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Tytuł:
Mental health of Filipino seafarers: the contributory factors and the strategies applied onboard ship
Autorzy:
Sarinas, B. G. S.
Botante, J. D. D.
Nacion, J. S.
Bernas, M. L. B.
Rodriguez, O.
Powiązania:
https://bibliotekanauki.pl/articles/2172470.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
mental health
seafarers
Filipino
onboard test
stress fatigue
seafarers problems
Opis:
Mental health is equally important with physical health. Many reports found out that poor mental health is one of the major factors of depression among seafarers. This study ascertains the factors affecting mental health and the strategies applied by Filipino seafarers to combat these issues. A survey was used as a research design. A total of 100 seafarers taken through convenience and snowball sampling answered the validated researcher-made questionnaire. The questionnaire was sent in the JBLFMU Alumni Portal, messenger, and Gmail. Frequency, percentage, and rank were used. Themes were used to classify the strategies applied by seafarers to counteract mental health issues onboard ship. The results revealed that the major contributory factor affecting the mental health of Filipino seafarers is stress, while they believed that a positive outlook in life makes one’s self free from mental health problems onboard. The top three factors are stress, fatigue, and separation from families and friends. The top three strategies to counteract factors that affect seafarers’ mental health onboard ship are staying positive, socializing with crewmates, and communicating with family.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2022, 16, 1; 125--134
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-constrained topology optimization using constant criterion surface algorithm
Autorzy:
Mrzygłód, M.
Powiązania:
https://bibliotekanauki.pl/articles/201310.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multi-constrained topology optimization
stress and fatigue constraints
constant criterion surface algorithm
Opis:
This paper sets out to describe a multi-constrained approach to topology optimization of structures. In the optimization, a constant criterion surface algorithm and the multi-constraint procedure is used. The multi-constraint procedure consists of constraints normalization and equivalent design space assembling. The work is illustrated by an example of the L-shaped domain optimization with the horizontal line support and complex loads. The example takes into consideration stress, fatigue and compliance constraints. The separate and simultaneous application of constraints resulted in significant differences in structure topology layouts. The application of a fatigue constraint gave more conservative results when compared to static stress or compliance limitations. The multi-constrained approach allowed effectively lowering the mass of the structure while satisfying all constraints.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 2; 229-236
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of process engineering factors on stabilization of screw joint
Autorzy:
Nieoczyn, A.
Krzysiak, Z.
Tarkowski, S.
Skic, A.
Rachwał, B.
Plizga, K.
Brumercik, F.
Powiązania:
https://bibliotekanauki.pl/articles/132154.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
screw joint
protective coats
lubrication
friction moment
moment of torque
fatigue stress
Opis:
The stabilization of screw joint and influence of factors protecting against loosening of the joint have been discussed in the present article. The results of experimental examinations associated with the impact of the type of protective coat on threaded section and lubrication on the value of tightening torque have been also presented.
Źródło:
Advanced Technologies in Mechanics; 2016, 3, no. 1 (6); 12-18
2392-0327
Pojawia się w:
Advanced Technologies in Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue life of metallic material estimated according to selected models and load conditions
Autorzy:
Kluger, K.
Łagoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/281337.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
uniaxial fatigue
multiaxial fatigue
mean stress
Opis:
The authors present results of a fatigue test for specimens made of the aluminium Allom 2017A-T4 and alloy steels S355J2WP and S355J2G3 subjected to constant-amplitude proportional combined bending with torsion including mean stress values and for the S355J2WP alloy steel under uniaxial constant-amplitude and random loading with both zero and non zero mean stress values. The test results were compared with the results of calculations according to the models proposed by Goodman, Gerber and Morrow as well as the stressstrain parameter. In the case of calculations based on the stresses, the multiaxial stress state was reduced to a uniaxial one using the Huber-Mises relationship. As for the method based on strain energy density, the multiaxial stress state was reduced to the uniaxial one with use of the stress-strain parameter. The plane in which the stress-strain parameter of shear loadings reaches its maximum value is assumed to be the critical plane.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 3; 581-592
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue life estimation for selected materials in multiaxial stress states with mean stress
Autorzy:
Kluger, K.
Łagoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/949216.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
multiaxial fatigue
mean stress
stress model
Opis:
This paper proposes a model for estimating fatigue life under multiaxial stress states, based on critical plane concepts, taking into account the effect of mean shear stress. The fatigue life test results calculated on the basis of the proposed model are compared to the experimental ones related to 2017A-T4 and 6082-T6 aluminium alloy, S355J0 alloy steel under constant-amplitude bending, torsion and proportional combinations of bending and torsion; Ti-6Al-4V alloy under tension-compression, torsion and combination tension-compression – torsion. For the results obtained, statistical analysis is performed by comparing the calculation results proposed by Findley and Dang Van criteria with the experimental data.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 2; 385-396
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the irregularity coefficient of loading on calculated fatigue life
Autorzy:
Pawliczek, R.
Kluger, K.
Powiązania:
https://bibliotekanauki.pl/articles/281651.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fatigue
irregularity coefficient
mean stress
Opis:
The paper presents comparison of two methods for determination of the fatigue damage degree in a material subjected to random loadings with participation of the mean loading and including the irregularity coefficient of the loading. The authors estimated effectiveness of the method where the stress history was transformed considering the global mean value of the load history and the method for which the stress mean value of the distinguished loading cycles was taken into account. When the irregularity coefficient of loading increases, we can observe significant divergences of the calculated fatigue life of the material related to the model of amplitude transformation because of the loading mean value.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 791-798
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Odkształceniowy model kumulacji uszkodzeń zmęczeniowych w zakresie obciążeń niskocyklowych
Strain-based damage accumulation model for low cycle fatigue
Autorzy:
Szusta, J.
Seweryn, A.
Powiązania:
https://bibliotekanauki.pl/articles/387389.pdf
Data publikacji:
2007
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
pękanie
uszkodzenie
odkształcanie
damage
fatigue
stress
Opis:
W pracy przedstawiono propozycję modelu obliczania trwałości zmęczeniowej elementów konstrukcyjnych w warunkach złożonych obciążeń, w zakresie małej liczby cykli. Prezentowane podejście składa się z dwóch bloków obliczeniowych. Pierwszy służy do wyznaczania składowych tensora naprężenia i odkształcenia. Zawiera związki konstytutywne i prawo kinematycznego wzmocnienia. Wykorzystano w nim wielopowierzchniowy model Mroza. W drugim bloku znajdują się zależności określające zmianę miary kumulacji uszkodzeń oraz kryterium pękania. W modelu kumulacji uszkodzeń wykorzystano podejście związane z przyrostem plastycznych odkształceń postaciowych na płaszczyźnie fizycznej.
The paper presents the description of damage accumulation for analysis of fatigue life of structural elements under non-proportional loading states. The numerical algorithm consists of two calculation blocks. First presents method for calculation components of stress and strain tensors using multisurface hardening rule proposed by Mróz. Those components have been used for calculation of fatigue life in second block. Increment of damage accumulation has been addicted from increment of shear strain on physical plane.
Źródło:
Acta Mechanica et Automatica; 2007, 1, 2; 69-72
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nielokalna metoda wyznaczania granicznej trwałości zmęczeniowej materiału z defektami geometrycznymi
Nonlocal method for fatigue limit determination of defective material
Autorzy:
Karolczuk, A.
Nadot, Y.
Dragon, A.
