Статті в журналах з теми "Fatigue lifespan"
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1
Nagórska, M., R. Nagórski, and K. Błażejowski. "Selected Aspects Of Design Lifespan Of Flexible Pavement With Anti-Fatigue Course." Archives of Civil Engineering 61, no. 1 (March 1, 2015): 103–18. http://dx.doi.org/10.1515/ace-2015-0007.
Повний текст джерелаАнотація:
AbstractThe aim of the study is to compare flexible pavement design lifespans and the main factors which create their values for a standard structure and one with an anti-fatigue course AF at different parameter values of pavement and its load, relevant to their design processes. Depending on the mixture used for the anti-fatigue course or the course thickness, durability improvement of the pavement (compared to the durability of a standard structure) can be obtained by extending the design lifespan of the asphalt base course or by extending the design lifespan of the AF course. On sections with predominantly slow traffic, the lifespan decreases significantly compared to sections with typical vehicle speed - the relative decrease is greater if anti-fatigue course is applied.
2
Qin, Zhen, and Wen Tao Xu. "Random Dynamic Fatigue Analysis of Body Structures of Coach." Applied Mechanics and Materials 97-98 (September 2011): 765–70. http://dx.doi.org/10.4028/www.scientific.net/amm.97-98.765.
Повний текст джерелаАнотація:
In this paper, an efficacious and accurate method for analyzing random vibration and fatigue lifespan of coaches with high degrees of freedom is developed. Based on the design requirements for structure strength and fatigue lifespan of a coach, the finite element model of its body structure was used to investigate the dynamic behavior of the coach running on a randomly uneven road. The vibration characteristic was derived using the pseudo excitation method (PEM). The fatigue lifespan is discussed by means of the Miner rule, and the fatigue resistance is also studied. The reliability of the proposed method is numerically verified.
3
Liu, Zhongxiang, Tong Guo, Xiaming Yu, Shilei Niu, and José Correia. "Corrosion Fatigue Assessment of Bridge Cables Based on Equivalent Initial Flaw Size Model." Applied Sciences 13, no. 18 (September 11, 2023): 10212. http://dx.doi.org/10.3390/app131810212.
Повний текст джерелаАнотація:
Bridge cables under traffic loads are more prone to failure during the service life due to the corrosion–fatigue coupling effect. In this study, a novel lifespan model based on the equivalent initial flaw size (EIFS) theory is established to analyze the various stages of the lifespan of steel wires. Additionally, a comprehensive corrosion-fatigue lifespan calculation method for parallel steel wire cable is established based on the series–parallel model. A case study of the Runyang Suspension Bridge is conducted to evaluate the evolution of corrosion-fatigue damage in bridge cables during the service life. The results indicate that under the action of corrosion-fatigue, steel wires are more prone to crack initiation, and their fracture toughness is further reduced. In cases where the corrosion level is relatively low, the steel wires of the bridge cables experience no corrosion-fatigue fracture. When the steel wires have initial defects and are subject to corrosion-fatigue conditions, their fracture lifespan is dependent on the severity of the corrosive medium. The reduction in the service life of the cables under the corrosion environment is much greater than that under heavy loads. This research may contribute to the understanding of corrosion-fatigue damage in bridge cables, involving assessment, maintenance, and replacement for bridge cables.
4
Wu, Y. J. "Low-Cycle Fatigue Behavior of Hydrostatic Extruded AZ80 Mg Alloy." Journal of Physics: Conference Series 2694, no. 1 (January 1, 2024): 012026. http://dx.doi.org/10.1088/1742-6596/2694/1/012026.
Повний текст джерелаАнотація:
Abstract The fatigue properties of conventional and hydrostatic extruded AZ80 Mg alloy were fully studied under strain-controlled mode. The hydrostatic extrusion can effectively increase the tensile strength, but decrease the elongation. Consequently, the low cycle fatigue lifespan of the hydrostatic extruded specimens was shorter than that of the conventional extruded ones. The Manson-Coffin-Basquin relationship was adopted to describe the fatigue lifespan of the extruded AZ80 alloys. Finally, the fracture surfaces were observed by scanning electron microscope. The fatigue crack stable propagation zone of the hydrostatic extruded sample has decreased significantly compared with that of the conventional extruded sample. The hydrostatic extruded specimen has small reverse plastic zone size, which leads to microscopically rough fatigue crack propagation zone.
5
Lepagneul, Juliette, Loïc Tadrist, Jean-Michel Sprauel, and Jean-Marc Linares. "Fatigue lifespan of a planetary roller-screw mechanism." Mechanism and Machine Theory 172 (June 2022): 104769. http://dx.doi.org/10.1016/j.mechmachtheory.2022.104769.
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Mironov, Vladimir I., Dmitry A. Ogorelkov, and Olga A. Lukashuk. "Analysis of Fatigue Damage Accumulation in Structural Materials under Quasi-Random Load." Solid State Phenomena 299 (January 2020): 1178–83. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.1178.
Повний текст джерелаАнотація:
The spectrum of stresses at a hazardous point on bearing metal structures of mining, road-building and transporting machines, as a rule, is random by nature. Objective complexity of the fatigue process and variety of fatigue crack nucleation mechanisms are the main causes of errors in prediction of their lifespan, along with an experimentally untestable hypothesis of linear summation of damages. The method of complete stress-strain diagrams uses a representative parameter of the fatigue process, selected in accordance with the results of testing, carried out on trained thin specimens of a specific material. The summation of fatigue damages is based on experimental kinematic curves, whose intersection with a load vector is used as a criterion of fatigue failure. It is shown that the approach proposed to calculate the lifespan gives certain advantages, as far as individual properties of the material are concerned, and when it comes to describing the kinetics of the fatigue process and determining the limiting state of the material in a structure.
7
Domingo-Espin, Miquel, J. Antonio Travieso-Rodriguez, Ramon Jerez-Mesa, and Jordi Lluma-Fuentes. "Fatigue Performance of ABS Specimens Obtained by Fused Filament Fabrication." Materials 11, no. 12 (December 11, 2018): 2521. http://dx.doi.org/10.3390/ma11122521.
Повний текст джерелаАнотація:
In this paper, the fatigue response of fused filament fabrication (FFF) Acrylonitrile butadiene styrene (ABS) parts is studied. Different building parameters (layer height, nozzle diameter, infill density, and printing speed) were chosen to study their influence on the lifespan of cylindrical specimens according to a design of experiments (DOE) using the Taguchi methodology. The same DOE was applied on two different specimen sets using two different infill patterns—rectilinear and honeycomb. The results show that the infill density is the most important parameter for both of the studied patterns. The specimens manufactured with the honeycomb pattern show longer lifespans. The best parameter set associated to that infill was chosen for a second experimental phase, in which the specimens were tested under different maximum bending stresses so as to construct the Wöhler curve associated with this 3D printing configuration. The results of this study are useful to design and manufacture ABS end-use parts that are expected to work under oscillating periodic loads.
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Jerez-Mesa, R., J. A. Travieso-Rodriguez, J. Llumà-Fuentes, G. Gomez-Gras, and D. Puig. "Fatigue lifespan study of PLA parts obtained by additive manufacturing." Procedia Manufacturing 13 (2017): 872–79. http://dx.doi.org/10.1016/j.promfg.2017.09.146.
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Qiu, Ju, Jingwei Shi, Huaizhong Su, Jinling Zhang, Juan Feng, Qian Shi, and Xiaoyu Tian. "Fatigue Lifespan of Engine Box Influenced by Fan Blade Out." IOP Conference Series: Materials Science and Engineering 265 (November 2017): 012026. http://dx.doi.org/10.1088/1757-899x/265/1/012026.
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Ding, Chao Yi, Gang Qiang Li, and Hong Che Guo. "Fatigue Analysis of Wind Turbine." Applied Mechanics and Materials 229-231 (November 2012): 621–24. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.621.
