Proposal of Determination Procedure About Fatigue Safety Factors for Arbitrary Best Fit Curves

2003 ◽  
Author(s):  
Nobuchika Kawasaki
Keyword(s):  
Fatigue Test ◽  
Surface Finish ◽  
Test Results ◽  
Safety Factors ◽  
Determination Procedure ◽  
The Difference ◽  
Best Fit

Fatigue safety factors cover not only the scattered range of fatigue test results obtained from test specimens, but also the difference in the fatigue lives between the test specimens and vessels / piping in plants. Therefore necessary safety factors have a relation to the accuracy of a best fit curve which is determined by the test results and the component’s conditions. This paper describes a determination procedure of fatigue safety factors for a new best fit curve so that designers can determine adequate safety factors for arbitrary best fit curves and material databases. This determination procedure is explained using a 316FR fatigue database, and the safety factors for new 316FR best fit curve are shown. These safety factors are estimated based on the accuracy of the best fit curve, and are calculated for each surface finish in the designed vessels and piping. Therefore the adoption of accurate best fit curves in limited conditions will result in smaller safety factors than the present code.

Test Method of the εrms-N Curves of Laminated Composite Beams

2008 ◽  
Vol 44-46 ◽  
pp. 311-316
Author(s):  
Chuang Shao ◽  
Sen Ge ◽  
Hua Tao ◽  
Claude Bathias
Keyword(s):  
Resonance Frequency ◽  
Fatigue Test ◽  
Laminated Composite ◽  
Test Method ◽  
Cantilever Beams ◽  
Test Results ◽  
Vibration Fatigue ◽  
The Difference ◽  
Double Cantilever Beams ◽  
Laminated Composite Beams

Two kinds of beam specimens made of composite laminated panel were designed and used to do vibration fatigue test for ε-N curves. the shapes of various simulated joint configurations for the specimens were adopted in order to get the accurate results. They were two kinds of double-cantilever beams supplied by T-mode stiffener and L-mode stiffener. All beam specimens were tested under the same shape of narrowband spectrum and the several loadings of random vibration by shaker excitation. The bandwidth of the narrowband random spectrum was 1/3 octave bandwidth whose centre frequency was the first resonance frequency of the cantilever beam, so that it reduced influences of the difference of specimens resonance frequency. Fitting vibration fatigue test results, the ε-N curves would be obtained then. The vibration test shows that this method of getting ε-N vibration curve is feasible. It can be used in practice.

Development of New Design Fatigue Curves in Japan: Discussion of Effect of Surface Finish on Fatigue Strength of Nuclear Component Materials

2019 ◽  
Author(s):  
Motoki Nakane ◽  
Yun Wang ◽  
Hisamitsu Hatoh ◽  
Masato Yamamoto ◽  
Akihiko Hirano ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Carbon Steel ◽  
Fatigue Test ◽  
Surface Finish ◽  
Evaluation Method ◽  
Maximum Height ◽  
Test Results ◽  
Nuclear Component ◽  
Fatigue Evaluation

Abstract Based on the world wide fatigue test database, The Design Fatigue Curve (DFC) Phase 1 and 2 subcommittees established in The Japan Welding Engineering Society (JWES) have been developed new design fatigue curves which are applied for the nuclear component materials, in air environment. The effects of the design factor, such as mean stress, size effect and surface finish, etc. on the fatigue curves are also discussed with the fatigue database in order to construct fatigue evaluation method for the new design fatigue curves. The subcommittees also have studied the applicability of newly developed fatigue evaluation method to the nuclear component materials. This paper reports the fatigue test results of machined finished small-scale test specimens which are used for the verification of proposed fatigue evaluation method. The materials subjected to the fatigue tests are austenitic stainless steel SUS316LTP, low-alloy steels SQV2A and SCM435H, and carbon steel STPT370. Specimens finished with lathe machining are subjected to the tests. The planed maximum height roughness of the specimen are 25 and 100 μm. The fatigue test results show that the surface finish effect on the fatigue strength in the high cycle region of the austenitic stainless steel can be negligible. On the other hand, fatigue strength of the carbon steel and low alloy steel is decreased as increasing the surface roughness of the specimen. Especially, decrease of fatigue strength for the specimens with more than 100 μm maximum height roughness is larger than that of conventional estimation. It is presumed that severe roughness introduced by lathe machining tends to behave as notches and increase the stress concentration at the specimen surface, and resulted in unexpected decrease of fatigue strength.

scholarly journals Influence of Tool Length and Profile Errors on the Inaccuracy of Cubic-Machining Test Results

