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Journal articles on the topic 'Mean stress method'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Papuga, Jan, Ivona Vízková, Maxim Lutovinov, and Martin Nesládek. "Mean stress effect in stress-life fatigue prediction re-evaluated." MATEC Web of Conferences 165 (2018): 10018. http://dx.doi.org/10.1051/matecconf/201816510018.

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The paper compares various methods for computing the equivalent stress amplitude for stress cycles of non-zero mean value in stress-life fatigue prediction. A set of 11 calculation methods is evaluated. In addition to formulations based on common static or fatigue properties, the Walker formula and the generalized Linear formula are included in the investigation. These two methods use an optimization routine to find the material parameters. The final response of the methods is compared and discussed. The Walker method provides a better solution. The generalized Linear method produces inferior results, i.e. the linear fit of the segment of the Haigh diagram is not an optimal solution.

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2

Yamamoto, Norio, and Kazuyoshi Matsuoka. "Fatigue Assessment Method considering an Effect of Mean Stress." Journal of the Society of Naval Architects of Japan 2001, no. 190 (2001): 499–505. http://dx.doi.org/10.2534/jjasnaoe1968.2001.190_499.

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3

Burger, Robert, and Yung-Li Lee. "Assessment of the Mean-Stress Sensitivity Factor Method in Stress-Life Fatigue Predictions." Journal of Testing and Evaluation 41, no. 2 (January 2013): 20120035. http://dx.doi.org/10.1520/jte20120035.

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4

Munday, Edgar G. "The Effect of Mean Stress Components in High-Cycle, Biaxial Fatigue." International Journal of Mechanical Engineering Education 31, no. 2 (April 2003): 177–86. http://dx.doi.org/10.7227/ijmee.31.2.10.

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A new method is presented to obtain the effect of mean stress components in high-cycle, biaxial fatigue. It is assumed that the time-varying stress state can be represented as a superposition of mean components, and proportionally applied alternating components. The method takes into account the relative orientation of the mean and alternating principal stress axes by making the ‘equivalent mean stress’ depend on the alternating components as well as the mean stress components. The method correlates well with the available data. The new method is compared with three popular methods.

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5

Wang, Yu Sheng, Wen Xuan Ma, Ming Li, and Hao Jin. "Method of Life Prediction of Engine Cylinder Cover." Advanced Materials Research 677 (March 2013): 236–40. http://dx.doi.org/10.4028/www.scientific.net/amr.677.236.

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Cylinder cover is an important component of the engine. It is damaged by low cycle thermal fatigue, high cycle thermal fatigue and creep in operation. Thus, the life and reliability of the cylinder cover are important criteria for engines. The temperature field and stress field of the cylinder cover are computed by the sequentially coupled analysis method: the elastic strain, plastic strain and creep strain of the dangerous point on the cylinder cover are analyzed in ten startup-working-shut down cycles; and it is proved in theory that low cycle thermal fatigue is the primary factor affecting the service life of the cylinder cover and the startup time of the engine is an appropriate parameter to estimate the life of thecylinder cover. The creep has little influence on the stress amplitude, and makes the mean stress increased. The relaxation is coexisting with creep in high temperature; it reduces the increase speed of mean stress. After finite cycles, the mean stress tends to constant gradually. Therefore, the creep-fatigue interaction can equal to thermo-mechanical fatigue whose stress amplitude and mean stress are constant. At last, the mean service life of cylinder is predicted.

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6

IWASA, Masaki, and Toshio HATTORI. "Evaluation Method for Fatigue Strength of FRP/MetalAdhesive Joints Considering Mean Stress." Journal of The Adhesion Society of Japan 39, no. 5 (2003): 177–82. http://dx.doi.org/10.11618/adhesion.39.177.

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7

Iwasa, Masaaki, and Toshio Hattori. "Evaluation Method for Fatigue Strength of FRP/Metal Adhesive Joints Considering Mean Stress." Journal of Engineering Materials and Technology 125, no. 4 (September 22, 2003): 402–5. http://dx.doi.org/10.1115/1.1605114.

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The fatigue strength of two types of FRP/metal adhesive joints at low temperature, a double lap joint and an embedded joint, was evaluated analytically and experimentally. First, the stress singularity parameters of the delamination edges under mechanical and thermal loadings were analyzed by FEM for various delamination lengths. The delamination propagation rate of the double lap joint under mechanical cyclic loadings at room temperature was measured. Using the relationship between the measured propagation rates and the analyzed ranges of stress singularity intensity, we estimated the fatigue strength of the embedded joint, which coincided well with the measured one. Second, we developed an evaluation method that separates the effects of temperature on fatigue strength into two effects: thermal residual stress and low temperature. Third, the fatigue strengths of the double lap joints were measured for various mean stresses. Fatigue limit of adhesive joints was experimentally measured and compared with analytical intensity of stress singularity. A method for evaluating the fatigue strength of adhesive joints by taking mean stress into account was developed.

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8

Najem Clarke, Shima, David W. Goodpasture, Richard M. Bennett, J. Harold Deatherage, and Edwin G. Burdette. "Effect of Cycle-Counting Methods on Effective Stress Range and Number of Stress Cycles for Fatigue-Prone Details." Transportation Research Record: Journal of the Transportation Research Board 1740, no. 1 (January 2000): 49–60. http://dx.doi.org/10.3141/1740-07.