Powiązania:
https://bibliotekanauki.pl/articles/386604.pdf
Data publikacji:
2007
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
zmęczenie materiału
naprężenie
fatigue
stress intensity
Opis:
W pracy zaprezentowano nową metodę analizy wpływu nierównomiernych rozkładów naprężeń w płaszczyźnie krytycznej na trwałość zmęczeniową materiałów konstrukcyjnych. Metoda wyróżnia odmienny wpływ gradientów naprężeń stycznych i normalnych na procesy zmęczeniowe. Nielokalne naprężenia styczne i normalne w płaszczyźnie materiału o stałej orientacji (płaszczyzna krytyczna) są uśredniane do naprężeń lokalnych. Proces uśredniania jest przeprowadzany na dwóch różniących się wielkością powierzchniach, odpowiednio dla naprężeń stycznych i normalnych. Wyznaczone w ten sposób lokalne naprężenia w płaszczyźnie krytycznej są wprowadzane do kryterium wieloosiowego zmęczenia materiału w celu oszacowania granicy zmęczenia. Zaproponowana metoda została zweryfikowana na podstawie badań zmęczeniowych próbek wykonanych ze stali C36 ze sztucznie wprowadzonymi defektami geometrycznymi.
The paper presents a new way to reduce the nonuniform shear and normal stress distribution to the uniform ones. The reduction is performed by averaging process of shear and normal stresses over two overlapping characteristic areas. Using this concept various multiaxial critical plane fatigue failure criteria could be used to estimate fatigue life. In the present paper, the Matake multiaxial fatigue failure criterion was verified on defective material subjected to proportional loading.
Źródło:
Acta Mechanica et Automatica; 2007, 1, 1; 45-50
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue stress analysis of orthotropic steel bridge decks in Xinghai Bay Cross-sea Bridge
Autorzy:
Li, Wenwu
Qin, Sifeng
Wang, Huili
Powiązania:
https://bibliotekanauki.pl/articles/230385.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
płyta stalowa
płyta ortotropowa
linia wpływu
naprężenie zmęczeniowe
most morski
Xinghai
orthotropic deck
steel deck
influence line
fatigue stress
cross-sea bridge
Opis:
Fatigue properties of orthotropic steel bridge deck of Xinghai Bay Cross-sea Bridge in Dalian were analyzed. The segment model of orthotropic bridge deck was established by using the finite element software Abaqus. The intersection between diaphragm and U-rib was selected to analysis. The fatigue loading model III was adopted which was provided by “Specifications for Design of Highway Steel Bridge”. First, the transverse stress influence line and the transverse severest loading position were determined. Then, five loading regions were selected near the transverse severest position. The stress amplitude of the intersection was ascertained through loading on the longitudinal bridge for each region. Finally, the fatigue checking for the intersection was carried out. The results showed that the maximum fatigue stress amplitude of orthotropic deck in Xinghai Bay Cross-sea Bridge met the requirements of "Specifications for Design of Highway Steel Bridge".
Źródło:
Archives of Civil Engineering; 2020, 66, 1; 327-340
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the determination of maps of fatigue safety under multiaxial stochastic loads
O wyznaczaniu warstwic bezpieczeństwa zmęczeniowego przy wieloosiowych obciążeniach stochastycznych
Autorzy:
Kolenda, J.
Powiązania:
https://bibliotekanauki.pl/articles/209873.pdf
Data publikacji:
2011
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
zmęczenie
naprężenie stochastyczne
naprężenie równoważne
margines bezpieczeństwa zmęczeniowego
fatigue
scholastic stress
equivalent stress
fatigue safety margin
Opis:
The paper deals with fatigue safety of machines and structures subjected to stresses below the fatigue limit of the material. Multiaxial stationary stochastic stresses are considered which are modelled by an equivalent stress in the form of a Gaussian process. The equivalence conditions are based on the Huber-Mises-Hencky strength theory and on the theory of energy transformation systems. It is assumed that the mean values, power spectral densities and cross power spectral densities of the stress processes are known. The formula for the expected value of fatigue safety margin is derived which can be used for visualization of fatigue safety level in selected parts of structural elements by means of maps.
