Journal articles: 'Limit of endurance strength'

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Bian, X. X., G. Zhou, Liwei, and J. Z. Tan. "Investigation of bending fatigue strength limit of alloy steel gear teeth." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 3 (January 6, 2012): 615–25. http://dx.doi.org/10.1177/0954406211434670.

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An experimental investigation was conducted on the single-tooth pulsating bending fatigue of 38SiMnMo alloy steel at a frequency range of 140–150 Hz. Using both up–down test method and S–N curve extension method, statistical data in terms of curves and endurance limits were analysed. The testing and analytical results indicated that the ‘platform’ of fatigue curves exists and the S–N curve cannot be extended to the cyclic basic number Nb in order to obtain the endurance limit. Furthermore, on the basis of the life distribution optimization, the three-parameter Weibull distribution was used for statistical data analysis. The statistical analysis showed that the bending endurance limit of 38SiMnMo alloy steel gears estimated at 99 per cent reliability and 95 per cent confidence was 284 MPa, which was located at the slightly low part of the mean line in the chart range illustrated in the standards ISO6336 and GB3480. The results demonstrated that the method described in this article was valuable.

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Henderson, Bradley S., Katelyn F. Cudworth, Madison E. Wale, Danielle N. Siegel, and Trevor J. Lujan. "Tensile fatigue strength and endurance limit of human meniscus." Journal of the Mechanical Behavior of Biomedical Materials 127 (March 2022): 105057. http://dx.doi.org/10.1016/j.jmbbm.2021.105057.

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Han, J., W. T. Hwang, C. E. Lee, and H. K Kim. "Fatigue strength of a tensile-shear loaded clinched joint made from an al-5052 alloy sheet." International Journal of Engineering & Technology 9, no. 1 (February 25, 2020): 252. http://dx.doi.org/10.14419/ijet.v9i1.30221.

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The clinching process has been shown to be able to join dissimilar material sheets as an alternative to spot welding. In this study, monotonic and fatigue tests were conducted using tensile-shear specimens for an evaluation of the strengths of a joint. In the fatigue tests, an interface failure occurred. The fatigue ratio of the joint is 0.29, assuming a fatigue endurance limit at 2 x106 cycles. The maximum von-Mises stress of the joint at the load amplitude corresponding to the fatigue endurance limit is slightly higher than the yield strength of Al-5052 alloy. This indicates that the strength of the neck region is increased partially due to work hardening.

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Mlikota, Marijo, and Siegfried Schmauder. "A Newly Discovered Relation between the Critical Resolved Shear Stress and the Fatigue Endurance Limit for Metallic Materials." Metals 10, no. 6 (June 17, 2020): 803. http://dx.doi.org/10.3390/met10060803.

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The paper introduces a valuable new description of fatigue strength in relation to material properties and thus a new perspective on the overall understanding of the fatigue process. Namely, a relation between the endurance limits and the accompanying values of the critical resolved shear stress (CRSS) for various metallic materials has been discovered by means of a multiscale approach for fatigue simulation. Based on the uniqueness of the relation, there is a strong indication that it is feasible to relate the endurance limit to the CRSS and not to the ultimate strength, as often done in the past.

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Malysh, S. V., I. M. Kovenskiy, and L. Z. Chaugarova. "Influence of chrome electroplating on fatigue strength of parts." Oil and Gas Studies, no. 5 (November 12, 2020): 112–19. http://dx.doi.org/10.31660/0445-0108-2020-5-112-119.

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The article is devoted to the results of studies, which have been conducted on parts with electrolytic chromium in order to determine the effect of the coating on fatigue strength of their. The work was performed in observance of standards, which are fixed in GOST RV 2840-001-2008. Samples for the tests were made from standard gas turbine engine compressor blades. We used a VEDS- 1500 electrodynamic vibration stand with an UMK-12K power amplifier to excite vibrations. It has been shown that the minimum endurance limit of 46 kgf/mm2 based on 2 ∙ 107 cycles, established on uncoated parts, didn't decrease during fatigue tests of compressor blades with an electroplated chrome layer. It should be stressed that the influence of the geometry of the chrome-plated part on the reduction of the endurance limit has been established.

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Roth, Ralf, Lars Donath, Lukas Zahner, and Oliver Faude. "Muscle Activation and Performance During Trunk Strength Testing in High-Level Female and Male Football Players." Journal of Applied Biomechanics 32, no. 3 (June 2016): 241–47. http://dx.doi.org/10.1123/jab.2014-0303.

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For performance and injury prevention in sport, core strength and endurance are focused prerequisites. Therefore we evaluated characteristics of trunk muscle activation and performance during strength-endurance related trunk field tests. Strength-endurance ability, as total time to failure, and activation of trunk muscles was measured in 39 football players of the highest German female football league (Bundesliga) (N = 18, age: 20.7 y [SD 4.4]) and the highest national male under-19 league (N = 21, age: 17.9 y [0.7]) in prone plank, side plank, and dorsal position. Maximal isometric force was assessed during trunk extension and flexion, rotation, and lateral flexion to normalize EMG and to compare with the results of strength-endurance tests. For all positions of endurance strength tests, a continuous increase in normalized EMG activation was observed (P < .001). Muscle activation of the rectus abdominis and external oblique in prone plank position exceeded the maximal voluntary isometric contraction activation, with a significantly higher activation in females (P = .02). We conclude, that in the applied strength-endurance testing, the activation of trunk muscles was high, especially in females. As high trunk muscle activation can infer fatigue, limb strength can limit performance in prone and side plank position, particularly during high trunk muscle activation.

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Bark, H., M. Nizri, A. Tarasuik, and D. Heimer. "Effects of hyperphosphatemia on diaphragmatic strength and endurance." Journal of Applied Physiology 73, no. 1 (July 1, 1992): 82–87. http://dx.doi.org/10.1152/jappl.1992.73.1.82.

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Effects of an infusion of Na2HPO4 on diaphragm strength, endurance, and magnitude of recovery were evaluated in in situ canine diaphragm strips. Results showed no effect on maximal isometric tetanic tension. Twitch tension and tension in the low- (10-Hz) frequency range were significantly increased (P less than 0.01). Time to fatigue (endurance) increased by 38 +/- 4.5% in the group that received phosphorus compared with its control and decreased by 18.5 +/- 2.5% in the group that received dextrose compared with its control (P less than 0.005). Recovery from fatigue was also significantly improved after the phosphorus infusion. Serum ATP and 2,3-diphosphoglycerate levels were unchanged throughout the experiment. The results of this study support the notion that hyperphosphatemia improves diaphragmatic endurance and recovery from fatigue. The mechanisms involved may in part be due to the phosphate-buffering effects, which limit the extent of the muscle intracellular acidosis produced with fatigue.

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Abdurrahman, Wahid, and Muhamad Fitri. "The Fatigue Strength Analysis of ABS (Acrylonitrile Butadiene Styrene) Material Shaft Result of 3D Printing Process due to Rotating Bending Load." Materials Science Forum 1051 (January 25, 2022): 137–44. http://dx.doi.org/10.4028/www.scientific.net/msf.1051.137.