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Two important parameters in fatigue life evaluations of existing steel highway bridges are the number of stress cycles experienced and the effective stress range. The inaccuracies in predicting remaining fatigue life can be attributed to either one of these two parameters. However, the AASHTO guide specification has no provisions for the cycle-counting methods to be used to determine these two parameters. A sensitivity analysis that addresses the effects of cycle-counting methods on the effective stress range and the number of cycles for various fatigue-prone details in both main and secondary bridge members is described. A comparison of five cycle-counting methods (level-crossing counting, peak counting, simple-range counting, mean-crossing-peak counting, and rain-flow counting) by using a simple variable-amplitude strain-time history showed that both the stress range and the number of cycles are sensitive to cycle-counting methods. Two of the most commonly used cycle-counting techniques for highway bridge variable-amplitude loading are the mean-crossing-peak and the rainflow cycle-counting methods. A comparison of the two methods by using field data taken under normal traffic showed that the rainflow cycle-counting method is more conservative than the mean-crossing-peak method. The relationship between the mean-crossing-peak and the rainflow cycle-counting methods was determined in the form of a correlation coefficient and a linear regression line. There is a nearly perfect positive correlation between the two methods. Therefore, values obtained for the effective stress range and the number of cycles by the mean-crossing-peak method can be converted to values for the rainflow method.

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9

SUGAWARA, MOTOAKI, and KIYOHARU NAKANO. "A method of analyzing regional myocardial function : Mean wall stress-area strain relationship." Japanese Circulation Journal 51, no. 1 (1987): 120–24. http://dx.doi.org/10.1253/jcj.51.120.

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10

Zhao, Ping, and Hong Wen Yan. "Application Research on Haigh Diagram in the Wind Turbine Fatigue Analysis." Applied Mechanics and Materials 190-191 (July 2012): 931–35. http://dx.doi.org/10.4028/www.scientific.net/amm.190-191.931.

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The influence of mean stress on fatigue has to be considered by means of Haigh diagram, the actual stress range is modified to damage-equivalent range. There are three main methods for creating Haigh diagram, such as experiment and empirical relationships and six points, which has the different application field. The creating and application of Haigh diagram in GL certification for wind turbines is studied, and the solving method for the mean stress sensitivity is given.

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11

Hatanaka, Kenji, Junji Ogi, and Asanori Miyazaki. "Analysis of Crack Growth under Cyclic Loading with Mean Stress by Means of Elastic-Plastic Finite-Element Method." Transactions of the Japan Society of Mechanical Engineers Series A 59, no. 566 (1993): 2241–47. http://dx.doi.org/10.1299/kikaia.59.2241.

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12

Papuga, Jan, Lukáš Suchý, and Milan Růžička. "Mean shear stress effect built into the multiaxial fatigue strength estimation method of an integral type." MATEC Web of Conferences 300 (2019): 16010. http://dx.doi.org/10.1051/matecconf/201930016010.

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The effect of mean shear stress is implemented into the PIR criterion [1-2]. Results of the new solution are only slightly worse than the similarly improved PCN criterion described in [3]. Five methods of the integral type known to the author (PIR + new PIN, the Fogue method, the Liu & Zenner method, the Papadopoulos method) are evaluated here on a large set of experimental data (286 items). Because the integral solution is easier to handle, the simplified reduced formulas of each criterion for the case of purely axial loading are presented. Their relations each to other, and also to other common uniaxial mean stress effect methods are then studied and small numerical benchmark convening this load condition is prepared.

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13

Wang, Y. D., R. Lin Peng, and R. L. McGreevy. "A novel method for constructing the mean field of grain-orientation-dependent residual stress." Philosophical Magazine Letters 81, no. 3 (March 2001): 153–63. http://dx.doi.org/10.1080/09500830010017088.

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14

Niesłony, A., and M. Böhm. "Universal Method for Applying the Mean-Stress Effect Correction in Stochastic Fatigue-Damage Accumulation." Materials Performance and Characterization 5, no. 3 (July 5, 2016): MPC20150049. http://dx.doi.org/10.1520/mpc20150049.

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15

Wang, Min-Zhong, Bai-Xiang Xu, and Bao-Sheng Zhao. "On the Generalized Plane Stress Problem, the Gregory Decomposition and the Filon Mean Method." Journal of Elasticity 108, no. 1 (September 11, 2011): 1–28. http://dx.doi.org/10.1007/s10659-011-9352-3.

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16

Chen, Dai-Heng. "Consideration to the mean stress based line method for estimating the notch fatigue limit." Theoretical and Applied Fracture Mechanics 112 (April 2021): 102921. http://dx.doi.org/10.1016/j.tafmec.2021.102921.

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17

Song, Sam Hong, and Jin Bong Kim. "Stress Effects on Activity of Primary Cracks Initiating at Stress Concentrator." International Journal of Modern Physics B 17, no. 08n09 (April 10, 2003): 1567–72. http://dx.doi.org/10.1142/s0217979203019332.

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This study has been performed to investigate the stress distribution around defects that behave as stress concentrators and fracture mechanical analysis for cracks initiating at stress concentrators. The stress distribution was analyzed using Finite Element Method and non-dimensional stress intensity factor was determined by the mean stress method. This method could be applied to determine the activity of primary crack initiated at the stress concentrator in experiment. In addition, stress interaction effects around defects and cracks were compared.

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18

Pejkowski, Łukasz, and Dariusz Skibicki. "Multiaxial Fatigue Life Assessment Method Based on the Mean Value of Modified Second Invariant of the Deviatoric Stress." Solid State Phenomena 224 (November 2014): 15–20. http://dx.doi.org/10.4028/www.scientific.net/ssp.224.15.

