taken in different conditions or by used different measurement equipment. We consider D-optimal designs , i.e. the designs in that the determinant of the information matrix for the design attains the maximal value. We give the bounds of its value according to the number of objects in experiment, is it odd or even. The theoretical considerations we illustrate with example of construction of respectively design.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2014, 3, 302
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cyanobacteria microflora in a limestone spring (Troniny spring, Central Poland)
Autorzy:
Nowicka-Krawczyk, P.B.
Zelazna-Wieczorek, J.
Powiązania:
https://bibliotekanauki.pl/articles/57145.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
Cyanoprokaryota
microflora
species composition
species richness
limestone spring
crenobiont
Troniny village
Central Poland
Opis:
The paper reports a study of cyanobacterial diversity in a cold-water limestone limnocrene in Central Poland. Samples were collected from 1998 to 2000 and in June 2012. The morphology, population characteristics and species composition of the cyanobacteria assemblages were investigated, and the frequency of taxa was recorded. The large number of taxa identified (30) reflects the microhabitat heterogeneity of this spring. Some species considered epiphytes grew on limestone rocks. The occurrence of the majority of the most frequent taxa was related to the physicochemical characteristics of the spring, but none of them can be considered obligatory crenobionts characteristic of limestone springs. The studied spring is a unique ecosystem with an interesting cyanobacteria microflora whose occurrence is attributable to the spring’s water chemistry, low temperature and variety of microhabitats.
Źródło:
Acta Societatis Botanicorum Poloniae; 2013, 82, 3
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variability of spring riverflow of selected lowland rivers
Autorzy:
Piętka, Izabela
Mikulska, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2034234.pdf
Data publikacji:
2010-06-01
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Tematy:
spring flow
discharge
lowland rivers in Poland
Opis:
This paper aims at identification of changes in the spring discharge of six lowland rivers in Poland in 1966-2006. The contribution of the spring flow (February, March, April) in the annual flow was analysed as well as the 0.95 quantile time series of the daily flow. To investigate how the date of the occurrence of the spring riverflow changes, for each hydrological year the day up to which 50% of the annual flow had been reached was determined (CMD, the center of mass data). A test based on linear regression was applied, which determined the direction and rate of the changes. In five rivers, a statistically insignificant tendency to increase the contribution of the spring flow in the annual flow has been observed. A decreasing tendency in the spring discharge of all rivers has been shown; in two cases the changes are statistically significant. The tendencies in the CMD time series are not consistent.
Źródło:
Miscellanea Geographica. Regional Studies on Development; 2010, 14; 177-183
0867-6046
2084-6118
Pojawia się w:
Miscellanea Geographica. Regional Studies on Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Arab Spring and its influence on European Union Policy
Autorzy:
Araźna, Marzena
Powiązania:
https://bibliotekanauki.pl/articles/576191.pdf
Data publikacji:
2014-06-30
Wydawca:
Akademia Sztuki Wojennej
Tematy:
Arab Spring
European Union
European Neighborhood Policy
migration
Opis:
The scale of incidents related to Arab Awaking and the consequences of movement in MENA region surprised the European Union and international community. However, the report of the Arab Human Development Report predicted in 2009 that the Arab world will face security challenges associated with growing population, which can lead to internal tensions between different communities. The Arab Spring has contributed to the creation of new political, economic and social realities which forced EU to take necessary action to adapt to this situation. Significant efforts were taken according to financial support which was delivered in increased budgets of European Neighborhood Policy projects, The European Investment Bank (EIB), the European Bank for Reconstruction and Development (EBRD). Due to the fact of immigration from region increases anxiety on the South of EU. In order to prevent illegal border crossing EU established Joint Operation Hermes 2011 to resolve problem. However the Tunisami consequences are still considered as a threat to European Union security.
Źródło:
Security and Defence Quarterly; 2014, 3, 2; 81-96
2300-8741
2544-994X
Pojawia się w:
Security and Defence Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and performance analysis of a mechanically coupled spring compliant to out-of-plane oscillation
Autorzy:
Nguyen, Duong Van
Nguyen, Chien Quoc
Dang, Hieu Van
Chu, Hoang Manh
Powiązania:
https://bibliotekanauki.pl/articles/27309868.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
coupled spring
mode coupling
serpentine spring
Sigitta spring theory
finite element
method
sprzężenie trybów
element końcowy
metoda
Opis:
In this paper, a spring system symmetrically arranged around a circular plate compliant to out-of-plane oscillation is proposed. The spring system consists of single serpentine springs mutually coupled in a plane. Three theoretical mechanical models for evaluating the stiffness of the spring system are built, which are based on the flexural beam, Sigitta, and serpentine spring theories and equivalent mechanical spring structure models. The theoretically calculated results are in good agreement with numerical solutions using the finite element method, with errors less than 10% in the appropriate dimension ranges of the spring. Compared to similar spring structures without mechanical coupling, the proposed mechanically coupled spring shows advantage in suppressing the mode coupling.