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Prototyping a product using 3D (three-dimensional) printing process has been widely used. One of the materials commonly used is ABS (Acrylonitrile Butadiene Styrene). Currently, research did not refer to ASTM E-466 and tested specimens at 75% infill density without endurance limit analysis. The purpose of this research was to analyse the fatigue strength of 3D printed ABS material with infill density 100% due to rotating bending load according to ASTM E-466 standard, compare it with the 75% infill density test result and determine the value of its endurance limit. The research method used is experimental research by testing the fatigue strength of a number of ABS material specimens with four rotating bending load conditions until the specimen fails. The obtained result of the research is a S-N curve with maximum average cycle of 143702 at a stress of 26.87 MPa and minimum average cycle of 145 at a stress of 35.71 MPa. The shaft fatigue strength of ABS 3D printed with infill density 100% material has higher cycles at stresses below 37.1 MPa and lower cycles at stresses above 37.1 MPa compared to 75% infill density. The endurance limit obtained from the regression of the S-N curve is 16.25 MPa.

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Savel’ev, A. N., E. A. Savel’eva, D. O. Anisimov, and O. D. Prokhorenko. "APPLICATION OF STRESS WAVES EMISSION FOR DETERMINATION OF FATIGUE CHARACTERISTICS OF MATERIAL." Izvestiya. Ferrous Metallurgy 62, no. 2 (March 30, 2019): 141–47. http://dx.doi.org/10.17073/0368-0797-2019-2-141-147.

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Results of experimental evaluation of the fatigue characteristics of tested samples material are considered based on emission of stress waves. Using previously published data on synergistically organized acoustic emission, an experiment was prepared and performed. In experiments on different materials, possibility of using acoustic emission signal for operative determination of mechanical characteristics and, above all, the limit of endurance were demonstrated. Samples for strength testing of materials were made of five steel grades and one grade of Br AZh9-4 bronze. Five experiments were conducted on each of the materials. The samples in the experiment underwent a fine-step loading, at each step of it radiation of signal occurred simultaneously, and another series of dislocations was prepared, that could reach surface of crystal and emit a stress wave at the next moment of loading. Thus, the joint radiation of energy dislocations prepared for movement was already formed. A comparison of experimental data, obtained on the basis of acoustic emission, with calculated values of endurance limit, obtained by empirical formulas through the ultimate strength of this material, performed by the Fisher criterion, has shown their adequacy at a significance level of 5 %. Evaluation of the experimental results of endurance limit determination on basis of acoustic emission by the Cochran test indicates that variances of measurement results in experiment are uniform for all types of used materials. The results have shown that such method on the basis of synergistically organized acoustic emission allows us to quickly obtain experimental values of endurance limit of material with sufficiently high degree of accuracy.

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de Leon, Michael B., Arman Ray Nisay, and Hyung-Seop Shin. "Evaluation of electrical fatigue limits in REBCO coated conductor tapes through static fatigue testing at 77 K." Superconductor Science and Technology 35, no. 2 (December 22, 2021): 025009. http://dx.doi.org/10.1088/1361-6668/ac32ac.

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Abstract Significant development has been made toward guaranteeing the performance of high-temperature superconducting (RE)Ba2Cu3O7−x coated conductor (CC) tapes in superconducting devices such as high-field magnets and coils. To understand the superconducting behaviors of CC tapes used in such devices under various mechanical- and thermal-induced loads, their mechanical and electromechanical properties should be evaluated in consideration of their application environments. Under static or cyclic fatigue loads, critical current (I c) can degrade as a result of damage to the superconducting layer, even under loads that do not exceed the irreversible stress limits for I c degradation (σ irr). Therefore, prediction of the stress level that can degrade I c under various conditions, such as the endurance limit (stress), is significant for actual coil or magnet applications of CC tapes. A static fatigue tester for CC tapes at 77 K was used in this study to apply a static fatigue load to a 12 mm wide GdBa2Cu3O7−x CC tape specimen under simultaneous axial tension and bending stresses in a U-shaped configuration. Bending mandrels were used to superimpose various bending strains onto the applied static axial tensile strain, and I c across various voltage tap separations was measured over time, up to 100 h. The electrical static fatigue strength and endurance limit for I c degradation were determined based on the 95% I c retention criterion and 100 h of elapsed time, respectively. Results show that bending strain, dependent on mandrel diameter, can greatly influence I c degradation behaviors and that I c can drop considerably in the bent sections compared to the straight sections over time. Analyses of the combined strains in the bent sections allowed the prediction of diameter-dependent electrical static endurance limits under subcritical crack growth. The CC tape’s electrical static endurance limit was greatly affected at smaller bending diameters. When CC coils with diameters smaller than or equal to 50 mm are made using 12 mm wide CC tapes, the electrical static endurance limit is low, roughly ⩽0.63σ irr.

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Basgil, Mehmet Can, Cem Kurtoglu, Koray Soygun, Yunus Uslan, and Teyfik Demi̇r. "Dynamic and static load performance of dental biomaterial systems with conical implant-abutment connections." Bio-Medical Materials and Engineering 31, no. 5 (November 13, 2020): 319–28. http://dx.doi.org/10.3233/bme-206008.

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BACKGROUND: The stability of the implant-abutment interface is an important factor that influences load distribution on the marginal bone. OBJECTIVE: In this study, three dental implants with the same connection were subjected to different dynamic loading cycles. The fracture strengths and the horizontal compatibility of implants were assessed. METHODS: Eighty four implant specimens were embedded in a polyacetal cylinder as simulated bone loss of 3 mm from the implant platform. Three of the implants were used to determine the endurance limit. The other specimens were subdivided into four subgroups (n = 6): three for dynamic + static loading, and one for static loading (control group). The tests were performed by applying a compression load. The dynamic loading experiments included three different cycles with endurance upper limit loads at a frequency of 10 Hz. RESULTS: The differences between the fracture strength values of the implant brands were found to be statistically significant. However, there were no meaningful differences between the fracture strength values of implants of the same brand. The specimens of the DTI implant system had the lowest strength (647.9 ± 41.5 N) and the SEM analysis indicated that the Implantium implant system had the shortest horizontal gaps. CONCLUSIONS: There was a negative correlation between the fracture strengths and size of the microgaps. The importance of these in vitro results needs to be validated by clinical trials because the loads in the mouth can be applied from various angles.

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Yushin, E. S. "SUBSTANTIATION OF THE SPECIFIC CRITERION FOR THE CORROSIVE EFFECT OF FORMATION MEDIA ON THE CYCLIC STRENGTH OF STEEL OF DOWNHOLE EQUIPMENT." Энергия: экономика, техника, экология, no. 3 (2020): 60–64. http://dx.doi.org/10.7868/s2587739920030088.

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The article provides the substantiation of the specific coefficient of corrosion influence, considered per unit of the limit of short-term strength of the metal, with the help of which it is possible to simplify the most approximate calculation of the limited endurance limit of steels of oil and gas equipment operating under cyclic loads, as well as perform subsequent resource calculations.

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Liu, Hsuan-Chih, Yu-Hui Zeng, and Chun-Li Lin. "Mechanical Comparison of a Novel Hybrid and Commercial Dorsal Double Plating for Distal Radius Fracture: In Vitro Fatigue Four-Point Bending and Biomechanical Testing." Materials 14, no. 20 (October 18, 2021): 6189. http://dx.doi.org/10.3390/ma14206189.

