A General Fatigue Evaluation Method (Elastic Stress or Plastic Strain with Constant or Varying Principal Direction)

1980 ◽  
Vol 102 (3) ◽  
pp. 287-293 ◽  
Author(s):  
F. S. Kelley
Keyword(s):  
Plastic Strain ◽  
Principal Stress ◽  
Evaluation Method ◽  
Elastic Stress ◽  
Principal Direction ◽  
Stress Strain ◽  
General Fatigue ◽  
Fatigue Evaluation ◽  
Code Procedure

A method is proposed for ASME Section III fatigue evaluations which can be applied in the elastic or plastic ranges with constant or varying principal stress/strain directions. The generality of the method is demonstrated. For biaxial or triaxial loadings, the method is shown to be more consistent than the Code procedure given in NB-3228.1.

Comparison of Strain Rate Calculation Methods for Environmental Fatigue Correction Evaluation

2012 ◽  
Author(s):  
Seiji Asada
Keyword(s):  
Strain Rate ◽  
Principal Stress ◽  
Evaluation Method ◽  
Calculation Methods ◽  
Sample Problem ◽  
Nuclear Facility ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Rate Calculation ◽  
Fatigue Evaluation

A Code Case for procedure to determine strain rate and Fen for environmental fatigue evaluation is under preparation in the ASME BPV Committee on Construction of Nuclear Facility Components (III). The draft Code Case is to incorporate two methods for strain rate calculation. One is based on NB-3216.1 “Constant Principal Stress Direction” that comes from the JSME Environmental Fatigue Evaluation Method. The other is based on NB-3216.2 “Varying Principal Stress Direction” that was proposed by M. Gray et al. In this paper, both methods are explained and compared by using a sample problem.

Thermal Fatigue Evaluation Model of a Microelectronic Chip in Terms of Interfacial Singularity

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Xiaoguang Huang ◽  
Zhiqiang Wang
Keyword(s):  
Thermal Fatigue ◽  
Evaluation Method ◽  
Evaluation Model ◽  
Thermomechanical Properties ◽  
Fatigue Tests ◽  
Strain Intensity ◽  
Intensity Factors ◽  
Singular Stress ◽  
Stress Strain ◽  
Fatigue Evaluation

Abstract Thermal fatigue failure of microelectronic chip often initiates from the interface between solder and substrate, and the service life of the chip is largely dependent on the singular stress–strain at this interface. To provide a reasonable life evaluation method, three thermal fatigue evaluation models, including strain-based and stress–strain based, have been established in terms of the interfacial singular fields. Thermal fatigue lives of different chips under different thermal cycles are obtained by thermal fatigue tests, and the stress and strain intensity factors and singular orders at the solder/substrate interface are computed at the same conditions, to determine the material constants in the established models. The thermal fatigue lives predicted are in acceptable agreement with the experimental results. What is more, the application of these thermal fatigue models demonstrates a fact that the thermal fatigue of the microelectronic chips can be evaluated uniformly no matter what the shapes, dimensions of the chip, and the thermomechanical properties of the solders are, as long as the relevant stress–strain intensity factors and singular orders are obtained.

Proposal for Determination of Strain Rate in Environmental Fatigue Correction Evaluation

2009 ◽  
Author(s):  
Seiji Asada
Keyword(s):  
Principal Stress ◽  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Time History ◽  
Strain History ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Fatigue Evaluation

To calculate an accurate environmental fatigue life correction factor (Fen) for evaluation of environmental fatigue, a detailed strain time history is needed. The strain history is determined by dividing the stress difference history with the Young’s modulus. ASME B&PV Code, Section III, NB-3216 has two methods of derivation of stress differences. One is NB-3216.1, “Constant Principal Stress Direction.” The other is NB-3216.2 “Varying Principal Stress Direction.” Determination methods for strain rates for two kinds of calculation methods of stress differences are proposed by applying the JSME Code for Environmental Fatigue Evaluation Method for Nuclear Power Plants. Also a sample calculation is performed for a typical nozzle to verify the proposed methods.

scholarly journals Research on Strength Test Technology and Fatigue Evaluation Method of Bogie Frame and Body Bolster

