Journal articles: 'Fatigue aging'

1

Tralongo, Paolo, Daniela Respini, and Francesco Ferraù. "Fatigue and aging." Critical Reviews in Oncology/Hematology 48 (October 2003): S57—S64. http://dx.doi.org/10.1016/j.critrevonc.2003.07.003.

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Hunter, Sandra K. "Aging and Muscle Fatigue." Medicine & Science in Sports & Exercise 38, Supplement (May 2006): 46. http://dx.doi.org/10.1249/00005768-200605001-00158.

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Hunter, Sandra K. "Aging and Muscle Fatigue." Medicine & Science in Sports & Exercise 38, Supplement (May 2006): 46. http://dx.doi.org/10.1249/00005768-200605001-00299.

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4

Balducci, L. "Anemia, fatigue and aging." Transfusion Clinique et Biologique 17, no. 5-6 (December 2010): 375–81. http://dx.doi.org/10.1016/j.tracli.2010.09.169.

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Ma, Liyong, Chi Liu, Minglei Ma, Zhanying Wang, Donghao Wu, Lijuan Liu, and Mingxing Song. "Fatigue Fracture Analysis on 2524 Aluminum Alloy with the Influence of Creep-Aging Forming Processes." Materials 15, no. 9 (April 30, 2022): 3244. http://dx.doi.org/10.3390/ma15093244.

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The different creep-aging forming processes of 2524 aluminum alloy were taken as the research object, and the effects of creep-aging temperature and creep stress on the fatigue-crack propagation properties of the alloy were studied. The research results showed the following under the same sintering time of 9 h, at creep-aging temperatures of 100 °C, 130 °C, 160 °C, and 180 °C, respectively, with an increase in creep-aging temperature: the fatigue-crack propagation rate was promoted, the spacing of fatigue striations increased, and the sizes of dimples decreased while the number was enlarged; this proves that the fatigue property of the alloy was weakened. Compared with the specimens with creep deformation radii of 1000 mm and 1500 mm, the creep deformation stress was the smallest when the forming radius was 1800 mm, with a higher threshold value of fatigue-crack growth in the near-threshold region of fatigue-crack propagation (ΔK ≤ 8 MPa·m1/2). Under the same fatigue cycle, the specimens under the action of larger creep stress endured a longer fatigue stable-propagation time and a faster fracture speed. Comparing the effect of creep-aging temperature and creep stress, the creep-aging temperature plays a dominant role in the fatigue-crack propagation of creep-aged 2524 aluminum alloy.

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Liu, Xing, Shaopeng Wu, Ling Pang, Yue Xiao, and Pan Pan. "Fatigue Properties of Layered Double Hydroxides Modified Asphalt and Its Mixture." Advances in Materials Science and Engineering 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/868404.

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This study investigated the influence of layered double hydroxides (LDHs) on the fatigue properties of asphalt mixture. In this paper, different aging levels (thin film oven test (TFOT) and ultraviolet radiation aging (UV aging for short)) of bitumen modified with various mass ratios of the LDHs were investigated. The TFOT and UV aging process were used to simulate short-term field thermal-oxidative aging and long-term field light UV aging of bitumen, respectively. The influences of LDHs on the fatigue properties of LDHs were evaluated by dynamic shear rheometer (DSR) and indirect tensile fatigue test. Results indicated that the introduction of LDHs could change the fatigue properties of bitumen under a stress control mode. The mixture with modified bitumen showed better fatigue resistance than the mixture with base bitumen. The results illustrated that the LDHs would be alternative modifiers used in the bitumen to improve the lifetime of asphalt pavements.

7

HAYASHI, KOUSUKE, TAKANORI NAGANO, MICHIHIKO MORIYAMA, XISHU WANG, and NORIO KAWAGOISHI. "EFFECTS OF AGING STRUCTURES AND HUMIDITY ON FATIGUE PROPERTIES OF MARAGING STEEL." International Journal of Modern Physics: Conference Series 06 (January 2012): 306–11. http://dx.doi.org/10.1142/s2010194512003352.

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Effects of aging structures and humidity on fatigue properties of 350 grade 18% Ni maraging steel were investigated under rotating bending in relative humidity of 25% and 85%. Aging conditions tested were a conventional single aging and a double one which was aged at low temperature after the conventional aging. In each aging, under and peak aged steels were prepared. Tensile strength was increased by the double aging without reduction of the ductility. Proportional relation between fatigue limit and Vickers hardness held until 750HV in low humidity. However fatigue strength was largely decreased by high humidity, especially in the peak aged steel at the single aging. The decrease in fatigue strength by high humidity was mainly caused by the acceleration of a crack initiation due to the anodic dissolution. The acceleration of a crack initiation was larger in the steel peak aged at the single aging with larger precipitated particles.

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Li, Shilei, Yanli Wang, and Xitao Wang. "Effects of Thermal Aging on the Low Cycle Fatigue Behaviors of Cast Duplex Stainless Steels." Metals 9, no. 3 (March 25, 2019): 378. http://dx.doi.org/10.3390/met9030378.

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The low cycle fatigue (LCF) behaviors of cast duplex stainless steel (CDSS) thermally aged at different times were investigated under different strain amplitudes. The effects of thermal aging on the LCF lives of CDSS are closely related to the strain amplitude. At a low strain amplitude, the fatigue life of the material increases significantly after thermal aging, while the LCF life decreases with an increasing aging time at a high strain amplitude. After thermal aging at 400 °C for 10,000 h, the fatigue fracture morphologies of CDSS change from fatigue fringes to mixture features including fatigue fringes in austenite and cleavage cracks in ferrite. Severe plastic deformation in ferrite of the aged CDSS under a high strain amplitude causes the cleavage cracking of ferrite. The premature failure of ferrite accelerates the propagation of fatigue crack and shortens the fatigue life at a high strain amplitude.

9

Nakagawa, Keiyu, and Teruto Kanadani. "Effects of Microstructures on the Mechanical Properties of Dilute Al-Si Alloys." Key Engineering Materials 345-346 (August 2007): 821–24. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.821.

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In this paper, we investigated effects of aging at 473K on the relationship between microstructure in the vicinity of the grain boundaries and fatigue strength for Al-1.2%Si alloy. Results obtained show the following features. (1) As aging time, tA increase, the tensile strength (σB) and 0.2% proof stress (σ0.2) increase slowly, but gradually decrease after reaching a maximum at around 18 ks. On the other hand, fracture elongation shows an opposite trend, suggesting that at aging times above 18ks, over aging occurs. (2) The fatigue strength lowers with increasing aging time, however, when the aging time is more than 18 ks at 473K, the fatigue strength remains almost the same. (3) When the aging time is more than 6 ks, grain boundary precipitates with a size greater than several 10s of nm are observed. (4) When the aging time is 18 ks, an accumulation of dislocations are observed at the grain boundaries and in the vicinity of grain boundary precipitates, and dislocations increase with the number of stress cycles. (5) When the aging time is more than 6 ks, the fatigue fracture surface is mainly intergranular. These results suggest that reduction of fatigue strength results from propagation of micro-cracks which are initiated at the large precipitates on the grain boundaries.