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This study compares the absolute and relative stabilities of a novel hybrid dorsal double plating (HDDP) to the often-used dorsal double plating (DDP) under distal radius fracture. The “Y” shape profile with 1.6 mm HDDP thickness was obtained by combining weighted topology optimization and finite element (FE) analysis and fabricated using Ti6Al4V alloy to perform the experimental tests. Static and fatigue four-point bending testing for HDDP and straight L-plate DDP was carried out to obtain the corresponding proof load, strength, and stiffness and the endurance limit (passed at 1 × 106 load cycles) based on the ASTM F382 testing protocol. Biomechanical fatigue tests were performed for HDDP and commercial DDP systems fixed on the composite Sawbone under physiological loads with axial loading, bending, and torsion to understand the relative stability in a standardized AO OTA 2R3A3.1 fracture model. The static four-point bending results showed that the corresponding average proof load values for HDDP and DDPs were 109.22 N and 47.36 N, that the bending strengths were 1911.29 N/mm and 1183.93 N/mm, and that the bending stiffnesses were 42.85 N/mm and 4.85 N/mm, respectively. The proof load, bending strength and bending stiffness of the HDDPs were all significantly higher than those of DDPs. The HDDP failure patterns were found around the fourth locking screw hole from the proximal site, while slight plate bending deformations without breaks were found for DDP. The endurance limit was 76.50 N (equal to torque 1338.75 N/mm) for HDDP and 37.89 N (equal to torque 947.20 N/mm) for DDP. The biomechanical fatigue test indicated that displacements under axial load, bending, and torsion showed no significant differences between the HDDP and DDP groups. This study concluded that the mechanical strength and endurance limit of the HDDP was superior to a commercial DDP straight plate in the four-point bending test. The stabilities on the artificial radius fractured system were equivalent for novel HDDP and commercial DDP under physiological loads in biomechanical fatigue tests.

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Stalnichenko, O. I. "Investigation of the cyclic strength of deposited parts, hardened by ultrasonic shock processing." Transport development, no. 1(2) (June 27, 2018): 158–62. http://dx.doi.org/10.33082/td.2018.1-2.15.

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The possibilities of application of ultrasonic shock treatment for hardening of parts restored by surfacing are investigated. The results of a study of cyclic durability on samples of steel 35 Ø 27 and 70 mm. Strengthening is given by UUO, which makes it possible to increase the endurance limit to the level of the parent metal.

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Gui, Long Ming, Xiao Chun Jin, Hong Tao Li, and Mei Zhang. "High Cycle Fatigue Performances of Advanced High Strength Steel CP800." Advanced Materials Research 989-994 (July 2014): 238–41. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.238.

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A low carbon content and improved steel making practices have imparted advanced high strength steel (AHSS) CP800 with superior combination of strength, ductility and weldability. Its performance in fatigue, however, is not well understood. Stress-controlled high cycle fatigue (HCF) tests were conducted to obtain stress vs. fatigue life curve (S-N curve), and the fatigue limit of CP800. The follow HCF performances were obtained. , SRI1=1940MPa, b=-0.09972, Nc1=2.89×106, and R2= 0.88. The collected material data are used as a basis of comparison of CP800 with more common grades of structural steel. CP800 steel shows high strength, comparable ductility, and high fatigue limit level. The test results indicate that compare to that of lower strength common grades of structural steels, CP800 steel has a much higher fatigue endurance limit (say, 476MPa), about 0.6 of its tensile strength (TS). Thus, provides a distinct advantage.

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Molokov, K. A., V. V. Novikov, G. P. Turmov, and Ya R. Domashevskaya. "Calculated Model of Endurance Limit Estimation Based on Structural-Strain Analysis of the Critical Condition of Ferrite-Perlite Steels with Macrocracks in Ship Structures." Key Engineering Materials 887 (May 2021): 627–33. http://dx.doi.org/10.4028/www.scientific.net/kem.887.627.

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In this study, a structural-deformation analysis of the process of crack development is performed, on the basis of which an engineering methodology is developed for assessing the endurance limit and resource of large-sized structures. A simple analytical dependence (correlation аналитическая зависимость) was obtained, which allows one to determine the critical size of macrocracks for ferritic-pearlitic steels without using the well-known Griffith formula. The results of calculating the cracks critical lengths of various steels depending on their yield strength are presented. The analytical dependence of the calculation of the fatigue limit for the most dangerous symmetric loading cycle according to the standard set of mechanical characteristics of ferrite-pearlite steel is presented. The obtained results make it possible to calculate the endurance limit of structural elements of marine equipment and other structures subject to cyclic loads

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Aşik, Emin Erkan, Gül Ipek Nakaş, and Şakir Bor. "The Processing and Fatigue Characterization of TiNi and Ti-6Al-4V Porous Materials." Key Engineering Materials 493-494 (October 2011): 930–35. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.930.

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Porous titanium alloys have been extensively studied in biomedical applications due to their elastic moduli similar to that of bone compared to other implant materials. Accordingly, TiNi and Ti-6Al-4V foams have been widely characterized in terms of their various mechanical properties; however, their fatigue properties have not been well studied, even though, it has a vital importance in structural applications such as medical implants. In this study, porous titanium alloys were processed via sintering at 1200 °C for 2 hours employing Mg space holder technique. TiNi and Ti-6Al-4V alloys with a porosity of 49 and 51 vol.%, respectively, were mechanically characterized by monotonic and cyclic compression tests. The compressive strength was determined to be 148 MPa for TiNi foams whereas 172 MPa for Ti-6Al-4V foams with homogenously distributed pores having diameters in the range of 250-600 µm. Endurance limit values were determined relative to the yield strength of each porous alloy in order to enable the comparison of fatigue behavior. The fatigue tests applied with a frequency of 5 Hz and a constant stress ratio (σmin/σmax) of 0.1 have revealed that porous TiNi alloys have an endurance limit of approximately 0.6 σy whereas porous Ti-6Al-4V alloys have an endurance limit of approximately 0.75 σy. The differences and similarities in the microstructure and their effect on mechanical behavior of the two alloys were also studied by employing scanning electron microscope (SEM).

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Voyzey, George A. "Intervention Strategies for Individuals With Early Alzheimer's Disease and COPD." Perspectives on Gerontology 18, no. 1 (January 2013): 27–33. http://dx.doi.org/10.1044/gero18.1.27.

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An elderly individual's ability to generate a functional cough is compromised by the loss of expiratory muscle strength (sarcopenia) and reduced elastic recoil of the lungs, resulting in reduced expiratory flow rates and velocity and a decreased intrathoracic airway pressure increasing the risk for aspiration and pneumonia. The addition of COPD and Alzheimer's disease to the individual's comorbidities limit a successful respiratory therapy program and the speech-language pathologist's interventions. The following activities promote expiratory muscle strength building and endurance for individuals diagnosed on the Global Deterioration Scale Stage 3 through early Stage 6. The respiratory therapist and attending physician should provide baselines and benchmarks for the speech-language pathologist throughout the individual's treatment. The activities listed here need to be a component of a multidisciplinary intervention that includes upper extremity exercise and walking for strength building and endurance.

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Xie, C., Q. H. Fang, L. X. Li, J. K. Chen, Y. W. Liu, and Y. N. Wang. "The impact of twin lamella thickness distribution on strength and endurance limit in nanotwinned copper." Mechanics of Materials 84 (May 2015): 91–99. http://dx.doi.org/10.1016/j.mechmat.2015.01.017.

