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Journal articles on the topic 'Mean strain effect'

Author: Grafiati

Published: 27 April 2023

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Guo, Yi, Yun Rong Luo, and Qing Yuan Wang. "Mean Strain Effect on the Cyclic Stress-Strain Behavior of Steel Structure Materials Q235." Advanced Materials Research 602-604 (December 2012): 430–34. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.430.

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The low cycle fatigue (LCF) behavior of Q235 steel under mean strain control has been investigated. A serious of the strain controlled cyclic loading experiments with several combinations of strain amplitudes and mean strains have been performed. Significant cyclic hardening and mean stress relaxation were observed in all cases. Fractography by scanning electron microscopy (SEM) was used to determine the LCF failure mechanisms and fatigue crack propagation modes of the Q235 steel.

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Ellyin, F. "Effect of Tensile-Mean-Strain on Plastic Strain Energy and Cyclic Response." Journal of Engineering Materials and Technology 107, no. 2 (1985): 119–25. http://dx.doi.org/10.1115/1.3225786.

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Tests have been conducted to determine the effect of tensile-mean-strain on cyclic properties, low cycle fatigue, and total absorbed plastic strain energy to failure of ASTM A-516 Grade 70 carbon low alloy steel. Stable hysteresis loops at half-life are presented for different strain controlled tests. The cyclic properties were determined by a least squares fit technique. The results of tensile-mean-strain are compared with fully-reversed fatigue tests. The absorbed plastic strain energy per cycle was measured and compared with a proposed relationship for non-Masing material behavior. A relationship of the form Wf=KNfα is found to be a good representation of the data. It is observed that the material tends toward a steady-state condition independent of the level of the mean strain provided the fatigue life is greater than one thousand cycles.

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Butler, James P., Hiroshi Miki, Stephanie Squarcia, Rick A. Rogers, and John L. Lehr. "Effect of macroscopic deformation on lung microstructure." Journal of Applied Physiology 81, no. 4 (1996): 1792–99. http://dx.doi.org/10.1152/jappl.1996.81.4.1792.

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Butler, James P., Hiroshi Miki, Stephanie Squarcia, Rick A. Rogers, and John L. Lehr. Effect of macroscopic deformation on lung microstructure. J. Appl. Physiol.81(4): 1792–1799, 1996.—Using an anisotropic theory of diffuse light scattering in lungs, we measured the fractional changes in geometric mean linear intercepts in orthogonal directions when freshly excised rabbit lungs were subjected to isovolume uniaxial strains. Results from the optical technique were compared with morphometric estimates of fractional changes in mean linear intercepts from the same strained and unstrained (control) lobes, with the conclusion that diffuse light scattering is adequate to estimate changes in mean free paths in different directions. We compared optical estimates of fractional changes in mean linear intercepts with the macroscopic strain field measured by displacements of pleural markers; this relationship did not significantly differ from the line of identity. We conclude that the microscopic strain field is closely matched to the macroscopic strain field during uniaxial distortion. This suggests that surface reorientation may not play a large role in the origin of the low shear modulus of the lung, but this cannot be definitively stated without comparison of these experimental results to specific model predictions of the changes in mean linear intercepts in shear deformation.

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IINO, Jun, Hideshi HANAZAKI, and Yasuaki KOHAMA. "The Effect of Mean Strain on the Stably Stratified Turbulence." Transactions of the Japan Society of Mechanical Engineers Series B 67, no. 664 (2001): 3068–75. http://dx.doi.org/10.1299/kikaib.67.3068.

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Scorza, Daniela, Andrea Carpinteri, Giovanni Fortese, Camilla Ronchei, Sabrina Vantadori, and Andrea Zanichelli. "Multiaxial fatigue life estimation in low-cycle fatigue regime including the mean stress effect." MATEC Web of Conferences 165 (2018): 16002. http://dx.doi.org/10.1051/matecconf/201816516002.

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The goal of the present paper is to discuss the reliability of a strain-based multiaxial Low-Cycle Fatigue (LCF) criterion in estimating the fatigue lifetime of metallic structural components subjected to multiaxial sinusoidal loading with zero and non-zero mean value. Since it is well-known that a tensile mean normal stress reduces the fatigue life of structural components, three different models available in the literature are implemented in the present criterion in order to take into account the above mean stress effect. In particular, such a criterion is formulated in terms of strains by employing the displacement components acting on the critical plane and, then, by defining an equivalent strain related to such a plane. The Morrow model, the Smith-Watson-Topper model and the Manson-Halford model are applied to define such an equivalent strain. The effectiveness of the new formulations is evaluated through comparison with some experimental data reported in the literature, related to biaxial fatigue tests performed on metallic specimens under in-and out-of-phase loadings characterised by non-zero mean stress values.

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Yip, Ming-Chuen, and Yi-Ming Jen. "Mean Strain Effect on Crack Initiation Lives for Notched Specimens Under Biaxial Nonproportional Loading Paths." Journal of Engineering Materials and Technology 119, no. 1 (1997): 104–12. http://dx.doi.org/10.1115/1.2805962.

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This paper discusses the mean strain effect on the crack initiation lives for notched specimens under biaxial nonproportional loading paths. Elastic-plastic finite element method was used to evaluate the local stresses and strains. Several prediction models related to the mean stress/strain effect were employed to correlate the experimental results with reference fatigue data for smooth specimens. It is found that Fatemi-Socie model gives good prediction for the present research with the assistance of finite element method. The stress behavior in this deflection-controlled tests is discussed in this study, and the failure surfaces are also examined after tests.

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de Beeck, Hanne Op, Lieven J. R. Pauwels, and Johan Put. "Schools, strain and offending: Testing a school contextual version of General Strain Theory." European Journal of Criminology 9, no. 1 (2012): 52–72. http://dx.doi.org/10.1177/1477370811421646.