10

Wang, S. Q., Jin He Liu, and Dao Lun Chen. "Influence of Heat Treatment on Fatigue Resistance of Electron Beam Welded Dissimilar Titanium Alloy Joints." Advanced Materials Research 891-892 (March 2014): 1539–44. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1539.

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The purpose of this study was to evaluate the influence of heat treatment on the microstructural change and low cycle fatigue (LCF) resistance of an electron beam welded (EBWed) dissimilar joint between Ti-6Al-4V and Ti17 alloys. The aging with solution (STA) had a more significant effect on the microstructure and hardness than aging, compared to the as-welded joint. The post-welded joints in both aging and STA conditions were basically cyclic stable at low strain amplitudes up to 0.6%, while cyclic softening occurred at higher strain amplitudes. The fatigue life in the aging condition was slightly longer than that in the STA condition at the lower strain amplitudes. Fatigue crack initiation occurred from the specimen surface or near-surface defect, and fatigue crack propagation was characterized mainly by the fatigue striations coupled with secondary cracks in both aging and STA conditions.

11

Tanaka, Kazuto, and Masatoshi Uchiyama. "Effect of Vitamin-E Addition on Fatigue Crack Growth Property of Ultra High Molecular Weight Polyethylene." Key Engineering Materials 417-418 (October 2009): 93–96. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.93.

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In order to understand the influence of gamma-irradiation, accelerated aging and Vitamin-E addition on the fatigue crack growth properties of UHMWPE, fatigue crack growth tests of UHMWPE plates using compact tension specimens were carried out. The specimen conditioned in -irradiation and accelerated aging (the -aging specimen) has faster fatigue crack growth rate than the virgin specimens. For the Vitamin-E added specimen (the VE specimen), however, K threshold of the -aging VE specimen is smaller than that of the VE specimen. This result shows that the addition of Vitamin-E reduced the decrease of K threshold by -irradiation and accelerated aging.

12

Xu, Gang, Yixin Zhou, Yu Zhu, Rui Wang, and Xianhua Chen. "Effect of Weather Aging on Viscoelasticity and Fatigue Performance of Asphalt Mastic." Materials 14, no. 20 (October 18, 2021): 6163. http://dx.doi.org/10.3390/ma14206163.

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The long-term effect of climate factors, such as sunlight, oxygen, and water, leads to the performance degradation of the asphalt mastic, which is the binding part in the asphalt mixture. It is not conducive to satisfy the long-term performance requirements of long-life asphalt pavement. In this study, five kinds of base asphalt mastic and styrene-butadiene-styrene (SBS) modified asphalt mastic were prepared with the filler-asphalt ratio of 0.6, 0.8, 1.0, 1.2, and 1.4. The indoor simulated weather aging tests were carried out considering multi-factors including sunlight, oxygen, and water. The master curves of the complex shear modulus and phase angle of the asphalt mastic with different aging degrees were obtained by the frequency sweep test. The curves of fatigue damage characteristics and fatigue life were fitted based on the viscoelastic continuum damage (VECD) model. The influence of weather aging on the viscoelasticity and fatigue performance of asphalt mastic were analyzed. Results indicated that the effect of weather aging increases the elastic component and decreases the viscous component. The fatigue performance of SBS modified asphalt mastic was better than that of base asphalt mastic. As the aging degree deepens, the brittle failure characteristics of asphalt mastic with a higher filler–asphalt ratio were more obvious. The base asphalt mastic becomes more sensitive to the strain level due to weather aging, and its fatigue life increased under the low strain loading and decreased under the high strain loading. The fatigue performance of SBS modified asphalt mastic was less sensitive to the strain level. The fatigue life reduced after aging under low and high strain load. Taking the impact of weather aging on the fatigue performance into consideration, the optimal filler–asphalt ratios of the base asphalt mastic SBS modified asphalt mastic are 1.0 and 1.2, respectively.

13

Zhang, Jian Yu, Chong Qiang Sun, Li Bin Zhao, Lei Peng, and Bin Jun Fei. "Experiment Research of Environment Effects on Fatigue Life of Carbon/Bismaleimide Composite Laminates with Central Hole." Key Engineering Materials 452-453 (November 2010): 525–28. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.525.

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The effects of humidity and ultraviolet radiation aging on fatigue properties of carbon/ bismaleimide composites and coating protection action were presented. Specimens with central hole are made of carbon/bismaleimide laminates. Compression-compression (C-C) fatigue tests under normal lab environment were operated respectively for four groups of specimen, (1) specimen under normal lab environment, (2) specimen under UV radiation aging with dryness, (3) specimen under UV radiation aging with moisture, and (4) specimen with coating under UV radiation aging with moisture. Variance analysis of experimental outcomes gave significances of the environment effects on C-C fatigue life of specimens. The results reveal that UV radiation have remarkable effects on the C-C fatigue life of the composite laminates under the same humidity, whereas combined action of UV radiation (300MJ/ m2) and humidity have no significant effects on the C-C fatigue life. Coating can provide effective protect the specimen from UV radiation aging.

14

Shortz, Ashley E., and Ranjana K. Mehta. "Cognitive challenges, aging, and neuromuscular fatigue." Physiology & Behavior 170 (March 2017): 19–26. http://dx.doi.org/10.1016/j.physbeh.2016.11.034.

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15

Song-tao, Lu, Luo Zhaohui, and Xie Juan. "Fatigue performance of aging asphalt mixtures." Polimery 60, no. 02 (February 2015): 126–31. http://dx.doi.org/10.14314/polimery.2015.126.

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16

Cook, Karon F., Ivan R. Molton, and Mark P. Jensen. "Fatigue and Aging With a Disability." Archives of Physical Medicine and Rehabilitation 92, no. 7 (July 2011): 1126–33. http://dx.doi.org/10.1016/j.apmr.2011.02.017.

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17

Sainis, Salil, Aakarshit Kalra, G. Dinesh Babu, and M. Nageswara Rao. "Weibull Analysis of the Effect of Modified Aging Treatments on Fatigue Life of Cast Aluminium Alloy 354." Advanced Materials Research 800 (September 2013): 356–60. http://dx.doi.org/10.4028/www.scientific.net/amr.800.356.