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Stress invariants approach to the multiaxial fatigue life estimation is generally based on the root mean square value of second invariant of the deviatoric stress amplitude and the value of hydrostatic stress. Such an approach omits a significant part of the information about multiaxial load history. It is particularly noticeable in case of non-proportional loadings, which lead to a reduction of fatigue life (i.e. [1–3]). In this work a new method based on the mean value of modified second invariant of the deviatoric stress has been presented.

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19

Ogata, Chihiro, Kenji Shojima, and Keiji Yanase. "Estimation for Fatigue Behavior of Notched Plate with Mean Stress Effect." Materials Science Forum 750 (March 2013): 256–59. http://dx.doi.org/10.4028/www.scientific.net/msf.750.256.

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In this paper, McEvily’s fatigue crack growth equation is modified and newly combined with the modified Goodman equation to estimate the fatigue strength with arbitrary mean stress, σm. Firstly, based on McEvily’s equation, the threshold stresses for fatigue crack initiation and propagation with stress ratio R = –1 or σm = 0 are predicted with reasonable accuracy. Then, a simple calculation is presented to predict the fatigue strength with arbitrary mean stress. The adequacy of present method is examined based on the comparison with the available experimental data in the literature.

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20

Kong, Y. S., Mohd Zaidi Omar, L. B. Chua, and S. Abdullah. "Fatigue Life Prediction of Leaf Spring through Multi Mean S-N Approach." Applied Mechanics and Materials 663 (October 2014): 83–87. http://dx.doi.org/10.4028/www.scientific.net/amm.663.83.

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Parabolic leaf spring is a suspension component for heavy vehicles where spring itself experiences repeated cyclic loading under operating condition. Fatigue life of the parabolic leaf spring is vital since the deflection of the spring is large and continuous. To determine the fatigue life of the parabolic leaf spring, material properties input to the design is important. The objective of this study is to predict the fatigue life of a parabolic leaf spring based on two different material grades which are SAE 5160 and SAE 51B60H under constant amplitude loading through various mean stress method. SAE 51B60H is the material with slightly higher carbon, manganese and chromium content compared to material SAE 5160. Chemical composition differences between SAE 5160 and SAE 51B60H have significant effects on the mechanical properties and fatigue life. In this analysis, finite element method together with multi mean curve stress life (S-N) approach has been implemented to estimate the fatigue life of the spring. Goodman, Gerber and Interpolate mean stress correction method were adopted to correct the damage calculation for mean stress. The results show that interpolate and Goodman method predict the fatigue life of the material with higher accuracy. On the other hand, material SAE 51B60H yields higher fatigue life compared to material SAE 5160.

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21

Udo, Ryujiro, Hide-aki Nishikawa, Hisamitsu Hato, Katsumasa Miyazaki, Kiyotaka Masaki, and Hiroshi Numakura. "Effect of Loading Method and Mean Stress on Fatigue Strength of Super Duplex Stainless Steel." Tetsu-to-Hagane 103, no. 4 (2017): 201–7. http://dx.doi.org/10.2355/tetsutohagane.tetsu-2016-103.

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22

Hwang, Dong Hyeon, and Sung-San Cho. "Mean stress effects in fretting fatigue life estimation method using fatigue damage gradient correction factor." Journal of Mechanical Science and Technology 31, no. 9 (September 2017): 4195–202. http://dx.doi.org/10.1007/s12206-017-0817-6.

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23

Candra, I. Wayan. "PENGARUH RELAKSASI PROGRESIF DAN MEDITASI TERHADAP TINGKAT STRES PASIEN HIPERTENSI." Jurnal Riset Kesehatan Nasional 1, no. 2 (May 28, 2019): 102. http://dx.doi.org/10.37294/jrkn.v1i2.46.

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Hypertension is a risk factor to the three biggest causes of premature death. The psychological impact is happening is that patients undergo stress, anxiety, depression, fear and anxiety. The method used is a quasi-experimental research design using design with equivalent control group design. The sampling technique is done by simple random sampling. Number of samples 70 people for a progressive relaxation group and for group meditation. Data analysis techniques of progressive relaxation effect of interventions to decrease stres levels by Paired t-test. Effect of meditation interventions to decrease stres levels also Paired t-test. Effectiveness of progressive relaxation and meditation in reducing stres using independent t-test.The results showed significant effect the progressive relaxation of the stres levels in hypertension patients. The mean value before 56.2571 and 41.7429 afterward, t=7,992 and p=0.000.Meditation can reduce stres levels in hypertension patients significantly.The mean value previously 59.4000, 24.1714 afterward, t = 11 223, p = 0.000. Meditation more effective than progressive relaxation in lowering stres levels in patients with hypertension in the Health Center of North Kuta, Badung, 2016. The difference in means at 14.5143 while the progressive relaxation group the mean difference in the meditation group 35.2286, t=-5712 and p=0.000. Conclusion the progressive relaxation and meditation can lower the stress level in patients of hypertension (p=0.000).Meditation is more effective to lower the stress level in patients of hypertention (p=0.000)Key Wards: Progressive Relaxation, Meditation,Stress,Hypertention

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24

Lambert, Ronald. "Fatigue Damage Prediction for Combined Random and Static Mean Stresses." Journal of the IEST 36, no. 3 (May 1, 1993): 25–32. http://dx.doi.org/10.17764/jiet.2.36.3.9852521p1145l0t7.