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Christiner, Thomas, Johannes Reiser, István Gódor, Wilfried Eichlseder, Franz Trieb, and René Stühlinger. "The fatigue endurance limit of a high strength CrNi steel in a fretting dominated regime." Tribology International 59 (March 2013): 97–103. http://dx.doi.org/10.1016/j.triboint.2012.01.014.

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Langhorne, Patricia J., Vernon A. Squire, Colin Fox, and Timothy G. Haskell. "Break-up of sea ice by ocean waves." Annals of Glaciology 27 (1998): 438–42. http://dx.doi.org/10.3189/s0260305500017869.

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The manner in which sea ice breaks up determines its floe-size distribution. This, together with any redistribution due to ocean currents or winds, alters the fluxes between the atmosphere and the underlying ocean. Many materials fail at stresses well below their flexural strength when subject to repeated bending, such processes being termed fatigue. in some materials a stress exists below which the material will maintain its integrity even if subjected to an infinite number of load cycles. This stress is termed the endurance limit. We report a scries of field experiments to investigate the fatigue behaviour of first-year sea ice that subjected in situ cantilever beams to repeated bending with zero mean stress. These tests suggest that an endurance limit exists for sea ice, and that it is approximately 60% of the flexural strength. Using theory and data from wave experiments performed in similar conditions to the fatigue experiments, estimates are made of the conditions under which wave-induced break-up occurs. These indicate that fatigue may be a neglected ingredient of sea-ice failure due to wave-induced motion.

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Zhou, Shichao, Tao Zhang, Lugee Li, Jiedan Yang, Min Zhang, Chengyong Wang, and Yong Zhang. "Fatigue Behavior of Zr58Cu15.46Ni12.74Al10.34Nb2.76Y0.5 Bulk Metallic Glass Fabricated by Industrial-Grade Zirconium Raw Material." Metals 11, no. 2 (January 21, 2021): 187. http://dx.doi.org/10.3390/met11020187.

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In this work, the fatigue behavior of a low-cost Zr58Cu15.46Ni12.74Al10.34Nb2.76Y0.5 (at%) bulk metallic glass (BMG) fabricated by industrial-grade Zirconium raw material was investigated under three-point bending loading mode. X-ray, fatigue tests under different stress amplitude and fatigue fractography were conducted in order to characterize the amorphous structure, fatigue stress-life (S-N) curve and fracture mechanism, respectively. It is found that the X-ray diffraction (XRD) result showed a fully amorphous structure due to high glass-forming ability, cracks initiated from inclusions near the rectangular corners at tensile surfaces and the fatigue endurance limit (~168 MPa) and fatigue ratio (~0.13) termed as fatigue endurance limit divided by ultimate tensile strength in stress amplitude were comparable to the similar BMG prepared by high pure raw materials.

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Gorash, Yevgen, and Donald MacKenzie. "On cyclic yield strength in definition of limits for characterisation of fatigue and creep behaviour." Open Engineering 7, no. 1 (June 23, 2017): 126–40. http://dx.doi.org/10.1515/eng-2017-0019.

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AbstractThis study proposes cyclic yield strength as a potential characteristic of safe design for structures operating under fatigue and creep conditions. Cyclic yield strength is defined on a cyclic stress-strain curve, while monotonic yield strength is defined on a monotonic curve. Both values of strengths are identified using a two-step procedure of the experimental stress-strain curves fitting with application of Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit. Comparison of cyclic strength and fatigue limit reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the cyclic yielding. A typical long-term strength curve in time-to-failure approach for creep analysis has two inflections corresponding to the cyclic and monotonic strengths. These inflections separate three domains on the long-term strength curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Therefore, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the cyclic yielding. These assumptions are confirmed using three structural steels for normal and high-temperature applications. The advantage of using cyclic yield strength for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic stress-strain curve identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the cyclic yield strength.

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Shigaki, Leonardo, Cynthia Gobbi Alves Araújo, Mariane Guizeline Calderon, Thais Karoline Cezar Costa, Andreo Fernando Aguiar, Leonardo Oliveira Pena Costa, and Rubens A. da Silva. "Effects of Volume Training on Strength and Endurance of Back Muscles: A Randomized Controlled Trial." Journal of Sport Rehabilitation 27, no. 4 (July 1, 2018): 340–47. http://dx.doi.org/10.1123/jsr.2016-0253.

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Context: Strength/resistance training volume has historically been supported in the American College of Sports Medicine recommendations. However, for the back muscles, exercise prescription related to the number of sets, such as single versus multiple, is not well established in the literature. Objective: The purpose of this study was to compare the effects of 2 training volumes on strength and endurance of back-extensor muscles in untrained young participants with regard to a repeated-measures design. Design: Randomized controlled trial. Setting: Laboratory of functional evaluation and human motor performance. Participants: Forty-four untrained young participants (mean age = 21 y) were randomized into single-set (n = 14), multiple-set (MSG, n = 15), and untrained control (n = 15) groups. Intervention: The single-set group and MSG underwent a 10-week progressive resistance training program (2 d/wk) using a 45° Roman chair. Main Outcome Measures: Back maximal strength (dynamometer) and isometric and dynamic endurance (time limit, trunk extension–flexion cycles, and electromyography muscle fatigue estimates). Results: The results showed differences between the MSG and control group for isometric endurance time (mean = 19.8 s; 95% confidence interval, −44.1 to 4.8), but without time intervention significance. Significant improvement after training (P < .05) was found predominantly during dynamic endurance (number of repetitions) for both the MSG (+61%) and single-set group (+26%) compared with preintervention, whereas the control group reported no benefit. There was no significant (P > .05) difference in either strength or electromyography estimates after training. Conclusions: Both multiple and single volume training were efficient in promoting better back endurance during dynamic performance based on mechanical variables (time and number of repetitions).

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Tagirov, Damir, Vladislav Kulitskiy, Nikolay Belov, and Rustam Kaibyshev. "Effect of Liquid Hot Isostatic Pressing on Structure and Mechanical Properties of an Aluminum Alloy." Materials Science Forum 794-796 (June 2014): 845–50. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.845.

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The effect of liquid hot isostatic pressing (LHIP) on microstructure and mechanical properties of a high-strength cast Al-6Zn-2Mg-0.5Fe-0.7Ni alloy was examined. LHIP eliminates shrinkage porosity that highly improves strength and fatigue limit. Yield stress (YS) and ultimate tensile strength (UTS) in T6 condition increased from 135 to 470 MPa and from 410 to 510 MPa, respectively. Endurance limit on the base of 107 cycles increased from 95 to 140 MPa. However, a small number of gas pores with an average size less than 2 μm retains. LHIP suppresses the crack initiation on coarse cavities. However, brittle intergranular fracture occurs in the hipped alloy through the breaking of eutectic phase Al9FeNi. As a result, elongation-to-failure was of 1.2% and the fatigue strength is equal to one of AA356.02 alloy subjected to LHIP.

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Wang, Shyh-Jen, and Marvin W. Dixon. "A New Criterion for Positive Mean Stress Fatigue Design." Journal of Mechanical Design 119, no. 1 (March 1, 1997): 135–37. http://dx.doi.org/10.1115/1.2828776.