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Cast aluminium alloy 354 has extensive applications in the automobile industry. Due to its attractive combination of mechanical properties and excellent castability, it is being used in production of automobile components like the compressor wheel for turbochargers. Performance of this component under fatigue loading conditions is a critical issue. The present study explores the possibility of improving the fatigue life of the component by bringing in process changes (i) adopting a two-step aging treatment in place of the normally used single step aging treatment (ii) adopting a lower artificial aging temperature (171°C) instead of the temperature normally used for artificial aging (188°C) while performing T61 treatment. In all cases Weibull analysis of fatigue test results was carried out. Weibull analysis of Ultimate Tensile Strength (UTS) values obtained after artificial aging at 171°C and 188°C was also carried out. Among the four variants of two-step aging treatment carried out, the one consisting of 100°C for 5 hours followed by 170°C for 5 hours was found to have the best characteristic fatigue life for the components. The modified T61 treatment where aging was carried out at 171°C instead of the normally used 188°C yielded better characteristic fatigue life as well as better Ultimate Tensile Strength (UTS).

18

Silvestri, Tais, Gabriel Kalil Rocha Pereira, Luis Felipe Guilardi, Marilia Pivetta Rippe, and Luiz Felipe Valandro. "Effect of Grinding and Multi-Stimuli Aging on the Fatigue Strength of a Y-TZP Ceramic." Brazilian Dental Journal 29, no. 1 (February 2018): 60–67. http://dx.doi.org/10.1590/0103-6440201801735.

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Abstract This study aimed to investigate the effect of grinding and multi-stimuli aging on the fatigue strength, surface topography and the phase transformation of Y-TZP ceramic. Discs were manufactured according to ISO-6872:2008 for biaxial flexure testing (diameter: 15 mm; thickness: 1.2 mm) and randomly assigned considering two factors “grinding” and “aging”: C- control (as-sintered); CA- control + aging; G- ground; GA- ground + aging. Grinding was carried out with coarse diamond burs under water-cooling. Aging protocols consisted of: autoclave (134°C, 2 bars pressure, 20 hours), followed by storage for 365 days (samples were kept untouched at room temperature), and by mechanical cycling (106 cycles by 20 Hz under a load of 50% from the biaxial flexure monotonic tests). Flexural fatigue strengths (20,000 cycles; 6 Hz) were determined under sinusoidal cyclic loading using staircase approach. Additionally, surface topography analysis by FE-SEM and phase transformation analysis by X-ray Diffractometry were performed. Dixon and Mood methodology was used to analyze the fatigue strength data. Grinding promotes alterations of topographical pattern, while aging apparently did not alter it. Grinding triggered t-m phase transformation without impacting the fatigue strength of the Y-TZP ceramic; and aging promoted an intense t-m transformation that resulted in a toughening mechanism leading to higher fatigue strength for as-sintered condition, and a tendency of increase for ground condition (C < CA; G = GA). It concludes that grinding and aging procedures did not affect deleteriously the fatigue strength of the evaluated Y-TZP ceramic, although, it promotes surface topography alterations, except to aging, and t-m phase transformation.

19

Zhang, Runhua, Jo E. Sias, Eshan V. Dave, and Reyhaneh Rahbar-Rastegar. "Impact of Aging on the Viscoelastic Properties and Cracking Behavior of Asphalt Mixtures." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 6 (May 8, 2019): 406–15. http://dx.doi.org/10.1177/0361198119846473.

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Aging can significantly affect the viscoelastic properties and cracking behavior of asphalt mixtures, causing increase in stiffness, reduction in relaxation capability, and increase in brittleness. Eleven mixtures are evaluated using different laboratory conditioning protocols to evaluate how the properties of asphalt mixtures, including viscoelastic properties, fatigue, and fracture behavior will change over time. Comparisons between different aging levels and mixtures are conducted by using complex modulus (E*) (field cores are included), simplified viscoelastic continuum damage (S-VECD) approach, semi-circular bending (SCB), and disk shaped compact tension (DCT) fracture tests. The climatic aging index developed by the NCHRP 09-54 project is utilized in this study to calculate the appropriate field aging duration corresponding to the different laboratory aging protocols. Pavement evaluation tools FlexPAVETM and IlliTC are also used to predict and compare the fatigue and thermal cracking performance of these mixtures. The results of E* and S-VECD tests indicate that the mixtures are more prone to fatigue cracking with aging, and the two long-term conditioning protocols induce statistically similar changes in linear viscoelastic and fatigue properties. However, prediction of fatigue performance from FlexPAVE TM does not show a consistent trend once pavement structure and traffic are considered. Fracture tests and IlliTC predictions show the virgin mixtures and those with soft base binders will have better capability to resist cracking after long-term aging. In this study, the two mixtures with the largest difference between high and low temperature performance grade (PG) show the largest change in fracture and fatigue properties with aging.

20

Diao, Hang, Tianqing Ling, Zhan Zhang, Bo Peng, and Qiang Huang. "Multiscale Fatigue Performance Evaluation of Hydrated Lime and Basalt Fiber Modified Asphalt Mixture." Materials 16, no. 10 (May 9, 2023): 3608. http://dx.doi.org/10.3390/ma16103608.

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Long-life pavement construction is an important research direction for sustainable road development. Fatigue cracking of aging asphalt pavement is one of the main reasons that affects its service life, and improving the fatigue resistance of aging asphalt pavement has become a key factor in promoting the development of long-life pavement. In order to enhance the fatigue resistance of aging asphalt pavement, hydrated lime and basalt fiber were selected to prepare a modified asphalt mixture. The resistance to fatigue is evaluated by the four-point bending fatigue test and self-healing compensation test, based on the energy method, the phenomenon-based approach, and other methods. The results of each method of evaluation were also compared and analyzed. The results indicate that the incorporation of hydrated lime can improve the adhesion of the asphalt binder, while the incorporation of basalt fiber can stabilize the internal structure. When incorporated alone, basalt fiber has no noticeable effect, while hydrated lime significantly improves the fatigue performance of the mixture after thermal aging. Mixing both ingredients produced the best improvement effect under various conditions, with a fatigue life improvement of 53%. In the multi-scale evaluation of fatigue performance, it was found that the initial stiffness modulus was unsuitable as a direct evaluation index of fatigue performance. Using the fatigue damage rate or the stable value of dissipated energy change rate as an evaluation index can clearly characterize the fatigue performance of the mixture before and after aging. The self-healing rate and self-healing decay index clearly reflected the fatigue damage healing process under repeated loading and could be used as relevant indices for evaluating the new-scale fatigue performance of asphalt mixtures.

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Tian, Ni, Xu Jiang, Yaozhong Zhang, Zijie Zeng, Tianshi Wang, Gang Zhao, and Gaowu Qin. "Effect of Precipitates on the Mechanical Performance of 7005 Aluminum Alloy Plates." Materials 15, no. 17 (August 28, 2022): 5951. http://dx.doi.org/10.3390/ma15175951.

