Journal articles: 'High fatigue cycles'

1

Oshida, Yoshiki, and P. C. Chen. "High and Low-Cycle Fatigue Damage Evaluation of Multilayer Thin Film Structure." Journal of Electronic Packaging 113, no. 1 (March 1, 1991): 58–62. http://dx.doi.org/10.1115/1.2905367.

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A five-layered (Cu/Cr/Kapton® /Cr/Cu) metallic thin film structure was subjected to a completely reversed bending fatigue cycling with a wide ranges of applied strain amplitudes from 0.25 percent to about 30 percent. A new model for determination of the number of cycles to fatigue failure NF was proposed for single-crack and multi-crack formations. Within a strain amplitude ranging from 1 to 10 percent, a Manson-Coffin’s relationship was recognized for both the number of cycles to crack initiation NC and NF with exponents of 0.39 and 0.51, respectively. Selected fatigued test samples were further subjected to X-ray diffraction line analysis for dislocation density (ρ) calculation, which was related to the number of fatigue cycles N and strain amplitude (Δ εT) in an empirical formula. It was also found that dislocation densities accumulated up to both Nc and NF were related to applied strain amplitudes. Consequently, if applied strain amplitude is known and progressive change in dislocation density is measured, one can predict the remaining fatigue life as well as fatigue cycles which were already consumed.

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Heinz, Stefan, and Dietmar Eifler. "Very High Cycle Fatigue and Damage Behavior of Ti6Al4V." Key Engineering Materials 664 (September 2015): 71–80. http://dx.doi.org/10.4028/www.scientific.net/kem.664.71.

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High frequency fatigue tests were carried out with a 20 kHz ultrasonic testing facility to investigate the cyclic deformation behavior of Ti6Al4V in the Very High Cycle Fatigue (VHCF) regime in detail. The S,Nf -curve at the stress ratio R = -1 shows a significant decrease of the stress amplitude and a change from surface to subsurface failures in the VHCF regime for more than 107 cycles. Microscopic investigations of the distribution of the α-and β-phase of Ti6Al4V indicate that inhomogeneities in the phase distribution are reasons for the internal crack initiation. Scanning electron microscopy as well as light microscopy were used to investigate the internal crack initiation phenomenon in the VHCF-regime. Beside the primary fatigue crack additional defects like micro cracks and crack clusters were observed in the fatigued specimens. SEM-investigations of specimens which were loaded up to 1010 cycles without failure show irreversible microstructural changes inside the specimens. Two step tests were performed to evaluate the influence of internal fatigue induced defects observed in specimens which did not fail within 1010 cycles.

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Zhang, Wei Chang, Ming Liang Zhu, and Fu Zhen Xuan. "Experimental Characterization of Competition of Surface and Internal Damage in Very High Cycle Fatigue Regime." Key Engineering Materials 754 (September 2017): 79–82. http://dx.doi.org/10.4028/www.scientific.net/kem.754.79.

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Axially push-pull cyclic tests of a low strength rotor steel were performed up to the very high cycle fatigue regime at ambient environment under ultrasonic frequency. Fatigue tests were interrupted at selected number of cycles for surface morphology observation and roughness measurement with the help of a 3D surface measurement system (Alicona InfiniteFocusSL). The fatigue extrusions and slip band developed on the specimen surface were recorded. The influence of stress level on the number and morphology of slip band was discussed. The surface roughness of fatigue specimens was found to be increased with the increasing of fatigue cycles. The fatigued specimens were finally cracked from surface or interior micro-defects after observation of fracture surface by scanning electron microscopy. The internal damage behavior consists of crack initiation and early propagation from micro-defect, crack growth within the fish eye, and fast crack growth. It is observed that there exists a competition between surface and internal fatigue damage in the very high cycle fatigue regime, i.e., surface damage is gradually developed with the increasing of fatigue cycles, while the critical interior micro-defect can be dominant for fatigue cracking.

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Weibel, Dominic, Frank Balle, and Daniel Backe. "Ultrasonic Fatigue of CFRP - Experimental Principle, Damage Analysis and Very High Cycle Fatigue Properties." Key Engineering Materials 742 (July 2017): 621–28. http://dx.doi.org/10.4028/www.scientific.net/kem.742.621.

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Structural aircraft components are often subjected to more than 108 loading cycles during their service life. Therefore the increasing use of carbon fiber reinforced polymers (CFRP) as primary lightweight structural materials leads to the demand of a precise knowledge of the fatigue behavior and the corresponding failure mechanisms in the very high cycle fatigue (VHCF) range. To realise fatigue investigations for more than 108 loading cycles in an economic reasonable time a novel ultrasonic fatigue testing facility (UTF) for cyclic three-point bending was developed and patented. To avoid critical internal heating due to viscoelastic damping and internal friction, the fatigue testing at 20 kHz is performed in resonance as well as in pulse-pause control resulting in an effective testing frequency of ~1 kHz and the capability of performing 109 loading cycles in less than twelve days. The fatigue behavior of carbon fiber twill 2/2 fabric reinforced polyphenylene sulfide (CF-PPS) and carbon fiber 4-H satin fabric reinforced epoxy resin (CF-EP) was investigated. To study the induced fatigue damage of CF-PPS and CF-EP in the VHCF regime in detail, the fatigue mechanisms and damage development were characterized by light optical and SEM investigations during interruptions of constant amplitude tests (CAT). Lifetime-oriented investigations showed a significant decrease of the bearable stress amplitudes of CF-PPS and CFEP in the range between 106 to 109 loading cycles. The ultrasonically fatigued thermoset matrix composite showed a significantly different VHCF behavior in comparison to the investigated thermoplastic matrix composite: No fiber-matrix debonding or transversal cracks were present on the specimen edges, but a sudden specimen failure along with carbon fiber breakage have been observed. The fatigue shear strength at 109 cycles for CF-PPS could be determined to τa, 13 = 4.2 MPa and to τa, 13 = 15.8 MPa for the thermoset material CF-EP.

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He, Chao, Yong Jie Liu, and Qing Yuan Wang. "Very High Cycle Fatigue Properties of Welded Joints under High Frequency Loading." Advanced Materials Research 647 (January 2013): 817–21. http://dx.doi.org/10.4028/www.scientific.net/amr.647.817.

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Very high cycle fatigue (VHCF) properties of welded joints under ultrasonic fatigue loading have been investigated for titanium alloy (TI-6Al-4V) and bridge steel (Q345). Ultrasonic fatigue tests of base metal and welded joints were carried out in ambient air at room temperature at a stress ratio R=-1. It was observed that the fatigue strength of welded joints reduced by 50-60% as compared to the base metal. The S-N fatigue curves in the range of 107~109 cycles of base metal and welded joints for both materials exhibited the characteristic of continually decreasing type. The fatigue failure still occurred after 107 cycles of loading, and the fatigue limit in traditional does not exist. The fatigue facture mainly located in the weld metal region at low cycle fatigue range, but in the fusion area in HCF and VHCF. Analysis of fracture surfaces analyzed by SEM revealed that the fatigue cracks initiated from welding defects such as pores, cracks and inclusions.