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Based on the idea that schools are important socializing settings for adolescents (Gottfredson, 2001), the school contextual version of General Strain Theory (Agnew, 1999) is tested in this article. The main hypothesis of this study is that strain at the school level affects individual offending by creating individual strain. Findings suggest that school contextual effects differ: convincing contextual effects are found for violent offending but not for general offending. Furthermore, although the school mean level of strain does significantly affect individual violent offending, this effect does not proceed by creating individual strain. It is therefore suggested that the school mean level of strain either has a direct effect on violent offending or influences other important individual offending mechanisms such as social learning or lifestyle risks.

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Natesan, Elanghovan, Johan Ahlström, Stefan Eriksson, and Christer Persson. "Effects of Temperature on the Evolution of Yield Surface and Stress Asymmetry in A356–T7 Cast Aluminium Alloy." Materials 14, no. 24 (2021): 7898. http://dx.doi.org/10.3390/ma14247898.

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As the electrification of vehicle powertrains takes prominence to meet stringent emission norms, parts of internal combustion engines like cylinder heads are subjected to an increased number of thermal load cycles. The cost-effective design of such structures subjected to cyclic thermo-mechanical loads relies on the development of accurate material models capable of describing the continuum deformation behaviour of the material. This study investigates the effect of temperature on the evolution of flow stress under cyclic loading in A356-T7 + 0.5% Cu cast aluminium alloy commonly used in modern internal combustion engine cylinder heads. The material exhibits peak stress and flow stress asymmetry with the stress response and flow stress of the material under compressive loading higher than under tension. This peak and flow stress asymmetry decrease with an increase in temperature. To compare this stress asymmetry against conventional steel, cyclic strain-controlled fatigue tests are run on fully pearlitic R260 railway steel material. To study the effect of mean strain on the cyclic mean stress evolution and fatigue behaviour of the alloy, tests with tensile and compressive mean strains of +0.2% and −0.2% are compared against fully reversed (Rε = −1) strain-controlled tests. The material exhibits greater stress asymmetry between the peak tensile and peak compressive stresses for the strain-controlled tests with a compressive mean strain than the tests with an identical magnitude tensile mean strain. The material exhibits mean stress relaxation at all temperatures. Reduced durability of the material is observed for the tests with tensile mean strains at lower test temperatures of up to 150 °C. The tensile mean strains at elevated temperatures do not exhibit such a detrimental effect on the endurance limit of the material.

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Kang, Jidong, Liting Shi, Jie Liang, Babak Shalchi-Amirkhiz, and Colin Scott. "The Influence of Specimen Geometry and Strain Rate on the Portevin-Le Chatelier Effect and Fracture in an Austenitic FeMnC TWIP Steel." Metals 10, no. 9 (2020): 1201. http://dx.doi.org/10.3390/met10091201.

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We studied the Portevin-Le Chatelier effect and fracture behavior of a FeMnC TWIP steel using high speed digital image correlation by varying the specimen geometry (flat vs. round) and test strain rate (0.001 vs. 0.1 s−1). The results show that the mean flow stress, the mean strain hardening rate and the mean strain rate sensitivity parameters are all independent of the specimen geometry and are uncorrelated with the presence or not of Portevin-Le Chatelier (PLC) bands, the type of PLC bands observed or the critical strain for band formation. However, both the fracture strains and stresses and the PLC behavior are highly geometry and/or strain rate dependent. Dynamic strain aging (DSA) and in particular the presence of PLC instabilities appears to play an important but as yet unclear role in promoting premature necking and final fracture.

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Warley, R. L., D. L. Feke, and I. Manas-Zloczower. "Transient effects in dynamic modulus measurement of silicone rubber, part 2: Effect of mean strains and strain history." Journal of Applied Polymer Science 104, no. 4 (2007): 2197–204. http://dx.doi.org/10.1002/app.25136.

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Baena, Marta, Cristina Barris, Ricardo Perera, and Lluís Torres. "Influence of Bond Characterization on Load-Mean Strain and Tension Stiffening Behavior of Concrete Elements Reinforced with Embedded FRP Reinforcement." Materials 15, no. 3 (2022): 799. http://dx.doi.org/10.3390/ma15030799.

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Based on the characterization of the bond between Fiber-Reinforced Polymer (FRP) bars and concrete, the structural behavior of cracked Glass-FRP (GFRP)-Reinforced Concrete (RC) tensile elements is studied in this paper. Simulations in which different bond-slip laws between both materials (FRP reinforcement and concrete) were used to analyze the effect of GFRP bar bond performance on the load transfer process and how it affects the load-mean strain curve, the distribution of reinforcement strain, the distribution of slip between reinforcement and concrete, and the tension stiffening effect. Additionally, a parametric study on the effect of materials (concrete grade, modulus of elasticity of the reinforcing bar, surface configuration, and reinforcement ratio) on the load-mean strain curve and the tension stiffening effect was also performed. Results from a previous experimental program, in combination with additional results obtained from Finite Element Analysis (FEA), were used to demonstrate the accuracy of the model to correctly predict the global (load-mean strain curve) and local (distribution of strains between cracks) structural behavior of the GFRP RC tensile elements.

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Wei, Wen Lan, Li Hong Han, Yao Rong Feng, Jian Xun Zhang, and Hang Wang. "Low Cycle Fatigue Behavior of N80Q Steel under the Influence of Mean Strains." Materials Science Forum 944 (January 2019): 1067–75. http://dx.doi.org/10.4028/www.scientific.net/msf.944.1067.

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The service conditions of thermal recovery wells make the casing repeatedly bear the tension and compression load and form low cycle fatigue. Meanwhile, many factors, such as pre-strain and creep, lead to the formation of asymmetrical low cycle fatigue (R≠-1), which is the low cycle fatigue behavior under the influence of mean strain. This work studied the effect of mean strain on low cycle fatigue behavior of N80Q steel. Different strain amplitude conditions were selected for low cycle fatigue test, which were 0.5%, 0.7%, 1.0%, 1.5% and 2.0% respectively. Then tests at mean strains of-0.8%, 0%, 0.5% and 1.0% were conducted under constant strain amplitude. And the microstructure and fracture surface of the material after the tests were characterized using scanning electron microscopy and transmission electron microscopy, respectively. The results show that the mean strain makes the fatigue life reduce significantly under the condition of constant strain amplitude, and is related to the amplitude of the mean strain. The value of the mean strain and the strain amplitude will ultimately affect the fatigue life. And the fatigue life is related to the maximum absolute value of strain and has a linear relationship in the double logarithmic coordinate system. The SEM results of fracture morphology show that the brittleness feature of the crack growth area with high mean strain decreases significantly. And the fracture cross-section observation shows that the crack propagation is transgranular propagation. The TEM results show that a large number of dislocations pile-up is formed at lath subgrain boundary.