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In this study, the strength, elongation, and fatigue properties of 7005 aluminum alloy plates with different configurations of precipitates were investigated by means of tensile tests, fatigue tests, and microstructural observation. We found that the number and size of GP zones in an alloy plate matrix increased and the distribution was more uniform after the aging time was extended from 1 h to 4 h at 120 °C, which led to a rise in both strength and elongation of alloy plates with the extending aging time. The fatigue life of the alloy plates shortened slightly at first, then significantly prolonged, and then shortened again with the aging time extending from 1 h to 192 h and a fatigue stress level of 185 MPa and stress ratio (R) = 0. After aging at 120 °C for 96 h, the precipitates in the alloy plate matrix were almost all metastable η′-phase particles, which had the optimal aging strengthening effect on the alloy matrix, and the degree of mismatch between the α-Al matrix and second-phase particles was the smallest; the fatigue crack initiation and propagation resistances were the largest, leading to the best fatigue performance of alloy plates, and the fatigue life of the aluminum plate was the longest, up to 1.272 × 106 cycles. When the aging time at 120 °C was extended to 192 h, there were a small number of equilibrium η phases in the aluminum plates that were completely incoherent with the matrix and destroyed the continuity of the aluminum matrix, easily causing stress concentration. As a result, the fatigue life of alloy plates was shortened to 9.422 × 105 cycles.

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Yin, Shu Ying, Li Jia Chen, and Xin Wang. "Influence of Heat Treatment on Low-Cycle Fatigue Behavior of AZ61 Magnesium Alloy." Advanced Materials Research 287-290 (July 2011): 883–87. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.883.

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In order to identify the influence of solid solution, aging and solid solution plus aging treatments on the low-cycle fatigue behavior of the extruded AZ61 magnesium alloy, the low-cycle fatigue tests were performed at room temperature for the extruded AZ61 magnesium alloy with different treating states. The results indicate that the cyclic stress response behavior of the extruded AZ61 magnesium alloy exhibits both cyclic strain hardening and stability. The solid solution, aging and solid solution plus aging treatments tend to decrease the cyclic deformation resistance of the extruded AZ61 alloy in most conditions. The solid solution treatment can enhance the fatigue lives of the extruded AZ61 alloy at medium total strain amplitudes. In addition, the aging treatment can prolong the low-cycle fatigue lives of the AZ61 alloy at most total strain amplitudes, while the case for the solid solution plus aging treatment is just contrary. For the extruded AZ61 alloy with different treating states, a linear relationship between cyclic stress amplitude and plastic strain amplitude is noted.

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Liu, Hong Tao, Mi Feng Zhao, Fangting Hu, Li Juan Zhu, Zhi Yi Liu, Xiao Feng Bai, and Lei He. "Effect of Pre-Stretching and Under-Aging Treatment on Fatigue Crack Resistance of Al-Cu-Mg Alloy Casing Pipe." Materials Science Forum 1071 (October 18, 2022): 67–73. http://dx.doi.org/10.4028/p-vff7jl.

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The effect of pre-stretching and under-aging treatment on microstructure and fatigue crack resistance of Al-4.1Cu-1.27Mg-0.47Mn-0.02Ti alloy has been investigated in present work. The results showed that the fatigue strength corresponding to 107 stress cycle numbers of the sample pre-stretched 4% and under-aged at for 2 hours reached up to 280MPa, 80MPa higher than that pre-stretched 0% and peak-aged at for 8 hours. Microstructural observations showed that fine and uniformly dispersed S’ plates were present in the sample treated by pre-stretching and under-aging, whereas, a coarse S’ plate was formed in the sample when treated by 0% pre-stretching and peak-aging. It is indicated that the pre-stretching and under-aging treatment promotes the dispersoid formation of strengthening particles, enhancing the fatigue crack resistance and resultant fatigue strength. Keywords: Al-Cu-Mg alloy, fatigue, pre-stretching, aluminum alloy casing pipe

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Zhang, You Hong, Qian Zhang, Xin Long Chang, Chun Guo Yue, Shi Ying Zhang, and Wan Lei Liu. "Life Prediction of Aluminum Alloy Structure Subjected to Corrosion Fatigue and Corrosion Damage." Applied Mechanics and Materials 166-169 (May 2012): 1887–90. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1887.

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The strength of the aging structure deteriorates mainly as a result of corrosion and fatigue damage. In this paper, the life prediction methods of corroded and corrosion fatigued aluminum alloy structure were proposed. The stress multiplication of aluminum alloy structure subjected to corrosion damage was simulated by ANSYS software. We proposed the AFGROW software simulation method to predicate the numerical simulation of corrosion fatigue crack growth. At last, the life cycles of structures subjected to corrosion damage and corrosion fatigue were estimated, and a very good performance of the proposed methods are achieved after validation with the experimental data.

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Sorokin, Genady A., and V. V. Shilov. "HYGIENIC ASPECTS OF CHRONIC FATIGUE AND AGING." Hygiene and sanitation 96, no. 7 (March 27, 2019): 627–31. http://dx.doi.org/10.18821/0016-9900-2017-96-7-627-631.

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The aim of the study was to establish relations between the acute and chronic fatigue of workers, and between chronic fatigue and age dynamics of indices of health. In 859 women, white-collar workers, with normal fatigue at work of various degree and different physiological labor intensity there was determined an annual gain of professional risks (GPR): syndromes of motor, visual, and non-specific chronic fatigue; indices of the physical performance; morbidity with temporary disability. During the year the health is deteriorating both in 59% of women who are very tired at work, and 63% of women with chronic fatigue syndrome. Under a high level of the physiological intensity of labor GPR increases by 2 times for diseases of the cardiovascular system and by 2.2-times for the disorders of the musculoskeletal system. For hygienic evaluation rate of aging working in harmful conditions, there are required values of age population trends in health indices observed in favorable habitat, without the harmful effects of professional and non-professional factors.

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Wu, Shao Peng, Jun Han, and Xing Liu. "Evaluation of Fatigue Properties for Ultraviolet Radiation Aged Bitumen and Mixture." Advanced Materials Research 217-218 (March 2011): 181–86. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.181.

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Bitumen is widely used in road construction. Due to heavy traffic loads and environmental factors, bitumen properties will change during service life. Bitumen will age due to diffusion of oxygen and UV radiation. Repeated loading will result in decreasing strength because of fatigue. In this paper, one layer clay powder was used to modify base bitumen with different mass contents. Then the influences of ultraviolet radiation (UV) aging on the dynamic fatigue properties of the layered clay powder were evaluated by Dynamic Shear Rheomoter (DSR) and Universal Testing Machine (UTM). The ageing evaluation shows that the ageing resistance of bitumen is improved and this improvement is more notable in bitumen fatigue than mixture.

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Li, Gen, Jiajun Liu, Jian Sun, and Chengqi Sun. "Effects of Natural Aging and Discontinuous Cyclic Loading on High Cycle Fatigue Behavior of Steels." Metals 13, no. 3 (March 3, 2023): 511. http://dx.doi.org/10.3390/met13030511.