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Shao, Chuang, Claude Bathias, Danièle Wagner, and Hua Tao. "Very High Cycle Fatigue Behavior and Thermographic Analysis of High Strength Steel." Advanced Materials Research 118-120 (June 2010): 948–51. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.948.

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Very high cycle fatigue behavior of high strength steel, were investigated using ultrasonic fatigue testing equipment at 20 kHz up to 109cycles. S-N curves at room temperature with different stress ratio (R=0.01 and R=0.1) was determined. The experimental results show that fatigue strength decrease with increasing number of cycles between 105 and 109. SEM examination of fracture surface reveals that fatigue damage was governed by the formation of cracks, and subsurface crack initiation was in the very long life range. The results shown that the portions of life attributed to subsurface crack initiation between 107 and 109 cycles are 99%.

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Zhou, Cheng En, Gui An Qian, and You Shi Hong. "Fractography and Crack Initiation of Very-High-Cycle Fatigue for a High Carbon Low Alloy Steel." Key Engineering Materials 324-325 (November 2006): 1113–16. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1113.

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Very-High-Cycle Fatigue (VHCF) is the phenomenon of fatigue damage and failure of metallic materials or structures subjected to 108 cycles of fatigue loading and beyond. This paper attempts to investigate the VHCF behavior and mechanism of a high strength low alloy steel (main composition: C-1% and Cr-1.5%; quenched at 1108K and tempered at 453K). The fractography of fatigue failure was observed by optical microscopy and scanning electron microscopy. The observations reveal that, for the number of cycles to fatigue failure between 106 and 4×108 cycles, fatigue cracks almost initiated in the interior of specimen and originated at non-metallic inclusions. An “optical dark area” (ODA) around initiation site is observed when fatigue initiation from interior. ODA size increases with the decrease of fatigue stress, and becomes more roundness. Fracture mechanics analysis gives the stress intensity factor of ODA, which is nearly equivalent to the corresponding fatigue threshold of the test material. The results indicate that the fatigue life of specimens with crack origin at the interior of specimen is longer than that with crack origin at specimen surface. The experimental results and the fatigue mechanism were further analyzed in terms of fracture mechanics and fracture physics, suggesting that the primary propagation of fatigue crack within the fish-eye local region is the main characteristics of VHCF.

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Wei, Kang, and Bo Lin He. "Failure Mechanism of Very High Cycle Fatigue for High Strength Steels." Key Engineering Materials 664 (September 2015): 275–81. http://dx.doi.org/10.4028/www.scientific.net/kem.664.275.

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In recent years, the core engineering components of high-speed train, automobiles and aircrafts are required to endure fatigue loads up from 108 to 1010 cycles. The present study results show that in the very high cycle fatigue (VHCF) regimes of more than 107 cycles, the fatigue failure of high strength steel materials can occur below the traditional fatigue limit, hence the VHCF investigations of high strength steels not only help to further understand the fatigue essence and mechanism, but also do research on the fatigue design and life assessment method. This paper summarizes works of VHCF researches for high strength steels in recent years, such as the characteristics of S-N curve, the observations on fish-eye, which is one of the typical characteristics of fracture surface, crack initiation, crack propagation, etc. The present work also analyzes the fatigue mechanisms and briefly discusses several factors that affect VHCF properties, such as hydrogen effect, inclusion effect, frequency effect. Some possible and prospective aspects of future researches are also proposed.

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Daniel Varecha, Slavomir Hrcek, Otakar Bokuvka, Frantisek Novy, Libor Trsko, Ruzica Nikolic, and Michal Jambor. "Fatigue Safety Coefficients for Ultra – High Region of Load Cycles." Communications - Scientific letters of the University of Zilina 22, no. 4 (October 1, 2020): 97–102. http://dx.doi.org/10.26552/com.c.2020.4.97-102.

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In this paper the authors introduce results from the field of the fatigue safety of selected steels in the region of ultra - high number of loading cycles. The fatigue tests were carried out at high frequency tension - compression loading (f = 20 kHz, T = 20 ± 5°, R = -1) in the region from N = 106 to N = 109 cycles. The fatigue safety coefficients were calculated by four methods (Goodman, Gerber, ASME elliptic and Soderberg). The percentage reduction of the fatigue safety coefficients (N = 109 vs. N = 106 cycles) was at Goodman, 7.99 ÷ 10.83 %, Gerber, 5.27 ÷ 8.26 %, ASME, 1.89 ÷ 6.42 % and Soderberg, 6.51 ÷ 10.25 %.

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Wu, Liang Chen, and Dong Po Wang. "Investigation of High Cycle and Low Cycle Fatigue Interaction on Fatigue Behavior of Welded Joints." Applied Mechanics and Materials 217-219 (November 2012): 2101–6. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.2101.

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Samples of Q345 steel welded joints were tested to failure under low cycle fatigue(LCF),high cycle fatigue(HCF) and combined fatigue(CCF) using an apparatus that is capable of providing interactive LCF/HCF loading. The stress ratio R is 0.5 and the frequency of HCF is about 19kHz. The result indicates that not only high frequency minor cycles superimposed on low frequency major cycles , but also low frequency minor cycles superimposed on high frequency major cycles can do remarkable damage to fatigue performance of welded joints. The CCF strength is characterized by amplitude envelope. If CCF fatigue life is characterized by LCF life, adverse effect of HCF component is underestimated. If CCF fatigue life is characterized by HCF life, adverse effect of LCF component is overrated.

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Jin, Ling Ling, Cai Yan Deng, Dong Po Wang, and Rui Ying Tian. "Research on Ultra-High Cycle Fatigue Property of 45 Steel." Advanced Materials Research 295-297 (July 2011): 1911–14. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1911.

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Fatigue property of 45 steel was studied in this paper with the method of ultrasonic fatigue testing, and SEM was used to analyze microscopic characteristics of the fatigue fracture. Fatigue test results show that: S-N curves descend continuously after 108 cycles, there is no fatigue limit as the traditional fatigue conception describes. Therefore, it is very dangerous to design welded structure working in the ultra-high cycle interval with the fatigue strength corresponding to 5×106 cycles. In the super-long life range, the fatigue property of welded joints is worse than the base metal. SEM analysis shows that: fatigue crack mainly initiates from the defects in the surface or sub-surface.

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Basaldella, Marco, Marvin Jentsch, Nadja Oneschkow, Martin Markert, and Ludger Lohaus. "Compressive Fatigue Investigation on High-Strength and Ultra-High-Strength Concrete within the SPP 2020." Materials 15, no. 11 (May 26, 2022): 3793. http://dx.doi.org/10.3390/ma15113793.