Повний текст джерелаАнотація:
This article combines with finite element method and the rain flow count method, which is using the nominal stress method developed a wind turbine used for structural fatigue analysis method, with 2.0 MW wind and machine hub to analyze the fatigue, calculated the operation lifespan fatigue load of wind turbine in the 20 years. By choosing the hot point of hub, analyzes the wheels fatigue damage characteristics. The calculation results show that: the selection of hot point wheels meet with the requirements of GL standard Fatigue design. This paper can be used in large wind turbine development design and in the process of production design authentication.
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Bendaoui, Messaoud, Allaoua Kherraf, and Soumia Benbouta. "Simulation of damage under cyclic loading for API 5L X70 steel pipelines (fatigue test)." STUDIES IN ENGINEERING AND EXACT SCIENCES 5, no. 1 (March 29, 2024): 876–87. http://dx.doi.org/10.54021/seesv5n1-046.
Повний текст джерелаАнотація:
The most efficient way to move large volumes of gas and oil is through pipelines, either from points of production to storage locations or from storage locations to distributed points of end use. One of the main materials of gas transportation pipes is X70 material. Base on the importance of in-service API 5L X70 pipelines, it is important for the safe operation of this system to know the lifespan of pipelines, and predict fatigue crack growth (FCG) of API 5L X70 steel pipeline. The objective of this theme is to study the lifespan of pipelines used for the transport of natural gas, oil and water, manufactured by the company ALFAPIPE in the wilaya of Ghardaïa. The judicious choice for manufacturing metal is a crucial factor to ensure prolonged life duration and improve resistance to fatigue, as materials respond to loading with elastic or plastic deformation. Stresses applied to materials can result in permanent deformation, rupture, cracking or progressive degradation. Understanding the effects of applied stresses is essential for the selection and implementation of materials in industrial applications. Fatigue tests were carried out on API 5L X70 steel using simulations using ANSYS software. The life of different samples was determined for different thicknesses after applying repeated stresses. The obtained results demonstrate the material API 5L X70's sensitivity to fatigue and emphasize the significance of designing pipelines with sufficient safety margins to prevent premature failures caused by fatigue.
12
Putra, Teuku Edisah, Husaini, Hary Prakasa, Iskandar Hasanuddin, Muhammad Rizal, and Muhammad Nizar Machmud. "Fatigue Life Assessments of the SAE 5160 Carbon Steel Subjected to Uphill and Downhill Roads Strains." Defect and Diffusion Forum 402 (July 2020): 33–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.402.33.
Повний текст джерелаАнотація:
This study examines the fatigue life of the SAE 5160 carbon steel as the material for an automotive coil spring subjected to road strain. The strain signals were acquired by attaching a strain gauge on the component, driving a car up- and down-hill roads. The results of the fatigue life assessment based on the strain-life approach show that the downhill road resulted in a lifespan of 15,000 cycles to failure, which was 53% lower than the uphill road. This value was a result of braking when the vehicle is moving downhill, causing stress to the component leading to shorter fatigue life.
13
Devendorf, Andrew R., Carly T. Jackson, Madison Sunnquist, and Leonard A. Jason. "Approaching recovery from myalgic encephalomyelitis and chronic fatigue syndrome: Challenges to consider in research and practice." Journal of Health Psychology 24, no. 10 (November 28, 2017): 1412–24. http://dx.doi.org/10.1177/1359105317742195.
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There are unique methodological challenges to studying and assessing recovery in myalgic encephalomyelitis and chronic fatigue syndrome. This study explored these challenges through interviewing 13 physicians who treat myalgic encephalomyelitis and chronic fatigue syndrome. Our deductive thematic analysis produced four themes to consider when approaching recovery: lifespan differences in the illness experience; the heterogeneity of myalgic encephalomyelitis and chronic fatigue syndrome—case definitions, etiological stance, and misdiagnosis; patient follow-up and selection bias; and assessment logistics. We discuss how researchers and clinicians can use these considerations when working with patients, drafting recovery criteria, and interpreting treatment outcomes.
14
Rafiq, Nafisah Mohd, and Shijie Wang. "Thermal Barrier Coatings: An Insight into Conventional Plasma Spray and Water-Stabilized Plasma Spray." Coatings 12, no. 12 (December 7, 2022): 1916. http://dx.doi.org/10.3390/coatings12121916.
Повний текст джерелаАнотація:
Thermal barrier coating (TBC) systems have presented an ongoing design issue in bids to improve the lifespan of coatings. A TBC can support an extended lifespan by repairing cracks between interfacial layers during high thermal exposure while at the same time increasing coating thickness. Two deposition techniques, atmospheric plasma spray and water-stabilized plasma spray (WSP), have been distinguished to understand mechanical and thermal performance based on their contrasting torch systems and microstructural characterization. This insight paper will underline the superiority of WSP coating and the need to leverage existing technology by optimizing better deposition parameters for future fatigue-resistant TBC production.
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Christie, Anita D., Emily Seery, and Jane A. Kent. "Physical activity, sleep quality, and self-reported fatigue across the adult lifespan." Experimental Gerontology 77 (May 2016): 7–11. http://dx.doi.org/10.1016/j.exger.2016.02.001.
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Yin, Ming, and Li Zhong Wang. "Fracture Reason Analysis of Coal Compactor Roller Shaft." Advanced Materials Research 490-495 (March 2012): 2323–27. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.2323.
Повний текст джерелаАнотація:
The cause of the fatigue fracture of the coal compactor roller shaft is analyzed in this paper. By means of investigating the macro-fracture and micro-fracture analysis for the shaft roller, and use ANSYS software to simulate the fatigue stress to find out the reasons of the roller shaft fracture and thus provides theoretical support for further optimizing the design of the roller shaft structure.This lied a solid foundation for how to improve the designation of roller shaft and how to improve the lifespan of the roller shaft
17
Ben Hassine, Ahlem. "Α New Agent-based Solution for Bridge Lifespan Extension". Engineering, Technology & Applied Science Research 13, № 3 (2 червня 2023): 10916–21. http://dx.doi.org/10.48084/etasr.5958.
Повний текст джерелаАнотація:
Bridges are one of the most important and useful components of the transportation infrastructure, as they are crucial to many aspects of daily life, particularly in terms of economic development. However, bridges are vulnerable to several damages, malfunctions, and collapses that may considerably reduce their lifespan. The main causes of bridge fatigue are congested areas, excessive traffic, overloads, and additional vibration brought on by vehicles crossing them over. These elements reduce a bridge's longevity and raise maintenance costs. For a bridge to last as long as possible, it must not be crossed by an excessive number of cars and big trucks at once, and traffic should be kept under control. This study proposes an intelligent and autonomous multiagent-based system that incorporates a deep learning model to improve the monitoring of a bridge's crossing traffic. The idea was to propose a novel system for monitoring autonomously crossing vehicles in real-time to prevent the hastening of a bridge's infrastructure decline. The proposed system aimed to (i) increase the safety of drivers; (ii) lower maintenance costs; (iii) lessen the likelihood of bridge collapse, and (iv) lengthen bridge lifespans. Using a sample dataset, a straightforward deep learning model (CNN) was tested to improve bridge traffic monitoring. The performance of the proposed model was compared with the VGG-19 model. The results showed that the proposed model was effective in determining traffic congestion status with a 95% accuracy. As a result, the proposed system can be deployed on any bridge and can reduce crossing traffic overloads, extending its lifespan.
18
Zhou, Jie, Hong-Zhong Huang, and He Li. "A Novel Energy-Critical Multiaxial Fatigue Life Prediction for Low Cycle Fatigue under Mixed-Mode Loading." Metals 8, no. 12 (December 14, 2018): 1066. http://dx.doi.org/10.3390/met8121066.