Praca dotyczy bezpieczeństwa zmęczeniowego maszyn i konstrukcji poddanych naprężeniom poniżej granicy zmęczenia. Rozpatrywane jest wieloosiowe naprężenie stacjonarne, które zamodelowano jednoosiowym naprężeniem równoważnym w postaci procesu Gaussa. Warunki równoważności oparto na hipotezie wytężenia Hubera-Misesa-Hencky'ego i na teorii systemów transformacji energii. Założono znajomość wartości średnich, gęstości widmowych mocy i wzajemnych gęstości widmowych mocy naprężeń składowych. Wyprowadzono wzór na wartość oczekiwaną marginesu bezpieczeństwa zmęczeniowego, która może być użyta do wizualizacji poziomu bezpieczeństwa zmęczeniowego wybranych części konstrukcji za pomocą warstwic.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2011, 60, 2; 187-194
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the determination of maps of fatigue damage under uniaxial stochastic loads
O wyznaczaniu warstwic uszkodzeń zmęczeniowych przy jednoosiowych obciążeniach stochastycznych
Autorzy:
Kolenda, J.
Powiązania:
https://bibliotekanauki.pl/articles/209877.pdf
Data publikacji:
2011
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
zmęczenie
naprężenie stochastyczne
naprężenie równoważne
parametr uszkodzenia zmęczeniowego
fatigue
stochastic stress
equivalent stress
fatigue damage parameter
Opis:
The paper deals with fatigue damage accumulated in elements of machines and structures subjected to stresses in the high-cycle fatigue regime. Uniaxial stationary stochastic stresses are considered which are modelled by an equivalent stress in the form of a Gaussian process. The equivalence conditions are based on the theory of energy transformation systems. It is assumed that the mean value and the power spectral density of the original stress are known. The ratio of the required design life and the expected value of the time to failure is determined as the fatigue damage parameter the values of which can be used for visualization of fatigue damage of the material by means of maps.
Praca dotyczy uszkodzeń zmęczeniowych elementów maszyn i konstrukcji poddanych naprężeniom w zakresie ograniczonej wytrzymałości zmęczeniowej wysokocyklowej. Rozpatrywane jest jednoosiowe naprężenie stacjonarne, które zamodelowano naprężeniem równoważnym w postaci procesu Gaussa. Warunki równoważności oparto na teorii systemów transformacji energii. Założono znajomość wartości średniej i gęstości widmowej mocy naprężenia. Iloraz założonego czasu eksploatacji i wartości oczekiwanej czasu do chwili pęknięcia przyjęto jako parametr uszkodzenia zmęczeniowego, którego wartości mogą być użyte do wizualizacji stopnia uszkodzenia zmęczeniowego materiału za pomocą warstwić.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2011, 60, 2; 175-185
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Elaboration of the Method of Fatigue Testing of the Rotor of the Mosups Plane Propulsion System
Autorzy:
Głowacki, D.
Rodzewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/97933.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
UAV
propulsion system
stress analysis
fatigue tests
Opis:
This paper concerns fatigue testing of the rotor of the propulsion system for the MOSUPS – an unmanned aircraft designed in a joint wing configuration, and equipped with a ducted propeller. The work presents the analysis of the stresses and deformations of the rotor structure as well as the form of the loading cycle. The aim of the paper is to introduce the concept of a simplified method of fatigue testing of multi-blade rotors. With the sophisticated geometry of the rotor in mind – the authors applied the FEM tools and implemented the ANSYS and nCode programs. The prototype of the fatigue stand built by the authors is also presented in the paper.
Źródło:
Fatigue of Aircraft Structures; 2016, 8; 97-103
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-ray stress measurements in the institute of aviation possibilities and examples
Autorzy:
Gadalińska, E.
Malicki, M.
Powiązania:
https://bibliotekanauki.pl/articles/242492.pdf
Data publikacji:
2018
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
X-ray diffraction
residual stress measurements
fatigue
Opis:
From the point of view of the airplane construction, its fatigue lifetime and exploitation process, the stress states and levels are of crucial importance. The most appropriate experimental methods to determine stress values are diffraction methods with different radiation type employed. These methods allow the determination of the elastic lattice deformation and distortion (effectively the stress state) from the displacement and broadening of the diffraction peak. Diffraction methods are widely known as the experimental methods for determining not only the stress values but also the elastic properties of polycrystalline materials (also of all alloys types used in the aerospace industry). The advantages of diffraction experiments result from their non-destructive character and the possibility to obtain absolute values of stresses in different phases of each type of crystal material (the measurements are performed selectively only for crystallites contributing to the measured diffraction peak, i.e. for the grains having lattice orientations for which the Bragg condition is fulfilled). In the frame of this work, the laboratory possibilities of the Institute of Aviation in this area are presented as well as the exemplary results of stress measurements performed there.