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The modified Findley line is proposed by using ultimate strength and endurance limit as parameters to obtain a good initial approximation of an acceptable design. Comparing with experimental data, the modified Findley line could be a strong candidate for fatigue design criterion for parts made of a nonferrous materials, and be conservative for ferrous material parts.

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Kasyanov, Valeriy, Evgeny Kosenko, Vera Kosenko, and Vasily Krymsky. "Method for processing experimental strength data using statistical methods." E3S Web of Conferences 157 (2020): 02019. http://dx.doi.org/10.1051/e3sconf/202015702019.

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The selective calculation method has been successfully applied for several centuries due to its profitability. However, when calculating the failure-freeness in the case of fatigue fractures (often sudden), when there is a significant power relationship m = 10-15 for the super-cycle loading region between the strength (hardness, endurance limit) and the effective voltage, the reduction of the minimum component life will be 10-100 or more times. This is due to the unaccounted main part of the population. In our example, there are 104 50 = 9950 units of such parts, i.e., their potential failures. Therefore, for this case, the selective method is an intermediate stage of calculations.

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Molokov, K. A., V. V. Novikov, and A. P. German. "Analytical model for assessing fatigue limit of welded joints of ferritic-pearlitic steels." Advanced Engineering Research 20, no. 3 (October 5, 2020): 225–34. http://dx.doi.org/10.23947/2687-1653-2020-20-3-225-234.

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Introduction. Microdefects and zones with stress concentration in welded joints cause fatigue macrocracks. Such damage is potentially dangerous, especially if the fatigue life of the structure is almost exhausted. In this case, the crack size is close to the critical value, and it is crucial to determine its length. The paper considers the development of an engineering analytical model for assessing the critical crack length and endurance limit of welded joints with the formed grain in the structure of ferrite-pearlitic steels after welding. Materials and Methods. The theory and methods of fracture mechanics at the mesoscale are used. A simple analytical dependence is obtained, which provides determining the critical dimensions of a macrocrack for ferrite-pearlite steels without using the Griffiths formula. . The calculation results of the critical crack lengths of various steels depending on their yield strength are presented. An analytical dependence of the endurance limit calculation for the most dangerous symmetric loading cycle, according to the standard set of mechanical characteristics and the average grain diameter of ferrite-pearlite steel, is presented. Results. Structural deformation analysis of the crack propagation process has been performed. On its basis, an engineering technique for assessing the endurance limit is developed. A mathematical model that enables to calculate the endurance limit and the critical crack length in the components of welded assemblies of large-sized facilities, considering periodic loads of a symmetrical cycle, is developed. Using this model, it is possible to estimate the degree of metal sensitivity to the original characteristics (yield stress, Poisson's ratio, grain diameter, relative constriction, Young's modulus, power-law hardening coefficient, etc.).Discussion and Conclusion. Under stresses corresponding to the steel endurance limit, the critical crack opening rates of the tip and edges approach each other. Energetically, this moment approximately corresponds to the transition of the crack to an unstable state. The accumulation of one-sided plastic deformations causes the limiting state of plasticity of the region adjacent to the crack tip and its avalanche-like or sharply accelerated motion. This critical area is interrelated with the grain diameter of the material, the characteristic of critical plasticity and the critical opening at the crack tip at the fatigue limit. The proposed analytical dependences can be used to assess the residual life and the fatigue limit of welded structures, the influence of various factors on the fatigue limit of welded joints of ferrite-pearlitic steels used in mechanical engineering, shipbuilding, pipeline transport, etc

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Fintová, Stanislava, Libor Pantělejev, and Ludvík Kunz. "Microstructure and Mechanical Properties of Ultrafine-Grained Magnesium AZ91 Alloy." Materials Science Forum 782 (April 2014): 384–89. http://dx.doi.org/10.4028/www.scientific.net/msf.782.384.

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Microstructure, mechanical properties, cyclic plastic deformation behavior and fatigue strength of ultrafine-grained (UFG) magnesium alloy AZ91 processed by equal channel angular pressing (ECAP) were investigated. ECAP of originally cast alloy results in development of bimodal structure, improved yield stress, tensile strength and ductility when compared to the as-cast state. Endurance limit based on 107cycles is also improved, however exhibits large scatter. Initiation of fatigue cracks takes place in regions of large grains in the bimodal structure, where the content of Mg17Al12particles is low.

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TACHIBANA, Shunichi, Shunichi KAWACHI, Kunihiro YAMADA, and Takeshi KUNIO. "Effect of grain refinement on the endurance limit of plain carbon steels at various strength levels." Transactions of the Japan Society of Mechanical Engineers Series A 54, no. 507 (1988): 1956–61. http://dx.doi.org/10.1299/kikaia.54.1956.

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Desgorces, François-Denis, Xavier Sénégas, Judith Garcia, Leslie Decker, and Philippe Noirez. "Methods to quantify intermittent exercises." Applied Physiology, Nutrition, and Metabolism 32, no. 4 (August 2007): 762–69. http://dx.doi.org/10.1139/h07-037.

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The purpose of this study was to quantify intermittent training sessions using different types of exercise. Strength, sprint, and endurance sessions were performed until exhaustion. These sessions were quantified by the product of duration and heart rate (HR) (i.e., training impulse (TRIMP) and HR-zone methods), by the product of duration and rate of perceived exertion (RPE-based method), and a new method (work endurance recovery (WER)). The WER method aims to determine the level of exercise-induced physiological stress using the ratio of cumulated work – endurance limit, which is associated with the naparian logarithm of the ratio of work–recovery. Each session's effects were assessed using blood lactate, delayed onset muscle soreness (DOMS), RPE, and HR. Because sessions were performed until exhaustion, it was assumed that each session would have a similar training load (TL) and there would be low interindividual variability. Each method was used to compare each of the TL quantifications. The endurance session induced the higher HR response (p < 0.001), the sprint session the higher blood lactate increase (p < 0.001), and the strength session the higher DOMS when compared with sprint (p = 0.007). TLs were similar after WER calculations, whereas the HR- and RPE-based methods showed differences between endurance and sprint (p < 0.001), and between endurance and strength TL (p < 0.001 and p < 0.01, respectively). The TLs from WER were correlated to those of the HR-based methods of endurance exercise, for which HR was known to accurately reflect the exercise-induced physiological stress (r = 0.63 and r = 0.64, p < 0.05). In addition, the TL from WER presented low interindividual variability, yet a marked variability was observed in the TLs of HR- and RPE-based methods. As opposed to the latter two methods, WER can quantify varied intermittent exercises and makes it possible to compare the athletes’ TL. Furthermore, WER can also assist in comparing athlete responses to training programs.

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Danninger, Herbert, Christian Sohar, Christian Gierl Mayer, Agnieszka Betzwar-Kotas, and Brigitte Weiss. "Gigacycle Fatigue Response of PM versus Ingot Metallurgy Tool Steels." Materials Science Forum 672 (January 2011): 23–30. http://dx.doi.org/10.4028/www.scientific.net/msf.672.23.

