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Wyświetlanie 1-15 z 993
Tytuł:
The effect of annealing and anisotropic behaviour on tensile and fatigue properties of AA 8090
Autorzy:
Abass, M. H.
Mahmud, F.
Alali, M. S.
Abood, A. N.
Powiązania:
https://bibliotekanauki.pl/articles/378497.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
AA 8090
anisotropic behavior
annealing
tensile strength
fatigue strength
AA8090
zachowanie anizotropowe
wyżarzanie
wytrzymałość na rozciąganie
wytrzymałość zmęczeniowa
Opis:
Purpose: This paper aims to assess microstructures and mechanical properties of annealed and un-annealed Al-Li alloys (AA8090) and provide valid information regarding influence of anisotropy on tensile properties, fatigue lives. Design/methodology/approach: The methodology included investigating the influence of annealing on grain size, tensile strength and fatigue lives of AA8090. Optical microscope, scanning electron microscope and X-ray diffraction were utilized to analyse the crystallographic texture. Findings: The results showed that the un-annealed alloy exhibited much finer grain structure in three directions, namely longitudinal (L) rolling direction, L-45° and Long transverse (LT) combined with stronger crystallographic texture. Regarding to mechanical properties, un-annealed alloy presented superior tensile strength with strong anisotropic behaviour. L and LT grains direction showed highest tensile strength value of 550 MPa and L-45° showed lowest tensile strength value of 420 MPa. Results of fatigue test revealed that annealed Al-Li alloy has lower fatigue lives with high influence of test direction on fatigue properties. Higher variation in fatigue life to failure links with un-annealed alloy over annealed alloy. Examination of fractured surface showed that the morphology of fractured surface is a mixture of ductile and brittle fractures in both annealed and un-annealed alloys with more brittle behaviour in un-annealed alloy. Research limitations/implications: The main challenge of this work is the determination of the test direction (test angle in respect to rolling direction), which is necessary to provide correct information regarding mechanical properties. Further study of low cycle fatigue can be done in future, which will be an excellent indication to mechanical properties of this alloy since it provides more understanding to the behaviour of the material and better comprehend crack propagation and strain stress concentration. Practical implications: AA8090 alloy is an important candidate for aerospace and aircraft industries. Influence of annealing heat treatment and rolling direction on mechanical properties of AA8090 alloy provides more accurate information to the manufacturers who deal with this alloy. Originality/value: This study is affording a significant information regarding the effect of annealing and anisotropic behaviour on mechanical properties of AA8090. To our knowledge, there are few reports that study this combination of factors on AA8090 alloy.
Źródło:
Archives of Materials Science and Engineering; 2019, 99, 1/2; 5-12
1897-2764
Pojawia się w:
Archives of Materials Science and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anti-fatigue mats, low back pain, and electromyography: An interventional study
Autorzy:
Aghazadeh, Javad
Ghaderi, Mahmoud
Azghani, Mahmood-Reza
Khalkhali, Hamid-Reza
Allahyari, Teimour
Mohebbi, Iraj
Powiązania:
https://bibliotekanauki.pl/articles/2177404.pdf
Data publikacji:
2015-03-30
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
low back pain
anti-fatigue mat
muscle co-activation
EMG
Opis:
Objectives Increasing bilateral gluteus medius co-activation has been identified as one of the most important factors in developing low back pain due to prolonged standing in healthy people. This study aims to investigate the impact of an anti-fatigue mat on the bilateral gluteus medius co-activation pattern and to report the low back pain subjectively in 2 different standing positions on the normal rigid surface and on the anti-fatigue mat. Material and Methods While carrying out an easy simulated profession, 16 participants who had no low back pain background were requested to stand for 2 h in each position, with and without using the anti-fatigue floor mat, respectively. At the beginning of standing process and at every 15 min until the time of 120 min lapses, electric activities for the bilateral gluteus medius co-activation and subjective pain level in low back area were collected by the surface electromyogeraphy (EMG) and the visual analogue scale (VAS), respectively in each position. Results The obtained findings revealed that the anti-fatigue mat significantly decreased subjective pain level in low back area among 15 participants (p < 0.05). However, there was objectively no significant difference in the bilateral gluteus medius co-activation pattern among the participants between the position 1 and the position 2 (p > 0.05). The findings obtained under this study related to the impact of the anti-fatigue mat upon the low back pain based on the increase of > 10 mm on the VAS threshold, which showed that this intervention had no significant impact upon decreasing the number of patients suffering from the low back pain and also minimizing the bilateral gluteus medius co-activation in both pain developer groups (p > 0.05). However, 73% of the participants preferred to apply it. Conclusions It seems that the anti-fatigue mat may be useful in reducing the low back pain although it objectively didn’t significantly change the gluteus medius co-activation pattern related to the low back pain.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2015, 28, 2; 347-356
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena zasobu trwałości zmęczeniowej ustrojów nośnych maszyn podstawowych górnictwa odkrywkowego
Assessment of fatigue life resources of load carrying structures in opencast mining basic machines
Autorzy:
Alenowicz, J.
Onichimiuk, M.
Wygoda, M.
Powiązania:
https://bibliotekanauki.pl/articles/348881.pdf
Data publikacji:
2011
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
ustroje nośne
górnictwo odkrywkowe
maszyny
wymiarowanie
badania
zmęczenie
load carrying structures
opencast mining
machines
research
fatigue
Opis:
Przedstawiono specyfikę pracy i budowy maszyn podstawowych górnictwa odkrywkowego. Podano zasady wymiarowania ustrojów nośnych tych maszyn oraz istniejące niedogodności. Wskazano na przyczyny powstawania pęknięć zmęczeniowych powyższych ustrojów. Omówiono dotychczasowe sposoby oceny zasobu trwałości zmęczeniowej na podstawie badań. Zamieszczono opis i schemat działania systemu ciągłego monitoringu stanu wytężenia ustrojów nośnych maszyn podstawowych. Podano zalety wynikające z zastosowania systemu w bieżącej eksploatacji powyższych maszyn. Zaprezentowano możliwości wdrożenia systemu w kopalniach odkrywkowych węgla brunatnego.
Specificity of operation and construction of opencast mining basic machines has been presented in the paper. Regulations of load carrying structures dimensioning and existing inconveniences have been discussed. Reasons of fatigue fracturing in these structures have been indicated. Previous assessment methods of fatigue life resources based on research have been presented. Description and operational scheme of a system of constant monitoring of load carrying structure effort of opencast mining basic machines has been placed. Advantages resulting from system implementation in current exploitation of machines have been given. Possibilities of system implementation in brown coal opencast mines have been discussed.
Źródło:
Górnictwo i Geoinżynieria; 2011, 35, 3/1; 43-53
1732-6702
Pojawia się w:
Górnictwo i Geoinżynieria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical thermo-mechanical strength analysis of an IC engine component
Autorzy:
Ali, M. A. N.
Hussein, R. A.
Hussein, H. A.