Повний текст джерелаАнотація:
Fatigue failure evolution is a process of damage accumulation under continued stresses and forces. The mechanical component is always subjected to various loadings and the lifespan is mainly governed by fatigue. The low cycle fatigue (LCF) is a key failure mode of many components. In order to estimate the LCF life under multiaxial loadings in practical design, a modified model is proposed, based on the Fatemi-Socie (FS) and Smith-Watson-Topper (SWT) models, which considers the effects of shear and tensile behaviours. Then a novel judgment criterion is presented to distinguish the mixed-mode loadings and the procedures to employ the proposed model are also presented. Furthermore, two types of materials (TC4 and GH4169) and comparisons with the FS, Wang-Brown (WB) and redefined SWT (Re-SWT) models are employed to verify the accuracy and effectiveness of the proposed model, which has shown more reasonable predictions than the other models.
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Gambarini, Gianluca, Gabriele Miccoli, Marco Seracchiani, Tatyana Khrenova, Orlando Donfrancesco, Maurilio D’Angelo, Massimo Galli, Dario Di Nardo, and Luca Testarelli. "Role of the Flat-Designed Surface in Improving the Cyclic Fatigue Resistance of Endodontic NiTi Rotary Instruments." Materials 12, no. 16 (August 8, 2019): 2523. http://dx.doi.org/10.3390/ma12162523.
Повний текст джерелаАнотація:
The aim of this study was to investigate the role of the flat-designed surface in improving the resistance to cyclic fatigue by comparing heat-treated F-One (Fanta Dental, Shanghai, China) nickel–titanium (NiTi) rotary instruments and similar prototypes, differing only by the absence of the flat side. The null hypothesis was that there were no differences between the two tested instruments in terms of cyclic fatigue lifespan. A total of 40 new NiTi instruments (20 F-One and 20 prototypes) were tested in the present study. The instruments were rotated with the same speed (500 rpm) and torque (2 N) using an endodontic motor (Elements Motor, Kerr, Orange, CA, USA) in the same stainless steel, artificial canal (90° angle of curvature and 5 mm radius). A Wilcoxon–Mann–Whitney test was performed to assess the differences in terms of time to fracture and the length of the fractured segment between the flat- and non-flat-sided instruments. Significance was set at p = 0.05. The differences in terms of time to fracture between non-flat and flat were statistically significant (p < 0.001). In addition, the differences in terms of fractured segment length were statistically significant (p = 0.034). The results of this study highlight the importance of flat-sided design in increasing the cyclic fatigue lifespan of NiTi rotary instruments.
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Mallor, C., S. Calvo, J. L. Nuñez, R. Rodriguez-Barrachina, and A. Landaberea. "A probabilistic fatigue crack growth life approach to the definition of inspection intervals for railway axles." Frattura ed Integrità Strutturale 16, no. 59 (December 22, 2021): 359–73. http://dx.doi.org/10.3221/igf-esis.59.24.
Повний текст джерелаАнотація:
Different options that rely on fracture mechanics are currently used in engineering during the design and assessment of components. One of the most important aspects is the time taken for a crack to extend to its critical size. If this time is long enough, a design concept based on inspection intervals can be applied, as is it the case of a railway axle component. To define inspection intervals that ensure the continuous and safe operation of a damage-tolerant railway axle, a reliable estimation of its fatigue crack growth life is required. Due to the uncertainties involved in the fatigue process, inspections must be devised not only considering the uncertainties in the performance of the inspection technique, but also based on a probabilistic lifespan prediction. From this premise, this paper presents a procedure for determination of inspection intervals that uses a conservative fatigue crack growth life estimation based on the lifespan probability distribution. A practical example to illustrate the reliability-based inspection planning methodology in a railway axle under random bending loading is given. The inspection intervals are further assessed in terms of overall probability of detecting cracks in successive inspections and in terms of probability of failure, considering the probability of detection curve of the non-destructive testing technique. The procedure developed provides recommendation for the definition of inspection intervals and associated inspection techniques.
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Fodor, Antal, and Pál Boza. "Designing Fatigue Experiment for Investigating Polymer Specimens." MACRo 2015 1, no. 1 (March 1, 2015): 269–74. http://dx.doi.org/10.1515/macro-2015-0026.
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AbstractThe using of „technical materials” speeded up lately. Because of this, parts are being designed from plastic, which have to sustain extreme stresses. The proper definition of material qualities is expensive; despite in every phase of designing, we need it to be done perfectly. In every industrial section it is important to work with exact material qualities, especially areas where there are strict safety rules (in connection with the lifespan). In this work we will introduce how to design suitable fatigue stress for the plastic samples and how to define the fatigue qualities of the various materials of Rapid Prototyping. This information could be important to change damaged equipments and parts in the military. Due to this, we performed the design of fatigue tests to help the designers elaborate military, safety improvements and proper renewing technologies.
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Er-Remyly, Omar, Mouna Ben Zohra, Amine Riad, and Abdelilah Alhamany. "Design and Development of Shape Memory Alloy Actuator for Preventing and Protecting Electrical Wires." International Journal of Mathematical, Engineering and Management Sciences 8, no. 3 (June 1, 2023): 424–43. http://dx.doi.org/10.33889/ijmems.2023.8.3.024.
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Fatigue failure of wires is a frequent issue that evolves over time as a result of utilizing the profile under variable stress and temperature. In this article, an innovative study makes it possible to propose a protective tool for metal profiles against fatigue using shape memory alloys (SMA). Smart actuators like SMA are able to push back sudden stresses above the elastic limit, therefore, are characterized by high resistance to fatigue and even against corrosion due to their strong thermomechanical coupling. Besides, the study provides the results necessary to add a layer based on the shape memory tube to protect the important connectors for industrial systems and automotive industries. The conductivity of electrical current in various electronic devices depends on the copper material, which is good at conducting electricity and heat but weak against mechanical forces and hence easily susceptible to fatigue. Thereby, the elastic regime of copper is different from that of SMA, and in order to adapt the properties of two materials, a mathematical study can describe the behaviour of two combined systems is important for the analysis of the cyclic effect and for adapting the proposed actuator in wiring technology. Therefore, the study shows the great potential of the proposed SMA tube with its superelastic behaviour to increase the predicted lifespan of metallic wires against corrosion and fatigue. The lifetime of the conduction system with the protective SMA is increased remarkably and can reach up to 105cycles under the action of the stress of an amplitude of 550 MPa, the finite element simulation shows that the system of SMA combined with a 4 mm wire undergoing significant stress up to 490 MPa that can reach a deformation of 7% and return to the initial state without residual deformation. The simulation's results look at the evolution of stress, strain, fatigue lifetimes, and anticipated damage, and they match the experimental results of SMA tube properties rather well. Consequently, the verification of the proposed model confirms the improvement in the lifespan of studied wires compared to wires without SMA encapsulation.
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Korycki, Adrian, Christian Garnier, Silvia Irusta, and France Chabert. "Evaluation of Fatigue Life of Recycled Opaque PET from Household Milk Bottle Wastes." Polymers 14, no. 17 (August 25, 2022): 3466. http://dx.doi.org/10.3390/polym14173466.