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In this work, the gigacycle fatigue response of several tool steel grades has been studied using an ultrasonic resonance testing device. It showed that both with ingot metallurgy (IM) and powder metallurgy (PM) tool steels, a true fatigue limit does not exist up to 10E10 cycles. PM steels resulted in significantly higher endurance strength levels than IM grades. However, there was virtually no effect of the composition and hardness of the materials, both for PM and IM grades cold work tool steels and high speed steels exhibiting virtually the same S-N curves. In the IM tool steel grades, crack initiation started at large primary carbides or carbide clusters, while in the PM grades, nonmetallic inclusions were the critical sites. In any case it is very important to avoid introducing residual stresses into the specimen surfaces during preparation, which would markedly shift the endurance strength levels.

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Vinogradov, Alexei, Evgeni Vasilev, Vladimir Kopylov, Mikhail Linderov, Alexander Brilevesky, and Dmitry Merson. "High Performance Fine-Grained Biodegradable Mg-Zn-Ca Alloys Processed by Severe Plastic Deformation." Metals 9, no. 2 (February 5, 2019): 186. http://dx.doi.org/10.3390/met9020186.

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The tensile strength, fatigue, and corrosion fatigue performance of the magnesium alloy ZX40 benefit strongly from hybrid deformation processing involving warm equal-channel angular pressing (ECAP) at the first step and room temperature rotary swaging at the second. The general corrosion resistance improved as well, though to a lesser extent. The observed strengthening is associated with a combined effect of substantial microstructure refinement down to the nanoscale, reducing deformation twinning activity, dislocation accumulation, and texture transformation. The ultimate tensile strength and the endurance limit in the ultrafine-grained material reached or exceeded 380 and 120 MPa, respectively, which are remarkable values for this nominally low strength alloy.

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Černý, Ivo, and Jiří Sís. "Evaluation of Fatigue Strength of Different Thickness Laser Welded S355 Steel Sheets Considering Microstructure, Surface Conditions and Residual Stresses." Key Engineering Materials 713 (September 2016): 82–85. http://dx.doi.org/10.4028/www.scientific.net/kem.713.82.

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The paper contains results of experimental programme aimed at evaluation of fatigue resistance of laser welded 6 mm and 10 mm thick sheets of a low alloy structural S355 steel. High cycle fatigue tests were performed to verify fatigue strength of the sheets containing laser welds performed with optimised laser welding parameters. Surface of the sheets was in as-received conditions simulating real welding applications. The results are compared to each other and to fatigue S-N curve of the S355 material evaluated on quite small standard specimens. Endurance limit of the 10 mm thick laser welded sheet was by more than by 30% higher than that of the 6 mm thick sheet. In connection with this effect, all fatigue cracks in the 6 mm thick sheets initiated in the weld area unlike the 10 mm sheet, where cracks initiated both in the weld area and outside it indicating no or just minor unfavourable effect of the welding. However, fatigue strength and endurance limit of small material specimens were considerably higher even in comparison with the 10 mm welded sheets. The results are discussed considering, results of microstructure analyses, different values and distribution of residual stresses and also differences between surface conditions of the sheets and the standard specimens.

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Ismail, Mohammad, Bala Muhammad, Abdirahman Ali Yussuf, Zaiton Majid, and Mohamed ElGelany Ismail. "Mechanical capabilities and fire endurance of natural rubber latex modified concrete." Canadian Journal of Civil Engineering 38, no. 6 (June 2011): 661–68. http://dx.doi.org/10.1139/l11-035.

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Compressive, indirect tensile, and flexural strengths characteristics of natural rubber latex modified concrete (NRLMC) were studied and reported — Part I. In addition, a comparative investigation between normal concrete (NC) and NRLMC, conducted on fire endurance was also presented — Part II. Normal and modified elements containing latex–water ratios within 0–10% were prepared and cured in accordance with the Japan Industrial Standard. Fire endurance capacity was assessed at five temperature levels; ambient temperature (27 °C), 150, 300, 500, and 800 °C. However, elevated heating (800–1300 °C) was further applied for the purpose of monitoring behavior at the verge of disintegration. Specimens were allowed to cool in the oven prior to compressive strength tests until room temperature is attained. Test results indicate that significant mechanical capabilities could be achieved by the inclusion of an appropriate quantity of latex concentrate and proper selection of befitting curing regime. Interestingly, the superiority of NRLMC over NC is maintained even under fire, up to the critical limit of latex-film capability performance.

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Wang, Boyu, and Rishi Gupta. "Performance of Repaired Concrete under Cyclic Flexural Loading." Materials 14, no. 6 (March 11, 2021): 1363. http://dx.doi.org/10.3390/ma14061363.

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There is limited research reported on the effect of cyclic loading on cement-based repair materials as conducting such tests is time consuming. To overcome this issue, this study utilized a novel loading regime consisting of cycle groups with increasing stress amplitude to accelerate the test process. The Palmgren-Minder rule was used to estimate the fatigue life of repaired specimens. Specimens repaired with Mix M (cementitious repair mortar), which was estimated to have the highest 2-million-cycle fatigue endurance limit (77.4%), showed the longest fatigue life (95,991 cycles) during the cyclic loading test, the highest slant, and splitting bond strength among all repair mixes. The estimated two-million cycle fatigue endurance limit of Mix S (70.8%) was very similar to that was reported in literature (71%) using the traditional loading method. This study confirms the usefulness of Palmgren-Minder rule on estimating the fatigue life of repaired specimens. Additionally, the use of the novel loading regime showed the benefit of shortening the test process while producing results similar to those from using traditional loading methods. To improve the prediction accuracy, future research is required to modify the failure criteria to accommodate specimens that may not fail even when the average flexural strength is met.

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Zhemchuzhnikova, Daria, and Rustam Kaibyshev. "Effect of Rolling on Mechanical Properties and Fatigue Behavior of an Al-Mg-Sc-Zr Alloy." Materials Science Forum 794-796 (June 2014): 331–36. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.331.

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An aluminum alloy with a chemical composition of Al–6%Mg–0.35%Mn–0.2%Sc–0.08%Zr–0.07%Cr (in wt.) was rolled up to different reductions of 75, 88 and 95% at 360oC and at ambient temperature. The static mechanical properties and the high-cyclic fatigue (HCF) life were examined. It was shown that the hot rolling results in increased yield stress (YS) and ultimate tensile strength (UTS). However, ductility and fatigue limit of the hot rolled alloy and initial as-cast ingot are nearly the same. The combination of hot and cold rolling leads to significant improvement of tensile strength and fatigue resistance, while ductility tends to reduce with increasing the rolling reduction. The cold rolled alloy exhibits the endurance limit under fatigue conditions, while the alloy in the both as-cast and hot rolled conditions exhibits only fatigue strength. The effect of the deformation structure on the mechanical properties is discussed.

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Melian, Natasha Teixeira da Cunha, Joaquim Henrique Lorenzetti Branco, Guilherme Torres, Alexandro Andrade, and Darlan Laurício Matte. "Relationship between handgrip strength, peripheral muscle strength, and respiratory muscle endurance in women with fibromyalgia: a cross-sectional study." Acta Fisiátrica 28, no. 2 (June 30, 2021): 97–104. http://dx.doi.org/10.11606/issn.2317-0190.v28i2a185921.