Powiązania:
https://bibliotekanauki.pl/articles/2106442.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
analiza numeryczna
silnik spalinowy
naprężenie
trwałość zmęczeniowa
numerical analysis
IC engine piston
geometrical shape
thermo-mechanical strength
stress intensity
fatigue life
Opis:
This research investigates a thermo-mechanical strength of three geometrical shape designs of an internal combustion (IC) engine piston by a finite element analysis (FEA). FEA was performed using Solidworks software for modelling geometrical piston designs, and the models were imported into ANSYS software for thermo-mechanical fatigue simulation. The work focused on predicting high stress intensity and indicated the fatigue critical regions and life of the piston shape design. AL7075-T6 aluminium alloy was used as a piston material and thermo-mechanical fatigue simulation was conducted based on the experimental stress-number of cycles recorded data from literature. Analytical results showed the similarity of the critical failure positions to some real failures in the IC engine piston, and the shape design modification of the piston. Hence, this concept can be used to satisfy the IC engine design needs at low cost.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 1--11
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shoulder girdle muscle activity and fatigue in traditional and improved design carpet weaving workstations
Autorzy:
Allahyari, Teimour
Mortazavi, Narges
Khalkhali, Hamid Reza
Sanjari, Mohammad Ali
Powiązania:
https://bibliotekanauki.pl/articles/2177075.pdf
Data publikacji:
2015-10-21
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
muscle activity
surface electromyography
muscle fatigue
carpet weaving
workstation
perceived fatigue
Opis:
Objectives Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. Material and Methods The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg’s Category-Ratio scale (Borg CR-10). Results Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. Conclusions The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2016, 29, 2; 345-354
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Survey of modern trends in analysis of continuum damage mechanics
Autorzy:
Ambroziak, A.
Kłosowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933193.pdf
Data publikacji:
2006
Wydawca:
Politechnika Gdańska
Tematy:
continuum damage mechanics
ductile damage
fatigue damage
viscoplasticity
Opis:
A brief review of the damage mechanics literature is given. As this area of scientific research is very modern, the authors have restricted themselves to about 100 most impor-tant books and papers. Basic equations to introduce the isotropic model in the framework of thermodynamics are given in a form easily applicable in numerical symulations.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 4; 437-454
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical model for estimating the period of creep-fatigue crack growth in construction materials at high temperature
Matematyczny model oceny czasu wzrostu pęknięcia w wyniku pełzania - zmęczenia dla materiałów konstrukcyjnych przy wysokiej temperaturze
Autorzy:
Andrejkiv, O.
Lesiv, R.
Powiązania:
https://bibliotekanauki.pl/articles/386614.pdf
Data publikacji:
2007
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
model matematyczny
zmęczenie
równanie różniczkowe
mathematical model
fatigue
differential equation
Opis:
In this work we propose mathematical model of important scientific and technical problem – estimating of remaining lifetime of constructions elements subjected to high temperature fatigue. The differential equation, with initial and final conditions, for assessing the remaining lifetime of three-dimensional solid was obtained. This mathematical model is formulated, based on energetic approach. Proposed approach gave us the possibility to combine fatigue and creep loadings in the single equation. Known in scientific materials experimental data confirmed the correctness of this model.
W tej pracy zaproponowano matematyczny model obliczeniowy dla istotnego zagadnienia naukowo - inżynierskiego, tj. oceny czasu życia elementów konstrukcyjnych poddanych wysokotemperaturowemu zmęczeniu. Uzyskano różniczkowe równanie dla pewnych początkowych i końcowych warunków do oceny trwałości elementów trójwymiarowych. Powyższy model matematyczny sformułowano na podstawie podejścia energetycznego. Zaproponowane podejście umożliwia połączenie obciążeń zmęczeniowych i pełzania w jednym równaniu. Znane z literatury wyniki doświadczeń potwierdziły słuszność proponowanego medelu.