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 4; 629--643
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural transverse vibrations of helical springs in sections covered with elastic coatings
Autorzy:
Michalczyk, K.
Powiązania:
https://bibliotekanauki.pl/articles/200869.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
helical spring vibrations
natural frequencies
free transverse vibrations
axially loaded spring
spring with coatings
drgania sprężyny śrubowej
częstotliwości naturalne
wolne wibracje
Opis:
It has been demonstrated in previous studies that local elastomer coatings covering the end coils of helical springs can efficiently reduce the amplitudes of circum-resonant vibrations in such springs. The analysis of the influence that elastic coatings have on the frequencies and modes of natural transverse vibrations of springs is presented in this paper. The concept of the equivalent beam of the Timoshenko type is utilized in calculations of the frequencies and modes of transverse vibrations. The model developed allows users to determine the frequencies and modes of symmetric as well as antisymmetric vibrations of axially loaded springs with elastic coatings of arbitrary length. A comparison of the results obtained using FEM analysis, in which the model represented the actual spring geometry, with the results obtained by means of the presented model indicates its high accuracy.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 6; 949-959
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identity Negotiation in the Arab Spring Discourse: the Egyptian Case
Autorzy:
Qabani, Abdullah
Powiązania:
https://bibliotekanauki.pl/articles/2129787.pdf
Data publikacji:
2021-12-30
Wydawca:
Akademia Pedagogiki Specjalnej. Language and Society Research Committee
Tematy:
Arab Spring
Identity
Mubarak
Egypt
Tahrir Square
Discourse analysis
Power
Opis:
In both Eastern and Western traditions, political discourse and its relation to identity have been studied. The focus of this paper is the construction of identity and self-presentation strategies in the discourse of Mubarak of Egypt during the time known as “the Arab Spring”. This study aims to answer questions about how Mubarak constructs the various identities evident in his discourse, what kinds of resources are brought into effect, and how the multiple identities contribute to the aims of political discourse in general. While Mubarak recruited the considerable coercive power at his disposal, at the same time, he sought the power of discourse to construct and defend his legacy. Furthermore, he used the power of discourse to project his account of the external interference in domestic affairs and to recruit shared identities (based on nationalism).
Źródło:
Language, Discourse & Society; 2021, 9 (2); 63-80
2239-4192
Pojawia się w:
Language, Discourse & Society
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Corruption and the “Arab spring” As one of the main elements leading to revolutions
Autorzy:
Mnawar, Abdulrahman
Powiązania:
https://bibliotekanauki.pl/articles/531279.pdf
Data publikacji:
2015-09-15
Wydawca:
Fundacja Instytut Nauki o Polityce
Tematy:
corruption, Arab spring, revolutions
Opis:
Corruption in the Arab world in general and in the “Arab spring” countries in particular is one of the most important hidden elements led to revolutions and uprisings. The accumulated different types of corruption made the Arab societies hopeless and pushed them to lose faith in the capabilities of their regimes/governments to achieve the economic and social justice, as those regimes and the small category benefiting from them are the main cause of corruption. Therefore, fighting corruption requires the willingness of the state with clear structural systems and regulations in the states’ institutions. In addition, is needed a comprehensive plan at the short, medium and long term.