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Fibromyalgia (FM) is a disease characterized by generalized and chronic musculoskeletal pain. It is common, the presence of other symptoms such as fatigue, depression, sleep disorders, leading patients to adopt a sedentary lifestyle. Objective: Verify the muscular and respiratory strength of women with FM. Method: Is a cross-sectional study that evaluated 41 women with clinical diagnosis of FM. We analyzed handgrip strength (HS), the strength of the lower limbs, and respiratory muscle endurance using the spirometric maneuver. Results: Patients with FM had a significant reduction in HS, both in the dominant and non-dominant upper limb. Furthermore, peripheral muscle strength in the lower limbs was reduced because on average, participants exceeded the normative five-repetition sit-to-stand test times stipulated for the age groups. Approximately two-thirds of the sample had maximal voluntary ventilation values below the lower limit of normality. We detected inverse and moderate correlation between peripheral muscle strength and HS of non-dominant upper limb (r= −0.472; p= 0.002) and inverse and weak correlation with the HS of dominant upper limb (r= −0.374; p= 0.016); weak correlations between respiratory muscle endurance and HS of dominant upper limb (r= 0.299; p= 0.058), HS of non-dominant upper limb (r= −0.317; p= 0.043), and peripheral muscle strength (r= −0.372, p= 0.017); and strong correlation between HS of dominant upper limb and non-dominant upper limb (r= 0.899; p<0.001). Conclusion: Women with FM present with reduced muscle strength in the upper and lower limbs, as well as lower respiratory muscle resistance.

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Čamagić, Ivica, Nemanja Vasić, Predrag Živković, Aleksandar Radović, Tamara Sedmak, Meri Burzić, and Zijah Burzić. "Compatibility of Endurance Limit and Fatigue Crack Growth Parameters in Evaluation of Low Alloyed Steel Welded Joint Behaviour." Advanced Materials Research 1111 (July 2015): 121–26. http://dx.doi.org/10.4028/www.scientific.net/amr.1111.121.

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Analysis of fracture toughness of high-strength low alloyed steel, Nionikral-70, welded joint constituencies, subjected to variable load is given in this paper, using two parameters. Crack initiation resistance is determined by testing of endurance limit and by designing of Wöhler curves. Crack propagation resistance is determined by testing of crack growth rate, and accordingly determination of Paris equation parameters. Analysis of fracture toughness is given based on testing results, comparing obtained values for base metal, weld metal and heat affected zone.

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Riekehr, Stefan, Volker Ventzke, Sabine Wagner, Werner Beck, and Nikolai Kashaev. "Comparison of different titanium alloys welded by Yb:YAG fibre laser for thin sheet applications used for T-ducts in bleed air systems." MATEC Web of Conferences 321 (2020): 11027. http://dx.doi.org/10.1051/matecconf/202032111027.

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Research in aerospace applications includes the replacement of well-known materials by newly developed alloys or by new manufacturing methods for the existing materials. In the frame of TiB-Air project funded by the German Federal Ministry for Economic Affairs and Energy (BMWi) the development of a process chain consisting of deep drawing at elevated temperatures, chemical milling, contour machining by laser cutting and laser beam welding to produce pneumatic T-ducts used in bleed air systems is in focus. This production process of sheet metal parts could lower costs in terms of the process itself and the used materials: low alloyed Ti-alloys. Commercially pure titanium alloy (cp-Ti) is commonly used for these structures because of its balanced mechanical properties regarding tensile strength, yield strength, plastic strain and fatigue strength as well as good resistance against corrosion and oxidation. The possibility to substitute cp-Ti by low-alloyed Ti-alloys is examined in this work, by the comparison of two different low alloyed Ti-alloys, namely KS1.2ASN and Ti XT, with a cp-Ti alloy (Grade 4). Mechanical properties of the base materials, their weldability and the mechanical assessment of the laser beam welded butt joints in terms of static, cyclic and fracture mechanical behaviour is compared for sheet materials, with a thickness of 0.9 mm. Defect-free welding according to EN13919 acceptance criteria B was possible for all three alloys, no porosity problems occurred. The low strength alloy KS1.2ASN exhibited mechanical anisotropy between longitudinal direction and transverse direction in the tensile test, welded specimens of this alloy broke in the base material. Due to the tensile properties, both weld and base material of KS1.2ASN showed the least values for the fatigue strength and endurance limit strength. Ti XT and Grade 4 showed similar mechanical anisotropy and fractured in the base material, too. Fatigue strength of Ti XT is below Grade 4, but for the 50%-percentile the endurance limit strength is equal. Fracture mechanical testing showed that KS1.2ASN is a very promising alloy in the welded condition.

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Protas, Elizabeth J., and Sandrine Tissier. "Strength and Speed Training for Elders with Mobility Disability." Journal of Aging and Physical Activity 17, no. 3 (July 2009): 257–71. http://dx.doi.org/10.1123/japa.17.3.257.

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The purpose of this study was to pilot test a function-focused exercise intervention consisting of strength and gait-speed training in elders with reduced walking speed, decreased walking endurance, and functional impairment. Twelve participants, 77.2 years old (± 7.34), whose usual gait speed was <0.85 m/s, with walking endurance of <305 m in 5 min, and who were functionally impaired participated in a moderate-intensity exercise intervention. The training occurred 3 times per week, 75 min per session, for 3 months and combined 4 weeks of gait-speed training, walking exercise, and functional strengthening. The participants demonstrated mean usual gait speeds (≥1.0 m/s), endurance (≥350 m), and functional ability (≥10 score on performance battery) that were within normal limits after 12 weeks of training. Fastest gait speed (≥1.5 m/s) and muscle strength also improved significantly. Improvements were maintained during follow-up testing after 3–6 months. In summary, a 12-week intervention for frail, mobility-disabled participants led to improvements in walking, function, and strength.

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Eyercioglu, O., D. Walton, and T. A. Dean. "Comparative bending fatigue strength of precision forged spur gears." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 211, no. 4 (April 1, 1997): 293–99. http://dx.doi.org/10.1243/0954406971522051.

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To determine the bending fatigue strength of precision forged spur gears and to compare the results with those obtained from conventional cut gears, single tooth bending fatigue tests were carried out on both through-hardened and induction-hardened gear teeth. The gears were produced from rolled bar cut blanks, disc forged blanks or precision forged teeth blanks. For this purpose, a special test fixture was designed and built for an Amsler high-frequency vibrophore fatigue testing machine. The results show that the endurance limit of precision forged gears is significantly higher than those obtained from cut gears. The bending fatigue strength of forged gears was some 12.5 per cent higher than the cut teeth in a through-hardened condition and 8.4 per cent higher for the induction-hardened teeth. The effect of surface roughness at the tooth root area on the bending fatigue strength of the forged gears is also shown.

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Kim, Ho Kyung. "Evaluation of Fatigue Endurance Foran Ultra Lightweight Inline Skate Frame." Advanced Materials Research 739 (August 2013): 431–36. http://dx.doi.org/10.4028/www.scientific.net/amr.739.431.

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In order to evaluate the fatigue endurance for an ultra lightweight inline skate frame, FEM analyses was performed. The tensile properties and an S-N curve were determined through tensile and fatigue tests on a modified Al-7075+Sc alloy. The yield and ultimate tensile strengths were 553.3 MPa and 705.5 MPa, respectively. The fatigue endurance limit of this alloy was 201.2 MPa. To evaluate the fatigue endurance of the inline skate frame, the S-N data were compared with the stress analysis results through FEM analyses of the frame. The maximum von Mises stress of the frame was determined to be 106 MPa through FEM analysis of the frame, assuming that the skater weight is 75 kg. Conclusively, on the basis of the fatigue limit, the inline skate frame has a safety factor of approximately 2.0.