Źródło:
Acta Mechanica et Automatica; 2007, 1, 1; 7-10
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kierunki rozwoju badań ultradźwiękowych na przykładzie badań osi kolejowych
The Ways of Ultrasonic Tests Development Using Example of the Railway Axles Examination
Autorzy:
Antolik, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/214844.pdf
Data publikacji:
2014
Wydawca:
Instytut Kolejnictwa
Tematy:
zestaw kołowy
badania ultradźwiękowe
pęknięcie zmęczeniowe
blok kalibracyjny
wheelset
ultrasonic tests
fatigue crack
calibration block
Opis:
W artykule opisano początki stosowania badań ultradźwiękowych w przemyśle światowym oraz w polskim kolejnictwie, a także realizowany w Polsce zakres certyfikacji w badaniach nieniszczących według normy ISO 9712:2012. Ponadto zwrócono szczególną uwagę na certyfikację personelu badań ultradźwiękowych w kolejnictwie, wraz z określeniem przyczyn, które doprowadziły do jej uruchomienia. Wykonano kwerendę literaturową, a następnie przedstawiono stan normalizacji, określający wymagania dla badań ultradźwiękowych osi kolejowych. Opisano obecny stan techniki z uwzględnieniem podziału na możliwości badań osi w etapie produkcji i eksploatacji, w zależności czy badana oś jest pełna czy drążona. Przedstawiono możliwości automatyzacji procesów badawczych i możliwe kierunki rozwoju dla nowoczesnych technik ultra-dźwiękowych Phased Array lub TOFT i SAFT. Stwierdzono, że technika ultradźwiękowa jest jedną z najbardziej rozwiniętych technik badań nieniszczących, a ciągłe doskonalenie możliwości sprzętowych ukierunkowane jest na łatwość odczytu i zapisu wskazań oraz na znaczne przyspieszenie prowadzonych badań. Rozwijana jest również technika bezkontaktowa, która znacznie ułatwia prowadzenie badania w warunkach, gdzie niedopuszczalne jest stosowanie substancji sprzęgających.
The article describes the beginnings of ultrasonic testing in the global industry and in Polish railways, as well as, the implemented in Poland range of NDT certification according to the norm ISO 9712:2012. Moreover, the article shows the big role of the NDT staff's certification in railways and specifies the causes that led to its launch. First, the review of the literature was done. Afterwards, the condition of normalization that describes the requirements for ultrasonic rail axes testing was showed. The next step of the research methodology was to present the existing state of art taking into account the division of axis' research opportunities at the stage of production and during operation and depending on whether the text axle is full of hollow. The article specifies the automation opportunities of research methodology and possible directions of development of ultrasonic techniques for modern techniques of Phased Array of TOFT and SAFT. It is found that ultrasonic technique is one of the most developed NDT techniques and the continuous improvement of the hardware capabilities is focused on ease of reading and writing of indications and significant acceleration of research. The high level of rolling stock reliability according to European standards must be reach using ultrasonic testing. The modern techniques like TOFT, SAFT or Phassed Array are very helpful to increase testing sensitivity and save a lot of time during interpretation of the results. The automatic testing process is usable only to test naked axles during production process because it is hard to calibrate the ultrasonic flaw detector for testing more complicated shapes including wheelsets.
Źródło:
Problemy Kolejnictwa; 2014, 163; 7-24
0552-2145
2544-9451
Pojawia się w:
Problemy Kolejnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural diagnosis of rail vehicles and method for redesign
Diagnozowanie konstrukcji pojazdów kolejowych i sposób ich przeprojektowania
Autorzy:
Aristizabal, M.
Barbosa, J. L.
Betancur, G. R.
Castañeda, L. F.
Żółtowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/328553.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
structural diagnostic
redesign
rail vehicles
bolster beam
fatigue
aluminium
diagnostyka strukturalna
przeprojektowanie
pojazd szynowy
wzmocnienie wiązki
zmęczenie
Opis:
Structures of rail vehicles are designed for a useful structural life of 30 years. However, structural problems which reduce the mechanical performance of the structure might appear due to normal operation conditions and, in some cases, make it unsuitable for a safe operation. This document presents the structural diagnosis of a metro system and the method for the redesign of structural elements of rail vehicles that was derived from this diagnosis, so that the structural performance of both the element and the whole structure is improved. It is based on the European standards related with aluminium and railway applications, and considers the necessary aspects to produce a safe solution for the final design.