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TAO, G., and Z. XIA. "Mean stress/strain effect on fatigue behavior of an epoxy resin." International Journal of Fatigue 29, no. 12 (2007): 2180–90. http://dx.doi.org/10.1016/j.ijfatigue.2006.12.009.

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Chiou, Yung-Chuan, and Ming-Chuen Yip. "Effect of mean strain level on the cyclic stress–strain behavior of AISI 316 stainless steel." Materials Science and Engineering: A 354, no. 1-2 (2003): 270–78. http://dx.doi.org/10.1016/s0921-5093(03)00016-9.

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Cosson, Emmanuel, Monique Herisse, Dominique Laude, et al. "Aortic stiffness and pulse pressure amplification in Wistar-Kyoto and spontaneously hypertensive rats." American Journal of Physiology-Heart and Circulatory Physiology 292, no. 5 (2007): H2506—H2512. http://dx.doi.org/10.1152/ajpheart.00732.2006.

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In humans, increased body weight and arterial stiffness are significantly associated, independently of blood pressure (BP) level. The finding was never investigated in rodents devoid of metabolic disorders as spontaneously hypertensive rats (SHR). Using simultaneous catheterization of proximal and distal aorta, we measured body weight, intra-arterial BP, heart rate and their variability (spectral analysis), aortic pulse wave velocity (PWV), and systolic and pulse pressure (PP) amplifications in unrestrained conscious Wistar-Kyoto (WKY) rats and SHR between 6 and 24 wk of age. Aortic proximal systolic and diastolic pressure, PP, and mean BP were significantly higher in SHR than in WKY rats and increased significantly with age (with the exception of PP). PP amplification increased with age but did not differ between strains. PWV was significantly associated with heart rate variability. PWV was significantly higher (via two-way variance analysis) in SHR than in WKY rats (strain effect) and increased markedly with age in both strains (age effect). Adjustment of PWV to mean BP attenuated markedly both the age and the strain effects. After adjustment for body weight, either alone or associated with mean BP, the age effect was not more significant, but the strain effect was markedly enhanced. In conscious unanesthetized SHR and WKY rats, aortic stiffness is consistently associated with body weight independent of age and mean BP. An intervention study should consider in the objectives systolic BP and PP amplifications measured in conscious animals, central control of body weight, and autonomic nervous system.

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Loginov, Yu N., S. I. Stepanov, and E. V. Khanykova. "Effect of Pore Architecture of Titanium Implants on Stress-Strain State upon Compression." Solid State Phenomena 265 (September 2017): 606–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.606.

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The problem of stress-strain state upon compression of implant of titanium alloy with cellular architecture was formulated by means of ABAQUS software and finite element analysis. The volume of the material was segmented on the unit cells characterized by specific configuration. The boundary conditions and physical equations were stated to describe the correlation between stresses and strains. The calculations of stress values, area reduction and mean stress were performed. The increased strain rates were revealed in horizontal pore cell walls. Joint simulating of several individual unit cells was provided. Zone seeing tensile stresses were observed in the segment of radius of the unit cell. The estimation of threatening sections location of the construction was conducted.

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Polák, Jaroslav, and Martin Petrenec. "Fatigue Behavior of Ferritic-Pearlitic-Bainitic Steel – Effect of Positive Mean Stress." Key Engineering Materials 417-418 (October 2009): 577–80. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.577.

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The fatigue properties of ferritic-pearlitic-bainitic steel using specimens produced from massive forging were measured in stress controlled regime with positive mean stress. The cyclic creep curves and cyclic hardening/softening curves were evaluated. The fatigue life was plotted in dependence on the mean stress and on the plastic strain amplitude. The principal contribution to the drop of the fatigue life with the mean stress is due to the increase of the plastic strain amplitude in cycling with mean stress.

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Li, J., Y. Qiu, X. Tong, and L. Gao. "An improved strain-energy density model considering the effect of mean stress." Materiali in tehnologije 54, no. 4 (2020): 513–19. http://dx.doi.org/10.17222/mit.2019.256.

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Xia, Z. "Effect of mean stress and ratcheting strain on fatigue life of steel." International Journal of Fatigue 18, no. 5 (1996): 335–41. http://dx.doi.org/10.1016/0142-1123(96)00088-6.

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Spätig, Philippe, Jean-Christophe Le Roux, Matthias Bruchhausen, and Kevin Mottershead. "Mean Stress Effect on the Fatigue Life of 304L Austenitic Steel in Air and PWR Environments Determined with Strain- and Load-Controlled Experiments." Metals 11, no. 2 (2021): 221. http://dx.doi.org/10.3390/met11020221.

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The mean stress effect on the fatigue life of 304L austenitic steel was evaluated at 300 °C in air and pressurized water reactor (PWR) environments. Uniaxial tests were performed in strain-control and load-control modes, with zero mean stress and a positive mean stress of 50 MPa. A specific procedure was used for the strain-controlled experiments to maintain the strain amplitude and mean stress constant. The strain-controlled data indicate that the application of positive mean stress decreases the fatigue life for a given strain amplitude in air and PWR environments. The data also show that the life reduction is independent of the environments, suggesting that no synergistic effects between the mean stress and the LWR environment occur. The load-controlled experiments confirm that the application of positive mean stress increases fatigue due to cyclic hardening processes. This observation is much less pronounced in the PWR environment. All data were analyzed using the Smith–Watson–Topper (SWT) stress–strain function, which was shown to correlate well with all strain- and load-controlled data with and without mean stress in each environment. In the SWT–life curve representation, the life reduction in the PWR environment was found fully consistent with the NUREG-CR6909 predictions.