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Metallic components may not be used immediately and are stored for several months or years after fabrication in some cases, which experience long-term natural aging. Moreover, the fatigue-beared components commonly suffer discontinuous cyclic loadings in service. In this paper, the effects of natural aging and discontinuous loading on high cycle fatigue life and failure mechanism were investigated through rotating bending fatigue tests. The long-term natural aging (e.g., more than 20,000 h) reduced the fatigue life of both 25CrMo4 and 30CrMnSiA steels, and this effect was irrespective of the roughness of the specimen surface. The effect of natural aging on the failure mechanism was related to the microstructure of materials. The natural aging promoted the probability of multi-site crack initiation for 25CrMo4 steel, but had no influence on the crack initiation mode of 30CrMnSiA steel. The discontinuous cyclic loading had no harmful influence on the fatigue life of 25CrMo4 steel, and it had no influence on the failure mechanism. The specimens under continuous and discontinuous cyclic loadings both failed from single-site crack initiation or multi-site crack initiation at the specimen surface.

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Yi, Ming Wei, Delehei, Jin Cai Wang, and Xue Da Feng. "Effect of Ultraviolet Light Aging on Fatigue Properties of Asphalt." Key Engineering Materials 599 (February 2014): 125–29. http://dx.doi.org/10.4028/www.scientific.net/kem.599.125.

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The ultraviolet aging effects on fatigue properties of asphalt were studied by using Dynamic Shear Rheometer (DSR). The low-temperature fatigue performance of asphalt has been tested in this paper with the strain-controlled mode of DSR. The samples were compacted under the temperature of 10°C and the constant strain of 2.0% in strain-controlled mode fatigue test. And the results showed that ultraviolet aging decreases the fatigue life-span of asphalt significantly.

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Li, Ruixia, Shangjun Yu, Hailong Chen, Jiahui Wu, Yijun Chen, and Jinchao Yue. "Effects of a Complex Environment on Fatigue and Self-Healing Characterization of Asphalt Composites Containing Rock Asphalt." Materials 17, no. 10 (May 19, 2024): 2453. http://dx.doi.org/10.3390/ma17102453.

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In recent years, asphalt pavement has been subjected to varied environmental conditions during its service life, conditions that predispose it to deformation and cracking. To enhance the performance of asphalt pavement, rock asphalt has been selected as a modifier due to its good compatibility with virgin asphalt binder and its ability to improve the fatigue cracking resistance of asphalt mixtures. Although scholars have conducted some studies on rock asphalt mixtures, research on the fatigue and self-healing performance of these mixtures under conditions such as ultraviolet (UV) aging and freeze–thaw remains limited. This paper presents findings from a study that employs a combined fatigue-healing test to assess the impact of such complex environmental factors on the fatigue and self-healing properties of fine aggregate matrix (FAM) mixtures containing three types of rock asphalts, i.e., Buton, Qingchuan (QC), and Uintaite Modifier (UM). The analysis of fatigue-healing test results, grounded in viscoelastic continuum damage (VECD) theory, indicates that rock asphalt can extend the fatigue life of FAM mixtures, albeit with a concomitant decrease in their self-healing capabilities. The study further reveals that UV aging, freeze–thaw, and UV aging–freeze–thaw conditions all led to a diminution in the fatigue and self-healing properties of FAM mixtures. However, FAM mixtures containing rock asphalt demonstrated greater resilience against these reductions. Atomic force microscope (AFM) results indicate that UV aging reduced the number of bee-structures and enlarged their area, whereas the incorporation of rock asphalt enhanced the uniformity of these structures’ distribution, thereby improving the fatigue cracking resistance of FAM mixtures. Fourier transform infrared spectroscopy (FTIR) analysis reveals that while UV aging increased the carbonyl and sulfoxide indices within the asphalt binder, rock asphalt is effective in mitigating this effect to a certain degree, thereby enhancing the aging resistance of FAM mixtures.

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Pang, Ling, Lu Long, Shao Peng Wu, and Wan Lu. "Effects of UV Aging on the High-Temperature and Fatigue Performances of Asphalt Mortar." Advanced Materials Research 306-307 (August 2011): 1698–701. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1698.

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Ultraviolet(UV) radiation is one of the main factors induce asphalt aged in the field in-service. Asphalt mortar greatly affects the pavement performance. It is scarce that studies concerning UV aging on the performance of asphalt mortar. In this paper, asphalt mortar with a 1.0 F/A (filler to asphalt)after UV aging were subjected to the test of the Dynamic Shear Rheometer (DSR).Effects of UV aging on the High-Temperature and fatigue performances of asphalt mortar were studied by using the rutting parameter G*/sinδ, fatigue parameter G*sinδ and dynamic viscosity. The results show UV aging had prominent effect on asphalt mortar’s properties, with the decrease of film thickness and increase of UV aging temperature, the ability of rut resistance enhances and fatigue performance weakens.

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Brates, Danielle, Michelle S. Troche, and Sonja M. Molfenter. "The Role of Fatigue in the Aging Swallow: A Review." OBM Geriatrics 05, no. 02 (October 29, 2020): 1. http://dx.doi.org/10.21926/obm.geriatr.2102166.

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Fatigue is a term commonly used to describe patient performance and/or subjective experience in the evaluation and management of swallowing disorders (known as dysphagia). There is an association between fatigue and aging, as well as fatigue and many dysphagia-causing diseases/disorders. Therefore, speech-language pathologists (SLPs) are justifiably aware of and concerned about the potential impact of fatigue on swallowing performance and mealtime behavior. However, there is minimal agreement on and understanding of what constitutes swallowing-related fatigue, how it is identified and measured, who is at risk, and its impact on swallowing function, overall health, and quality of life. The purpose of this review is to discuss the role of fatigue in swallowing and eating behavior in the context of aging, and how fatigue may be measured and managed clinically. We review the concept of fatigue and its clinical implications for swallowing function and mealtime behavior through the dichotomous framework of self-perceived fatigue versus measurable fatigability. Quantitative fatigability and patient-reported fatigue are discussed. We conclude with implications for future research.

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Sakane, M., M. Ohnami, and M. Sawada. "Biaxial Low Cycle Fatigue of Unaged and Aged 1Cr-1Mo-1/4V Steels at Elevated Temperature." Journal of Engineering Materials and Technology 113, no. 2 (April 1, 1991): 244–53. http://dx.doi.org/10.1115/1.2903399.

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This paper describes the biaxial low cycle fatigue of unaged and aged 1Cr-1Mo-1/4V rotor steels at 823 K in air. Combined push-pull and reversed torsion tests were carried out on these steels and the biaxial fatigue data were obtained. Aging significantly reduced the hardness of the steel but had no effect on the crack direction in biaxial low cycle fatigue. Aging also had no effect on the data correlation using the biaxial strain parameters, but had a significant effect on the data correlation using the biaxial stress parameters. The change in the effective stress parameter in correlating the biaxial fatigue data due to aging is discussed in connection with the material softening.