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Closed form analytical expressions have been derived and are proposed for use to predict accumulated fatigue damage and fatigue life of structural elements subjected to a combination of fully reversed narrow-band Gaussian random and static mean stresses. Such mean stresses can significantly alter fatigue life. The proposed method of combining random alternating and mean stresses shows excellent agreement with published experimental data for a steel alloy. Reasonable agreement is maintained, surprisingly, even for static tensile stress values up to near the material's yield stress where the failure mode shifts from that of typical brittle fatigue to that of stress rupture (i.c.,creep). Numerical examples are provided to illustratc the application.

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25

Wang, Guo Jun, Mei Hua Jiang, Shi Shun Zhu, and An Tao Xu. "Bending Fatigue Design Method for Double Sides Loaded Gears." Key Engineering Materials 419-420 (October 2009): 865–68. http://dx.doi.org/10.4028/www.scientific.net/kem.419-420.865.

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Bending fatigue is one of the main failure modes of gears. The method of gear fatigue design was discussed in many papers. Most of them are based on GB/T3480-83.But study shows that the method current widely used only fits for the single side loaded gear. For double sides loaded gear, only a mean stress modification coefficient is concerned compared to single side loaded gear. A new formula based on fatigue theory is given to modify the mean stress in consideration of the load character of doubled sides loaded gear. The method given in the paper is an addition to the traditional gear design method.

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Gyekenyesi, A. L. "Thermoelastic Stress Analysis: An NDE Tool for Residual Stress Assessment of Metallic Alloys." Journal of Engineering for Gas Turbines and Power 124, no. 2 (March 26, 2002): 383–87. http://dx.doi.org/10.1115/1.1417982.

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The primary objective of this report involves studying and developing various experimental techniques for accurate measurement of the mean stress effect in thermoelastic stress analysis (TSA, also recognized as SPATE: stress pattern analysis by thermal emission). The analysis of cyclic mean stresses at the coupon level directly relates to the measurement of residual stresses in structures. In a previous study by the authors, it was shown that cyclic mean stresses significantly influenced the TSA results for titanium and nickel-based alloys, although, difficulties were encountered concerning the quantification of the mean stress effect because of large test-to-test variations. This study continues the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in-depth analysis is included which involves analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point on a structure subjected to a cyclic load can be simultaneously obtained. The rather complex analysis of the temperature response involves obtaining the first and second harmonic amplitudes for 16384 infrared detectors (128×128 focal plane array). Upon establishing a protocol for mean stress measurements in the laboratory using the TSA technique, the next step is to utilize the method to assess residual stress states in complex structures during manufacturing and life.

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LIU, KUI, WEI-ZHENG YUAN, BING-HE MA, CHENG-YU JIANG, and JIN-JUN DENG. "METHOD AND SIMULATION OF THE USE OF MICRO SHEAR STRESS SENSOR ARRAY IN DETECTING BOUNDARY-LAYER SEPARATION POINT." International Journal of Information Acquisition 03, no. 01 (March 2006): 9–14. http://dx.doi.org/10.1142/s0219878906000770.

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At the boundary layer's separation point, the mean of the shear stress drops to a small value while its fluctuation increases dramatically. Based on the thermal method, we can fabricate a MEMS-based shear stress sensor array to bend with the curved surface, which can measure the shear stress profile of the boundary layer. This paper presents two methods, mean and RMS of the shear stress difference max value and the second order of the array signals difference algorithm, to calculate the location of the flow separation point. Through combination of the two methods and analyzing the 2D circular column CFD simulation data, the position of the separation point can be determined accurately.

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28

Gao, Jianxiong, Zongwen An, and Haixia Kou. "Fatigue life prediction of wind turbine rotor blade composites considering the combined effects of stress amplitude and mean stress." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 232, no. 6 (January 17, 2018): 598–606. http://dx.doi.org/10.1177/1748006x17751495.

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To predict fatigue life of wind turbine rotor blade composites under random loads, the combined effects of stress amplitude and mean stress are considered. First, the generalized σ–N curved surface is introduced to characterize the fatigue properties of composites under constant amplitude cyclic load. Then, a modified Miner’s rule is developed to reveal the evolution process of fatigue damage under variable amplitude cyclic loads. Finally, a fatigue life prediction model is presented based on the total probability formula and the modified Miner’s rule, which can reflect the combined effects of stress amplitude and mean stress on fatigue life. The experimental data of wind turbine rotor blade composites are used to illustrate the specific process of the proposed method; the results indicate that the prediction values of the developed method are reasonable and effective.

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Heidari, Mahdi, Maria A. Nikolinakou, and Peter B. Flemings. "Coupling geomechanical modeling with seismic pressure prediction." GEOPHYSICS 83, no. 5 (September 1, 2018): B253—B267. http://dx.doi.org/10.1190/geo2017-0359.1.