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The influence of the compressive strength of concrete on fatigue resistance has not been investigated thoroughly and contradictory results can be found in the literature. To date, the focus of concrete fatigue research has been on the determination of the numbers of cycles to failure. Concerning the fatigue behaviour of high-strength concrete (HPC) and, especially, ultra-high-strength concrete (UHPC), which is described by damage indicators such as strain and stiffness development, little knowledge is available, as well as with respect to the underlying damage mechanisms. This lack of knowledge has led to uncertainties concerning the treatment of high-strength and ultra-high-strength concretes in the fatigue design rules. This paper aims to decrease the lack of knowledge concerning the fatigue behaviour of concrete compositions characterised by a very high strength. Within the priority programme SPP 2020, one HPC and one UHPC subjected to monotonically increasing and cyclic loading were investigated comparatively in terms of their numbers of cycles to failure, as well as the damage indicators strain and stiffness. The results show that the UHPC reaches a higher stiffness and a higher ultimate strain and strength than the HPC. The fatigue investigations reveal that the UHPC can resist a higher number of cycles to failure than the HPC and the damage indicators show an improved fatigue behaviour of the UHPC compared to the HPC.

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Issler, Stephan, Manfred Bacher-Hoechst, and Steffen Schmid. "Fatigue Designing of High Strength Steels Components Considering Aggressive Fuel Environment and Very High Cycle Fatigue Effects." Materials Science Forum 783-786 (May 2014): 1845–50. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1845.

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Automotive components for injection systems are subjected to load spectra with up to 1E9 load cycles during the expected service life. However, fatigue testing with such a large number of cycles using original components is extremely time-consuming and expensive. A contribution for fatigue reliability assessment is available by the application of specimen testing and the transfer of the results to components including the verification by component spot tests.In this contribution very high cycle fatigue results in laboratory air and in ethanol fuel using notched specimens of high strength stainless steel are discussed. The influence of testing frequency was studied using ultrasonic and conventional test techniques. The validation and transfer of these accelerated testing results to components is one of the main challenges for a reliable fatigue designing.KeywordsVery High Cycle Fatigue (VHCF), automotive components, fuel injection, bio-fuels, corrosion fatigue, testing concepts, fatigue design concepts

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Zhao, Xiao, Jian Jun Zhao, and Yong Jie Liu. "Fatigue Behavior of GH4169 Alloy up to Very High Cycles." Advanced Materials Research 535-537 (June 2012): 928–31. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.928.

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The present paper deals with experimental studies on the long life fatigue behavior of GH4169 alloy. Using the ultrasonic fatigue testing technique, specimens of hourglass shape were fatigue tested in air at room temperature under fully reversed cyclic loading conditions (R=-1). The very high cycle fatigue property of GH4169 alloy was studied and the initiation mechanisms of fatigue cracks were investigated and analyzed with scanning electron microscopy (SEM) and energy dispersive atomic X-ray (EDX). Preliminary results indicate that the S-N curve displays a bilinear decreasing tendency within 109 cycles and fatigue failure initiates from inclusions/defects on the specimen surface.

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Bokůvka, Otakar, Michal Jambor, Slavomír Hrček, Ján Šteininger, and Libor Trško. "Design of Shaft Respecting the Fatigue Limit for Ultra-High Number of Cycles." Periodica Polytechnica Transportation Engineering 47, no. 1 (March 12, 2018): 6–12. http://dx.doi.org/10.3311/pptr.11562.

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Advances in engineering solutions in recent few decades caused that conventional fatigue limit (for steels and cast irons given for number of 107 cycles) is no more sufficient. Construction parts of newly introduced transport vehicles, operating at high velocities and at long distances, reach during their lifetime very high numbers of loading cycles, in order of 109. For this reason, values of fatigue limits for 109 cycles must be considered in design and construction of transport vehicles. In this study, authors present how dramatically will change the design of shaft, when fatigue limit for 109 cycles is considered.

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Zhao, Xiao, and Jian Jun Zhao. "Experimental Study on Ultra-High Cycle Fatigue Property of Q345 Welded Joint." Advanced Materials Research 538-541 (June 2012): 1488–91. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1488.

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The present paper deals with experimental studies on the ultra-high cycle fatigue property of Q345 bridge steel. Using the ultrasonic fatigue testing technique, specimens of Q345 welded joint with hourglass shape were designed using an analytical method combining with the finite element method and then fatigue tested in air at room temperature under fully reversed cyclic loading conditions (R=-1). The results show that the S-N curves of welded joints and relative base material specimens show continuously decreasing tendency in the very high cycle regime (105-109 cycles). Fatigue property of welded joint is much lower than that of base material and the fatigue strength of welded joint is only 45.0% of base material. Fracture can still occur on welded joints beyond 5 106 cycles, which indicates the fatigue limit defined at lifetime of 5 106 cycles cannot guarantee a safe design.

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Bratasena, M. E., T. Kato, O. Umezawa, Y. Ono, and M. Komatsu. "High-cycle fatigue strength of 22Cr-12Ni austenitic stainless steel at 77 K." IOP Conference Series: Materials Science and Engineering 1302, no. 1 (May 1, 2024): 012001. http://dx.doi.org/10.1088/1757-899x/1302/1/012001.

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Abstract The high-cycle fatigue strength of 22Cr-12Ni austenitic stainless steel was evaluated at 77 K for three types of materials with partially recrystallized (PR), finely recrystallized (FR), and solution-treated (ST) microstructures. Subsurface crack initiation was detected at the lower stress level and/or higher cycles in the materials, such that the fatigue crack initiation sites were shifted from the specimen surface to the interior of the specimen with increasing cycles. The ST showed a significant decrease in fatigue strength over 106 cycles due to subsurface crack initiation. Both PR and FR showed a significant improvement in their high-cycle fatigue strength in the high-cycle regime, although the increase in fatigue strength in the low-cycle regime was approximately equal to the increase in tensile strength.

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Li, Tang, Qing Yuan Wang, Q. F. Dou, Chong Wang, and M. R. Sriraman. "Investigations on Fatigue Properties of Die Cast Magnesium Alloy AZ91HP at Very High Cycles." Key Engineering Materials 353-358 (September 2007): 235–38. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.235.

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Very high cycle fatigue (VHCF) properties of high-pressure die cast Magnesium alloy AZ91HP have been investigated. Ultrasonic fatigue tests up to 109 cycles were conducted at the loading frequency of 20 kHz, under R=-1 condition and in ambient air. The experimental results show that specimens fail even after 107 cycles although the scatter seems to be large probably due to the presence of materials defects. However, there seems to be a fatigue limit at about 109 cycles. The fractures contain typical brittle features, with the fatigue cracks seen to initiate from the porosity in the material, either from the surface or beneath.