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Bottger, A., M. den Bieman, Æ. Lankhorst, H. A. van Lith, and L. F. M. van Zutphen. "Strain-specific response to hypercholesterolaemic diets in the rat." Laboratory Animals 30, no. 2 (1996): 149–57. http://dx.doi.org/10.1258/002367796780865736.

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The cholesterolaemic effect of 2 hypercholesterolaemic diets was tested in 12 rat inbred strains. Diet I is a commercial diet supplemented with 2.0% (w/w) cholesterol and 5.0% (w/w) olive oil, diet II is identical to diet I with addition of 0.5% (w/w) sodium cholate. Strains with the highest plasma cholesterol response after diet I (BN and LEW) also had the highest cholesterol response after diet II (hyperresponders, mean response>3.5 mmol/l). In the strains DA, SHR, BC, WAC, LOU, PVG and BUF the strain mean cholesterol response remained below 1.3mmol/l after both diets (hyporesponders). Strains F344 and OM had an intermediate cholesterol response after both diets (normoresponders, mean response between 1.3 and 3.5 mmol/l). Only in the strains LOU, PVG and SHR there appeared to be a significant higher cholesterol response after diet II when compared with the cholesterol response after diet I. In the strain WKY this difference was of a borderline significance ( P=0.052) and this strain turned from a normoresponder after diet I into a hyperresponder after diet II. Liver cholesterol levels as measured after feeding diet II for two weeks also appeared to be strain-specific. No correlation was found between the plasma cholesterol response after diet II and the liver cholesterol levels. Changes in plasma phospholipid and triglyceride levels have been measured for both diet I and diet II. For group means a correlation between the cholesterol response and the change in phospholipid levels was found (r=0.86 for diet I, P<0.001 and r=0.76 for diet II, P<0.01). No such correlation was found for triglyceride levels.

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Pawliczek, Roland, and Tadeusz Lagoda. "Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions." Materials 14, no. 11 (2021): 2738. http://dx.doi.org/10.3390/ma14112738.

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The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

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Shu, Dong Wei, and Iram Raza Ahmad. "Effect of Specimen Dimensions in Dynamic Torsion Testing." Advanced Materials Research 97-101 (March 2010): 667–70. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.667.

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The effect of specimen’s mean radius to average wall-thickness ratio rs/t, has been studied using the Split Hopkinson Torsional Bar. The rs/t ratio was varied between 6.5 and 39 keeping the outer diameter and the gauge length of the specimen constant. Higher strain rates and strains are observed for specimens with larger specimen radius to wall-thickness ratio rs/t. However no monotonic trend of the shear stress with rs/t variation is found. A sharp decrease in the torsional stiffness of the specimen is observed with increasing the specimen’s rs/t ratio. The rs/t ratio can also be used as a useful dimension to enhance the strain rate in tubular specimens.

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Skoczen, B. "Generalization of the Coffin Equations With Respect to the Effect of Large Mean Plastic Strain." Journal of Engineering Materials and Technology 118, no. 3 (1996): 387–92. http://dx.doi.org/10.1115/1.2806825.

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Introduction of a correction factor accounting for large mean plastic strain to the kinetic law for the rate of damage per cycle is proposed. Integration of the corrected kinetic damage law under the assumption of a stable hysteresis loop (constant strain amplitude, constant mean plastic strain) leads to a generalized Coffin-Manson formula. The formula is useful for calculation of the fatigue life of structures after transition of transient ratchetting to the plastic shakedown state. Integration of the damage law is performed also for the case of superimposed cyclic and monotonic strain. The results of calculations are compared with the experimental results reported by Coffin (1970) and described by the author using a quasilinear criterion. An improved fatigue failure criterion for this case is presented and a good convergence with the results of tests for Nickel A samples is shown.

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Ting, D. S. K., and M. D. Checkel. "The Effect of Mean Turbulent Strain Rate on the Flame Speed of Premixed, Growing Flames." Journal of Engineering for Gas Turbines and Power 123, no. 1 (2000): 175–81. http://dx.doi.org/10.1115/1.1339990.

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This paper presents a flame growth model based on experimental measurements of flame speed and mean turbulent strain rate. Methane/air mixtures of 0.7 and 0.9 equivalence ratios were centrally spark-ignited in a 125 mm cubical chamber. Based on schlieren images and combustion pressure traces, a linear correlation was found between the turbulent flame speed and the turbulent strain rate. For these unity-Lewis-number and near-zero-Markstein-number flames, the effectiveness of turbulent strain in enhancing the flame speed was found to increase linearly with the mean flame radius over the range of conditions tested.

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PARK, SUNG HYUK, SEONG-GU HONG, BYOUNG HO LEE, and CHONG SOO LEE. "FATIGUE LIFE PREDICTION OF ROLLED AZ31 MAGNESIUM ALLOY USING AN ENERGY-BASED MODEL." International Journal of Modern Physics B 22, no. 31n32 (2008): 5503–8. http://dx.doi.org/10.1142/s0217979208050723.

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Fatigue behavior of rolled AZ31 magnesium alloy, which shows an anisotropic deformation behavior due to the direction dependent formation of deformation twins, was investigated by carrying out stress and strain controlled fatigue tests. The anisotropy in deformation behavior introduced asymmetric stress-strain hysteresis hoops, which make it difficult to use common fatigue life prediction models, such as stress and strain-based models, and induced mean stress and/or strain even under fully-reversed conditions; the tensile mean stress and strain were found to have a harmful effect on the fatigue resistance. An energy-based model was used to describe the fatigue life behavior as strain energy density was stabilized at the early stage of fatigue life and nearly invariant through entire life. To account for the mean stress and strain effects, an elastic energy related to the mean stress and a plastic strain energy consumed by the mean strain were appropriately considered in the model. The results showed that there is good agreement between the prediction and the experimental data.

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Servetnik, A. N. "A Walker-based mean strain correction models for low-cycle fatigue life prediction." Industrial laboratory. Diagnostics of materials 89, no. 1 (2023): 67–73. http://dx.doi.org/10.26896/1028-6861-2023-89-1-67-73.

