Optimization of Environmental Fatigue Evaluation: Step 1

2007 ◽  
Author(s):  
Takao Nakamura ◽  
Masanobu Iwasaki ◽  
Seiji Asada
Keyword(s):  
Evaluation Method ◽  
Fatigue Curve ◽  
Design Stage ◽  
Total System ◽  
Analysis Method ◽  
Safety Factors ◽  
Alternative Evaluation ◽  
Plant Construction ◽  
Fatigue Evaluation ◽  
Design And Construction

In order to introduce environmental effects into fatigue evaluation of design and construction codes, the environmental fatigue evaluation method should not only be established, but the conservativeness of the codes, such as safety factors of design fatigue curve and simplified elastic-plastic analysis method (Ke factor), etc. should also be reviewed. Then plant designers should optimize total system of fatigue evaluation according to the objective of the codes by properly selecting design transient conditions and stress analysis methods used in fatigue evaluations as necessary. In addition, investigation of measures for reducing fatigue should be performed to mitigate possible fatigue initiators and alternative evaluation methods in case that the evaluation result should exceed the criteria specified in the design and construction codes. This paper discusses the present status in the review of these items for the Japanese PWR plants and future prospects to tackle on the application of environmental fatigue evaluation in design stage of plant construction.

Study on Incorporation of a New Design Fatigue Curve Into the JSME Environmental Fatigue Evaluation Method

2019 ◽  
Author(s):  
Seiji Asada ◽  
Shengde Zhang ◽  
Masahiro Takanashi ◽  
Yuichirou Nomura
Keyword(s):  
Nuclear Power ◽  
Evaluation Method ◽  
Fatigue Curve ◽  
Fatigue Analysis ◽  
Analysis Method ◽  
Energy Research ◽  
Research Committee ◽  
Engineering Society ◽  
Fatigue Evaluation ◽  
Generation Facility

Abstract A new fatigue analysis method was developed in the Subcommittee on Design Fatigue Curve in the Atomic Energy Research Committee in the Japan Welding Engineering Society JWES). If the new design fatigue curves are incorporated into the Environmental Fatigue Evaluation Method of the Japan Society of Mechanical Engineers (JSME), the environmental fatigue analysis can be optimized. The Subgroup on Fatigue Evaluation of the Subcommittee on Nuclear Power in the Main Committee on Power Generation Facility Codes in the JSME is reviewing the new design fatigue curves to incorporate into the JSME Environmental Fatigue Evaluation Method. This paper discuss the new design fatigue curves which is under review.

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.

Applicability of Seismic Fatigue Evaluation by JSME Code Case, NC-CC-008

2019 ◽  
Author(s):  
Akihito Otani ◽  
Izumi Nakamura ◽  
Tomoyoshi Watakabe ◽  
Masaki Morishita ◽  
Tadahiro Shibutani ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Evaluation Methodology ◽  
Response Analysis ◽  
Analysis Method ◽  
Seismic Evaluation ◽  
Fatigue Evaluation ◽  
Conservative Result ◽  
Current Rule

Abstract A Code Case, JSME S NC1, NC-CC-008, in the framework of JSME Nuclear Codes and Standards has been published. New seismic evaluation methodology for piping by utilizing advanced elastic-plastic response analysis method and strain-based fatigue criteria has been incorporated into the code case. It can achieve more rational seismic design than the current rule. This paper demonstrates validity and applicability of fatigue evaluation method proposed in the code case. Experimental results of a shaking table test for a piping model is used for comparing the evaluation by the current rule with one by the code case. As a result, it is confirmed that the code case can provide a rational and conservative result in the fatigue evaluation of piping. Moreover, cycle counting in the fatigue evaluation was examined for further progress of the code case.

Development of Creep–Fatigue Evaluation Method for 316FR Stainless Steel

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Yuji Nagae ◽  
Shigeru Takaya ◽  
Tai Asayama
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Evaluation Method ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Creep Damage ◽  
Fatigue Curve ◽  
Time To Failure ◽  
Creep Fatigue ◽  
Fatigue Evaluation

In the design of fast reactor plants, the most important failure mode to be prevented is creep–fatigue damage at elevated temperatures. 316FR stainless steel is a candidate material for the reactor vessel and internal structures of such plants. The development of a procedure for evaluating creep–fatigue life is essential. The method for evaluating creep–fatigue life implemented in the Japan Society of Mechanical Engineers code is based on the time fraction rule for evaluating creep damage. Equations such as the fatigue curve, dynamic stress–strain curve, creep rupture curve, and creep strain curve are necessary for calculating creep–fatigue life. These equations are provided in this paper and the predicted creep–fatigue life for 316FR stainless steel is compared with experimental data. For the evaluation of creep–fatigue life, the longest time to failure is about 100,000 h. The creep–fatigue life is predicted to an accuracy that is within a factor of 2 even in the case with the longest time to failure. Furthermore, the proposed method is compared with the ductility exhaustion method to investigate whether the proposed method gives conservative predictions. Finally, a procedure based on the time fraction rule for the evaluation of creep–fatigue life is proposed for 316FR stainless steel.