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Wang, Pengfei, Weiqiang Wang, Ming Zhang, Qiwen Zhou, and Zengliang Gao. "Effects of Specimen Size and Welded Joints on the Very High Cycle Fatigue Properties of Compressor Blade Steel KMN-I." Coatings 11, no. 10 (October 13, 2021): 1244. http://dx.doi.org/10.3390/coatings11101244.

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The effects of specimen size and welded joints on the very high cycle fatigue properties of compressor blade steel KMN-I were studied by ultrasonic fatigue testing. It was found that the S-N curve of large specimens had a slow decline above 107 cycles, and fatigue failure still occurred in the very high cycle regime (>107 cycles), while the very high cycle fatigue characteristics of welded specimens was less obvious, and the fatigue limit was observed. Metallographic observation and SEM analysis were carried out on the fracture of the specimens. The results showed that surface fractures were mostly observed in the large specimens, and only a small number of cracks initiated from non-metallic inclusions above 107 cycles. The cracks of welded specimens initiated from the surface below 107 cycles and initiated from the internal matrix above 107 cycles. In addition, the formation mechanism of GBF (granular bright facet) was analyzed by the “dispersive decohesion of spherical carbide” theory, and the fatigue strength and fatigue life were predicted, which was consistent with the experimental results.

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Cao, X. J., M. R. Sriraman, and Qing Yuan Wang. "Fatigue in Ti-6Al-4V at Very High Cycles." Materials Science Forum 561-565 (October 2007): 259–62. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.259.

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The importance of determining and understanding the very high cycle fatigue behaviors of materials has gained strength in recent years. Ti-alloys, in view of their high strength-to-weight ratio, have a range of structural applications. Of these, Ti-6Al-4V, belonging to the alpha-beta type is the most widely used. The present paper deals with investigations on the fatigue behavior of TC4, the Chinese equivalent to Ti-6Al-4V, up to very high cycles. Fatigue testing was carried out on a piezoelectric ultrasonic fatigue machine operating at 20 kHz frequency. Hourglass shaped resonant specimens were tested in ambient air at room temperature under completely reversed loading conditions (R = -1). Failure in the alloy was seen to occur right up to the gigacycle regime, with the fractures being found to initiate from the surface unlike in steels. The fracture surfaces exhibit brittle characteristics containing river patterns and cleavage facets, as well as striations.

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Huang, Zhi Yong, Wei Wei Du, Danièle Wagner, and Claude Bathias. "Relation between the Mechanical Behaviour of a High Strength Steel and the Microstructure in Gigacycle Fatigue." Materials Science Forum 636-637 (January 2010): 1459–66. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.1459.

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Many components can reach or exceed 109 cycles in their service time. When fatigue life is beyond 106, the Wöhler S-N curve was always considered to be asymptotic in horizontal axis, but the fatigue behaviour over 106 cycles can not be neglected. It is not usual to carry out a fatigue test beyond 109 cycles due to the conventional fatigue test’s constraints, time consuming and expensive. High strength steel is widely applied in automobile, railway industry after surface treatment in order to improve performance of material in practice. Carburizing process hardens surface to increase wear and fatigue resistance and shot peening has a beneficial effect on the material fatigue strength from the surface residual compressive stresses. A piezoelectric gigacycle fatigue machine is used to do the tests in gigacycle regime on specimens with different surface treatments. The effect of different surface treatments is investigated in gigacycle regime at a frequency of 20KHz with a fixed stress ratio R=0.1 at room temperature. Moreover, Scanning Electron Microscopy (SEM) observations of fracture surfaces are analyzed to evaluate the mechanism of damage related to surface treatments, microstructure scored inclusion size. The role of inclusions and microstructure is emphasized at 109 cycles.

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Ebara, Ryuichiro. "Grain Size Effect on Low Cycle Fatigue Behavior of High Strength Structural Materials." Solid State Phenomena 258 (December 2016): 269–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.269.

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This paper presents grain size effect on low cycle fatigue behavior of high strength maraging steel with gain size of 20,60 and 100μm and Ti-6Al-4V alloy with grain size of 0.5,1.4 and 5.1μm. Low cycle fatigue strength of the maraging steel depends on grain size in number of cycles up to 103.The smaller the grain size, the higher the low cycle fatigue strength was. Quasci-cleavage fracture surfaces were predominant for material with grain size of 20μm,while intergranular fracture surfaces were predominant for materials with larger grain size in number of cycles lower than 60. Striation was predominant for all tested materials in number of cycles higher than 60.Low cycle fatigue strength of Ti-6Al-4V alloy also depends on grain size in number of cycles up to 104. Grain size dependent transgranular fracture surfaces were predominant for materials with ultra-fine grain size of 0.5μm and fine grain size of 1.4μm.

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Nový, František, Libor Trško, Robert Ulewicz, and Sylvia Dundeková. "Influence of Electrodeposited Coatings on Ultra-High-Cycle Fatigue Life of S235 Structural Steel." Materials Science Forum 818 (May 2015): 37–40. http://dx.doi.org/10.4028/www.scientific.net/msf.818.37.

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The article deals with experimental results of fatigue life of plain carbon steel electrodeposited with nickel, chromium and iron-zinc coatings in the ultra-high-cycle region of loading (N = 6×106 ÷ 1010 cycles) obtained at high-frequency fatigue testing (f ≈ 20 kHz, T = 20 ± 5 °C, R = -1). The results confirm continuous decrease of S-N curves after N = 107 cycles. Electrodeposited coatings caused decrease of the fatigue life in the low and high-cycle fatigue region. In the ultra-high cycle region the influence of electrodeposited coatings on fatigue properties is negligible. There was observed no significant influence of thickness of electrodeposited coatings on fatigue lifetime decrease.

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Chapetti, Mirco D. "Prediction of threshold for very high cycle fatigue (N>107 cycles)." Procedia Engineering 2, no. 1 (April 2010): 257–64. http://dx.doi.org/10.1016/j.proeng.2010.03.028.

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Song, Zongxian, Wenbin Gao, Dongpo Wang, Zhisheng Wu, Meifang Yan, Liye Huang, and Xueli Zhang. "Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature." Materials 14, no. 4 (February 20, 2021): 1001. http://dx.doi.org/10.3390/ma14041001.

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This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.

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Abdel Wahab, Magd, Irfan Hilmy, and Reza Hojjati-Talemi. "On the Use of Low and High Cycle Fatigue Damage Models." Key Engineering Materials 569-570 (July 2013): 1029–35. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.1029.