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A Walker-based mean strain correction model of low-cycle fatigue (LFC) life prediction is proposed for high loaded parts. The model is based on a function depending on the strain range and strain ratio controlled in the strain-controlled LCF test of fatigue specimens and a constant reflecting the material sensitivity to strain ratio. The independence from the stress cycle parameters which can change during the strain-controlled LCF test is an obvious advantage of the model. The model was verified using the results of strain-controlled LCF tests of smooth titanium alloy Ti-6A1-4V ELI and iron-based alloy specimens conducted at room temperature. The proposed model was compared to the Smith - Watson - Topper and Walker models that take into account the mean stress effect. The proposed model provided the best prediction accuracy for titanium alloy. For Iron-based alloys the results obtained by the Walker model and the model proposed are close to each other. A simplified model based on the analysis of model parameters tailing into account the mean strain effect for predicting fatigue life of aeroengine critical parts is developed using a limited amount of experimental data when only the results of Rε = 0 tests are known. A comparison of the predicted life with the number of cycles to failure showed satisfactory results of fatigue life prediction for Ti-6A1-4V ELI and Iron-based alloys specimens.

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Zhu, Shun-Peng, Qiang Lei, Hong-Zhong Huang, Yuan-Jian Yang, and Weiwen Peng. "Mean stress effect correction in strain energy-based fatigue life prediction of metals." International Journal of Damage Mechanics 26, no. 8 (2016): 1219–41. http://dx.doi.org/10.1177/1056789516651920.

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NOLTING, A. E., and D. L. DU QUESNAY. "THE EFFECT OF MEAN STRAIN FATIGUE DAMAGE CAUSED BY FULLY OPEN LOADING CYCLES." Canadian Metallurgical Quarterly 44, no. 2 (2005): 195–204. http://dx.doi.org/10.1179/cmq.2005.44.2.195.

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Rutherford, B. A., A. R. Cisko, P. G. Allison, and J. B. Jordon. "Effect of Tensile Mean Strain on Fatigue Behavior of Al-Li Alloy 2099." Journal of Materials Engineering and Performance 29, no. 8 (2020): 4928–33. http://dx.doi.org/10.1007/s11665-020-04983-8.

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Ariyama, Takashi. "Effect of mean strain on the cyclic deformation and stress relaxation in polypropylene." Polymer Engineering and Science 35, no. 18 (1995): 1455–60. http://dx.doi.org/10.1002/pen.760351805.

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Tsuji, Nobuhiro, Naoya Kamikawa, and Yoritoshi Minamino. "Effect of Strain on Deformation Microstructure and Subsequent Annealing Behavior of IF Steel Heavily Deformed by ARB Process." Materials Science Forum 467-470 (October 2004): 341–48. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.341.

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Ultra low-carbon interstitial free (IF) steel having ferrite (b.c.c.) single phase was deformed to various equivalent strains ranging from 0.8 to 5.6 by the accumulative roll bonding (ARB) process at 500°C. The microstructure and crystallographic feature of the deformed specimens were characterized mainly by FE-SEM/EBSD analysis. Grain subdivision during the plastic deformation up to very high strain was clarified quantitatively. After heavy deformation above 4.0 of strain, the specimens showed the lamellar boundary structure uniformly, in which the mean spacing of the lamellar boundaries was about 200nm and more than 80% of the boundaries were high-angle ones. Annealing behavior of the ARB processed IF steel strongly depended on the strain. The specimens deformed to medium strains exhibited discontinuous recrystallization characterized by nucleation and growth, while the specimens deformed above strain of 4.0 showed continuous recrystallization. The recrystallization behaviors are discussed on the basis of the microstructural and crystallographic parameters quantitatively measured in the as-deformed samples.

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Wang, C. H. "Effect of Stress Ratio on Short Fatigue Crack Growth." Journal of Engineering Materials and Technology 118, no. 3 (1996): 362–66. http://dx.doi.org/10.1115/1.2806819.

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A model of short fatigue crack growth is proposed, which is based on the blocked slip concept and the shear decohesion mechanism. The analysis is extended to the case of mean stress loading. A theoretical proof is presented for the transfer of slip bands across grain boundaries. The rate of growth is proportional to the shear strain range and the maximum plastic zone size. There are no adjustable parameters in the theory for the case of high strain level, when the plastic strain dominates the decohesion process. Otherwise only one constant is needed, which may be derived from long crack growth data. The model is shown to provide satisfactory predictions of experimental results under uniaxial loading with various stress amplitudes and mean stresses.

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Pearce, Lindsay E., H. Tuan Truong, Robert A. Crawford, Gary F. Yates, Sonia Cavaignac, and Geoffrey W. de Lisle. "Effect of Turbulent-Flow Pasteurization on Survival of Mycobacterium avium subsp.paratuberculosis Added to Raw Milk." Applied and Environmental Microbiology 67, no. 9 (2001): 3964–69. http://dx.doi.org/10.1128/aem.67.9.3964-3969.2001.

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ABSTRACT A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity ofMycobacterium avium subsp.paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated in raw whole milk for 15 s at 63, 66, 69, and 72°C in duplicate trials. No strains survived at 72°C for 15 s; and only one strain survived at 69°C. Means of pooled Dvalues (decimal reduction times) at 63 and 66°C were 15.0 ± 2.8 s (95% confidence interval) and 5.9 ± 0.7 s (95% confidence interval), respectively. The mean extrapolatedD 72°C was <2.03 s. This was equivalent to a >7 log10 kill at 72°C for 15 s (95% confidence interval). The mean Z value (degrees required for the decimal reduction time to traverse one log cycle) was 8.6°C. These five strains showed similar survival whether recovery was on Herrold's egg yolk medium containing mycobactin or by a radiometric culture method (BACTEC). Milk was inoculated with fresh fecal material from a high-level fecal shedder with clinical Johne's disease. After heating at 72°C for 15 s, the minimum M. avium subsp.paratuberculosis kill was >4 log10. Properly maintained and operated equipment should ensure the absence of viable M. avium subsp. paratuberculosisin retail milk and other pasteurized dairy products. An additional safeguard is the widespread commercial practice of pasteurizing 1.5 to 2° above 72°C.