Повний текст джерелаАнотація:
Polyethylene terephthalate (PET) is among the most used thermoplastic polymers in large scale manufacturing. Opaque PET is increasingly used in milk bottles to save weight and to bring a glossy white aspect due to TiO2 nanoparticles. The recyclability of opaque PET is an issue: whereas the recycling channels are well established for transparent PET, the presence of opaque PET in household wastes weakens those channels: opaque bottles cannot be mixed with transparent ones because the resulting blend is not transparent anymore. Many research efforts focus on the possibility to turn opaque PET into resources, as one key to a more circular economy. A recent study has demonstrated the improvement of the mechanical properties of recycled PET through reactive extrusion. In the present work, the lifespan of recycled opaque PET has been evaluated throughout tensile–tensile fatigue loading cycles at various steps of the recycling process: The specimens are obtained from flakes after grinding PET wastes (F-r-OPET), from a subsequent homogenization step (r-OPET-hom) and after reactive extrusion (Rex-r-OPET). Virgin PET is also considered as a comparison. First, tensile tests monitored by digital image correlation have been carried out to obtain the elastic modulus and ultimate tensile stress of each type of PET. The fatigue properties of reactive REx-r-OPET increase, probably associated with the rise of cross-linking and branching rates. The fatigue lifespan increases with the macromolecular weight. The fracture surface analysis of specimens brings new insight regarding the factors governing the fatigue behavior and the damaging mode of recycled PET. TiO2 nanoparticles act as stress concentrators, contributing to void formation at multiple sites and thus promoting the fracture process. Finally, the fatigue life of REx-r-OPET is comparable to those of virgin PET. Upcycling opaque PET by reactive extrusion may be a relevant new route to absorb some of the growing amounts of PET worldwide.
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Guan, Xiaoyan, Jie Tang, and Jianzhi Chen. "Influence of Loading Waveform on the Fatigue Life of 34CrNi3MoVA Steel." Metals 14, no. 1 (January 16, 2024): 110. http://dx.doi.org/10.3390/met14010110.
Повний текст джерелаАнотація:
Mechanical components often experience fatigue loading from various waveform conditions during their operational lifespan. However, the underlying mechanisms through which variations in loading waveform affect the fatigue life of components remain unclear. Thus, this study conducted tension–compression fatigue experiments on 34CrNi3MoVA steel specimens under the same stress amplitude with different waveforms (cosine, triangular, sawtooth, and reverse sawtooth) to investigate the effects of loading waveform variations on the cyclic strain hardening behaviors, the fatigue fracture failure, and the fatigue life. The results indicated that specimens under different waveforms all exhibited cyclic strain hardening. The fatigue cyclic hardening level progressively increased in the order of cosine, triangular, and sawtooth waveforms, resulting in a continuous increase in cyclic saturation strain amplitude. The analysis of fatigue fractures demonstrated a consistent increase in both the initiation and propagation zone areas in the order of cosine, triangular, and sawtooth waveforms, and the boundary between the propagation and final fracture zones gradually shifted from a straight to a curved shape. The influence mechanisms of cyclic loading waveforms on the fatigue life of specimens were analyzed based on the energy dissipation, leading to the development of a universal fatigue life prediction model applicable to different waveform conditions, the model was then verified with the reverse sawtooth wave specimens and resulted in a prediction error less than 15%. The study is expected to serve as a significant guide for predicting and evaluating the fatigue life of mechanical components under various fatigue loading conditions.
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Pástor, Miroslav, Pavol Lengvarský, Martin Hagara, Alžbeta Sapietová, and Patrik Šarga. "Experimental Investigation of the Fatigue Lifespan of Anchor Bolts with Consideration of Loading History." Applied Sciences 11, no. 23 (December 2, 2021): 11399. http://dx.doi.org/10.3390/app112311399.
Повний текст джерелаАнотація:
Preloaded bolted connections are one of the most used approaches for anchoring steel structures and equipment. Preload is induced by a mechanical tightening of the nut with the required torque. In the case of anchor bolts embedded in a concrete base, the prescribed tightening procedure has to be followed for safe and reliable operation. The present paper addresses the problem of anchoring a new casting pedestal using the original anchor bolts. The aim was to verify the original anchoring system’s reliable and safe operation, taking into account the current condition of the bolts. The analysed anchoring bolts are subjected to cyclic (disappearing) stress during the rotation of the casting pedestal. If the interplays between the anchor bolt and the concrete foundation were damaged, production would shut down, resulting in high economic losses. For this reason, the authors used a modified nut with a lightened first thread when investigating the actual state of the anchoring and setting the required preload. The shape and dimensions of the nut were determined based on the results of numerical modelling. The experimental measurements consisted of two phases. In the first phase, the values of axial forces in the anchor bolts at the required preload were set using the designed dynamometers. The second phase was focused on the operational measurements. The methodology of measuring the axial forces and the interpretation of the results obtained, including a comprehensive view of the anchoring safety, provides relevant evidence of the functionality and effectiveness of the proposed solution. Based on the results of the operational measurement and the prescribed handling of the casting pedestal, the lifespan of the anchoring was determined to be 3650 days under the loading cycles to date.
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Sukmana, Irza, Fauzi Ibrahim, Mohammad Badaruddin, and Hadi Nur. "Low cycle fatigue properties of extruded magnesium AZ31B." FME Transactions 50, no. 3 (2022): 422–32. http://dx.doi.org/10.5937/fme2203422s.
Повний текст джерелаАнотація:
The low cycle fatigue behavior of magnesium (Mg) AZ31B was observed at room temperature, in which its extrusion process led to differences in tensile and compressive stresses, with an increase in the grain structure and mechanical properties. The extrusion process results showed changes in the microstructure due to cyclic load-deformation at the longitudinal section with grain direction and shape. Furthermore, Mg AZ31B also showed transitional behavior from cyclic softening to hardening when the strain amplitude was increased. At a strain amplitude of 0.006 - 0.01 mm/mm, the Bauschinger phenomenon was observed. The effect factor was calculated by the yield stress and strain at compression stress. Furthermore, precipitation or local failure of the second phase was the main factor that caused the Bauschinger phenomenon. The fatigue fracture characteristics based on deformation due to cyclic loading include precipitation, fatigue striation, dimples, micro-cracks, and beach mark fatigue. Therefore, the correlation of the total failure cycle with plastic and the elastic strain was obtained as an equation to predict the lifespan of Mg AZ31B.
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Nguyen, Thanh Q., Hieu C. Doan, Luan C. Vuong, H. Nguyen-Xuan, and Nhi K. Ngo. "Fretting Fatigue Damage Nucleation and Propagation Lifetime Using a Central Point Movement of Power Spectral Density." Shock and Vibration 2020 (January 22, 2020): 1–16. http://dx.doi.org/10.1155/2020/4985134.
Повний текст джерелаАнотація:
This paper presents a new perception in evaluating fretting fatigue damage nucleation and propagation lifetime under periodically forced circulation. A new approach, which is proposed in this paper, is to measure the change of the central point of power spectral density (CP-PSD) in different structural stiffness degradation stages. A notable aspect of this study lies in the combination between vibration amplitude and forced frequency of the fatigue-causing factors in beam structures. Additionally, it is found that randomization of the first phase from 0 to 2π yields more accurate modelling of the fatigue phenomenon. Results show that the CP-PSD parameter is significantly more sensitive compared to the regularly damage-evaluating parameters such as natural frequency, eigenvalues, or stress value. This reflects different levels of fatigue cycle effect on the structure in the experiment. At the same time, CP-PSD also categorizes the degradation level on different points on the structure under the periodically forced circulation. In addition, this paper also quantifies the relation between the changes of CP-PSD and each fatigue state. Results of this research will be a reference source to evaluate the lifespan of the structure by experimental methods.
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Arun Kumar, S., M. Muralidharan, P. Ashoka Varthanan, C. Vigneshkumaran, A. Bala Kumaran, and S. Nishanth. "Fatigue Strength Improvement of TIG Welded Joint by Shot Peening Process." Applied Mechanics and Materials 867 (July 2017): 81–87. http://dx.doi.org/10.4028/www.scientific.net/amm.867.81.