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In this paper, Continuum Damage Mechanics (CDM) theory is applied to low cycle and high cycle fatigue problems. Damage evolution laws are derived from thermodynamic principles and the fatigue number of cycles to crack initiation is expressed in terms of the range of applied stresses, triaxiality function and material constants termed as damage parameters. Low cycle fatigue damage evolution law is applied to adhesively bonded single lap joint. Damage parameters as function of stress are extracted from the fatigue tests and the damage model. High cycle fatigue damage model is applied to fretting fatigue test specimens and is integrated within a Finite Element Analysis (FEA) code in order to predict the number of cycles to crack initiation. Fretting fatigue problems involve two types of analyses; namely contact mechanics and damage/fracture mechanics. The high cycle fatigue damage evolution law takes into account the effect of different parameters such as contact geometry, axial stress, normal load and tangential load.

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Geilen, Max Benedikt, Marcus Klein, and Matthias Oechsner. "On the Influence of Ultimate Number of Cycles on Lifetime Prediction for Compression Springs Manufactured from VDSiCr Class Spring Wire." Materials 13, no. 14 (July 20, 2020): 3222. http://dx.doi.org/10.3390/ma13143222.

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For the generation of fatigue curves by means of fatigue tests, an ultimate number of cycles must be chosen. This ultimate number of cycles also limits the permissible range of the fatigue curve for the design of components. This introduces extremely high costs for testing components that are to be used in the Very High Cycle Fatigue regime. In this paper, we examine the influence of the ultimate number of cycles of fatigue tests on lifetime prediction for compression springs manufactured from VDSiCr class spring wire. For this purpose, we propose a new kind of experiment, the Artificial Censoring Experiment (ACE). We show that ACEs may be used to permissibly extrapolate the results of fatigue tests on compression springs by ensuring that a batch-specific minimum ultimate number of cycles has been exceeded in testing. If the minimum ultimate number of cycles has not been exceeded, extrapolation is inadmissible. Extrapolated results may be highly non-conservative, especially for models assuming a pronounced fatigue limit.

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Fintová, Stanislava, Libor Trško, Zdeněk Chlup, Filip Pastorek, Daniel Kajánek, and Ludvík Kunz. "Fatigue Crack Initiation Change of Cast AZ91 Magnesium Alloy from Low to Very High Cycle Fatigue Region." Materials 14, no. 21 (October 20, 2021): 6245. http://dx.doi.org/10.3390/ma14216245.

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Fatigue tests were performed on the AZ91 cast alloy to identify the mechanisms of the fatigue crack initiation. In different fatigue regions, different mechanisms were observed. In the low and high cycle fatigue regions, slip markings formation accompanied with Mg17Al12 particles cracking were observed. Slip markings act as the fatigue crack initiation sites. The size and number of slip markings decreased with decreased stress amplitude applied. When slip markings formation was suppressed due to low stress amplitude, particle cracking became more important and the cracks continued to grow through the particle/solid solution interface. The change of the fatigue crack initiation mechanisms led the S-N curve to shift to the higher number of cycles to the fracture, demonstrated by its stepwise character. A lower fatigue limit of 60 MPa was determined at 20 kHz for 2 × 109 cycles compared to the 80 MPa determined at 60 Hz for 1 × 107 cycles.

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Calabrese, Angelo Savio, Tommaso D’Antino, Pierluigi Colombi, and Carlo Poggi. "Low- and High-Cycle Fatigue Behavior of FRCM Composites." Materials 14, no. 18 (September 18, 2021): 5412. http://dx.doi.org/10.3390/ma14185412.

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This paper describes methods, procedures, and results of cyclic loading tensile tests of a PBO FRCM composite. The main objective of the research is the evaluation of the effect of low- and high-cycle fatigue on the composite tensile properties, namely the tensile strength, ultimate tensile strain, and slope of the stress–strain curve. To this end, low- and high-cycle fatigue tests and post-fatigue tests were performed to study the composite behavior when subjected to cyclic loading and after being subjected to a different number of cycles. The results showed that the mean stress and amplitude of fatigue cycles affect the specimen behavior and mode of failure. In high-cycle fatigue tests, failure occurred due to progressive fiber filaments rupture. In low-cycle fatigue, the stress–strain response and failure mode were similar to those observed in quasi-static tensile tests. The results obtained provide important information on the fatigue behavior of PBO FRCM coupons, showing the need for further studies to better understand the behavior of existing concrete and masonry members strengthened with FRCM composites and subjected to cyclic loading.

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Šulák, Ivo, Karel Obrtlík, and Ladislav Čelko. "High Temperature Low Cycle Fatigue Characteristics of Grit Blasted Polycrystalline Ni-Base Superalloy." Key Engineering Materials 665 (September 2015): 73–76. http://dx.doi.org/10.4028/www.scientific.net/kem.665.73.

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The present work is focused on the study of low cycle fatigue behavior of grit blasted nickel-base superalloy Inconel 713LC (IN 713LC). Grit blasting parameters are obtained. Button end specimens of IN 713LC in as-received condition and with grit blasted surface were fatigued under strain control with constant total strain amplitude in symmetrical cycle at 900 °C in air. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of both materials were obtained. Both materials exhibit the same stress-strain response. It has not been observed any improvement or reduction of low cycle fatigue life in representation of total strain amplitude versus number of cycles to failure of grit blasted material in comparison with as-received material. Surface relief and fracture surface were observed in SEM. The little effect of surface treatment on fatigue characteristics is discussed.

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31

Yang, Shaopeng, Peifeng Cheng, Fangzhong Hu, Wenchao Yu, Chi Zhang, Kaizhong Wang, and Maoqiu Wang. "Very High Cycle Fatigue Properties of 18CrNiMo7-6 Carburized Steel with Gradient Hardness Distribution." Coatings 11, no. 12 (December 2, 2021): 1482. http://dx.doi.org/10.3390/coatings11121482.

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As research of the high cycle fatigue of carburized gear steel could not meet the status quo of longer and longer service lives, research of very high cycle fatigue (VHCF) performance has become the focus of current research. The VHCF properties of case-hardening steel 18CrNiMo7-6 after being carburized with gradient hardness distribution were investigated by means of ultrasonic fatigue tests. The results showed that the carburized specimens with a case hardness of 705 HV and core hardness of 530 HV showed VHCF phenomenon, and the fatigue lives continuously increased to even 109 cycles as the stress amplitude decreased to about 500 MPa. Observations of the fracture surfaces of the fatigue specimens showed that the fatigue crack initiation sites were located in the transition area with the hardness at about 580 HV. It was found that the transition area had low VHCF properties, since the core did not show VHCF phenomenon, and the case had a higher hardness. A fine microstructure was observed in the granular bright facet (GBF) area, and the stress intensity factor ΔKGBF was measured to be 3.04 MPam−1/2. The 109 cycles fatigue life was predicted based on the inclusion size, and the 1010 cycles fatigue life was 490 MPa based on the prediction model.

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Labergere, Carl, Khemais Saanouni, Zhi Dan Sun, Mohamed Ali Dhifallah, Yisa Li, and Jean Louis Duval. "Prediction of Low Cycle Fatigue Life Using Cycles Jumping Integration Scheme." Applied Mechanics and Materials 784 (August 2015): 308–16. http://dx.doi.org/10.4028/www.scientific.net/amm.784.308.