Konstrukcje pojazdów szynowych przeznaczone są na okres eksploatacji 30 lat. Problemy użytkowania zmniejszają wydajność konstrukcji, co może pojawiać się z powodu anormalnych warunków eksploatacji i sprawia w niektórych przypadkach, że pojazd nie nadaje się do bezpiecznej eksploatacji. W tej pracy przedstawiono diagnozę strukturalną elementów systemu „metra” i sposób przebudowy elementów konstrukcyjnych pojazdów szynowych, które wynikają z diagnozy. To powoduje, że wydajność strukturalna elementu i całej konstrukcji jest lepsza. Całość postępowania jest oparta na europejskich standardach związanych z aplikacjami aluminium w kolejnictwie i wskazuje na niezbędne aspekty produkcji bezpiecznych rozwiązań dla końcowego efektu.
Źródło:
Diagnostyka; 2014, 15, 3; 23-31
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
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:
Analysis of fatigue cracks of cylinder heads in diesel engines
Autorzy:
Ashouri, H.
Beheshti, B.
Ebrahimzadeh, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/279801.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
thermo-mechanical fatigue
finite element analysis
cylinder head and valve bridge cracks
Opis:
Loading conditions and complex geometry have led cylinder heads to become the most challenging parts of diesel engines. One of the most important durability problems in diesel engines is due to cracks in the valves bridge area. The purpose of this study is thermo- -mechanical analysis of cylinder heads of diesel engines using a two-layer viscoplasticity model. The results of the thermo-mechanical analysis indicate that the maximum temperature and stress occurr in the valves bridge. The results of the finite element analysis correspond with the experimental tests carried out by researchers, and illustrate cracks in cylinder heads in this region. The results of the thermo-mechanical analysis show that when the engine is running, the stress in the region is compressive, caused by thermal loading and combustion pressure. When the engine is shut off, the compressive stress turns into tensile stress because of assembly loads. The valves bridge is under cyclic tensile and compressive stress state and thus is subject to low cycle fatigue. After several cycles fatigue cracks will appear in this region. The lifetime of this part can be determined through finite element analysis instead of experimental tests. The viscous strain is greater than the plastic strain which is not negligible.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 2; 369-383
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and analysis of cementless hip-joint system using functionally graded material
Autorzy:
Asiri, Saeed
Powiązania:
https://bibliotekanauki.pl/articles/2065758.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
functionally graded material
cementless hip-joint system
natural frequency
harmonic response
fatigue analysis
finite element analysis
modal analysis
odpowiedź harmoniczna
analiza zmęczeniowa
analiza elementów skończonych
analiza modalna
Opis:
Functionally Graded Materials (FGM) are extensively employed for hip plant component material due to their certain properties in a specific design to achieve the requirements of the hip-joint system. Nevertheless, if there are similar properties, it doesn’t necessarily indicate that the knee plant is efficiently and effectively working. Therefore, it is important to develop an ideal design of functionally graded material femoral components that can be used for a long period. A new ideal design of femoral prosthesis can be introduced using functionally graded fiber polymer (FGFP) which will reduce the stress shielding and the corresponding stresses present over the interface. Herein, modal analysis of the complete hip plant part is carried out, which is the main factor and to date, very few research studies have been found on it. Moreover, this enhances the life of hip replacement, and the modal, harmonic, and fatigue analysis determines the pre-loading failure phenomena due to the vibrational response of the hip. This study deals with the cementless hip plant applying the finite element analysis (FEA) model in which geometry is studied, and the femoral bone model is based in a 3D scan.