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We couple geomechanical modeling with seismic velocity to enhance the prediction of pressure and stresses in complex geologic settings. In these settings, pressure is controlled by mean and shear stresses rather than by only the vertical (overburden) stress. We estimate total mean and shear stresses from a geomechanical model. Effective mean and shear stresses are calculated from velocity using a relationship that we develop between velocity and these stresses. The pressure prediction process is iterated to attain convergence between the predicted pressure field and the one input in the geomechanical model. We also explicitly predict the full stress tensor. We apply our method along with the standard, vertical-effective-stress method to a salt basin beneath the Sigsbee Escarpment in the Mad Dog field, Gulf of Mexico. The methods are constrained to the same pressure data along a calibration well and are then used to predict pressure and stresses across the basin. We find that salt and basin bathymetry substantially perturb the stress field. The pressures predicted by the two methods differ the least at the calibration well and the most in areas where the total mean and shear stresses are the most different from those at the same burial depth at the calibration well. Our method is shown to predict pressures measured along a subsalt well better than the standard, vertical method. We calculate minimum stress and the drilling window along a vertical profile near salt and find that they significantly differ from the ones predicted by the standard, vertical method.

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Pityk, O., M. Pityk, and I. Kuzhda. "Social-stress Disorder. What Does it Mean for the people?" European Psychiatry 33, S1 (March 2016): S452—S453. http://dx.doi.org/10.1016/j.eurpsy.2016.01.1646.

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In 90th of 20 Russian psychiatrist Y.A. Alexandrovsky expressed opinion of presence the group of so-called social-stress disorders that was determined like psychogenic-actual for most people in definite social, economic and political situation.Used the method of clinic-psychopathological interview with patients who applied outpatient psychological consultation on the chair of psychiatry.The main changes in psychic state include following behaviors and clinical implications: loss of the value of human life, which is manifested in indifference to death in lowering caution when hazardous situations, willingness to sacrifice lives without any ideals. There is unrestrained lost for pleasure and moral promiscuity, exacerbation of personality typological traits, development of hyperstenic reactions (to self-destructive non-expedient behavior), hypostenic disorders, panic reactions, depression, dissociative and conversive irregularities, loss of communicational plasticity, loss of the ability to adapt to what happens with the preservation prospects of targeted actions, manifestations of cynicism, the tendency to antisocial actions. Patients had complaints on increase anxiety, pessimistic attitudes, existential vacuum, sense of uselessness and loss of perspectives, tendency to irrational perception of reality with including mechanisms of autistic and archaic thinking.Thus, psychological status of the population of Ukraine is a model of social-stress disorder and can be considered like a basis, which leads to the decreasing of the individual barrier of mental adaptation with the next manifestation of different forms of psychological maladjustment.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Herlinah, Herlinah, Herqutanto Herqutanto, and Nuri Purwito Adi. "The influence of Guided Imagery and Music (GIM) relaxation on primary school teachers’ stress." Health Science Journal of Indonesia 9, no. 1 (October 19, 2018): 45–50. http://dx.doi.org/10.22435/hsji.v9i1.463.

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Abstrak Latar belakang: Stres dapat menimpa berbagai profesi dan pekerjaan. Guru sekolah dasar merupakan salah satu profesi yang rentan terhadap stres. Stres ini dapat berpengaruh terhadap kinerja guru, oleh karena itu stress harus diatasi. Salah satu cara untuk menurunkan stres adalah relaksasi dengan terapi musik. Bagian dari terapi musik adalah Guided Imagery and Music (GIM). Penelitian ini untuk mengetahui pengaruh relaksasi GIM terhadap stres guru sekolah dasar negeri di kabupaten Sekadau, Kalimantan barat. Metode: 40 orang responden guru diikut sertakan dalam penelitian ini melalui cluster random sampling. Desain penelitian menggunakan metode quasi eksperiment pre-post dengan grup kontrol. Data yang dikumpulkan meliputi karakteristik individu dan masa kerja, stressor kerja (menggunakan kuesioner SDS) dan stres guru (menggunakan kuesioner SCL-90). Relaksasi GIM diberikan sebanyak 5 sesi dalam waktu ±20 menit setiap sesi selama 1 minggu. Hasil: 77.5% responden memiliki tingkat stress sedang pada stressor beban pekerjaan kualitatif berlebih. Penilaian awal stress didapatkan 77.5% responden mengalami gejala psikopatologi dengan gejala terbanyak adalah obsesi-kompulsif (27.5%). Terdapat penurunan rerata stres yang bermakna pada guru SD yang mendapat relaksasi GIM dengan perbedaan mean 3.00±6.29 (p=0.046) dan peningkatan rerata stress pada kelompok kontrol -1.45±7.72 (p=0.412). Kesimpulan: Intervensi GIM berpengaruh terhadap penurunan tingkat stress pada guru SD yang menjalani relaksasi GIM. (Health Science Journal of Indonesia 2018;9(1):45-50) Kata kunci: Relaksasi GIM, Stres guru, Guru sekolah dasar Abstract Background: Stress is a common hazard in a lot of professions and occupation. Primary school teachers are one of the most vulnerable profession to have stress. Stress may impact on teachers’ performance and therefore must be treated. One of the ways to alleviate stress is relaxation by musical theraphy. A part of musical theraphy is Guided Imagery and Music (GIM) relaxation. The purpose of the research is to know the influence of GIM relaxation method on stress’ level of primary school teachers in district Sekadau, West Kalimantan. Methods: 40 teachers participated in this research and were chosen by cluster random sampling method. The study design was pre-post quasi experiment with control group. The collected data included respondents’ individual characteristics and length-of-employment, work stressors (using SDS questionnaire) and teachers’ stress (using SCL-90 questionnaire). GIM relaxation method was provided in 5 sessions where conducted for 20 minutes during the period of one week. Results: 77.5% of respondents have medium stress levels, which were excessive qualitative workloads stressors. In early stress assessment, 77.5% respondent showed psychopatology symptoms, where the most frequent symptom was obsessive-compulsive (27.5%). There was a significant decrease in stress level in primary school teachers who received the GIM relaxation with a mean difference of 3.00±6.29 (p=0.046) and an increase of stress’ level in control group with a mean difference of -1.45±7.72 (p=0.412). Conclusion: GIM intervention has an effect on reducing stress level in primary school teachers who have undergone GIM relaxation. (Health Science Journal of Indonesia 2018;9(1):45-50) Keywords: GIM relaxation, Teachers’ stress, primary school teachers