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In this paper, cycles jumping scheme integration is used to numerically integrate fully coupled constitutive equations in order to predict the low cycle fatigue life under cyclic loading. This procedure avoids the calculation of the full loading cycles (some millions of loading cycles) while considering the transient stages due to the hardening (at the beginning) and the high damage-induced softening during the last tens of loading cycles. The model parameters have been identified using the results obtained from a 316L steel cylindrical specimen subject to symmetric tension-compression loading path. The effects of the specimen size as well as the mesh size on the fatigue life prediction are investigated.

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Ebara, Ryuichiro, R. Nohara, Rintaro Ueji, A. Ogura, Y. Ishihara, and S. Hamaya. "High Cycle Fatigue Behavior of Cold Forging Die Steel." Key Engineering Materials 417-418 (October 2009): 225–28. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.225.

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High cycle fatigue behavior of the representative cold forging die steel, YXR3 with Rockwell C scale hardness number of 60.0 is investigated. Axial fatigue strength of plane and notched bar specimens with stress concentration factor, Kt of 1.5, 2.0 and 2.5 is presented. The emphasis is placed upon the subsurface crack initiation observed on notched specimens failed at number of cycles over than 106 cycles. Crack initiation and propagation mode of cold forging die steel is discussed with respect to fracture surface morphology.

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34

Chen, Zhi Wu, Zhen Ya Lu, Xu Ming Chen, Ying Zhang, and Xuan Cheng. "Effects of Electrical Characters on Electrical Fatigue Behavior in PLZT Ferroelectric Ceramics." Key Engineering Materials 280-283 (February 2007): 159–62. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.159.

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Electrical fatigue tests have been conducted on PLZT ferroelectric ceramics. It was found that the higher the applied electrical field magnitude, the faster the Pr decreases; the samples under the same electrical field magnitude but with square wave have higher fatigue rate than that of sine wave. It was observed that at low frequency of applied field (50Hz and 500Hz), the polarization decreased very quickly and dropped below 70% of the original value within 106.2 switching cycles, however, when fatigue test were conducted at high frequencies of 100kHz and 300kHz, the polarization did not change significantly even after 109 cycles. The SEM analysis indicated that the facture mode was mainly of trans-granular for the virgin non-fatigued sample, while of inter-granular for the fatigue sample. The quantitative information on the 90° domain switching was measured in situ using X-ray diffraction. The effects of electrical characters on electrical fatigue behavior were explained according to the mechanism of electrical fatigue in PLZT ferroelectric ceramics.

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Lee, Yoonseok, Seungchan Cho, Changwook Ji, Ilguk Jo, and Moonhee Choi. "Impact of Morphology on the High Cycle Fatigue Behavior of Ti-6Al-4V for Aerospace." Metals 12, no. 10 (October 14, 2022): 1722. http://dx.doi.org/10.3390/met12101722.

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The mechanical properties of Ti-6Al-4V alloy are affected by its microstructures. However, the effects of these microstructures on the high cycle fatigue behavior of Ti-6Al-4V alloy with a mixed structure (α + β phases) remain unknown. In this study, three alloy specimens were prepared using different hot-deformation methods, and their microstructures were investigated by optical microscopy and scanning electron microscopy. Fatigue tests were then performed to determine their high cycle fatigue and fatigue crack propagation behavior. All specimens showed a bimodal structure, but the morphology of each phase (e.g., diameter, shape, and volume fraction) showed notable differences. Among the samples prepared, the forged sample (FS) showed the lowest fatigue strength in all cycles. The fatigue strength of the homogeneously rolled sample (HS) was slightly higher than that of the rolled sample (RS) below 106 cycles but lower above 106 cycles. Compared with those of RS and HS, the secondary α (αs) grain width of FS was twofold larger. The interconnected primary α (αp) phase clusters in HS appeared to promote microcrack propagation.

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36

Tang, Wei Wei, Hong Wang, and Jin Gan Dai. "Fatigue Behavior of Medium Carbon Steel by Symmetric Bending Ultrasonic Frequency Method." Advanced Materials Research 393-395 (November 2011): 102–5. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.102.

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The S-N curves of medium carbon steel(MCS) are determined by the ultrasonic symmetric bending fatigue system (20 KHz). The results show that two S-N curves of MCS display the characteristic of “continually decreasing type” up to 109 cycles and exhibit no traditional horizontal plateau beyond 106 cycles. When the fatigue cycles are over 109, fatigue failure do occurs. By comparison of the two curves of 2mm thick and 5mm thick MCS, the results show that in the high-cycle stage(107cycles), size effect has no significant impact on fatigue Properties. This can also be explained by the theory of crack initiation, in high cycle stage, fatigue crack initiation exists in the sample surface, and in ultra-high-cycle stage, fatigue crack initiation exists in internal initiation.

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37

Perez Mora, Ruben, Gonzalo Domínguez Almaraz, Thierry Palin-Luc, Claude Bathias, and José Luis Arana. "Very High Cycle Fatigue Analysis of High Strength Steel with Corrosion Pitting." Key Engineering Materials 449 (September 2010): 104–13. http://dx.doi.org/10.4028/www.scientific.net/kem.449.104.

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This work deals with very high cycle fatigue tests on high strength steel subject to the corrosive action of salt solution. Tests were carried out at constant load ratio R = -1 on corrosion treated and non-treated specimens and sea water flow specimens of R5 steel, which according to an International Classification Society of offshore systems is steel graded with the highest ultimate tensile strength to manufacture mooring chains and accessories intended to position mooring applications such as mooring of mobile offshore units, mooring of floating production units and mooring of offshore loading systems. Fatigue endurance on pre-corroded specimens was quite dispersed but with a mean value of 360 MPa, whereas for the non corroded specimens the fatigue endurance was located between 420 MPa at 105 - 106 cycles, and 380 MPa at 109 cycles. Concerning the sea water flow specimens, important increase in fatigue life is observed in reducing the applied load. Dispersion on fatigue endurance for the pre-corroded and sea water flow specimens was related to the complex process of corrosion on the specimen surface; nevertheless, the resulting pitting holes were associated to fracture origin in these specimens. Furthermore, fatigue failure origin was systematically localized at a circular, elliptical or irregular surface pitting hole formed during the corrosion process; special attention was focused on the pitting holes related to fatigue failure. Finite element results were obtained for the hemispherical voids placed on the specimen surface in order to determine the corresponding stress concentration; these results were associated with the real fracture origin pitting holes observed on specimens with pre-corrosion and sea water flow corrosion. Finally, some conclusions were obtained concerning pitting holes, stress concentration and fatigue life for the pre-corroded and sea water flow corroded specimens.