Źródło:
Journal of KONES; 2018, 25, 3; 159-166
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective fatigue damage summation
Autorzy:
Kolenda, J.
Powiązania:
https://bibliotekanauki.pl/articles/260094.pdf
Data publikacji:
2006
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
fatigue
design criteria
damage cumulation
stress modeling
Opis:
The cumulative fatigue damage caused by uniaxial variable stress is considered. To facilitate the lifetime prediction at complex stress patterns, has been defined an effective stress of constant parameters, claimed to be equivalent to the sequence of original stresses in terms of fatigue life of material. The equivalence conditions are based on the theory of energy transformation systems. To the effective stress the Palmgren-Miner rule is applied. Thereby the cycle counting is not required.
Źródło:
Polish Maritime Research; 2006, 4; 11-14
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of residual stress distribution in riveted lap joint under tension
Autorzy:
Wronicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/245195.pdf
Data publikacji:
2018
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
joint
rivet
fatigue
residual stress
finite element
Opis:
Riveted joints are a common location of fatigue cracks in aircraft metal structures. Fatigue life of such joints as well as a place of cracks nucleation is strongly influence by a stress distribution in sheets, which is a result of residual stresses (mainly after riveting) and stresses induced by external loads. Stress distribution in two-row lap joint was investigated with the use of Finite Element Method. The joint consist of two 1.5 mm sheets and two protruding rivets with diameter equal to 4 mm, made of 2024 T3 (sheets) and 2117 T4 (rivets) aluminium alloys. The simulations covered a riveting process and tensile stages. The 3D models of joint with the universal rivets and with the brazier, rivets with a compensator were prepared. Elastoplastic material properties as well as geometric nonlinearity and contact phenomena were included. The results of simulations show that the residual stress distribution after release of tensile loading varies significantly from the distribution after riveting only. This fact should therefore be taken into account in a fatigue life estimation of such joints performed based on a FE calculation. The paper presents also the influence of the analysed rivet geometry on the stress distribution at the sheets faying surfaces.
Źródło:
Journal of KONES; 2018, 25, 4; 455-462
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavior of Steel Branch Connections during Fatigue Loading
Autorzy:
Sládek, A.
Patek, M.
Mičian, M.
Powiązania:
https://bibliotekanauki.pl/articles/353905.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
branch connection
stress analysis
fatigue bending test
Opis:
Fatigue behavior of the branch connection made of low-alloyed steel with yield stress of 355 MPa during low-cycle bending test is investigated in the article. Numerical prediction of the stress and strain distribution are described and experimentally verified by fatigue test of the branch connection sample. Experimental verification is based on low-cycle bending testing of the steel pipes welded by manual metal arc process and loaded by external force in the appropriate distance. Stresses and displacement of the samples induced by bending moment were measured by unidirectional strain gauges and displacement transducers. Samples were loaded in different testing levels according to required stress for 2.106 cycles. Increase of the stress value was applied until the crack formation and growth was observed. Results showed a high agreement of numerical and experimental results of stress and displacement.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1597-1601
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Advanced determination of safety factor of fatique strength of coiled springs
Autorzy:
Aryassov, G.
Petritshenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1429162.pdf
Data publikacji:
2008
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
coiled springs
fatigue failure
safety factor
alternate stress
endurance limit stress
Opis:
Coiled compression springs are widely used in suspension systems of vehicles, light weight trailers, trains etc and their task is to minimize dynamic loading effect to vehicles body or frame in different road condition over many years. In these systems, springs are exposed to large number of cycles of loading and determination of their durability and reliability quantities is important. Consequently, to increase the reliability of these systems, a more accurate determination of the values of the endurance limits of springs is necessary. Usually, in many strength problems, the major components of stress are static, with less accurately alternating stresses superposed. Most failures of springs are originated with stress of alternating type. The solution of problem is accomplished due to acting shear and axial stresses in plane of cross-section of spring wire. By existing theory, when springs are loaded by non-steady loading, then to consider of unlimited number of combinations of amplitude and mean stresses, the line of failure of the material must be used. Since experimental data for the line of failure of material are usually not at hand, it is customary to make a conservative approximation, that it is a straight line. However, use this straight line may give considerable mistakes on determination of the limit range stresses. To avoid fore aft mentioned mistakes, the method of approximation of the failure curve line by the line with the properly chosen parameters for the coiled compression and tension springs is proposed in this paper. Theory to use proper parameters in approximation of failure curve and calculation example with results is given as well.
Źródło:
Journal of Machine Engineering; 2008, 8, 4; 111-121
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress-life curve for high and low cycle fatigue
Autorzy:
Kurek, Andrzej
Kurek, Marta
Łagoda, Tadeusz
Powiązania:
https://bibliotekanauki.pl/articles/279479.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
stress-life curves
steels and alloys
low-cycle fatigue
high-cycle fatigue
Opis:
The paper contains a proposal of a new model for the stress-life curve. The new model reflects the nature of the stress curve occurring under current conditions, which means its shape of an inclined letter S. It can be used for both low and high cycle fatigue. Verification of the proposed model was performed on experimental results of ten various materials from three main types that are low-alloy, high-alloy and non-alloy steels.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 3; 677-684
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Partial cases of stressed-deformed condition of casing and pump compressor pipes
Autorzy:
Vasylyshyn, Vitalii
Taras, Iryna
Bekish, Iryna
Kornuta, Olena
Kornuta, Volodymyr
Powiązania:
https://bibliotekanauki.pl/articles/409894.pdf
Data publikacji:
2020
Wydawca:
STE GROUP
Tematy:
tubing
stress-strain state
fatigue life
tightening torque
Opis:
Threaded joints are the most technological for piling up in the fields. However, violations of standard threaded joints account for 70% of all complications in pipe processing and production. These malfunctions result in significant material losses, reduced well productivity, and contamination of the wells and environmental pollution. Particularly acute is the loss of these sealed joints during exploration and development of gas and gas condensate fields. The necessary increase in volumes and intensification of hydrocarbon energy production is envisaged by the increase of drilling depth, construction of slopes and horizontal wells. Horizontal drilling and fracturing are used to produce shale gas. The efficiency and safety of the operation of oil and gas wells in complex mining and technical conditions depend on the quality and reliability of casing and pumping columns, which requires the modernization of machinery and technology for the installation of wells. The most technological for column fitting in the fisheries sector is threaded joints. However, breach of standard threaded connections causes 70% of all complications with pump housings and columns. This leads to significant material losses, reduced production of raw materials, contamination of the interior and the environment. Therefore, the urgent task is to improve the threaded joints by increasing their reliability and efficiency under heavy workloads.