Źródło:
Polish Journal of Political Science; 2015, 1, 3; 36-49
2391-3991
Pojawia się w:
Polish Journal of Political Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new method for generating virtual models of nonlinear helical springs based on a rigorous mathematical model
Autorzy:
Michalczyk, Krzysztof
Warzecha, Mariusz
Baran, Robert
Powiązania:
https://bibliotekanauki.pl/articles/30148247.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Promocji Wiedzy
Tematy:
helical spring
spring design
spring stiffness
load-deflection curve
spring geometry
Opis:
This paper presents a new method for generating nonlinear helical spring geometries based on a rigorous mathematical formulation. The model was developed for two scenarios for modifying a spring with a stepped helix angle: for a fixed helix angle of the active coils and for a fixed overall height of the spring. It allows the development of compression spring geometries with non-linear load-deflection curves, while maintaining predetermined values of selected geometrical parameters, such as the number of passive and active coils and the total height or helix angle of the linear segment of the active coils. Based on the proposed models, Python scripts were developed that can be implemented in any CAD software offering scripting capabilities or equipped with Application Programming Interfaces. Examples of scripts that use the developed model to generate the geometry of selected springs are presented. FEM analyses of quasi-static compression tests carried out for these spring models showed that springs with a wide range of variation in static load-deflection curves, including progressive springs with a high degree of nonlinearity in characteristics, can be obtained using the proposed tools. The obtained load-deflection curves can be described with a high degree of accuracy by power function. The proposed method can find applications in both machine design and spring manufacturing.
Źródło:
Applied Computer Science; 2023, 19, 2; 96-111
1895-3735
2353-6977
Pojawia się w:
Applied Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimality of Spring Balance Weighing Designs
Optymalność w sprężynowych układach wagowych
Autorzy:
Graczyk, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/905658.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
A–optimal design
D–optimal design
spring balance weighing design
Opis:
In this paper, the problem of existence of optimal spring balance weighing designs is discussed. Two optimality criterions are compared and the appropriate optimality conditions are presented.
W pracy przedstawiono zagadnienie A- i D-optymalności sprężynowego układu wagowego. Rozważania teoretyczne zostały zobrazowane przykładem konstrukcji macierzy układu w oparciu o macierze incydencji układów zrównoważonych o blokach niekompletnych.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2013, 285
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure Refinement of Spring Steel 51CrV4 after Accelerated Spheroidisation
Autorzy:
Hauserova, D.
Dlouhy, J.
Kotous, J.
Powiązania:
https://bibliotekanauki.pl/articles/352039.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
spring steel
Accelerated Spheroidisation
refinement
hardening
Opis:
Material research of the spring steels tries to meet requirements of the industry, which are mainly higher yield and tensile strength. Steel 51CrV4 is widely used for spring production. Optimization of its properties lies in tensile and yield strength enhancement without decrease in ductility in quenched and tempered state. This can be accomplished by structural refinement. One possible way to refine final quenched and tempered structure is refinement of the soft annealed structure before quenching. The article is devoted to accelerated carbide spheroidisation and refinement (ASR) and subsequent hardening of the 51CrV4 spring steel. Samples with different carbide size were prepared by conventional soft annealing in atmosphere furnace and ASR process by induction heating. Influence of the structural refinement on the properties of quenched and tempered state was studied.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1473-1477
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristic of vehicle suspension coil spring : comparison of experiment and finite element method simulation
Autorzy:
Cuber, D.
Gandyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/243817.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
FEM
simulation
coil spring
vehicle suspension
Opis:
Coil springs do not always has regular geometry with constant pitch and constant mean diameter. Geometry of spring is more complex. Furthermore, spring stiffness could change with deflection. That makes calculation of spring stiffness more complicated than just putting four values into mathematical formula. In article has been presented two investigation methods of spring characteristic. Investigated object is a passenger vehicle suspension coil spring. Recognition spring characteristic is primary stage of vehicle dynamic suspension simulation. It has a very big impact on the vehicle height, comfort, handling and safety of vehicle. It is often assumed that vehicle spring has constant stiffness coefficient, which is sometimes a reason of incorrect suspension model. Vehicle springs rather has a progressive characteristic than linear. One of presented method is traditional, experimental compression test. Second, one is a measurement and modelling of spring geometry. Than analysing it in finite element method (FEM) simulation. Comparison has been done to check property of FEM process. Computed compression has been done in ABAQUS CAE 6.13-1 software. Analysis has shown that process of analysing is useful. There were obtained a good agreement between experimental research and computed model. In spite of irregular spring geometry, final characteristic is close to linear. Progressiveness is visible but not high.
Źródło:
Journal of KONES; 2015, 22, 4; 73-77
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of presowing laser radiation on spring wheat characters
Autorzy:
Drozd, D.
Szajsner, H.
Powiązania:
https://bibliotekanauki.pl/articles/25289.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
plant yield
spring wheat
laser radiation
wheat
Duncan test
laser light
Źródło:
International Agrophysics; 1999, 13, 1
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł

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