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Yu, Hui Chen, Cheng Li Dong, and Ying Li. "Fatigue Behavior of K447A Superalloy under Low Cycle Fatigue and Creep-Fatigue Interaction Conditions." Applied Mechanics and Materials 750 (April 2015): 121–26. http://dx.doi.org/10.4028/www.scientific.net/amm.750.121.

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Strain-controlled low cycle fatigue (LCF) and creep-fatigue interaction (CFI) tests of K447A are conducted at 760oC in order to investigate the effects of different dwell times and strain ratios on the fatigue behavior and life. For the cases of stain ratio Rε=-1 with balanced hold time, the tensile and compressive mean stresses will generate. For the case of stain ratio Rε=-1 with compressive holding 60s, the tensile mean stress will produce. For the case of stain ratio Rε=-1 with tensile holding 60s, the compressive mean stress will produce. For the cases of stain ratio Rε=0.1 and Rε=-1with no hold time, the tensile mean stress will produce. The cyclic damage accumulation (CDA) method and modified CDA method were employed to predict the fatigue life for K447A, respectively. The fatigue life predicted by CDA method is within the scatter band of 18.2X. The fatigue life predicted by the modified CDA method agrees very well with the experimental life and the predicted life is well within the scatter band of 3.1X, which means that the modified CDA method is able to consider the influences of dwell time and strain ratio on the fatigue life of K447A.

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SKALSKI, J. "NUCLEAR FISSION WITHIN THE MEAN-FIELD APPROACH." International Journal of Modern Physics E 18, no. 04 (April 2009): 798–807. http://dx.doi.org/10.1142/s0218301309012896.

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We discuss the mean-field instanton method for calculating decay rates of the sponteneous fission. Based on our recent work, we stress the role of the velocity-momentum relations which make the instanton action minimal, and the choice of a time-even density matrix and a time-odd hermitian operator as special variables making the adiabatic limit transparent. We also present an analytic study of a simple model of barrier tunneling, which illustrates the importance of the velocity-momentum constraints.

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Rho, Jaehee, and Ji Hoon Ryoo. "Application of Alignment Method for Measurement Invariance Testing and Latent Mean Analysis of Student Stress Scale." Korean Society for Educational Evaluation 33, no. 4 (December 31, 2020): 889–913. http://dx.doi.org/10.31158/jeev.2020.33.4.889.

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Schulz, Martin S., Kai Russe, Georgios Lampakis, and Michael J. Strobel. "Reliability of Stress Radiography for Evaluation of Posterior Knee Laxity." American Journal of Sports Medicine 33, no. 4 (April 2005): 502–6. http://dx.doi.org/10.1177/0363546504269723.

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Background Although stress radiography has been recommended for quantifying posterior tibial displacement in knees with posterior cruciate ligament insufficiency, the intratester reliability and intertester reliability of this measurement method have not been evaluated. Hypothesis Stress radiography is a reproducible measurement method in the assessment of posterior knee laxity in patients with posterior cruciate ligament lesions. Study Design Cohort study (diagnosis); Level of evidence, 2. Methods Stress radiographs of 787 patients with suspected posterior cruciate ligament lesions taken using the Telos device were evaluated independently by 3 testers: 2 of the testers were clinically experienced in the evaluation of stress radiographs, and 1 tester was a novice tester. Change in mean, standard error of measurement with calculated confidence intervals, and intraclass correlation coefficients were determined to assess intratester and intertester reliability. Results There was no significant intratester change in mean. Intratester standard error of measurement was 1.03 mm; 95% confidence intervals were ±2.02 mm for a single measurement and ±2.86 mm for a change in measurement. The intratester intraclass correlation coefficient was 0.95. Intertester reliability revealed a significant change in mean between the experienced testers and the novice tester (P <. 001). There was no substantial difference for the standard error of measurement of each tester. The mean intertester standard error of measurement was 1.41 mm; 95% confidence intervals were ±2.77 mm for a single measurement and ±3.91 mm for a change in measurement. The intertester intraclass correlation coefficient was 0.91. Conclusion Stress radiography was found to be a measurement method with a useful reliability for evaluation of posterior laxity in patients with posterior cruciate ligament lesions. The reproducibility of stress radiography may be influenced by multiple variables, and standardized methods are needed to minimize measurement error.

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Siciliano, Fulvio, Brian Allen, and David Ferguson. "Hot Torsion Tests - A Reliable Rolling Simulation Method for C-Mn Steels." Materials Science Forum 879 (November 2016): 1783–87. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1783.

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Torsion tests have been proven to be a successful method to simulate the hot rolling of steels. Simulation work performed at a laboratory scale together with the analysis of the resulting mean-flow-stress behavior, leads to important metallurgical information to be considered during full-scale rolling processes. In this work, two different hot deformation schedules of C-Mn steels have been performed on a Gleeble simulation system in hot torsion mode. In addition to the torsion tests, the mean-flow-stresses of industrial rolling data were analyzed. Industrial hot deformation schedules simulated using hot torsion and the mean-flow-stress values were plotted versus the inverse of absolute temperature in the same graph. All points match the same behavior showing that torsion testing is a reliable hot working simulation method.