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Lee, C. M., Á. Gylfason, P. Perlekar, and F. Toschi. "Inertial particle acceleration in strained turbulence." Journal of Fluid Mechanics 785 (November 12, 2015): 31–53. http://dx.doi.org/10.1017/jfm.2015.579.

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The dynamics of inertial particles in turbulence is modelled and investigated by means of direct numerical simulation of an axisymmetrically expanding homogeneous turbulent strained flow. This flow can mimic the dynamics of particles close to stagnation points. The influence of mean straining flow is explored by varying the dimensionless strain rate parameter $Sk_{0}/{\it\epsilon}_{0}$ from 0.2 to 20, where $S$ is the mean strain rate, $k_{0}$ and ${\it\epsilon}_{0}$ are the turbulent kinetic energy and energy dissipation rate at the onset of straining. We report results relative to the acceleration variances and probability density functions for both passive and inertial particles. A high mean strain is found to have a significant effect on the acceleration variance both directly by an increase in the frequency of the turbulence and indirectly through the coupling of the fluctuating velocity and the mean flow field. The influence of the strain on the normalized particle acceleration probability distribution functions is more subtle. For the case of a passive particle we can approximate the acceleration variance with the aid of rapid-distortion theory and obtain good agreement with simulation data. For the case of inertial particles we can write a formal expression for the accelerations. The magnitude changes in the inertial particle acceleration variance and the effect on the probability density function are then discussed in a wider context for comparable flows, where the effects of the mean flow geometry and of the anisotropy at small scales are present.

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Leszczyńska-Madet, B., and M. Richert. "The Effect of Dynamic Compression on the Evolution of Microstructure in Aluminium and its Alloys." Archives of Metallurgy and Materials 58, no. 4 (2013): 1097–103. http://dx.doi.org/10.2478/amm-2013-0132.

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Abstract In the work, the microstructure and selected properties of aluminium and its alloys (AlCu4Zr0.5, AlMg5, AlZn6Mg2.5CuZr) deformed with high strain rate were investigated. The cylindrical samples were compressed by a falling - weight-type impact-testing machine at the strain rate ranging from 1.77-6.06x102 s-1 in order to attain true strains between Φ = 0 - 0.62. After compression, the microhardness of the samples was tested and the microstructure was examined by means of both optical (LM) and transmission electron microscopy (TEM). Additionally the misorientation of selected microstructural elements using proprietary KILIN software was determined. The large density of shear bands, bands and microbands was the characteristic feature of the microstructure. The statistical width of the microbands observed in the microstructure was calculated using the mean chord method. The obtained data demonstrate reduction of the microbands width with the increase of deformation. The main object of investigations concerns the microstructure elements refinement affected by dynamic compression.

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Gibson, M. M., and B. A. Younis. "Calculation of Boundary Layers With Sudden Transverse Strain." Journal of Fluids Engineering 108, no. 4 (1986): 470–75. http://dx.doi.org/10.1115/1.3242605.

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Modifications to a Reynolds stress closure are proposed in which the weighting of the two components of the pressure-strain correlation is adjusted: the turbulence part is increased to conform with measured rates of return to isotropy and the contribution from the mean-strain part is reduced. Consequential changes are then needed in the other closure assumptions. Their effect is to make the model more generally applicable and to improve predictions of turbulent flows in complex strain fields. The revised model is tested here against the measured response of axisymmetric boundary layers to suddenly imposed rotation. The wall region of this flow is resolved by means of wall functions where it is assumed that the directions of the shear stress and the mean-strain rate are coincident.

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Liljedahl, L. E., R. W. Fairfull, and R. S. Gowe. "Age-regulated expression of genetic and environmental variation in fitness traits. 1. Genetic effects and variances for egg production in a factorial mating of six selected Leghorn strains." Canadian Journal of Animal Science 79, no. 3 (1999): 253–67. http://dx.doi.org/10.4141/a97-103.

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White Leghorn strains were crossed reciprocally in a complete factorial mating system producing 6 pure strains and 30 strain-crosses, which were kept in individual cages for two laying cycles, 133–496 and 547–909 d of age. The egg production in the second cycle (C2) of the various genotypes started about 10 – 20% lower and had a more linear and less persistent course than in the first cycle (C1). Strains exhibited very different patterns of age changes in both additive and non-additive genetic effects as well as in cytoplasmic effects. The additive autosomal and sex-linked genes (Ai and Zi) active in one laying cycle were quite different from those active in the other laying cycle as shown by low strain genetic correlations between their effects in C1 and C2. Further, the sets of Ai and Zi genes responded with effects quite opposite to each other in both C1 and C2 as indicated by highly negative strain genetic correlations between the Ai and Zi effects. The average non-additive genetic effect of sire strain i or dam strain j over all its crosses with other strains (hi) and the non-additive genetic effect due to the specific combination of genes occurring in each of the two reciprocal crosses between strain i and strain j (sij), showed very divergent patterns of age changes with a conspicuously greater divergence as age advanced. The overall non-additive genetic effect (mean heterosis) increased significantly with age across the two cycles. The strain crosses that most successfully maintained their rate of lay until the end of C2, also most successfully developed a rising age trend for total heterosis. The non-additive genes active in one laying cycle were significantly different from those active in the other laying cycle as shown by the moderately low strain genetic correlations between their effects in C1 and C2. The genotypic variance and its various components increased markedly with age, however, with a tendency to reach a plateau towards the end of both the first and the second laying cycle. The environmental variance increased parallel to the genotypic variance. Consequently, the phenotypic variance followed the same pattern of age changes. The results are discussed in relation to the theoretical aspects of ageing genetics. A model compatible with all the age trends of the genetic and environmental effects and variances is set up, assuming that ageing is composed of two main opposing forces. Finally, the results are briefly discussed from the animal breeding point of view. Key words: Ageing, fitness, laying hens, genetic effects, variation, expression

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Wen, Liwei. "Effect of Mean Grain Size on the Small-Strain Dynamic Properties of Calcareous Sand." Advances in Civil Engineering 2022 (July 18, 2022): 1–15. http://dx.doi.org/10.1155/2022/9291890.