2021 ◽  
Vol 1972 (1) ◽  
pp. 012038
Author(s):  
Cao Yu ◽  
Lu Chong ◽  
Li Zihua ◽  
Song Jie ◽  
Ding Xiebin
Keyword(s):  
Evaluation Method ◽  
Strength Test ◽  
Bogie Frame ◽  
Test Technology ◽  
Fatigue Evaluation

scholarly journals Studying the effect of elastic-plastic strain and hydrogen sulphide on the magnetic behaviour of pipe steels as applied to their testing

2018 ◽  
Vol 145 ◽  
pp. 05003
Author(s):  
Anna Povolotskaya ◽  
Eduard Gorkunov ◽  
Sergey Zadvorkin ◽  
Igor Veselov
Keyword(s):  
Plastic Strain ◽  
Initial Stress ◽  
Elastic Deformation ◽  
Hydrogen Sulphide ◽  
Strain State ◽  
Pipe Steel ◽  
Magnetic Behaviour ◽  
Pipe Steels ◽  
Stress Strain ◽  
Stress Strain State

The paper reports results of magnetic measurements made on samples of the 12GB pipe steel (strength group X42SS) designed for producing pipes to be used in media with high hydrogen sulphide content, both in the initial state and after exposure to hydrogen sulphide, for 96, 192 and 384 hours under uniaxial elastic-plastic tension. At the stage of elastic deformation there is a unique correlation between the coercive force measured on a minor hysteresis loop in weak fields and tensile stress, which enables this parameter to be used for the evaluation of elastic stresses in pipes made of the 12 GB pipe steel under different conditions, including a hydrogen sulphide containing medium. The effect of the value of preliminary plastic strain, viewed as the initial stress-strain state, on the magnetic behaviour of X70 pipe steels under elastic tension and compression is studied. Plastic strain history affects the magnetic behaviour of the material during subsequent elastic deformation since plastic strain induces various residual stresses, and this necessitates taking into account the initial stress-strain state of products when developing magnetic techniques for the determination of their stress-strain parameters during operation.

Stresses Around Wellbores in Nonlinear Rock

1968 ◽  
Vol 8 (03) ◽  
pp. 304-312 ◽  
Author(s):  
M.A. Mahtab ◽  
R.E. Goodman
Keyword(s):  
Finite Element Analysis ◽  
Principal Stress ◽  
Intermediate Principal Stress ◽  
The State ◽  
Initial Stresses ◽  
Stress Strain ◽  
Element Analysis ◽  
Deviator Stress ◽  
State Of Stress ◽  
Strain Data

ABSTRACT The state of stress around a vertical wellbore in rock following nonlinear stress-strain laws is examined by means of finite element analysis. The wellbore is considered an axisymmetric body with axisymmetric loading. The initial vertical and horizontal stresses are "locked" in the rock elements around the wellbore and a new state of stress is generated by the displacements which occur around the borehole. A point-wise variation of the elastic moduli is made on the basis of the new stress state and the triaxial data. The initial stresses are now reintroduced along with the changed moduli and original boundary constraints. This procedure is repeated until convergent stresses are reached. The effect of nonlinearity on stresses is examined for a 6,000-ft wellbore in a schistose gneiss and Berea sandstone using results of laboratory triaxial compression tests. The results show that the effect is restricted to one well radius from the bottom periphery of the hole. Beyond a distance of one-quarter radius, the effect of nonlinearity on stresses is almost always less than 5 percent for the cases considered. The consideration of a static pressure inside the well does not magnify the effect of nonlinearity on borehole stresses. INTRODUCTION The terms "wellbore" and "borehole" here designate cylindrical openings in the ground with vertical axis and a circular cross-section. A knowledge of the stress redistribution that occurs on excavating a wellbore is important in understanding the behavior of the lined or unlined hole, hydraulic fracture response, and the effect of stress redistribution on drillability; also it is important in predicting initial stresses in the virgin ground, and in analyzing the response of measuring instruments placed in the borehole. Our knowledge of the state of stress around a wellbore has been restricted to homogeneous, isotropic, elastic material and derives chiefly from the analysis by Miles and Topping1 and the photoelastic work of Galle and Wilhoit2 and Word and Wilhoit.3 In this investigation the state of stress is examined for a nonlinear elastic material by means of finite element analysis. Many rocks possess stress-strain curves that depart notably from straight lines in their initial or final portions. While the literature contains abundant stress-strain data from triaxial tests (axisymmetric loading) on cylindrical rock specimens, there is little information on rock deformability under nonaxisymmetric loading conditions such as occur at each point around the bottom of a wellbore. Although there is some knowledge of the effect of intermediate principal stress on rock strength, there is virtually nothing known about its effect on rock deformability; therefore, we have assumed here that the effect of intermediate principal stress can be ignored. A schistose gneiss4 and Berea sandstone5 were selected as representative rocks for this analysis. The traditional graphs of deviator stress (s1-s3) vs axial strain were reworked to give the tangent modulus as a function of the deviator stress for varying values of the minor principal stress. The result is a nesting family of skewed, bell-shaped curves for the gneiss (Fig. 1A) and the sandstone (Fig. 2A). A similar replotting of the lateral strain data defines the variation of Poisson's ratio (?) with the deviator stress and confining pressure. These curves, shown in Fig. 1B for the gneiss and in Fig. 2B for the sandstone, are not so well ordered as the tangent modulus curves. However, all of these display an increase of ? with deviator stress application, but the rate of increase diminishes with confinement. The ET and ? curves for the two rock types are tabulated in Tables 1A and 1B for use in a digital computer so that material properties corresponding to a given state of stress can be assigned by interpolation.