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Ye, Song, Xian Zhi Shao, and Lie Ping Wang. "The Impact Study of the Resistance to Ultraviolet Radiation Aging Agent on the Airport Road Surface Performance with the Modified Asphalt." Advanced Materials Research 723 (August 2013): 1068–75. http://dx.doi.org/10.4028/www.scientific.net/amr.723.1068.

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According to the test results of before and after the aging of asphalt performance,we analyse the dosage changes of the HALS anti ultraviolet ageing agent to improve SBS modified asphalt ultraviolet light resistance aging performance role. The test results show that GW-944 can better improve the ultraviolet resistance of asphalt aging performance, i.e., original sample asphalt have no other negative influence in a certain extent, and at the same time,also improve asphalt fatigue performance, low temperature performance and high temperature performance after the light aging, but the performance improvement needs to be in the right dosage range;Therefore,to the SBS modified asphalt we can use such ultraviolet aging agent for performance improvement,the research achievement for the airport asphalt pavement UV aging provide a technical basis for effective prevention and treatment.

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Yan, Yuan, Yanmei Yang, Maoping Ran, Xinglin Zhou, Lanlin Zou, and Minrui Guo. "Application of Infrared Spectroscopy in Prediction of Asphalt Aging Time History and Fatigue Life." Coatings 10, no. 10 (October 5, 2020): 959. http://dx.doi.org/10.3390/coatings10100959.

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Based on attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy and principal component analysis (PCA), four kinds of asphalt (two kinds of matrix asphalts, TPC70# and JL70# and two kinds of modified asphalts, SBS-1 and SBS-2) were aged using the rolling thin-film oven test (RTFOT). The multiple stress repeated creep recovery test (MSCR) was carried out on an AR1500ex dynamic shear rheometer (DSR). The PCA was carried out on the attenuated total reflection infrared spectrum of a pretreated aged asphalt, the principal component factors (oxidation factor and component change factor) were determined, the comprehensive index F was calculated, and a prediction model of aging time history was established and verified. A prediction model for the aging asphalt recovery rate R was established based on the functional group index. The relationship between the recovery rate R and aging time history of each aging asphalt was analyzed and the fatigue life of each aging asphalt based on the rate of dissipated energy change (RDEC) was compared. The correlation between the comprehensive index F and fatigue life of asphalt was also analyzed. The results show that the order of resistance to the high-temperature deformation of each aging asphalt is as follows: SBS-2 > SBS-1 > TPC70# > JL70#; the prediction model of aging asphalt recovery rate R based on functional group index has good reliability. Taking the loading cycle corresponding to the sudden increase of the inflection point of the curve, i.e., the fatigue life NRDEC, as the evaluation index, the fatigue life order of each aging asphalt is SBS-1 > SBS-2 > JL70# > TPC70#. There is a positive correlation between the fatigue life of aged asphalt and the comprehensive index F of asphalt. The correlation degree R2 is 0.85; i.e., with the increase of the comprehensive index F of asphalt, its fatigue life also increases. It was found that it is feasible to analyze the aging time history and fatigue life of asphalt by infrared spectroscopy, and it can provide a rapid and non-destructive prediction method for the practical engineering application of asphalt.

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Woo, Chang Su, and Wan Doo Kim. "Fatigue Life Prediction of Heat-Aging Vulcanized Natural Rubber." Key Engineering Materials 321-323 (October 2006): 518–21. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.518.

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Heat-aging effects on the material properties and fatigue life prediction of natural rubber were experimentally investigated. The rubber specimens were heat-aged in an oven at the temperature ranging from 50oC to 100oC for a period ranging from 1 day to 90days. Fatigue life prediction methodology of vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue test. Fatigue life prediction equation effectively represented by a single function using the Green-Lagrange strain. Predicted lives are in a good agreement with the experimental lives within a factor of two

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Wang, Lei, Yang Liu, Xiu Song, Guo Hua Xu, and Guang Pu Zhao. "Effects of Long-Time Aging on Fatigue Crack Propagation Behaviors of a Hardworking Ni-Based Superalloy." Advanced Materials Research 891-892 (March 2014): 1657–62. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1657.

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Fatigue crack propagation behaviors coupled with the microstructure evolution of a hardworking Ni-based superalloy after long-time aging at 1023K were studied, to provide fundamental data for the fatigue life prediction of the superalloy. The results show that the microstructures remarkably change and the fatigue crack propagation resistance decreases with the aging time prolongs. It is found that the precipitation and the growth of topologically close packed (TCP) phases as well as the coarsening of γ' phase and carbides on grain boundaries can significantly affect the fatigue crack growth rate. On one hand, coarsened γ' phase and carbides at grain boundaries block dislocation movements near the crack tip, thus the fatigue crack propagation is hindered in near-threshold region and Paris region. On the other hand, the stress concentration accumulates continually with carbides precipitation increases, so that the grain boundaries become the main fatigue crack propagation rout. As well as, the effect of the TCP phases on the fatigue crack propagation behavior ascribes to the size and the distribution of TCP phases. Very small quantity of TCP phases contribute to pinning dislocation and enlarging fatigue crack propagation absorption energy, but high quantity of TCP phases with short rod shape changed to the needle, which gradually precipitate uniformly within the grain after 1000h besides on grain boundaries in the earlier aging, leads to much higher stress concentration degree. Those discussed above are the most important reasons why the fatigue crack growth rate increases after long-time aging.

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Siddiqui, Rafiq Ahmed, Saeed Ali Al- Araimi, and Ahmet Turgutlu. "Influence of Aging Conditions on Fatigue Fracture Behaviour of 6063 Aluminum Alloy." Sultan Qaboos University Journal for Science [SQUJS] 6, no. 1 (December 1, 2001): 53. http://dx.doi.org/10.24200/squjs.vol6iss1pp53-60.

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Aluminum - Magnesium - Silicon (Al-Mg-Si) 6063 alloy was heat-treated using under aged, peak aged and overage temperatures. The numbers of cycles required to cause the fatigue fracture, at constant stress, was considered as criteria for the fatigue resistance. Moreover, the fractured surface of the alloy at different aging conditions was evaluated by optical microscopy and the Scanning Electron Microscopy (SEM). The SEM micrographs confirmed the cleavage surfaces with well-defined fatigue striations. It has been observed that the various aging time and temperature of the 6063 Al-alloy, produces different modes of fractures. The most suitable age hardening time and temperature was found to be between 4 to 5 hours and to occur at 460 K. The increase in fatigue fracture property of the alloy due to aging could be attributed to a vacancy assisted diffusion mechanism or due to pinning of dislocations movement by the precipitates produced during aging. However, the decrease in the fatigue resistance, for the over aged alloys, might be due to the coalescence of precipitates into larger grains.