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 1; 129--146
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Acute Creatine Supplementation on Fatigue and Anaerobic Performance
Autorzy:
Ateş, Osman
Keskin, Burcak
Bayraktar, Bulent
Powiązania:
https://bibliotekanauki.pl/articles/1055198.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
anaerobic performance
creatine
fatigue
soccer
Opis:
The aim of this study is to investigate the effect of acute creatine monohydrate supplementation on fatigue and anaerobic performance. Thirty young soccer players participated in this study. Participants continued their training without taking any food supplements for 5 days, taking 0.3 g of milk dust per kg for 5 days and using 0.3 g creatine monohydrate per kg for 5 days. A total of 6 × 35 m sprint times were used in the fatigue index with a 10-second rest period between them. Single repeated sprint times of 35 m were examined as well. Statistically significant differences (p < 0.05) were found both fatigue index and single repeated 35 m sprint time after creatine supplementation. However there was not a statistically significant difference (p > 0.05) in Rast Test results. In soccer, it is known that there is a strong positive correlation between game performance and the number of repeated sprint numbers in a game. In conclusion, there was a statistically significant effect of 0.3 g of acute creatine loading per kg over 5 days on the single repeated sprints and fatigue index values. The creatine monohydrate can be used as an ergogenic aid for recovery periods between high-intensity exercises to affect performance.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2017, 19, 3; 85-92
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptation of engineering FEA-based algorithms to LCF failure and material data prediction in offshore design
Autorzy:
Augustyniak, M.
Gajewski, P.
Świątek, K.
Powiązania:
https://bibliotekanauki.pl/articles/279187.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
low-cycle fatigue
finite element method
high-strength steel
stress gradient influence
Opis:
There is an ever growing industrial demand for quantitative assessment of fatigue endurance of critical structural details. Although FEA-based calculations have become a standard in engineering design, problems involving the Low-To-Medium cycle range (101 -104 ) remain challenging. This paper presents an attempt to optimally choose material data, meshing density and other algorithm settings in the context of recent design of the large offshore windfarm installation vessel, VIDAR. In this study, an attempt is made to assess default FEA-based procedures in RADIOSS software by comparing an experimental test against numerical analyses. Standard slender cylindrical (“I”) samples as well as originally designed “Z”-shaped samples made of A90 (S690)-grade steel have been loaded at various nominal stress ranges with or without local yielding. A good correlation has been found between FEA results and experimental cycles-to-failure in I-shaped samples, provided the software material data generator is avoided and Smith-Watson-Topper mean stress correction is used. In the case of Z-shaped samples, the calculated cycles-to-initiation of macro-crack is significantly lower (factor of 3) from the experiment. The observed discrepancy is argued to be due to stress gradient influence.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 4; 1345-1356
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparing of High-Cycle Fatigue Lifetimes in Un-corroded and Corroded Piston Aluminum Alloys in Diesel Engine Applications
Autorzy:
Azadi, M.
Aroo, H.
Parast, M. S. A.
Powiązania:
https://bibliotekanauki.pl/articles/2079778.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
bending fatigue
corrosion fatigue
piston aluminum alloys
diesel engines
immersion time
zginanie
zmęczenie korozyjne
tłoki
stopy aluminium
silnik Diesla
Opis:
Diesel engine components in the combustion chamber have been exposed to cyclic loadings under environmental effects, including high temperatures and corrosive fluids. Therefore, knowing the corrosion-fatigue behavior of materials is essential for designer engineers. In this article, pure fatigue and corrosion-fatigue behaviors of the piston aluminum alloy have been experimentally investigated. For such an objective, as-cast and pre-corrosive standard samples were tested by the rotary bending fatigue machine, under 4 stress levels. Some specimens were exposed to the corrosive fluid with 0.00235 % of the sulfuric acid for 100 and 200 hours. The results showed higher weight losses for 200 hours immersion times. As another result, it could be concluded that the lifetime decreased in pre-corrosive samples for both 100 and 200 hours of the immersion time, compared to that of as-cast specimens. However, such a lifetime reduction was more significant for 200 hours of the immersion time, especially within the high-cycle fatigue regime (or lower stress levels). Under high stress levels, both pre-corrosive sample types had almost similar behaviors. The field-emission scanning electron microscopy images of specimen fracture surfaces indicated that the brittle region of the fractured surface was larger for specimens after the 200 hours of corrosion-fatigue testing than the other specimen.
Źródło:
Archives of Foundry Engineering; 2021, 21, 1; 89-94
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 993

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