Development of 2012 Edition of JSME Code for Design and Construction of Fast Reactors: (4) Creep–Fatigue Evaluation Method for Modified 9Cr–1Mo Steel

2013 ◽  
Author(s):  
Shigeru Takaya ◽  
Yuji Nagae ◽  
Tai Asayama
Keyword(s):  
Evaluation Method ◽  
Time To Failure ◽  
Test Results ◽  
Fast Reactors ◽  
Material Test ◽  
Creep Fatigue ◽  
Summation Rule ◽  
Fatigue Evaluation ◽  
Failure Life ◽  
Design And Construction

This paper describes a creep–fatigue evaluation method for modified 9Cr–1Mo steel, which has been newly included in the 2012 edition of the JSME code for design and construction of fast reactors. In this method, creep and fatigue damages are evaluated on the basis of Miner’s rule and the time fraction rule, respectively, and the linear summation rule is employed as the failure criterion. Investigations using material test results are conducted, which show that the time fraction approach can conservatively predict failure life if margins on the initial stress of relaxation and the stress relaxation rate are embedded. In addition, the conservatism of prediction tends to increase with time to failure. Comparison with the modified ductility exhaustion method, which is known to have good failure life predictability in material test results, shows that the time fraction approach predicts failure lives to be shorter in long-term strain hold conditions, where material test data is hardly obtained. These results confirm that the creep–fatigue evaluation method in the code has implicit conservatism.

Visualization of Multiaxial Stress/Strain State and Evaluation of Failure Life by Developed Analyzing Program under Non-Proportional Loading

2014 ◽  
Vol 891-892 ◽  
pp. 1391-1396
Author(s):  
Shu Li Liu ◽  
Takamoto Itoh ◽  
Noriyuki Fujii
Keyword(s):  
Principal Stress ◽  
Strain State ◽  
Strain Range ◽  
Mean Stress ◽  
Damage Evaluation ◽  
Multiaxial Loading ◽  
Proportional Loading ◽  
Stress Strain ◽  
3D Loading ◽  
Failure Life

This study presents definitions of principal stress/strain range and mean stress/strain introduced by utilizing Itoh-Sakane criterion for multiaxial loading including non-proportional loading, and shows the method of calculating the non-proportional factor which expresses the severity of non-proportional loading under the multiaxial 3D loading. This paper also shows a method of visually presenting the stress/strain, the non-proportionality of loading and the damage evaluation.

scholarly journals Muscle fatigue evaluation method of driver at long time driving based on blood lactate level increase

2020 ◽  
Vol 86 (889) ◽  
pp. 19-00433-19-00433
Author(s):  
Takumi YAMAKAWA ◽  
Soichiro HAYAKAWA ◽  
Katsuhiro ASANO ◽  
Shigeyoshi TSUTSUMI ◽  
Ryojun IKEURA
Keyword(s):  
Muscle Fatigue ◽  
Blood Lactate ◽  
Lactate Level ◽  
Evaluation Method ◽  
Blood Lactate Level ◽  
Level Increase ◽  
Long Time ◽  
Fatigue Evaluation
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