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Ismail, Hanafi, Komethi Muniandy, and Nadras Othman. "Fatigue life, morphological studies, and thermal aging of rattan powder-filled natural rubber composites as a function of filler loading and a silane coupling agent." BioResources 7, no. 1 (January 6, 2012): 841–58. http://dx.doi.org/10.15376/biores.7.1.841-858.

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Fatigue life, morphological studies, and thermal aging properties of rattan powder-filled natural rubber (NR) composites were investigated as a function of filler loading and a silane coupling agent. NR composites were prepared by the incorporation of rattan powder in the range of 0 to 30 phr into a NR matrix with a laboratory size two roll mill. Thermal aging was carried out for 7 and 14 days at a temperature of 70 °C, and tensile testing was performed in order to determine the aging properties. The results indicated that the fatigue life of rattan powder-filled NR composites decreased with increasing rattan powder loading. Tensile strength and elongation at break decreased whilst tensile modulus, stress at 100% elongation (M100), and stress at 300% elongation (M300) increased after aging. Nevertheless, the addition of the silane coupling agent improved both fatigue life and the aging properties of NR composites due to better adhesion between the rubber matrix and the rattan filler which was confirmed by FTIR studies of composites and SEM studies of fatigue fractured surfaces.

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Li, Bo, Yu Wang, Peng Xiao, Aihong Kang, Yao Zhang, and Zhengguang Wu. "Investigation of Self-Healing Performance of Asphalt Mastic—From the Perspective of Secondary Aging." Materials 16, no. 24 (December 8, 2023): 7567. http://dx.doi.org/10.3390/ma16247567.

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Reclaimed asphalt pavement (RAP) has been widely utilized because it is an environmentally friendly and economical material. The performance of recycled asphalt mixtures will deteriorate gradually with the secondary aging process of asphalt, including the self-healing property. To further understand the self-healing characteristics of asphalt after secondary aging, taking 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics as objects, the fatigue self-healing test and fracture self-healing test were conducted to simulate the intermediate-and low-temperature healing behaviors of different asphalt mastics. The impact of healing time, healing temperature, and aging degree of mastics on the healing performance was systematically investigated. The results show that the original unaged asphalt mastics present excellent fatigue healing properties with an index of 0.796 and 0.888 for 70# petroleum and SBS-modified asphalt mastics, respectively. The secondary aging process causes significant impact on the healing properties, leading to a great drop in the corresponding index, which decreased to 47.5% and 72.5% of that of the unaged ones. The fracture healing ability of all mastics was much inferior to the fatigue healing. After secondary aging, the fracture healing index values of 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics were all as low as around 0.3, indicating similar performance can be found in the secondary aged SBS-modified asphalt mastics and 70# asphalt mastics. Overall, after secondary aging, the fatigue damage of SBS-modified asphalt mastics can be cured effectively by self-healing, but the fatigue and fracture self-healing properties of 70# asphalt mastics are difficult to recover. These results could provide an innovative view to understand the fatigue and fracture healing characteristics of recycled asphalt pavement after secondary aging.

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Wang, Dongsheng, Junyan Yi, and Decheng Feng. "Modelling and Laboratory Studies on the Adhesion Fatigue Performance for Thin-Film Asphalt and Aggregate System." Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/819083.

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Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more important effect on the adhesion performance comparing with aggregate. Basalt, which is regarded as hydrophobic aggregates with low silica content, has better adhesion performance to asphalt binder when compared with granite. The effects of aging on the adhesion fatigue performance are different for PG64-22 and rubber asphalt. Long-term aging is found to reduce the adhesion fatigue lives for rubber asphalt and aggregate system, while the effect of long-term aging for aggregate and PG64-22 binder system is positive. Generally the increased stress amplitude and test temperature could induce greater damage and lead to less fatigue lives for adhesion test system.

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Qin, Yong Chun, Sui Yuan Wang, Wei Zeng, Xiao Pei Shi, Jian Xu, and Song Chang Huang. "The Effect of Asphalt Binder Aging on Fatigue Performance of Evotherm WMA." Advanced Materials Research 535-537 (June 2012): 1686–92. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.1686.

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One of the main benefits advertised with the use of warm mix asphalt (WMA) is the decreasing aging of the asphalt binder resulting from the lower production temperature compared to conventional hot mix asphalt (HMA). Some tests were performed to determine the asphalt binder aging properties from WMA and HMA. Asphalt binders were recovered by extraction and distillation from asphalt mixtures premixed at different temperatures (140°C, 160°C, 180°C for HMA, 100°C and 120°C for WMA) in the mixing plant. Penetration@25°C, softening point (R&B) and rotational Brookfield viscosity tests were carried out. Results show that the aging of asphalt binder increases as the mixing temperature is elevated, and remarkably accelerates at the temperatures higher than 150°C. Warm mix asphalt (for example, mixing temperature at 100°Cor 120°C) can greatly reduce the aging of asphalt. Aging of the asphalt binder is one of the factors that would affect the mixture’s fatigue life. Four-point beam fatigue test samples were mixed and compacted at 140°C for HMA and 120°C for WMA, and fatigue tests with a frequency of 10 Hz and three constant strain levels (150 micro-strain, 300 micro-strain, 450 micro-strain, respectively) were performed. Results show that WMA’s fatigue life was higher than the control HMA, which indicates that it may reduce aging of asphalt binder and improve fatigue performance of asphalt mixture at lower production temperatures.

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Flanigan, Richard, Dean MacCarter, Linda M. Shecterle, and John A. St.Cyr. "D-Ribose Aids Fatigue in Aging Adults." Journal of Alternative and Complementary Medicine 16, no. 5 (May 2010): 529–30. http://dx.doi.org/10.1089/acm.2009.0535.

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Genenko, Yuri A., Julia Glaum, Michael J. Hoffmann, and Karsten Albe. "Mechanisms of aging and fatigue in ferroelectrics." Materials Science and Engineering: B 192 (February 2015): 52–82. http://dx.doi.org/10.1016/j.mseb.2014.10.003.

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Mahadevan, Sankaran, and Pan Shi. "Corrosion fatigue reliability of aging aircraft structures." Progress in Structural Engineering and Materials 3, no. 2 (2001): 188–97. http://dx.doi.org/10.1002/pse.77.

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Bendix, Laila, Mikael Thinggaard, Masayuki Kimura, Abraham Aviv, Kaare Christensen, Merete Osler, and Kirsten Avlund. "Association of Leukocyte Telomere Length with Fatigue in Nondisabled Older Adults." Journal of Aging Research 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/403253.