Повний текст джерелаАнотація:
Aluminium alloys are widely used in engineering fields because of its characteristics. Components used in the fields of automobile, aerospace such as gears, shafts, turbines. In the mechanical field materials can be joined using many processes like riveting, bolted joints or by using permanent joining techniques like welding, brazing or soldering. The welded joints are often used for structural applications due to the reason that they provide nearly the same strength of the parent material. But researches show that even though they provide good strength in tension, they fail much faster when they exposed to fatigue loading. This may be due to various reasons like improper welding sequence, improper preparation or improper welding parameters of the joint materials. The fatigue life may also get reduced due to stress concentration developed during the welding process. Fatigue failures often results in catastrophic failures. Many designs have been reported, have been occurred due to fatigue failures which resulted in heavy loss of human lifespan and goods. Materials with even higher tensile strength are found to fail at less number of cycles after welding.
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Ansari, Md Touhid A., Kalyan K. Singh, and Mohammad S. Azam. "Observations of fatigue damage development in woven glass fiber-reinforced polymer composite using transmission light photography technique." Polymers and Polymer Composites 30 (January 2022): 096739112211013. http://dx.doi.org/10.1177/09673911221101300.
Повний текст джерелаАнотація:
Fatigue behaviour is an important aspect for consideration while handling glass fiber-reinforced polymer (GFRP) composites. A combination of (0°/90°) and (±45°) plies are gaining practical interest in engineering applications due to their excellent mechanical properties. Properties of individual above-stated plies primarily influence the behaviour of laminates. Fatigue behaviour of on-axis (0°/90°) and off-axis (±45°) fiber orientated woven GFRP laminates was investigated. Tensile and tension-tension fatigue tests were performed on the prepared test coupons according to the ASTM standard. Fatigue test was conducted until failure at maximum applied stress of 90%, 70%, and 50% of the respective ultimate strength. Damage growth was monitored in the term of debond zones by employing the transmission light photography technique. Testing process was recorded by using a digital camera. The results were established in terms of the stress-strain curve, Wöhler curve, debond zones and dynamic stiffness. The fatigue strength of off-axis laminates was much lower than the on-axis laminates. Global damage has occurred in (0°/90°) laminates while (±45°) laminate witnessed localized damage. At higher stress levels, samples were failed at shorter lifespan with aggressive damage; however, on-axis specimens survived with longer fatigue life.
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Agrawal, Manoj Kumar, V. Bindu Sree, Preeti Maan, Bhishm Pratap, Rahman S. Zabibah, and Vishal Sharma. "FEA-Based Investigation of Fatigue Life and Durability of Materials and Structures in Automotive Applications." E3S Web of Conferences 430 (2023): 01115. http://dx.doi.org/10.1051/e3sconf/202343001115.
Повний текст джерелаАнотація:
In the rapidly evolving automotive industry, the longevity and reliability of materials and structures are paramount. This research paper presents a comprehensive Finite Element Analysis (FEA)-based investigation into the fatigue life and durability of materials and structures commonly employed in automotive applications. Utilizing state-of-the-art FEA tools, the study evaluates the stress distributions, strain concentrations, and fatigue-induced deformations under cyclic loading conditions representative of real-world automotive scenarios. A comparative analysis of various automotive materials, including advanced high-strength steels, aluminium alloys, and novel composite materials, is conducted to discern their fatigue performance. The results elucidate the critical regions susceptible to fatigue failure and provide insights into the underlying mechanisms governing material degradation. Furthermore, the study introduces a novel fatigue life prediction model, calibrated against experimental data, offering enhanced accuracy in predicting the lifespan of automotive components. The findings of this research not only contribute to the fundamental understanding of fatigue phenomena in automotive materials but also pave the way for the development of more durable and sustainable vehicles in the future. This work serves as a cornerstone for engineers and researchers aiming to optimize material selection and design strategies, ensuring safer and longer-lasting automotive structures.
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Bordjiba, Abdelhak, and Hamza Guenfoud. "Behavior of Recycled Asphalt to the Fatigue." Journal of Building Materials and Structures 6, no. 1 (March 31, 2019): 1–9. http://dx.doi.org/10.34118/jbms.v6i1.63.
Повний текст джерелаАнотація:
Climatic and traffic effects are the causes of aging of the surface layer of asphalt, which leads to the necessary renovation of the latter. The use of waste from the tread layer provides a viable and beneficial solution for the environment and the economy. However, this solution must meet the requirement of sustainable development, which necessitates that a road has a very long lifespan. In this study we investigated the performance of recycled asphalt in terms of fatigue (as an element of life-cycle control). All the formulas were tested by the fatigue test in order to define the influence of the proportions of the asphalt aggregates, penetrability of the new binder used, and the manufacturing temperature. The results obtained showed the relationship between the contribution binder (reproduced between the new binder and the old binder) and the fatigue resistance under the influence of the parameters that we have mentioned above. At the end an optimization study has been carried in order to determine exactly the doses required to formulate recycled asphalt resisted to fatigue, the optimization seeks to maximize the asphalt aggregates and minimized the temperature of manufacture with a class of the binder compatible.
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Brunton, Laura K., Elizabeth G. Condliffe, Gregor Kuntze, Leticia Janzen, Shane Esau, Clodagh M. Toomey, and Carolyn A. Emery. "More Than Just Adolescence: Differences in Fatigue Between Youth With Cerebral Palsy and Typically Developing Peers." Annals of Rehabilitation Medicine 45, no. 3 (June 30, 2021): 197–203. http://dx.doi.org/10.5535/arm.20250.
Повний текст джерелаАнотація:
Objective To quantify differences in fatigue and disordered sleep between adolescents with cerebral palsy (CP) and their typically developing peers. A secondary aim was to investigate the association between fatigue and disordered sleep in adolescents with CP.Methods A convenience sample of 36 youth with CP aged 10–18 years was matched for age and sex with 36 typically developing peers. The Fatigue Impact and Severity Self-Assessment (FISSA), the Patient-Reported Outcome Measurement Information System (PROMIS) fatigue profile, and the Sleep Disturbance Scale for Children (SDSC) were collected.Results Higher fatigue was reported in participants with CP than in their typically developing peers based on the FISSA total score (mean paired difference=19.06; 99% confidence interval [CI], 6.06–32.1), the FISSA impact subscale (mean paired difference=11.19; 99% CI, 3.96–18.4), and the FISSA Management and Activity Modification subscale (mean paired difference=7.86; 99% CI, 1.1–14.6). There were no differences between groups in the PROMIS fatigue profile (mean paired difference=1.63; 99% CI, -1.57–4.83) or the SDSC total score (mean paired difference=2.71; 99% CI, -2.93–8.35).Conclusion Youth with CP experienced significantly more fatigue than their peers as assessed by a comprehensive measure that considered both general and diagnosis-specific concerns. Sleep did not differ between youth with CP and their typically developing peers. These findings underscore the need to consider the clinical management of fatigue across the lifespan of individuals with CP to prevent the associated deterioration of functional abilities.
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Bordjiba, Abdelhak, and Hassib Rhailia. "Fatigue Resistance of BBSG Asphalt Mix with Recycled Asphalt Aggregate Addition." International Journal of Engineering Research in Africa 43 (June 2019): 25–32. http://dx.doi.org/10.4028/www.scientific.net/jera.43.25.
Повний текст джерелаАнотація:
Climatic and traffic effects are the causes of aging of the surface layer of asphalt, which leads to the necessary renovation of the latter. The use of waste from the tread layer provides a viable and beneficial solution for the environment and the economy. However, this solution must meet the requirement of sustainable development, which necessitates that a road has a very long lifespan. In this study we investigated the performance of recycled asphalt in terms of fatigue (as an element of life-cycle control). All the formulas were tested by the fatigue test in order to define the influence of the proportions of the asphalt aggregates, penetrability of the new binder used, and the manufacturing temperature. The results obtained showed the relationship between the contribution binder (reproduced between the new binder and the old binder) and the fatigue resistance under the influence of the parameters that we have mentioned above. At the end an optimization study has been carried out in order to determine exactly the doses required to formulate recycled asphalt resisted to fatigue The optimization seeks to maximize the asphalt aggregates and minimize the temperature of manufacture with a class of the binder compatible.