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Goergen, Fabian, Dieter Mevissen, Stefano Masaggia, Enrico Veneri, Jens Brimmers, and Christian Brecher. "Contact Fatigue Strength of Austempered Ductile Iron (ADI) in Gear Applications." Metals 10, no. 9 (August 25, 2020): 1147. http://dx.doi.org/10.3390/met10091147.

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Austempered Ductile Iron (ADI) is widely implemented to achieve lightweight and optimized components in power transmissions (e.g., internal gear in planetary stages), by substituting steel castings or a combination of Ductile Iron and steel-assembled structures. In this paper, the contact fatigue of two ADI grades (ADI J/S900-8; ADI J/S1200-3) is investigated by disk-on-disk tests. The disk-on-disk contact is an analogy model of the tooth contact and represents the tribological conditions at a specific point on the path of contact. The experimental results cover the endurance limit as well as the short time fatigue behavior for both ADI variants. In addition, the pitting characteristics and microstructural changes are analyzed in order to get a further understanding of the fatigue behavior of ADI.

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Barani, Araz Ardehali, and Dirk Ponge. "Optimized Thermomechanical Treatment for Strong and Ductile Martensitic Steels." Materials Science Forum 539-543 (March 2007): 4526–31. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4526.

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In this study the effect of thermomechanical treatment on the microstructure of austenite and martensite and the mechanical properties of a medium carbon silicon chromium spring steel with different levels of impurities is investigated. Results are presented for conventional heat treatment and for thermomechanical treatment (TMT). Compared to conventionally heat treated samples austenite deformation improves strength and ductility. Thermomechanically treated samples are not prone to embrittlement by phosphorous. TMT influences the shape and distribution of carbides within the matrix and at prior austenite grain boundaries. It is shown that utilization of TMT is beneficial for increasing the ultimate tensile strength to levels above 2200 MPa and at the same time maintaining the ductility obtained at strength levels of 1500 MPa by conventional heat treatment. The endurance limit is increased and embrittlement does not occur.

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Deng, Zong Cai, Hong Liang Deng, Jian Hui Li, and Guo Dong Liu. "Flexural Fatigue Behavior and Performance Characteristics of Polyacrylonitrile Fiber Reinforced Concrete." Key Engineering Materials 302-303 (January 2006): 572–83. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.572.

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This paper presents the results of an experimental investigation to determine the flexural fatigue strength and fatigue life of concrete beams reinforced with monofilament polyacrylonitrile fibers (PAN fiber for short). The performance of fresh concrete and the elastic and mechanical properties of hardened concrete are compared by samples with and without fibers. The toughness calculated according to both ASTM and JCI methods increased with the addition of fibers. The toughness indexes I5 was 3.8-4.2 times，I10 was 5.8—6.8 times that of the plain concrete. The equivalent strength was 0.63-0.87 MPa for PAN fiber reinforced concrete. When compared to plain concrete, the endurance limit of concrete beams only reinforced with PAN fiber is increased by 12 percent.

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Malikoutsakis, Michail, Ioannis Makris, Aggelos Pagonas, and Georgios Savaidis. "Characterization and performance of high strength steel 51CrV4 under cyclic loading." MATEC Web of Conferences 349 (2021): 02008. http://dx.doi.org/10.1051/matecconf/202134902008.

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The high alloyed spring steel 51CrV4 is widely used in engineering applications with high requirements on strength, durability, and safety. The present paper contains experimental results regarding its microstructural characterization and the mechanical behaviour, especially the fatigue life of 51CrV4. Fundamental S-N curves at fully reversed tension-compression and rotating bending have been determined covering the whole area of practical interest, from the Low Cycle Fatigue regime until the engineering endurance limit. These S-N curves can be directly used for the design as well as for the fatigue assessment of engineering components made of this material. The international literature contains very few and isolated data regarding the mechanical behaviour of 51CrV4, while corresponding material properties are totally missing. The material data and properties provided here may be implemented in international cyclic material databases for further exploitation in Industry and Academia.

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Moos, E., and J. Karger-Kocsis. "Effects of Knit Stretching and Matrix Crystallinity on the Fatigue Behaviour of Knitted Fabric-Reinforced Gf/Pet Composites." Advanced Composites Letters 6, no. 3 (May 1997): 096369359700600. http://dx.doi.org/10.1177/096369359700600303.

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In this study the tension-tension fatigue behaviour of weft-knitted glass fibre fabric-reinforced polyethylene terephthalate (GF/PET) composites was studied as a function of the stretching ratio of the knit The knits were stretched prior to consolidation in wale direction in 0, 25, 50 and 73%, respectively, in order to increase the anisotropy and to alter the mechanical properties of the composites. The influence of the matrix morphology (crystalline, amorphous) on the fatigue response was also investigated by using a composite with unstretched knit reinforcement. The results, displayed in normalized maximum fatigue stress Ms number of cycles (S-N) diagrams showed that the fatigue endurance limit of the GF/PET composites did not depend either on the knit stretching or the matrix crystallinity. The fatigue endurance limit, normalized to the static tensile strength, was found at ≍27 and ≍50 % for the knitted fabric-reinforced composite sheets tested in wale (W) and course (C) direction, respectively. The damage zone seemed to be localized for 1 and 2 rows of loops in C-and W-directions, respectively. This failure mode reflects the stress transfer and redistribution capability of the plain weft-knit reinforcement

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Xue, Hong Qian, and Danièle Wagner. "Very High Cycle Fatigue Behavior of Carbon Manganese Steels." Advanced Materials Research 146-147 (October 2010): 1780–83. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1780.

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An ultrasonic fatigue testing system capable of operating at temperatures at 250 has been introduce to study the fatigue behavior of carbon manganese steels (A42 and A48) and loading frequency of approximately 20 kHz. Endurance limit results were comparable to those generated at room temperature to determine the effect of temperature. Scanning electron microscopy was then used to determine the initiation sites and the failure mechanisms. Initial results indicate that fatigue strength decrease a little at 250 , interior inclusions were the major microstructural feature responsible for crack initiation in the alloy.

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Islamgaliev, Rinat K., Marina A. Nikitina, and Aidar F. Kamalov. "Enhanced Thermal Stability and Mechanical Properties of Ultrafine-Grained Aluminum Alloy." Materials Science Forum 667-669 (December 2010): 331–36. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.331.

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The paper reports on microstructure, strength and fatigue of ultrafine-grained (UFG) samples of the Al-Cu-Mg-Si aluminum alloy processed by high pressure torsion (HPT) at various temperatures. Application of the HPT treatment led to strong grain refinement, as well as to a raise of the mean-root square strains and dynamic precipitation. In case of optimal HPT treatment the UFG samples have demonstrated the enhanced thermal stability, an increase in ultimate tensile strength in 2.5 times and enhancement in fatigue endurance limit by 20 % in comparison with coarse-grained alloy subjected to standard treatment. It is shown that the regime of the HPT treatment governs the volume fraction of precipitates and segregations, thereby affecting a grain size and thermal stability of ultrafine-grained structure.

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Journal articles on the topic 'Limit of endurance strength'

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