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Oka, Hideki, Ryoichi Narita, Yoshiaki Akiniwa, and Keisuke Tanaka. "Effect of Mean Stress on Fatigue Strength of Short Glass Fiber Reinforced Polybuthyleneterephthalate." Key Engineering Materials 340-341 (June 2007): 537–42. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.537.

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Tension-compression fatigue tests under various mean stress conditions were conducted with round bar specimens of short glass fiber reinforced polybuthyleneterephthalate made by injection molding. Under cyclic loading with high mean stresses, the creep phenomenon became predominant and the ratcheting deformation increased with the number of cycles. This phenomenon is characteristic of plastics including short glass fiber reinforced plastics. The experimental data of the fatigue strength at the stress ratios above 0.7 were lower than the prediction based on the modified Goodman diagram. We propose to use the creep rupture strength, σc, instead of the tensile strength, σB, as the strength without mean stress and the parabolic equation for a constant life in the amplitude-mean stress (σa-σm) diagram. Our new design equation for the mean-stress effect on the fatigue strength on plastics is as follows: σa = σw – (σw / σc 2) σm 2, where σw is the fatigue strength at the stress ratio R=-1 and σa is the stress amplitude under a mean stress of σm. We also proposed a method to obtain the constant-life relation from limited experimental data.

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Cheng, Yung Chang, and Pongsathorn Pornteparak. "Improvement Design of Adhesive Layer on Honeycomb Structure for Railway Vehicle System by Uniform Design Method." Key Engineering Materials 830 (February 2020): 53–58. http://dx.doi.org/10.4028/www.scientific.net/kem.830.53.

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The purpose of this paper focuses on adhesive layer strength while having a thermal cycling of honeycomb composite sandwich structure by using the uniform design of experiments method improving the von Mises stress of honeycomb structure. Three system parameters of the honeycomb structure are selected as the control factors to be improved. Uniform design of experiment is applied to create a set of simulation experiments. Applying ANSYS/Workbench software, the finite element modelling is investigated and the von Mises stress of the honeycomb structure is calculated under metal-honeycomb core flatwise tensile test. From the numerical results, the best honeycomb structure dimension of all the experiments which causes the smaller von Mises stress is selected as the improved version of design. Finally, the best model of the experiments which causes the minimum equivalent stress is regarded as the improved version of design. Compared with the original design, the result of ASTM C297 improved version is 17.386 MPa, which mean improved 36.28%, ASTM C364 improved version is 19.015 MPa, which mean improved 25.26%, ASTM C365 improved version is 16.86 MPa, which mean improved 12.35%.

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Liu, Yao, Yashun Wang, Zhengwei Fan, Xun Chen, Chunhua Zhang, and Yuanyuan Tan. "A new universal multi-stress acceleration model and multi-parameter estimation method based on particle swarm optimization." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 234, no. 6 (June 3, 2020): 764–78. http://dx.doi.org/10.1177/1748006x20918793.

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High reliability and long-lifetime products usually work in multi-stress environment such as temperature, humidity, electricity, and vibration. How to evaluate the reliability of the product under multi-stress condition is an urgent problem to ensure the safe and reliable operation of the product. Accelerated test provides an efficient and feasible way; however, the existing acceleration models have some shortcomings, such as less stress type, neglecting the stress coupling, and multi-parameter estimation difficulties. Therefore, in this article, first, a new universal multi-stress acceleration model is derived based on the classical Arrhenius model. Second, a multi-parameter estimation method for multi-stress model is proposed by combining particle swarm optimization and maximum likelihood estimation. Six simulation cases are used to verify the effectiveness of the proposed multi-parameter estimation method. The results of Case 1 to Case 3 show that the maximum mean square error of five parameters in the multi-stress model without considering stress coupling is 3.71%. The results of Case 4 to Case 6 show that the maximum mean square error of nine parameters in the multi-stress model considering stress coupling is 7.69%. Finally, an application example is performed to investigate the performance of the universal multi-stress acceleration model and multi-parameter estimation method.

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Lu, Shan, Yunlai Su, Mao Yang, and Yan Li. "A Modified Walker Model Dealing with Mean Stress Effect in Fatigue Life Prediction for Aeroengine Disks." Mathematical Problems in Engineering 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/5148278.

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Mean stress effect plays an important role in fatigue life prediction, and it is discovered that maximum stress has nonnegligible influence on mean stress effect. Therefore, a modified Walker model is proposed to account for mean stress effect on fatigue life of aeroengine disks, which contains the influence of stress ratio and maximum stress on mean stress effect. Eight sets of fatigue data for standard smooth bars from six kinds of materials commonly used in aeroengine disks as well as two sets of experimental data from simulated specimens of turbine disks were employed to investigate the prediction capability of the proposed model against other candidate mean stress relationships. It is found that Goodman model generates most conservative results, while Morrow model overestimates fatigue life for most cases. SWT model yields similar results to Walker model but with less accuracy. The results of the modified Walker model turn out to be superior to those of any other candidate models for all cases examined, especially for large mean stress ones. Thus, the modified Walker model can be an effective method to predict fatigue lives of aeroengine disks influenced by mean stresses.