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Tian, Qing Chao, Xian Ping Dong, Hai Chao Cui, and Ke Xu. "Characterization of the Welded-Joint of High-Strength High-Toughness Seamless Steel Pipe under High-Cycle Fatigue Condition." Materials Science Forum 896 (March 2017): 202–8. http://dx.doi.org/10.4028/www.scientific.net/msf.896.202.

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The welded joint of a S890QL grade steel pipes containing 1.2% Ni have been prepared to characterize the use performance under high cycle fatigue test. It has been found that the fatigue strength of the welded joint is 290MPa with a fatigue life of more than 10 million cycles, and the obtained Basquin equation is σa=488*(2N)-0.02758 . It is found that the steel exhibits the whole bainite microstructure when the cooling rate is less than 1°C/s. The welded joint is divided into the weld zone, the coarse grain zone, the fine grain zone, the softening zone and the matrix. The fine grain characteristic in the welded area determines the good anti fatigue performance of the investigated steel.

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Song, Qingpeng, Jiwang Zhang, Ning Zhang, Wei Li, and Liantao Lu. "High cycle fatigue property and fracture behavior of high-strength austempered ductile iron." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 231, no. 4 (August 11, 2015): 423–29. http://dx.doi.org/10.1177/1464420715599800.

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The high cycle fatigue tests of high-strength austempered ductile iron of grade 1200/850/04 (ASTM 897 M-06) were conducted by the high frequency fatigue machine. The results show that the S–N curve decreases continuously and there is no conventional fatigue limit at 107 cycles. According to the fracture surface observations, at short fatigue life region the specimens fail from defects at specimen surface and at long fatigue life region the specimens fail from internal defects with fish-eye area around it. According to the defect sizes measured in the standard inspection areas of the material, the maximum defect size evaluated by the statistics of extreme values method is in accordance with that of the fatigue test results. Meanwhile, it is obvious that the fatigue strength of austempered ductile iron is influenced by the original defect size and the fatigue limit can be well evaluated by the Murakami equation.

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40

Zhang, A. L., D. Liu, and H. M. Wang. "Thermal Fatigue Crack Initiation of Laser Deposited High-temperature Titanium Alloy Ti60A in 20–700 °C." High Temperature Materials and Processes 32, no. 4 (August 16, 2013): 331–37. http://dx.doi.org/10.1515/htmp-2012-0141.

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AbstractThermal fatigue damage of high-temperature titanium alloys is of great concern for severe temperature-fluctuating environment, and the thermal fatigue crack initiation stage plays a crucial role in thermal fatigue life. In present study, thermal fatigue tests keeping 55 seconds at 700 °C followed by water cooling 15 seconds at 20 °C were performed for the laser deposited high-temperature titanium alloy Ti60A (Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si). Thermal fatigue cracks initiate after 800 thermal fatigue cycles with a length of 20 µm. Subsequently numerous cracks grow to 500 µm and cause severe degradation after 1000 cycles. To investigate the crack initiation behavior, microstructural changes during thermal fatigue process were examined by OM, SEM, EPMA and TEM. Thermal fatigue cracks initiate preferably at grain boundaries, α/β interfaces, microvoids, and abnormal coarsened α produced by oxygen interstitial solution. Mechanisms of thermal fatigue crack initiation are related to compatibility of local deformation and microstructural changes during thermal fatigue process.

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41

Zhou, Yan Fen, Stephen Jerrams, Lin Chen, and Mark Johnson. "The Determination of Multi-Axial Fatigue in Magnetorheological Elastomers Using Bubble Inflation." Advanced Materials Research 875-877 (February 2014): 507–11. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.507.

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Fatigue life is one of the most important physical characteristic that is investigated by materials engineers and scientists. The high dynamic loading experienced by machine parts necessitates understanding fatigue properties in critical components. Despite this requirement, elastomer fatigue criteria are imperfectly understood and even less is known about fatigue resistance in the emerging range of smart elastomers. In this paper, initial research into the equi-biaxial fatigue behaviour of magnetorheological elastomers (MREs) is described. Physical testing was carried out using a bubble inflation testing system. Silicone rubber based test samples were fatigued at different stress amplitudes ranging between 0.75MPa and 1.4MPa using engineering stress as the control mode. S-N (Wöhler) curves showing the plots of stress amplitude (σa) versus cycles to failure (N) are presented. Stress-strain behaviour throughout fatigue process is also described. For a fatigue test at a stress amplitude of 0.75MPa and no pre-stressing, it was found that stress softening occurred for the entire duration of the test, but was particularly pronounced in the first 100 cycles of testing.

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42

Scott-Emuakpor, Onome, M. H. Herman Shen, Tommy George, Charles J. Cross, and Jeffrey Calcaterra. "Development of an Improved High Cycle Fatigue Criterion." Journal of Engineering for Gas Turbines and Power 129, no. 1 (March 1, 2004): 162–69. http://dx.doi.org/10.1115/1.2360599.

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An integrated computational-experimental approach for prediction of total fatigue life applied to a uniaxial stress state is developed. The approach consists of the following elements: (1) development of a vibration based fatigue testing procedure to achieve low cost bending fatigue experiments and (2) development of a life prediction and estimation implementation scheme for calculating effective fatigue cycles. A series of fully reversed bending fatigue tests were carried out using a vibration-based testing procedure to investigate the effects of bending stress on fatigue limit. The results indicate that the fatigue limit for 6061-T6 aluminum is approximately 20% higher than the respective limit in fully reversed tension-compression (axial). To validate the experimental observations and further evaluate the possibility of prediction of fatigue life, an improved high cycle fatigue criterion has been developed, which allows one to systematically determine the fatigue life based on the amount of energy loss per fatigue cycle. A comparison between the prediction and the experimental results was conducted and shows that the criterion is capable of providing accurate fatigue life prediction.

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43

Xu, D. K., and E. H. Han. "Effect of Yttrium Content on the Ultra-High Cycle Fatigue Behavior of Mg-Zn-Y-Zr Alloys." Materials Science Forum 816 (April 2015): 333–36. http://dx.doi.org/10.4028/www.scientific.net/msf.816.333.

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In the super-long life regime, the fatigue behavior of as-extruded Mg-6wt%Zn-xY-0.8wt%Zr Mg alloys with Y content of 0, 1, 2 and 3 wt% have been investigated, respectively. The result indicated that for all measured S-N curves, a plateau existed in the regime of 5×106-108 cyc, and then the fatigue strength gradually decreased between 108 and 109 cycles. Therefore, only fatigue strength corresponding to 109 cycles can be determined. Compared with other alloys, the alloy with Y content of 2 wt% has the highest fatigue strength and its value is 105 MPa. SEM observations to fracture surfaces revealed that for all alloys, the fatigue crack mostly initiated at the surface or subsurface of samples failed within 106-109 cycles. Further observation indicated that the crack initiation was related with activated slip bands instead of phase particles and activated twins. Based on the measured results and Murakami equation, it demonstrates that the fatigue strength of alloys is more dependent on the hardness values.