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Calcareous sand was selected as the prior material for island reclamation in many coastal regions. The mechanical properties of the granular materials are greatly affected by their grain size distribution conditions. The shear modulus and damping ratio are two important parameters for earthquake ground response analysis and liquefaction evaluation. A series of resonant column tests had been performed on calcareous sands with varying median grain diameter and uniform coefficient. The dependence of the shear modulus and damping ratio of the calcareous sand on grain size has been confirmed in this examination. The test results reveal that the shear modulus decreases with a rise in shear strain for calcareous sand samples at a given confining pressure and relative density. The maximum shear modulus tends to increase with confining pressure and relative density. On the maximum shear modulus and void ratio plane, the trend lines of the measured results shift toward up and right position with a rise in grain diameter. The measured results indicate that the influence of uniform coefficient on the maximum shear modulus is neglectable. A revised empirical equation based on the Hardin model had been proposed considering the influence of grain diameter to estimate the maximum shear modulus of calcareous sand. The predicted values show satisfactory agreement with the measured results. The results manifest that the effect of grading condition on small-strain dynamic properties of calcareous sands cannot be neglected for the evaluation of seismic safety for reclamation engineering sites.

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KOMOTORI, Jun, and Masao SHIMIZU. "Grain size effect in the low cycle fatigue of a steel under mean strain." Transactions of the Japan Society of Mechanical Engineers Series A 55, no. 511 (1989): 401–8. http://dx.doi.org/10.1299/kikaia.55.401.

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IMAMURA, Koichi, and Osamu WARANABE. "710 Effect of mean strain on fatigue strength of perforated plate at elevated temperature." Proceedings of Ibaraki District Conference 2012.20 (2012): 193–94. http://dx.doi.org/10.1299/jsmeibaraki.2012.20.193.

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LUKAS, P., and L. KUNZ. "Effect of mean stress on cyclic stress-strain response and high cycle fatigue life." International Journal of Fatigue 11, no. 1 (1989): 55–58. http://dx.doi.org/10.1016/0142-1123(89)90048-0.

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Santamarina, J. C., and G. Cascante. "Stress anisotropy and wave propagation: a micromechanical view." Canadian Geotechnical Journal 33, no. 5 (1996): 770–82. http://dx.doi.org/10.1139/t96-102-323.

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Wave propagation is a constant-fabric macrophenomenon, suitable to microinterpretation. Both velocity and attenuation characterize state, including inherent and stress-induced anisotropy. The purpose of this research is to study the effect of isotropic and deviatoric stresses on wave propagation in particulate materials at low strains and to interpret results at the microlevel. A resonant-column device was midified to allow for the application of axial extension and axial compression deviatoric loading. The fixed-free boundary condition of the sample was maintained. Data for round, hard-grained sand show that shear wave velocity and attenuation are primarily dependent on the mean stress on the polarization plane, with minimal effect of the deviatoric component, in agreement with prior observations at stress ratios less than 23. Attenuation is strongly correlated with the mean stress in the polarization plane and the level of shear strain. Damping does not vanish at low strains, contrary to predictions based on hysteretic behaviour; hence, other loss mechanisms must take place at low strains. Low-strain wave parameters are adequately corrected for mid-strain using modified hyperbolic models. Measured velocity and damping trends during isotropic and anisotropic loading qualitatively agree with predictions based on regular arrays. Key words: mechanical waves, resonant column, damping, shear modulus, stress anisotropy, random vibration.

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Ni, Hai, and Zhirui Wang. "Dislocation mechanisms of mean stress effect on cyclic plasticity." Materials Testing 46, no. 7-8 (2004): 363–73. http://dx.doi.org/10.1515/mt-2004-0363.

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Abstract The dislocation mechanisms behind sagging behavior of autosuspension spring steels are far from being understood due to their complicated microstructures. In this study, systematic cyclic loading tests were carried out on two model materials - industrial pure iron and spheroidized 1045 steel – to understand the mechanisms behind sagging. It is found that it is the different dislocation microstructures that control the cyclic creep behavior of different materials. With iron samples with low mean stress values, higher mean stresses do not trigger cell structure formation mainly due to the little requirement for high plastic strain amplitude and hence the lack of necessity for high dislocation density, and a large number of dislocation interactions through large mobile dislocations. In the case of the 1045 steel samples, the collapse of pre-existent substructures and the movement of newly generated mobile dislocations are the main reasons for the cyclic softening observed. The massive reorganization process of dislocation configurations and the competition between softening and hardening both carry on throughout the entire cycling process, but the softening process is found to be the predominant factor.

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Zhang, Junhong, Weidong Li, Huwei Dai, Nuohao Liu, and Jiewei Lin. "Study on the Elastic–Plastic Correlation of Low-Cycle Fatigue for Variable Asymmetric Loadings." Materials 13, no. 11 (2020): 2451. http://dx.doi.org/10.3390/ma13112451.

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The mean stress effect in fatigue life varies by material and loading conditions. Therefore, a classical low cycle fatigue (LCF) model based on mean stress correction shows limits in asymmetric loading cases in both accuracy and applicability. In this paper, the effect of strain ratio (R) on LCF life is analyzed and a strain ratio-based model is presented for asymmetric loading cases. Two correction factors are introduced to express correlations between strain ratio and fatigue strength coefficient and between strain ratio and fatigue ductility coefficient. Verifications are conducted through four materials under different strain ratios: high-pressure tubing steel (HPTS), 2124-T851 aluminum alloy, epoxy resin and AZ61A magnesium alloy. Compared with current widely used LCF models, the proposed model shows a better life prediction accuracy and higher potential in implementation in symmetric and asymmetric loading cases for different materials. It is also found that the strain ratio-based correction is able to consider the damage of ratcheting strain that the mean stress-based models cannot.