Optimization of Environmental Fatigue Evaluation: Step 2

2009 ◽  
Author(s):  
Yuichirou Nomura ◽  
Kazuya Tsutsumi ◽  
Toshihide Inoue ◽  
Seiji Asada ◽  
Takao Nakamura
Keyword(s):  
Evaluation Method ◽  
Fatigue Curve ◽  
Pressure Vessels ◽  
Austenitic Steels ◽  
Transient Conditions ◽  
Future Studies ◽  
Data Scatter ◽  
Fatigue Evaluation ◽  
Design Factors ◽  
Typical Design

In order to introduce environmental effects into fatigue evaluation of design and construction codes, the environmental fatigue evaluation method should not only be established, but the conservativeness of the codes, design transient conditions and so on should also be reviewed. The former paper [1] presented in 2007 ASME Pressure Vessels and Piping Conference reviewed and discussed design factors of design fatigue curves, design transient conditions, stress analysis techniques and environmental fatigue evaluation methods. In this paper, rationalization of typical design transient conditions is discussed and design factors of a design fatigue curve for austenitic steels are studied. Rationalized numbers and/or conditions are proposed for the typical design transients that are dominant for fatigue evaluation. A mean fatigue curve of austenitic steels is analyzed by using a statistical method with the latest data. The design factors of the fatigue curve of austenitic steels are investigated for parameters decreasing fatigue life such as size effect, surface finish and data scatter and appropriate design factors are proposed. Future studies are discussed.

Study on Incorporation of a New Design Fatigue Curve into JSME Environmental Fatigue Evaluation Method

2019 ◽  
Vol 2019 (0) ◽  
pp. OS1317
Author(s):  
Seiji ASADA ◽  
Shengde ZHANG ◽  
Masahiro TAKANASHI ◽  
Yuichirou NOMURA
Keyword(s):  
Evaluation Method ◽  
Fatigue Curve ◽  
Fatigue Evaluation

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

Analysis of the Safety Factors of Municipal Road Undercrossing Existing Bridge Based on Fuzzy Analytic Hierarchy Process Methods

2021 ◽  
pp. 036119812110318
Author(s):  
Yonghong Yang ◽  
Yu Chen ◽  
Zude Tang
Keyword(s):  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Safety Evaluation ◽  
Safety Factors ◽  
Analytic Hierarchy ◽  
Road Engineering ◽  
Existing Bridges ◽  
Hierarchy Process ◽  
Engineering Projects

Increasing traffic volume and insufficient road lanes often require municipal roads to be reconstructed and expanded. Where a road passes under a bridge, the reconstruction and expansion project will inevitably have an impact on the bridge. To evaluate the safety impact of road engineering projects on bridges, this paper evaluates the safety of the roads and ancillary facilities of highway bridges involved in municipal road engineering projects. Based on a comprehensive analysis of the safety factors of municipal roads undercrossing existing bridges, a fuzzy comprehensive analytic hierarchy process (AHP) evaluation method for the influence of road construction on the safety of existing bridges is proposed. First, AHP is used to select 11 evaluation factors. Second, the target layer, criterion layer, and index layer of evaluation factors are established, then a safety evaluation factor system is formed. The three-scale AHP model is used to determine the weight of assessment indexes. Third, through the fuzzy comprehensive AHP evaluation model, the fuzzy hierarchical comprehensive evaluation is carried out for the safety assessment index system. Finally, the fuzzy comprehensive evaluation method is applied to the engineering example of a municipal road undercrossing an existing expressway bridge. The comprehensive safety evaluation of the existing bridge reflects the practicability and feasibility of the method. It is expected that, with further development, the method will improve the decision-making process in bridge safety assessment systems.

Study on Mean Stress Effects for Design Fatigue Curves

2016 ◽  
Author(s):  
Seiji Asada ◽  
Takeshi Ogawa ◽  
Makoto Higuchi ◽  
Hiroshi Kanasaki ◽  
Yasukazu Takada
Keyword(s):  
Evaluation Method ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Mean Stress ◽  
Research Committee ◽  
Stress Effects ◽  
Alloy Steels ◽  
Design Factors

In order to develop new design fatigue curves for austenitic stainless steels, carbon steels and low alloy steels and a new design fatigue evaluation method that are rational and have a clear design basis, the Design Fatigue Curve (DFC) subcommittee was established in the Atomic Energy Research Committee in the Japan Welding Engineering Society. Mean stress effects for design fatigue curves are to be considered in the development of design fatigue curves. The Modified Goodman approach for mean stress effects is used in the design fatigue curves of the ASME B&PV Code. Tentative design fatigue curves were developed and studies on the effect of mean stress and design factors are on-going. Development of design fatigue curves, effect of mean stress and design factors is needed to establish a new fatigue design evaluation method. The DFC subcommittee has studied correction approaches for mean stress effects and the approaches of modified Goodman, Gerber, Peterson and Smith-Watson-Topper were compared using test data in literature. An appropriate approach for mean stress effects are discussed in this paper.

Adequate Strength for Small High-Speed Vessels

1968 ◽  
Vol 5 (01) ◽  
pp. 63-71
Author(s):  
Philip J. Danahy
Keyword(s):  
Stress Analysis ◽  
High Speed ◽  
Structural Strength ◽  
Integrated Approach ◽  
Suggested Method ◽  
Impact Loads ◽  
Analysis Method ◽  
Safety Factors ◽  
Recreational Vessels

The paper presents a method for the determination of the critical minimum scantlings for small high-speed vessels. Particular attention is given to the shell plating strength for hydrodynamic impact loads. The suggested method uses an integrated approach involving assumed loads, suggested safety factors, and preferred stress-analysis method. The stress analysis uses plastic theory based partly on the works of J. Clarkson and Thein Wah. Included in the paper is a comparison of the relative structural strength of several commercial, military, and experimental hydrofoil vessels along with a few planing boats and a seaplane hull. This shows the variation of existing vessel structures and compares them to the results obtained by the suggested method. Most commercial, military, and recreational vessels exceed the minimum scantlings of the suggested method. The most significant deviation is the hull of the seaplane:

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