2021 ◽  
Vol 5 (2) ◽  
pp. 51
Author(s):  
Zongze Li ◽  
Hiroki Ogata ◽  
Ryuta Sato ◽  
Keiichi Shirase ◽  
Shigehiko Sakamoto
Keyword(s):  
Machine Tools ◽  
Test Accuracy ◽  
Test Results ◽  
Machining Error ◽  
Tool Profile ◽  
Machining Test ◽  
The Difference ◽  
Side Error ◽  
Profile Errors ◽  
Five Axis

A cubic-machining test has been proposed to evaluate the geometric errors of rotary axes in five-axis machine tools using a 3 × 3 zone area in the same plane with different tool postures. However, as only the height deviation among the machining zones is detected by evaluating the test results, the machining test results are expected to be affected by some error parameters of tool sides, such as tool length and profile errors, and there is no research investigation on how the tool side error influences the cubic-machining test accuracy. In this study, machining inaccuracies caused by tool length and tool profile errors were investigated. The machining error caused by tool length error was formulated, and an intentional tool length error was introduced in the simulations and actual machining tests. As a result, the formulated and simulated influence of tool length error agreed with the actual machining results. Moreover, it was confirmed that the difference between the simulation result and the actual machining result can be explained by the influence of the tool profile error. This indicates that the accuracy of the cubic-machining test is directly affected by tool side errors.

scholarly journals Experimental Study of the Space–Time Effect of a Double-Pipe Frozen Curtain Formation with Different Groundwater Velocities

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3830
Author(s):  
Shicheng Sun ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Bin Wang ◽  
Xiaogang Jiang ◽  
...  
Keyword(s):  
Freezing Temperature ◽  
Physical Model Test ◽  
Sand Layer ◽  
Test Results ◽  
Groundwater Velocity ◽  
Test Platform ◽  
The Difference ◽  
Freezing Test ◽  
Double Pipe ◽  
Thermal Physical Properties

Groundwater velocity has significant effects on the formation of a frozen curtain during freezing. In order to study the influence of the velocity on a frozen curtain, a large physical model test platform was established for double-pipe freezing. Based on this platform, freezing tests for different velocities were carried out. Quartz sand was selected as a similar material. The freezing temperature of the saturated sand layer was found by analyzing the results of the nuclear magnetic resonance (NMR). Based on the study of the thermal physical properties of the sand layer, the freezing test results were analyzed, and the results showed that the flow led to the differential development of the temperature between the upstream and downstream sections of the freezing pipes. Moreover, the larger the velocity, the greater the difference. The flow prolonged the overlapping time of the frozen curtains. Additionally, the flow slowed down the development of the frozen curtain area and the frozen curtain thickness. The larger the flow velocity, the greater the inhibition of the flow on the development of the frozen curtain. The test results can provide more references for the design and construction of freezing engineering with flowing groundwater.

Influence of Collagen Status on Microstructures of Porous Collagen/TCP Composites

2007 ◽  
Vol 330-332 ◽  
pp. 495-498
Author(s):  
Chao Zou ◽  
Wen Jian Weng ◽  
Xu Liang Deng ◽  
Kui Cheng ◽  
Pi Yi Du ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Cell Growth ◽  
Tricalcium Phosphate ◽  
Freeze Drying ◽  
Alkali Treatment ◽  
Test Results ◽  
Collagen Matrices ◽  
The Difference ◽  
Porous Composites ◽  
Better Than

Two starting collagens, sponge and floc collagen, were used to prepare collagen/tricalcium phosphate (TCP) composites. The resulting composites were porous and had 200μm pore size. However, there was a difference in the microstructure of the pore walls for the composites derived from the two collagens, the pore walls in sponge collagen/TCP composite were still porous and had 200 nm micropores size, TCP particles were trapped in collagen matrices. While floc collagen/TCP composite had smooth and dense walls in which TCP particles were embedded. The difference could be attributed to the starting collagen with different status. Sponge collagen has a soft structure, which easily becomes disassembled fibrils during alkali treatment, the disassembled fibrils are integrated again to form a dense morphology for pore walls after freeze-drying. While floc collagen has already a low disassembly degree, the alkali treatment could not be able to separate the fibrils, this remains as micropores in pore walls after freeze-drying. Both porous composites are significant in bone tissue engineering or regeneration. MTT test results showed the two composites had good cytocompatibility, and sponge collagen/TCP composite was somewhat better than floc collagen/TCP composite, which could result from that micropores derived roughness in pore walls of sponge collagen/TCP composite is suitable for cell growth.