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Pawliczek, Roland. "Influence of the Mean Load Value in Fatigue Block Loading on Strains." Key Engineering Materials 598 (January 2014): 195–200. http://dx.doi.org/10.4028/www.scientific.net/kem.598.195.

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This paper presents the results of the fatigue tests of the specimens made from S3555 steel and aluminum alloy AlCu4MgSi subjected to bending block loading with mean load value. The influence of the changes of the mean load conditions was investigated. During the tests strains were registered and relation between the load and the strains was analyzed. In the case of S355 steel it was observed, that additional hardening occurs when higher value of the mean load is applied at the beginning of the block loading. Other case, when the mean load was increased from zero to maximum, a creep effect of the material was registered. For the specimens made from aluminum alloy similar processes were not observed. The strain levels are almost the same apart from changes of the mean load in load sequence and the fatigue life of the specimens is the same.

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Dai, Xiang Sheng, and Jian Min Ma. "Behaviour of Tube under Axial Crush Load with Considering Effect of Heat Exchanged." Applied Mechanics and Materials 141 (November 2011): 224–32. http://dx.doi.org/10.4028/www.scientific.net/amm.141.224.

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Based on Johnson-Cook constitutive equation energy absorbed by tubes under axial crush load is studied by using Singace fold model with considering strengthening effects of strain rate,strengthening effects of strain and softening effect of temperature which should consider heat exchanged ; the total energy absorbed by tubes,mean load and load-displacement curve are obtained by method of divided step fold; and the relation between them and radius of tube,thickness of tube,fold velocity of tube is analysed.

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Cho, Byung W., Kyoung-Tak Kang, Hyuck M. Kwon, et al. "Biomechanical effect of anatomical tibial component design on load distribution of medial proximal tibial bone in total knee arthroplasty." Bone & Joint Research 11, no. 5 (2022): 252–59. http://dx.doi.org/10.1302/2046-3758.115.bjr-2021-0537.r1.

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Aims This study aimed to identify the effect of anatomical tibial component (ATC) design on load distribution in the periprosthetic tibial bone of Koreans using finite element analysis (FEA). Methods 3D finite element models of 30 tibiae in Korean women were created. A symmetric tibial component (STC, NexGen LPS-Flex) and an ATC (Persona) were used in surgical simulation. We compared the FEA measurements (von Mises stress and principal strains) around the stem tip and in the medial half of the proximal tibial bone, as well as the distance from the distal stem tip to the shortest anteromedial cortical bone. Correlations between this distance and FEA measurements were then analyzed. Results The distance from the distal stem tip to the shortest cortical bone showed no statistically significant difference between implants. However, the peak von Mises stress around the distal stem tip was higher with STC than with ATC. In the medial half of the proximal tibial bone: 1) the mean von Mises stress, maximum principal strain, and minimum principal strain were higher with ATC; 2) ATC showed a positive correlation between the distance and mean von Mises stress; 3) ATC showed a negative correlation between the distance and mean minimum principal strain; and 4) STC showed no correlation between the distance and mean measurements. Conclusion Implant design affects the load distribution on the periprosthetic tibial bone, and ATC can be more advantageous in preventing stress-shielding than STC. However, under certain circumstances with short distances, the advantage of ATC may be offset. Cite this article: Bone Joint Res 2022;11(5):252–259.

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Opalić, Milan, Krešimir Vučković, and Dragan Žeželj. "Effect of Rotational Speed on Thin-Rim Gear Bending Fatigue Crack Initiation Life." Key Engineering Materials 488-489 (September 2011): 456–59. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.456.

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Thin-rim gears are often used in aircraft applications in order to reduce weight. The objective of this study is to investigate the effect of rotational speed (centrifugal force) on bending fatigue crack initiation life of thin-rim gear manufactured from case carburized 14NiCrMo13-4 steel. Stresses in gear are determined from two-dimensional finite element model, assuming plane stress conditions. The fact that, in actual thin-rim gear operation, a significant reversed stress occurs at the root of the tooth adjacent to the loaded tooth is considered. Material is assumed to be homogenous, isotropic and linear elastic. Elastic strains are calculated from obtained stresses and corrected using Neuber’s rule to account plasticity effects. The number of load cycles required to initiate bending fatigue crack is predicted using strain-life approach for variety of gear rotational speeds and rim thicknesses. Strain-controlled fatigue properties were approximated from material hardness, while the mean stress as well as residual stress effects are included through Morrow’s mean stress correction. The proposed approach is validated by comparison with available experimental data from literature and used for parametric studies. Predicted numbers of load cycles required to initiate potential bending fatigue crack are presented for the variety of cases studied.

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Nikulin, Ilya, та Takahiro Sawaguchi. "Strain Ratio Effect on the Low Cycle Fatigue Behavior and Microstructure of High-Mn Austenitic Alloy Undergoing the Strain-Induced ε-Martensitic Transformation". Materials Science Forum 941 (грудень 2018): 1065–70. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1065.

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The effect of the strain asymmetry on low-cycle fatigue properties and microstructure of Fe–15Mn–10Cr–8Ni–4Si (in. wt. %) alloy undergoing the strain-induced ε-martensitic transformation (ε-MT) were investigated at strain ratios,R, of-1, -0.2, 0.2 and 0.5 under total strain-control mode with total strain amplitude of 0.01. At studied strain ratios the clear asymmetry in tension and compression stress providing tensile mean stress was observed in alloy deformed atRof-0.2, 0.2 and 0.5. The mean stress rapidly decreases to ~ 100 cycles and remain almost zero until failure. It was found that strain-induced ε-martensitic transformation and lattice rotation of austenite provide cyclic hardening of the studied alloy leading to the mean stress relaxation and provides the stability in hysteresis loops behavior at studiedR. As a consequence, the fatigue life,Nf, of the alloy remains on the level of the alloy deformed by LCF atR, of -1 (NfR=-1=9200 cycles). The details of the fatigue behavior, deformation mechanisms and microstructure evolution of the studied alloy are discussed.

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