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Abdelhak, Bordjiba, and Guenfoud Hamza. "Influence of the penetrability of the new bitumen and the temperature of manufacture on the resistance of the asphalt recycled to the fatigue." Selected Scientific Papers - Journal of Civil Engineering 13, no. 1 (December 1, 2018): 39–50. http://dx.doi.org/10.1515/sspjce-2018-0018.
Повний текст джерелаАнотація:
Abstract Climatic and traffic effects are the causes of aging of the surface layer of asphalt, which leads to the necessary renovation of the latter. The use of waste from the tread layer provides a viable and beneficial solution for the environment and the economy. However, this solution must meet the requirement of sustainable development, which necessitates that a road has a very long lifespan. In this study we investigated the performance of recycled asphalt in terms of fatigue (as an element of life-cycle control). All the formulas were tested by the fatigue test in order to define the influence of the proportions of the asphalt aggregates, penetrability of the new binder used, and the manufacturing temperature. The results obtained showed the relationship between the contribution binder (reproduced between the new binder and the old binder) and the fatigue resistance under the influence of the parameters that we have mentioned above. At the end an optimization study has been carried in order to determine exactly the doses required to formulate recycled asphalt resisted to fatigue, the optimization seeks to maximize the asphalt aggregates and minimized the temperature of manufacture with a class of the binder compatible.
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Islam, Md Nafiul, Md Zafar Iqbal, Milon Chowdhury, Mohammod Ali, Kiraga Shafik, Md Shaha Nur Kabir, Dae-Hyun Lee, and Sun-Ok Chung. "Stress and Fatigue Analysis of Picking Device Gears for a 2.6 kW Automatic Pepper Transplanter." Applied Sciences 11, no. 5 (March 3, 2021): 2241. http://dx.doi.org/10.3390/app11052241.
Повний текст джерелаАнотація:
A seedling picking device is an essential component for an automatic transplanter to automatically convey the seedling to the dibbling part. It is necessary to find the appropriate material and dimensions for the picking device gears to avoid mechanical damage and increase their durability. Therefore, the objectives of this research were to analyze the stress of a picking device gear mechanism in order to select suitable materials and dimensions, and to predict the fatigue life by considering the damage level. The picking device gear shaft divided the input power into two categories, i.e., crank and cam gear sets. Finite element analysis simulation and American Gear Manufacturers Association standard stress analysis theory tests were conducted on both of the crank and cam gear sets for different materials and dimensions. A test bench was fabricated to collect the load (torque) data at different gear operating speeds. The torque data were analyzed using the load duration distribution method to observe the cyclic load patterns. The Palmgren–Miner cumulative damage rule was used to determine the damage level of the picking mechanism gears with respect to the operating speed. The desired lifespan of the transplanter was 255 h to meet the real field service life requirement. Predicted fatigue life range of the picking mechanism gears was recorded as from 436.65 to 4635.97 h, making it higher (by approximately 2 to 18 times) than the lifespan of the transplanter. According to the analyses, the “Steel Composite Material 420H carbon steel” material with a 5 mm face width gear was suitable to operate the picking device for a 10-year transplanter service life. The analysis of stress and fatigue presented in this study will guide the design of picking device gears with effective material properties to maintain the recommended service life of the pepper transplanter.
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Thives, Liseane Padilha, Jorge C. Pais, Paulo A. A. Pereira, Manuel C. Minhoto, and Glicério Trichês. "Performance of Asphalt Rubber Mixture Overlays to Mitigate Reflective Cracking." Materials 15, no. 7 (March 23, 2022): 2375. http://dx.doi.org/10.3390/ma15072375.
Повний текст джерелаАнотація:
Adequately predicting overlay behaviour is essential for flexible pavement rehabilitation to reach the predicted lifespan. Reflective cracking is one of the main failure mechanisms affecting overlay performance. This failure may occur due to cracks in the lower layers that propagate to the overlay due to traffic loads, temperature variations, shrinkage cracking of cement-treated layers, and subgrade movements. This work aims to assess the reflective cracking phenomenon of asphalt rubber mixtures as an overlay through laboratory tests and numerical simulation. Four-point bending equipment and the reflective crack device were used to perform the laboratory tests. A numerical simulation through the finite element method was accomplished to estimate the von Mises strain and develop reflective cracking fatigue laws. The results showed that the asphalt rubber mixtures are suitable for extending overlay lifespan considering reflective cracking. The evaluated asphalt rubber mixtures presented reflective cracking resistance almost eight times greater than the conventional ones.
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Andud, Dahia, Salina Saidin, and Yupiter H. P. Manurung. "Fatigue Life Behaviour of Transverse Fillet Weld and Transverse Fillet on Weld of the HSLA S460G2+M Followed by HFMI/PIT." Applied Mechanics and Materials 899 (June 2020): 126–34. http://dx.doi.org/10.4028/www.scientific.net/amm.899.126.
Повний текст джерелаАнотація:
This study deals with the fatigue life assessment of the transverse fillet weld and transverse fillet weld on weld fatigue specimen of the offshore steel S460G2+M with a thickness of 10 mm. These specimens were joined using gas metal arc welding (GMAW) with ER80S-N1 filler metal of 1.0 mm in diameter and mixed gases of 80% Ar + 20% CO2 as the consumables. Upon the welding completion, some of the fatigue specimens are treated using high-frequency mechanical impact device called pneumatic impact treatment (HFMI/PIT). The treatment procedure uses 90Hz of frequency, 6 bars of pneumatic pressure and 2 mm pin radius with aims to enhance the lifespan of the specimen. These fatigue specimens are classified in as-welded and HFMI/PIT. The fatigue test was conducted to all fatigue specimens until failure using a 250KN Instron fatigue machine with a constant amplitude loading, a stress ratio of 0.1 and stress loading from 55% to 75% of the yield strength of the base material. The fatigue data were evaluated based on the International Institute of Welding (IIW) evaluation procedures. Further, the fatigue life comparison between the as-welded and HFMI/PIT of both fatigue specimens also with the FAT class recommendation of the IIW for transverse fillet weld is plotted in the S-N curve diagram. Based on the assessment, it is found that the HFMI/PIT fatigue specimens attained higher fatigue life than the as-welded of both fatigue specimens. The most significant of fatigue life improvement after the HFMI/PIT is the HFMI/PIT transverse fillet weld. These treated welds obtained 256 MPa of FAT class which is 79 % higher than FAT class recommended by the IIW for the transverse fillet weld. Besides, the multi-pass welds on the groove weld of the transverse fillet weld on welds are found to contribute to a lower fatigue life of this specimen due to the existing weld defects on the fractured surface of the groove weld.
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Ren, Weiwei, Jintao Tian, Rui Pang, and Yuanyuan Shang. "Ferroelectric SnPz/In2Se3 as a Stable and Durable Non-Volatile 2D Ferroelectric Memory Material." Crystals 13, no. 6 (June 11, 2023): 940. http://dx.doi.org/10.3390/cryst13060940.
Повний текст джерелаАнотація:
In ferroelectric memory, the repeated application of external electric fields can cause ferroelectric fatigue, limiting its stability and service life, especially as the storage unit size decreases. To address this issue, we conducted first-principles research on a SnPz/In2Se3 structure and examined its structure under different polarization directions. Our analysis revealed significant differences in the adsorption position of Sn atoms depending on the polarization direction, suggesting that SnPz/In2Se3 could be a highly stable ferroelectric storage material. Moreover, the polarization-induced changes in the electronic structure near the Fermi level, which allowed for the use of tunneling current and obtaining stored information without causing the ferroelectric fatigue effect during information readout. These findings highlight the potential of SnPz/In2Se3 to significantly extend the lifespan of ferroelectric materials, reduce energy consumption, and minimize the environmental impact of discarded electronic devices.