Źródło:
Management Systems in Production Engineering; 2020, 2 (28); 97-103
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Burnout among physiotherapists and length of service
Autorzy:
Śliwiński, Zbigniew
Starczyńska, Małgorzata
Kotela, Ireneusz
Kowalski, Tomasz
Kryś-Noszczyk, Karolina
Lietz-Kijak, Danuta
Kijak, Edward
Makara-Studzińska, Marta
Powiązania:
https://bibliotekanauki.pl/articles/2179020.pdf
Data publikacji:
2015-04-14
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
stress
physiotherapy
burnout
length of service
determinants
fatigue
Opis:
Objectives: The aim of this study was to identify factors that contribute to the development of burnout among physiotherapists with different length of service in physiotherapy. Material and Methods: The following research tools were used to study burnout: the Life Satisfaction Questionnaire (LSQ), based on FLZ (Fragebogen zur Lebenszufriedenheit) by Frahrenberg, Myrtek, Schumacher, and Brähler; the Burnout Scale Inventory (BSI) by Steuden and Okła; and an ad hoc questionnaire to collect socio-demographic data. The survey was anonymous and voluntary and involved a group of 200 active physiotherapists working in Poland. Results: A statistical analysis revealed significant differences in overall life satisfaction between length-of-service groups (p = 0.03). Physiotherapists with more than 15 years of service reported greater satisfaction than those with less than 5 years and between 5 and 15 years of service. The results suggest that burnout in those with 5-15 years of service is higher in physiotherapists working in health care centers and increases with age and greater financial satisfaction, while it decreases with greater satisfaction with friend and family relations and greater satisfaction with one's work and profession. In those with more than 15 years of service, burnout increases in the case of working in a setting other than a health care or educational center and decreases with greater satisfaction with one's work and profession. Conclusions: Job satisfaction and a satisfying family life prevent burnout among physiotherapists with 5-15 years of service in the profession. Financial satisfaction, age and being employed in health care may cause burnout among physiotherapists with 5-15 years of service. Physiotherapists with more than 15 years of service experience more burnout if they work in a setting other than a health care or educational center and less burnout if they are satisfied with their profession.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2014, 27, 2; 224-235
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue damage mechanisms and damage evolution near cyclically loaded edges
Autorzy:
Ebner, R.
Gruber, P.
Ecker, W.
Kolednik, O.
Krobath, O.
Jesner, G.
Powiązania:
https://bibliotekanauki.pl/articles/200051.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fatigue damage
crack nucleation
plastic strains
residual stress
Opis:
A combined experimental and numerical approach was applied to develop a basic understanding of the fatigue damage process taking place at edges exposed to cyclic mechanical loads. A recently developed cyclic edge-loading test was used in order to simulate the fatigue loading of the edges of manufacturing tools and to study the microscopic damage mechanisms. Accompanying finite element calculations were performed to provide a better understanding of the loading conditions at edges subjected to cyclic mechanical loads. A comparison of the numerical simulation with the experimental results revealed good accordance. Main results of the investigations are the distribution of plastic strains and their evolution with increasing number of cycles, the distribution of the residual stresses, the localisation and the evolution of damage at the microscale (microcracks and voids), and the localisation and growth of fatigue cracks. Micro-damage develops in the entire plastically deformed region. Fatigue crack nucleation was mainly found in deformation bands and fatigue crack growth was only observed near the transition region between the extensively and the slightly plastically deformed zone not at the loaded area but at the side area. The reason for that phenomenon is the formation of tensile residual stresses in this region which is favouring fatigue crack growth.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 2; 267-279
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of multiaxial state of stress and determine the fatigue lifetime for aluminum alloy during cyclic loadingunder in-and-out of phase shift Φ = 0° and Φ = 90
Autorzy:
Uhríčik, Milan
Kopas, Peter
Sága, Milan
Powiązania:
https://bibliotekanauki.pl/articles/41204259.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Kazimierza Wielkiego w Bydgoszczy
Tematy:
sinusoidal cyclic loading
multiaxial fatigue
stress
structural material
Opis:
This article deals with determining of fatigue lifetime of structural materials during by multiaxial cyclic loading. The theoretical part deals with the fatigue and with the criterions for evaluation of multiaxial fatigue lifetime. The experimental part deals with modeling of combined bending - torsion loading and determining the number of cycles to fracture in region low-cycle and high-cycle fatigue and also during of loading with the sinusoidal wave form under in phase Φ = 0° and out phase Φ = 90°.