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels

2009 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Amplitude ◽  
Surface Finish ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Loading ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

In February/March 2007, The NRC issued Regulatory Guide “RG1.207” and Argonne National Laboratory issued NUREG/CR-6909 that is now applicable in the US for evaluations of PWR environmental effects in fatigue analyses of new reactor components. In order to assess the conservativeness of the application of this NUREG report, Low Cycle Fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in air environment a fatigue behavior consistent with the ANL reference “air” mean curve, as published in NUREG/CR-6909. LCF tests in a PWR environment were performed at various strain amplitude levels (± 0.6% or ± 0.3%) for two loading conditions corresponding to a simple or to a complex strain rate history. The simple loading condition is a fully reverse triangle signal (for comparison purposes with tests performed by other laboratories with the same loading conditions) and the complex signal simulates the strain variation for an actual typical PWR thermal transient. In addition, two various surface finish conditions were tested: polished and ground. This paper presents the comparisons of penalty factors, as observed experimentally, with penalty factors evaluated using ANL formulations (considering the strain integral method for complex loading), and on the other, the comparison of the actual fatigue life of the specimen with the fatigue life predicted through the NUREG report application. For the two strain amplitudes of ± 0.6% and ± 0.3%, LCF tests results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates give “Fen” penalty factors close to those estimated using the ANL formulation (NUREG/6909). However, for the lower strain amplitude level and a triangle loading signal, the ANL formulation is pessimistic compared to the AREVA NP test results obtained for polished specimens. Finally, it was observed that constant amplitude LCF test results obtained on ground specimens under complex loading simulating an actual sequence of a cold and hot thermal shock exhibits lower combined environmental and surface finish effects when compared to the penalty factors estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins, whereas the current ASME approach seems sufficient to cover significant environmental effects for representative loadings and surface finish conditions of reactor components.

Local buckling capacity of C-shaped cold-formed steel sections with punched webs

1984 ◽  
Vol 11 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Robert Loov
Keyword(s):  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Average Yield ◽  
Steel Sections ◽  
Load Tests ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Best Fit ◽  
The Web

Load tests were carried out on 36 stub column samples of cold-formed steel studs having 38.1 mm wide × 44.5 mm long holes punched through their webs, steel thicknesses of 1.21–2.01 mm, and overall section depths of 63–204 mm. Based on these tests a best-fit equation for the effective width of the unstiffened portion of the web beside the holes has been developed. Suggested design equations have been proposed. The test results support the present equation for the average yield stress [Formula: see text] in Canadian Standards Association Standard S136-1974 but the present code equations for unstiffened plates are unduly conservative when applied to the design of the web adjacent to openings of the size considered.

scholarly journals Analysis of the Correlation between the Static and Fatigue Test Results of the Interlayer Bondings of Asphalt Layers

2016 ◽  
Vol 62 (1) ◽  
pp. 83-98 ◽  
Author(s):  
A. Szydło ◽  
K. Malicki
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Test Results ◽  
Static Tests ◽  
Bonding State ◽  
Road Pavement ◽  
The Future ◽  
Pavement Structure

Abstract The bonding state of the asphalt layers in a road pavement structure significantly affects its fatigue life. These bondings, therefore, require detailed tests and optimization. In this paper, the analyses of the correlation between the results of laboratory static tests and the results of fatigue tests of asphalt mixture interlayer bondings were performed. The existence of the relationships between selected parameters was confirmed. In the future, the results of these analyses may allow for assessment of interlayer bondings’ fatigue life based on the results of quick and relatively easy static tests.

Total Pressure Correction of a Sub-Miniature Five-Hole Probe in Areas of Pressure Gradients

2012 ◽  
Author(s):  
J. Town ◽  
A. Akturk ◽  
C. Camcı
Keyword(s):  
Pressure Measurement ◽  
Measurement Errors ◽  
Total Pressure ◽  
Pressure Gradients ◽  
Pressure Data ◽  
Flow Conditions ◽  
Complex Flow ◽  
Ducted Fan ◽  
The Difference ◽  
Best Fit

Five-hole probes, being a dependable and accurate aerodynamic tools, are excellent choices for measuring complex flow fields. However, total pressure gradients can induce measurement errors. The combined effect of the different flow conditions on the ports causes the measured total pressure to be prone to a greater error. This paper proposes a way to correct the total pressure measurement. The correction is based on the difference between the measured total pressure data of a Kiel probe and a sub-miniature prism-type five-hole probe. By comparing them in a ducted fan related flow field, a line of best fit was constructed. The line of best fit is dependent on the slope of the line in a total pressure versus span and difference in total pressure between the probes at the same location. A computer program, performs the comparison and creates the correction equation. The equation is subsequently applied to the five-hole probe total pressure measurement, and the other dependent values are adjusted. The validity of the correction is then tested by placing the Kiel probe and the five-hole probe in ducted fans with a variety of different tip clearances.

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