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Chen, Yuqiang, Hailiang Wu, Xiangdong Wang, Xianghao Zeng, Liang Huang, Hongyu Gu, and Heng Li. "Corrosion Mechanism and the Effect of Corrosion Time on Mechanical Behavior of 5083/6005A Welded Joints in a NaCl and NaHSO3 Mixed Solution." Crystals 12, no. 8 (August 16, 2022): 1150. http://dx.doi.org/10.3390/cryst12081150.
Повний текст джерелаАнотація:
The effect of corrosion time on the mechanical behavior of 5083/6005A welded joints in a 3.5% NaCl + 0.01 mol/L NaHSO3 solution was evaluated via scanning electron microscopy (SEM), polarization curve analysis, and X-ray photoelectron spectroscopy (XPS). The prediction model of fatigue life after corrosion was established based on the experimental results and the theory of fracture mechanics, and the formula for the effect of corrosion time on lifespan was determined. The results show that with increasing corrosion time, the corrosion of the sample becomes increasingly severe, and the elongation and fatigue life of the 5083/6005A welded joints decrease significantly. The corrosion resistance of the 5083/6005A welded joints decreases with increasing corrosion time because the corrosive medium promotes the destruction of the oxide film and thereby reduces the corrosion resistance. The corrosion products of the 5083/6005A welded joints are Al(OH)3 and AlCl3.
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Růžek, Roman, Martin Kadlec, and Lucie Petrusová. "Effect of fatigue loading rate on lifespan and temperature of tailored blank C/PPS thermoplastic composite." International Journal of Fatigue 113 (August 2018): 253–63. http://dx.doi.org/10.1016/j.ijfatigue.2018.04.023.
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Zhou, Jianjun, Bowen Yang, Shuaiyuan Li, and Junzhou Huo. "Fretting Fatigue Life Prediction of Dovetail Structure Based on Plastic Effect and Sensitivity Analysis of Influencing Factors." Materials 16, no. 9 (May 4, 2023): 3521. http://dx.doi.org/10.3390/ma16093521.
Повний текст джерелаАнотація:
Micro relative sliding exists on the contact surface of the main primary equipment’s surface structures, resulting in serious fretting fatigue. The plastic effect causes serious fatigue to the structure under alternating loads. Existing fatigue life prediction models fail to fully consider the shortcomings of fretting and plastic effects, which causes the prediction results to be significantly different to real-lifeworld in engineering situations. Therefore, it is urgent to establish a fretting damage fatigue life prediction model of contact structures which considers plastic effects. In this study, a plastic fretting fatigue life prediction model was established according to the standard structural contact theory. The location of dangerous points was evaluated according to a finite element simulation. The cyclic load maximum stress value was compared with the fretting fatigue test data to confirm the error value, and the error between the proposed fretting fatigue life model and the test value was within 15%. Concurrently, we combined this with mass data analysis and research, as it is known that the contact zone parameters have an impact on fretting fatigue and affect the structural lifespan. With the help of ABAQUS, the fretting numerical calculation of the dovetail tenon model was carried out to analyze the sensitive factors affecting the fretting fatigue life of the dovetail tenon structure. By keeping the fretting load unchanged, the contact area parameters such as contact surface form, contact area width and friction coefficient were changed in order to calculate the fretting stress value, σfretting and the dovetail structure was improved to extend its fretting fatigue life. Finally, it was concluded that fretting fatigue was most sensitive to the width and contact form of the contact area. In actual engineering design, multiple factors should be considered comprehensively to determine a more accurate and suitable width and form of the contact area. For the selection of friction coefficient, on the premise of saving costs and meeting the structural strength requirements, the friction coefficient should be as small as possible, and the problem can also be solved through lubrication during processing.
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Aleksić, Vujadin, Srđan Bulatović, Bojana Zečević, Ana Maksimović, and Ljubica Milović. "Numerical Determination of the Life of Steel Exposed To Low Cycle Fatigue." Advanced Technologies & Materials 48, no. 2 (December 2, 2023): 69–76. http://dx.doi.org/10.24867/atm-2023-2-005.
Повний текст джерелаАнотація:
In the paper, based on the results of the experimental research of high-strength low-alloy steel (HSLA), Nionicral 70 (NN-70), under conditions of low-cycle fatigue (LCF), a numerical analysis of stress and determination of the life of steel samples was performed. Experimental testing of the behavior of the samples were performed with controlled and fully reversible strain (/2 = const, R = min/max = -1), according to the standard ISO 12106:2003 (E). For computational analyses, the following were used: the method of least squares and the method of finite elements (FEM). On the basis of the analysis of the results of the stress-deformation state and the determination of the life span through the isolines of the life span and comparison with the results of experimental tests, a graphic representation is given. The analysis justified the effort to numerically solve the estimation of the lifespan of steel under low cycle fatigue (LCF).
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Mahakur, Vijay Kumar, A. C. Umamaheshwer Rao, and Pathapalli Venkateshwar Reddy. "Modelling and Analysis on the Fatigue Life of Gas Turbine Compressor Disc." MATEC Web of Conferences 393 (2024): 02004. http://dx.doi.org/10.1051/matecconf/202439302004.
Повний текст джерелаАнотація:
The disc itself revolves at an extremely rapid pace, putting a lot of strain on the turbine compressor disc. This exceptionally stressed part provides an impact on a particular location such as a bore, bolt hole, slot, or fillet. The bore area of the disc is an especially crucial zone, since any failure there would result in an unprecedented breakdown of the entire turbine. So in this study, the finite-element approach is employed to offer a numerical estimate of the lifespan of a gas turbine prototype disc. Engine start-up and shutdown, as well as significant throttle fluctuations during operation, can cause cyclic tensile stresses in this area. These cyclic tensile stresses will surpass the component's yield strength and may potentially induce low cycle fatigue failure. As a result, there is a need to improve the fatigue and fracture lifetime of the bore area in order to meet the expanding design life requirements.
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Zau, Andre T. Puati, Mpho J. Lencwe, S. P. Daniel Chowdhury, and Thomas O. Olwal. "A Battery Management Strategy in a Lead-Acid and Lithium-Ion Hybrid Battery Energy Storage System for Conventional Transport Vehicles." Energies 15, no. 7 (April 1, 2022): 2577. http://dx.doi.org/10.3390/en15072577.
Повний текст джерелаАнотація:
Conventional vehicles, having internal combustion engines, use lead-acid batteries (LABs) for starting, lighting, and ignition purposes. However, because of new additional features (i.e., enhanced electronics and start/stop functionalities) in these vehicles, LABs undergo deep discharges due to frequent engine cranking, which in turn affect their lifespan. Therefore, this research study seeks to improve LABs’ performance in terms of meeting the required vehicle cold cranking current (CCC) and long lifespan. The performance improvement is achieved by hybridizing a lead-acid with a lithium-ion battery at a pack level using a fully active topology approach. This topology approach connects the individual energy storage systems to their bidirectional DC-DC converter for ease of control. Besides, a battery management strategy based on fuzzy logic and a triple-loop proportional-integral (PI) controller is implemented for these conversion systems to ensure effective current sharing between lead-acid and lithium-ion batteries. A fuzzy logic controller provides a percentage reference current needed from the battery and regulates the batteries’ state-of-charge (SoC) within the desired limits. A triple-loop controller monitors and limits the hybridized system’s current sharing and voltage within the required range during cycling. The hybridized system is developed and validated using Matlab/Simulink. The battery packs are developed using the battery manufacturers’ data sheets. The results of the research, compared with a single LAB, show that by controlling the current flow and maintaining the SoC within the desired limits, the hybrid energy storage system can meet the desired vehicle cold cranking current at a reduced weight. Furthermore, the lead-acid battery lifespan based on a fatigue cycle-model is improved from two years to 8.5 years, thus improving its performance in terms of long lifespan.