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Introduction. Fatigue is often present in older adults with no identified underlying cause. The accruing burden of oxidative stress and inflammation might be underlying factors of fatigue. We therefore hypothesized that leukocyte telomere length (LTL) is relatively short in older adults who experience fatigue.Materials and Methods. We assessed 439 older nondisabled Danish twins. LTL was measured using Southern blots of terminal restriction fragments. Fatigue was measured by the Mob-T Scale based on questions on whether the respondents felt fatigued after performing six mobility items.Results. LTL was significantly associated with fatigue (P=0.023), showing an increase of 0.038 kb/fatigue score unit. Aging-related diseases and mental health did not explain the association, while lifestyle factors slightly attenuated the estimates.Conclusion. Our results support an association between LTL and fatigue. Further studies are required to confirm this finding and the link of LTL with oxidative stress/inflammation over the life course.

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Zhu, Guo Jun, Shao Peng Wu, Ran Liu, and Lei Zhou. "Study on the Fatigue Property for Aged Asphalt Mixtures by Using Four Point Bending Tests." Materials Science Forum 614 (March 2009): 289–94. http://dx.doi.org/10.4028/www.scientific.net/msf.614.289.

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The effects of aging on the fatigue property of polymer modified asphalt mixtures are investigated in this paper. Two kinds of aging procedures are adopted for the aging of specimens prepared with polymer modified asphalt mixtures. One is the short-time aging which means that the hot asphalt mixtures was heated in the oven for 4 hours at 135°C before compacted; The other called natural aging, with the original specimen exposed in the sunlight and subjected to the rain and temperature change for 3, 6 and 9 months. Four-Point Bending Test was conducted to evaluate fatigue properties of aged asphalt mixtures at 15°C compared with the original specimens. Test results indicate that the fatigue line of aged specimens have the same tendency as the original asphalt mixtures. However, the life of aged specimen is decreased significantly when compared with the original ones, especially of the natural aged specimens.

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Lin, Peng, Xueyan Liu, Shisong Ren, Jian Xu, Yi Li, and Mingliang Li. "Effects of Bitumen Thickness on the Aging Behavior of High-Content Polymer-Modified Asphalt Mixture." Polymers 15, no. 10 (May 16, 2023): 2325. http://dx.doi.org/10.3390/polym15102325.

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The film thickness of asphalt mixtures is critical for determining their performance and aging durability. However, understanding of the appropriate film thickness and its influence on performance and aging behavior for high-content polymer-modified asphalt (HCPMA) mixtures is still limited. This research aims to examine the relationship between film thickness, performance, and aging behavior of HCPMA mixtures in order to establish an optimal film thickness that ensures satisfactory performance and aging durability. HCPMA specimens with film thicknesses ranging from 6.9 μm to 17 μm were prepared using a 7.5% SBS-content-modified bitumen. Various tests, including Cantabro, SCB, SCB fatigue, and Hamburg wheel-tracking tests, were conducted to evaluate raveling, cracking, fatigue, and rutting resistance before and after aging. The key findings indicate that insufficient film thickness negatively affects aggregate bonding and performance, while excessive thickness reduces mixture stiffness and resistance to cracking and fatigue. A parabolic relationship between the aging index and film thickness was observed, suggesting that increasing film thickness improves aging durability up to a point, beyond which excessive thickness adversely impacts aging durability. The optimal film thickness for HCPMA mixtures, considering performance before and after aging and aging durability, falls within the 12.9 to 14.9 µm range. This range ensures the best balance between performance and aging durability, offering valuable insights for the pavement industry in designing and utilizing HCPMA mixtures.

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Shrayber, Marina. "Investigation of Fatigue Aging of Insulation of Traction Electric Motors of Diesel Locomotives Under Cyclic Load." Bulletin of scientific research results 2023, no. 4 (December 19, 2023): 27–35. http://dx.doi.org/10.20295/2223-9987-2023-4-27-35.

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Purpose: To analyze the processes of fatigue aging of the insulation of traction electric machines of locomotives under cyclic loads in operation. Methods: When solving typical problems of fatigue strength of insulating materials of electric locomotives, periodic loading cycles are used in the study. Results: The analysis of the processes of fatigue aging of insulation materials of electrical machines shows that the main parameters that increase the intensity of aging are the frequency and amplitude of the heating cycle. Thermomechanical stresses increase with rise of heating speed and temperature amplitude. Practical significance: Determination of the fatigue characteristics of the insulation material is very important when modeling its damage, which will increase the reliability of electric machines of modern locomotives at the stages of design, manufacture, modernization and operation.

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Yang, Sunglin, Heebeom Park, and Cheolmin Baek. "Fatigue Cracking Characteristics of Asphalt Pavement Structure under Aging and Moisture Damage." Sustainability 15, no. 6 (March 8, 2023): 4815. http://dx.doi.org/10.3390/su15064815.

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Structural characteristics influence assessment of fatigue cracking behavior. In the assessment of asphalt pavements, the asphalt structure and practical conditions must be considered. This study analyzes changes in the elastic modulus of the pavement of different asphalt mixtures amid aging and moisture damage through fatigue cracking tests. A model to predict the tensile strain at the bottom of the pavement layer is developed through a structural analysis based on the material properties. The results are comparatively analyzed using the Mechanistic-Empirical Pavement Design Guide to predict the fatigue crack life. The test results indicate that moisture damage significantly influences the material properties of asphalt pavement and can accelerate pavement damage as the asphalt ages. The coefficient values of the proposed fatigue-life prediction model can be used to predict the fatigue life depending on the age of the asphalt and its moisture damage after aging. The degree of fatigue damage can be predicted by calculating the tensile strain using the regression equation and elastic modulus according to the aging and moisture damage.

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Burke, Sarah Elizabeth, Immanuel B. H. Samuel, Qing Zhou, Benzi Kluger, Catherine Price, and Mingzhou Ding. "2210." Journal of Clinical and Translational Science 1, S1 (September 2017): 59. http://dx.doi.org/10.1017/cts.2017.210.

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OBJECTIVES/SPECIFIC AIMS: Identify objective neurological substrates of cognitive fatigue in Parkinson’s disease and in aging. METHODS/STUDY POPULATION: Structural and diffusion MRI. Behavioral assessments for aged adults and Parkinson’s disease. RESULTS/ANTICIPATED RESULTS: Gray and white matter deficits that correlate with deficits in the basal ganglia for fatigued Parkinson’s disease patients Versus anterior cingulate cortex in healthy aged adults with fatigue. DISCUSSION/SIGNIFICANCE OF IMPACT: Over 50% of patients with Parkison’s disease and 38% of healthy older adults suffer from cognitive fatigue. However, diagnostics are limited to subjective surveys and there are no treatments for either population. Therefore, objective measures are greatly needed for better diagnosis and development of treatment targets.

Journal articles on the topic 'Fatigue aging'

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