Źródło:
Studia i Materiały Informatyki Stosowanej; 2011, 5; 9-13
1689-6300
Pojawia się w:
Studia i Materiały Informatyki Stosowanej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of different machining processes on fatigue life performance of engineered surfaces: a short review
Autorzy:
Grzesik, Wit
Powiązania:
https://bibliotekanauki.pl/articles/2086274.pdf
Data publikacji:
2022
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
engineered part
surface roughness
stress concentration
fatigue life
Opis:
In this paper fundamental information on the influence of the real machined surfaces generated by different machining processes on the fatigue life of machine parts are presented. In the first part the various approaches for the assessment of the stress concentration factor and the correction of a fatigue life limit are discussed. In the second part the results of standard fatigue tests are compared with computed data and predictions using FEM based simulations. The effect of surface discontinues (valleys) in the real surface profiles is related to engineered parts made of different materials including steels, aluminium alloys, aerospace alloys and composites.
Źródło:
Journal of Machine Engineering; 2022, 22, 2; 18--30
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of stress gradient effect on fatigue life using Weibull based distribution function
Modelowanie efektu gradient naprężeń na trwałość zmęczeniową przy zastosowaniu funkcji bazującej na rozkładzie Weibulla
Autorzy:
Karolczuk, A.
Palin-Luc, T.
Powiązania:
https://bibliotekanauki.pl/articles/281344.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fatigue life
stress gradient effect
weakest link concept
Opis:
In the present paper, a new approach is developed in order to take into account the stress gradient effect on fatigue life of structural components. The proposed approach is based on the weakest link concept in which the shape coefficient of the Weibull distribution becomes a function of a local damage parameter. The function simulates the experimentally observed relationship between the shape of the fatigue life distribution and the stress level. Such an approach allows one to calculate the global probability distribution of the fatigue life for notched structural components in a wide range of fatigue life regime: 10⁴-10⁷ cycles typically. For comparison purposes, the approach is applied to calculate the number of cycles to crack initiation of structural elements under three probability levels: 5%, 63% and 95%. The calculated lifetimes are compared with the lifetimes obtained from experiments performed on notched cruciform specimens and notched round specimens subjected to constant amplitude loading.
W artykule zaprezentowano nową koncepcję uwzględnienia wpływu gradientu naprężeń na trwałość zmęczeniową elementów konstrukcyjnych. Przedstawione podejście bazuje na koncepcji najsłabszego ogniwa, w której współczynnik kształtu rozkładu Weibulla jest funkcją lokalnego parametru uszkodzenia. Zaproponowana funkcja symuluje obserwowany eksperymentalnie związek między kształtem rozkładu trwałości zmęczeniowej a amplitudą naprężenia. Podejście takie umożliwia wyznaczenie globalnego rozkładu prawdopodobieństwa zniszczenia dla elementów z karbem w szerokim zakresie trwałości: 10⁴-10⁷ cykli. Dla celów porównawczych zaproponowane podejście zostało zastosowane do obliczenia liczby cykli do inicjacji pęknięcia dla trzech poziomów prawdopodobieństwa, tj. 5%, 63% oraz 95%. Obliczone trwałości zmęczeniowe zostały porównane z trwałością eksperymentalną otrzymaną dla próbek krzyżowych z karbem oraz dla próbek cylindrycznych z karbem obrączkowym.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 297-311
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Testing internal mechanical stresses in flash-butt welded rail joints
Autorzy:
Mikłaszewicz, Ireneusz
Siwiec, Jakub
Powiązania:
https://bibliotekanauki.pl/articles/215467.pdf
Data publikacji:
2019
Wydawca:
Instytut Kolejnictwa
Tematy:
mechanical stress
rail joints
strain gauges
fatigue test
Opis:
The paper presents the results of internal stress tests in rails and flash-butt welded rail joints. Stress patterns were tested in rail joints just after flash-butt welding, as well as after fatigue tests. Stress tests were performed using the destructive strain gauges based test method. Stresses emerging in rails and in rail joints were compared for the steel grades R260 and R350HT. Stress measurements were performed in accordance with the requirements of PN EN 13674 1:2011+A1:2017.
Źródło:
Problemy Kolejnictwa; 2019, 185; 111-117
0552-2145
2544-9451
Pojawia się w:
Problemy Kolejnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 82

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