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Zhang, Ji, Zhu Bin He, and Shi Jian Yuan. "Investigation of Relationship between Material Flow Direction and Local Stress Field in Plastic Deformation." Materials Science Forum 575-578 (April 2008): 489–94. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.489.

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The maximum mean stress gradient direction in typical plane strain and axisymmetrical plastic deformation problems was calculated by numerical method to investigate relationships between material flow direction and related local stress field. Good agreement was found between the movement direction in the deforming bodies and the maximum mean stress gradient direction of the related local mean stress field. This agreement was also found in typical 3-D problems by numerical simulation and visualization.

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Schajer, G. S. "Measurement of Non-Uniform Residual Stresses Using the Hole-Drilling Method. Part II—Practical Application of the Integral Method." Journal of Engineering Materials and Technology 110, no. 4 (October 1, 1988): 344–49. http://dx.doi.org/10.1115/1.3226060.

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The Integral Method for calculating non-uniform residual stress fields using strain relaxation data from the incremental hole-drilling method is examined in detail. Finite element calculations are described which evaluate the calibration coefficients required for practical applications of the method. These calibration data are tabulated for a range of hole sizes and depths. It is found that the hole drilling method is not well adapted to measuring stresses remote from the surface, and a theoretical depth limit for stress measurements of 0.5 of the mean radius of the strain gauge rosette, rm, is identified. A practical depth limit is in the range 0.3–0.4 rm.

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Lee, Jong Il, Young Choi, Kwang Suck Boo, and Joon Hong Park. "A Study on Relationship between Hardness and Hydrostatic Stress." Key Engineering Materials 306-308 (March 2006): 619–24. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.619.

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Hardness is most likely to mean the resistance to indentation, and to the design engineer it often means an easily measured and specified quantity which indicates something about the strength and heat treatment of the metal. Especially, Vickers hardness is one of the most widely useful methods to obtain mechanical properties of a product. Firstly, in this study, a method to estimate hardness will be presented using FE simulations of Vickers hardness tests from the viewpoint that hardness indicates resistance to plastic deformation. To verify our method, the results of the simulations for several materials such as commercial aluminum alloy and steel will be compared with those of Vickers hardness tests for the materials. Secondly in this study, hardness numbers of the several materials will be obtained as a function of hydrostatic stress. Through the results of this study, the estimation of hardness number of a specific material will be very easy to obtain and access even though the material is under a kind of hydrostatic stress state.

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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 (January 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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Pallarés-Santasmartas, Luis, Joseba Albizuri, Nelson Leguinagoicoa, Nicolas Saintier, and Jonathan Merzeau. "The effect of mean axial and torsional stresses on the fatigue strength of 34CrNiMo6 high strength steel." MATEC Web of Conferences 300 (2019): 16004. http://dx.doi.org/10.1051/matecconf/201930016004.

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The present study consists of a theoretical, experimental and fractographic investigation of the effect of superimposed static axial and shear stresses on the high cycle fatigue behavior of a 34CrNiMo6 high strength steel in quenched and tempered condition (UTS = 1210 MPa), commonly employed in highly stressed mechanical components. The Haigh diagrams for the axial and torsional cases under different values of mean stress were obtained. In both cases, experimental results showed that increasing the mean stress gradually reduces the stress amplitude that the material can withstand without failure. The results of the present tests are compared with the theoretical predictions from Findley, based on the maximum damage critical plane; and the methods of Marin and Froustey, which are energetic based criterions. Froustey’s method shows the best agreement with experimental results for torsional fatigue with mean shear stresses, showing a non-conservative behaviour for the axial fatigue loading case. Macro-analyses and micro-analyses of specimen fracture appearance were conducted in order to obtain the fracture characteristics for different mean shear stress values under torsion fatigue loading.

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Hu, Pingsha, and Tapabrata Maiti. "A Nonparametric Mean-Variance Smoothing Method to Assess Arabidopsis Cold Stress Transcriptional Regulator CBF2 Overexpression Microarray Data." PLoS ONE 6, no. 5 (May 17, 2011): e19640. http://dx.doi.org/10.1371/journal.pone.0019640.

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ONO, Yuichi, Seiichiro KITAOKA, and Yoichi IKEGAMI. "Measurement of Mean Stress Using Electrodeposited Metal Foil with Microcircular Holes (Method by Fatigue Crack Propagation Rate)." Transactions of the Japan Society of Mechanical Engineers Series A 69, no. 683 (2003): 1088–93. http://dx.doi.org/10.1299/kikaia.69.1088.

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KITAOKA, Seiichiro, and Yuichi ONO. "Measurement of Mean Stress Using Electrodeposited Copper Foil with a Microcircular Hole : Method by Fatigue Crack Propagation." Proceedings of Conference of Chugoku-Shikoku Branch 2002.40 (2002): 137–38. http://dx.doi.org/10.1299/jsmecs.2002.40.137.

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KITAOKA, Seiichiro, Yuichi ONO, Yoichi IKEGAMI, and Yukio TANAKA. "Measurement of Mean Stress Using Electrodeposited Metal Foil with a Microcircular Hole : Method by Fatigue Crack Propagation." Proceedings of Conference of Chugoku-Shikoku Branch 2003.41 (2003): 29–30. http://dx.doi.org/10.1299/jsmecs.2003.41.29.

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Han, Han. "Determination of mean flow stress and friction coefficient by the modified two-specimen method in cold rolling." Journal of Materials Processing Technology 159, no. 3 (February 2005): 401–8. http://dx.doi.org/10.1016/j.jmatprotec.2004.06.005.

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