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Moore, Jacob P., and Christopher B. Williams. "Fatigue properties of parts printed by PolyJet material jetting." Rapid Prototyping Journal 21, no. 6 (October 19, 2015): 675–85. http://dx.doi.org/10.1108/rpj-03-2014-0031.
Повний текст джерелаАнотація:
Purpose – This paper aims to seek to fill a gap in the literature by characterizing the fatigue life and microstructure of a printed elastomer material, the TangoBlackPlus material. Design/methodology/approach – Because the TangoBlackPlus material is marketed as “rubber-like”, the printed elastomer specimens were tested according to the ASTM D4482-11 “Test Method for Rubber Property Extension Cycling Fatigue”. The microstructure of the printed material and multi-material interface was examined by slicing specimens and examining them under an optical microscope. Findings – Findings are developed to show the relationship between elongation and expected fatigue life. Findings also indicate that the smoother, non-support encased “glossy” surface finish option for PolyJet parts improve the fatigue life of components and that there are a number of microscopic voids in the TangoBlackPlus material that seem to be concentrated at layer and print head boundaries. Research limitations/implications – This paper provides a glimpse into the fatigue properties and microstructure of printed elastomeric parts, a previously unstudied area. This work is limited in that it only looks at specimens created in a single orientation, on a single machine, with a single material. More work is needed to understand the general fatigue properties of printed elastomers and the factors that influence fatigue life in these materials. Practical implications – The authors provide several design guidelines based on the findings and previous work that can be used to increase the fatigue life of printed elastomer components. Originality/value – As additive manufacturing (AM) technology moves from a prototyping tool to a tool used to create end use products, it is important to examine the expected lifespan of AM components. This work adds to the understanding of the expected product lifecycle of printed elastomer components that will likely be expected to withstand large repeated loading conditions.
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An, Qi, Hua Zhao, Peihai Li, and Maohai Fu. "Fatigue strength analysis of bogie frames under random loads." Advances in Mechanical Engineering 11, no. 9 (September 2019): 168781401987801. http://dx.doi.org/10.1177/1687814019878018.
Повний текст джерелаАнотація:
In this study, a method for analyzing the fatigue strength of a bogie frame under a random load was proposed. Based on the geometric features, a welded joint coordinate system was established to compute the stress components of each node in this coordinate system. With the influence of small amplitude cycles included, based on the corrected S–N curve and a method for calculating the equivalent constant amplitude stress, the node and comprehensive degree of utilization were calculated based on the anti-fatigue design grade of welded joints to evaluate the fatigue strength of a structure under a given lifespan. The FKM and International Institute of Welding methods were used to evaluate the fatigue strength of typical welded joints of a bogie frame. The characteristics of the node degree of utilization under different analytical methods were compared, and the results showed that when the time histories of the three stress components of the nodes had significant non-proportional features, the FKM method obtained conservative results. When the time histories of the three stress components of the nodes were synchronized, the criterion value specified by the International Institute of Welding method was the main factor affecting the distribution characteristics of the node degree of utilization. The analysis based on the International Institute of Welding method can effectively balance the lightweight design and reliability of the structure.
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Dominelli, Paolo B., and Yannick Molgat-Seon. "Sex, gender and the pulmonary physiology of exercise." European Respiratory Review 31, no. 163 (January 12, 2022): 210074. http://dx.doi.org/10.1183/16000617.0074-2021.
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In this review, we detail how the pulmonary system's response to exercise is impacted by both sex and gender in healthy humans across the lifespan. First, the rationale for why sex and gender differences should be considered is explored, and then anatomical differences are highlighted, namely that females typically have smaller lungs and airways than males. Thereafter, we describe how these anatomical differences can impact functional aspects such as respiratory muscle energetics and activation, mechanical ventilatory constraints, diaphragm fatigue, and pulmonary gas exchange in healthy adults and children. Finally, we detail how gender can impact the pulmonary response to exercise.
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Sunderland, Matthew, Megan J. Hobbs, Tracy M. Anderson, and Gavin Andrews. "Psychological distress across the lifespan: examining age-related item bias in the Kessler 6 Psychological Distress Scale." International Psychogeriatrics 24, no. 2 (September 21, 2011): 231–42. http://dx.doi.org/10.1017/s1041610211001852.
Повний текст джерелаАнотація:
ABSTRACTBackground: Old age respondents may differ systemically in their responses to measures of psychological distress over and above their actual latent distress levels when compared to younger respondents. The current study aimed to investigate the potential for age-related bias(es) in the Kessler 6 Psychological Distress Scale (K6) items.Methods: Data from the 2007 Australian National Survey of Mental Health and Wellbeing were analyzed using Item Response Theory to detect the presence of item bias in each of the K6 items. The potential for item bias was assessed by systematically comparing respondents classed as young (16–34 years), middle aged (35–64 years), and old aged (65–85 years). The significance and magnitude of the item bias between the age groups was assessed using the log-likelihood ratio method of differential item functioning.Results: After statistical adjustment, there were no biases of significant magnitude influencing the endorsement of K6 items between young and middle-aged respondents or between middle-aged and old age respondents. There was a bias of significant magnitude present in the endorsement of the K6 item addressing levels of fatigue between young and old age respondents.Conclusions: Despite the identification of significant item bias in the endorsement of K6 items between the age groups, the magnitude and influence of the bias on total K6 scores is likely to have little influence on the overall interpretation of group data when comparing psychological distress across the lifespan. Researchers should be cautious, however, when examining individual levels of fatigue related to psychological distress in older individuals.
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Liu, Chang, Xu Hong Guo, and Xin Xin Gao. "Numerical Simulation of Fatigue Crack Growth of New-Material Track Rollers." Applied Mechanics and Materials 157-158 (February 2012): 1471–76. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.1471.
Повний текст джерелаАнотація:
Because of the excellent mechanical properties of Austempered Ductile Iron (ADI), track rollers can be made out of this material. The casting may lead to cracks forming inside rollers and there will also be some scratches in the surface when rollers work, which will greatly affect the lifespan of rollers. It is helpful to use crack propagation method based on the Finite Element Method (FEM) to simulate the crack growth. Firstly, define the position and the value of the force imposed on rollers. If the load is compressive, contact pairs should be set between the crack surfaces. After the model is established, Stress Intensity Factors (SIF) KI and KII can be calculated with the node displacement theory by using the commands of FEM software. With the maximum principal stress theory, crack growth direction can be determined. Since the values of KI and KII calculated by the software are positive, we should judge weather the values are positive or negative to get a right propagating angle. The analysis applies linear elastic fracture mechanics and FEM modeling the crack propagation in the elastic state.
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Fodor, Antal. "DMA tests for 3D printed polymer specimens of fatigue test examination." MACRo 2015 2, no. 1 (October 1, 2017): 129–35. http://dx.doi.org/10.1515/macro-2017-0015.
Повний текст джерелаАнотація:
AbstractAlongside the using of „technical materials’, the direct 3D printed different plastic also speeded up lately. Accordingly to this, it is often designed parts, which have to sustain extreme stress. The proper definition of material qualities is expensive; despite in every phase of designing, we need it to be done perfectly. In every industrial section, it is important to work with exact material characteristics, especially in fields where strict safety rules have to be kept (in connection with the lifespan) the design of fatigue tests of 3D printed polymer specimens. We planned the examinations on the way to avoid the critical temperature range shown by the DMA examinations’ results in the bending point of the inner friction coming up in the local range. This information could be important for the Military to change the busted parts quickly and sound. That is the reason why we designed these examinations in this way, so, it could help for designers in the field of military, in development of security technology and improvement of recovery.