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44

Kuchariková, Lenka, Eva Tillová, Milan Uhríčik, Juraj Belan, and Ivana Švecová. "High-cycles Fatigue of Different Casted Secondary Aluminium Alloy." Manufacturing Technology 17, no. 5 (October 1, 2017): 756–61. http://dx.doi.org/10.21062/ujep/x.2017/a/1213-2489/mt/17/5/756.

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45

Savin, O., J. Baroth, C. Badina, S. Charbonnier, and C. Bérenguer. "Damage due to start-stop cycles of turbine runners under high-cycle fatigue." International Journal of Fatigue 153 (December 2021): 106458. http://dx.doi.org/10.1016/j.ijfatigue.2021.106458.

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46

Shimamura, Yoshinobu, Reo Kasahara, Hitoshi Ishii, Keiichiro Tohgo, Tomoyuki Fujii, Toru Yagasaki, and Soichiro Sumida. "Fretting Fatigue Behaviour of Alloy Steel in the Very High Cycle Region." MATEC Web of Conferences 300 (2019): 18002. http://dx.doi.org/10.1051/matecconf/201930018002.

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It is well known that fretting fatigue strength is much lower than the fatigue strength of smooth specimens and the fatigue limit disappears. Many studies on fretting fatigue have been reported but most of the studies have not cover fatigue properties in the very high cycle regime more than 107 cycles. In this study, an accelerated fretting fatigue testing method was developed by using an ultrasonic torsional fatigue testing machine with a clamping fretting pad. Fretting fatigue tests of CrMo steel were conducted by using the developed method. Test results showed that fretting fatigue failure occurs in the very high cycle region.

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47

Nečemer, Branko, Franc Zupanič, Tomaž Vuherer, and Srečko Glodež. "High-Cycle Fatigue Behaviour of the Aluminium Alloy 5083-H111." Materials 16, no. 7 (March 28, 2023): 2674. http://dx.doi.org/10.3390/ma16072674.

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This study presents a comprehensive experimental investigation of the high-cycle fatigue (HCF) behaviour of the ductile aluminium alloy AA 5083-H111. The analysed specimens were fabricated in the rolling direction (RD) and transverse direction (TD). The HCF tests were performed in a load control (load ratio R = 0.1) at different loading levels under the loading frequency of 66 Hz up to the final failure of the specimen. The experimental results have shown that the S–N curves of the analysed Al-alloy consist of two linear curves with different slopes. Furthermore, RD-specimens demonstrated longer fatigue life if compared to TD-specimens. This difference was about 25% at the amplitude stress 65 MPa, where the average fatigue lives 276,551 cycles for RD-specimens, and 206,727 cycles for TD-specimens were obtained. Similar behaviour was also found for the lower amplitude stresses and fatigue lives between 106 and 108 cycles. The difference can be caused by large Al6(Mn,Fe) particles which are elongated in the rolling direction and cause higher stress concentrations in the case of TD-specimens. The micrography of the fractured surfaces has shown that the fracture characteristics were typical for the ductile materials and were similar for both specimen orientations.

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Jambor, Michal, František Nový, Otakar Bokůvka, Libor Trško, and Monika Oravcová. "Influence of structure sensitising of the AlSi 316Ti austenitic stainless steel on the ultra-high cycle fatigue properties." MATEC Web of Conferences 157 (2018): 05011. http://dx.doi.org/10.1051/matecconf/201815705011.

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Austenitic stainless steels are the wide-spread materials, used mainly in the power industry. In that kind of engineering application, structural parts of rotating elements reach during their lifetime very high numbers of loading cycles, exceeding 107 numbers of cycles. With regard to this fact, the data of ultra-high cycle fatigue properties are needed to be used in the qualified design. Increasing demands on the efficiency cause the increase of the operating temperature, and exposition of these materials to the elevated temperatures can cause some important structural changes, which result in the sensitising of the structure. In this study authors present their own experimental results about fatigue properties of AISI 316Ti austenitic stainless steel after sensitising, in the ultra-high cycle region (Nf = 106 ~ Nf = 3×109 cycles). Fatigue tests were carried out using ultrasonic fatigue testing device with frequency f = 20 kHz at the coefficient of cycle asymmetry R = -1, and temperature T = 20±5°C. In the ultra-high cycle region was observed the continuous decrease of the fatigue properties of the AISI 316Ti, and there was recorded the negative effect of the sensitising on the ultra-high cycle fatigue properties of the AISI 316Ti.

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49

Altenberger, I., Ivan Nikitin, P. Juijerm, and Berthold Scholtes. "Residual Stress Stability in High Temperature Fatigued Mechanically Surface Treated Metallic Materials." Materials Science Forum 524-525 (September 2006): 57–62. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.57.

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Different classes of metallic materials (aluminum alloys, steels, titanium alloys) were mechanically surface treated by deep rolling and laser shock peening and isothermally fatigued at elevated temperature under stress control. The fatigue tests were interrupted after different numbers of cycles for several stress amplitudes and residual stresses and FWHM-values were measured by X-ray diffraction methods at the surface and as a function of depth. The results summarize the response of the surface treatment induced residual stress profiles to thermomechanical loading conditions in the High Cycle Fatigue (HCF)- as well as in the Low Cycle Fatigue (LCF) regime. The effects of stress amplitude, plastic strain amplitude, temperature and frequency are addressed in detail and discussed. The results indicate that residual stress relaxation during high temperature fatigue can be predicted for sufficiently simplified loading conditions and that thermal and mechanical effects can be separated from each other. A plastic strain based approach appears to be most suitable to describe residual stress relaxation. Frequency effects were found to be not very pronounced in the frequency range investigated.

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Wang, Q. Y., Hong Yan Zhang, S. R. Sriraman, and S. L. Liu. "Super Long Life Fatigue of AE42 and AM60 Magnesium Alloys." Key Engineering Materials 306-308 (March 2006): 181–86. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.181.

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Magnesium alloys, on account of their lightweight, find useful applications in the automotive sector. During service, they experience very high number of fatigue cycles. Therefore, the understanding of their long life fatigue behavior becomes extremely important. This is possible by using ultrasonic fatigue testing, which is the only feasible way of doing it. In this study, the two such alloys viz. AE42 and AM60 has been investigated for their long life fatigue characteristics under fully reversed loading conditions, using a piezoelectric fatigue testing machine operating at a frequency of 20 kHz. The S-N data does not reach a horizontal asymptote at 107 cycles in either of the alloys. However, the alloy AM60 seems to show a fatigue limit at about at 109 cycles. The fractures examined by scanning electron microscopy (SEM) were found to be brittle in character. In very high cycle fatigue conditions, the crack was found to initiate from the specimen subsurface.

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Journal articles on the topic 'High fatigue cycles'

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