Alternative Approaches for ASME Code Simplified Elastic-Plastic Analysis

2017 ◽  
Author(s):  
Sampath Ranganath ◽  
Nathan A. Palm
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Correction Factor ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Asme Code ◽  
Alternative Approaches ◽  
Fatigue Evaluation ◽  
Technical Basis

Subsection NB, Section III of the ASME Code provides rules for the fatigue evaluation of nuclear pressure vessel and piping components. The stress analysis in ASME code evaluation is generally based on linear elastic analysis. Simplified rules using an elastic-plastic strain correction factor, Ke, are provided in Section III to account for plastic yielding when the primary plus secondary stress intensity range exceeds the 3Sm limit. While the simplified elastic-plastic analysis rules are easy to apply and do not require nonlinear analysis, the application of the Ke correction factor can produce extremely conservative results. This paper investigates different analytical methods that are available for simplified elastic-plastic analysis and proposes an alternative method that is not overly conservative (compared to the Code Ke) and offers a more realistic approach to simplified elastic-plastic analysis. The proposed methodology is applicable for both vessel (NB-3200), core support structures (NG-3200) and piping components (NB-3600) and does not require new finite element analysis. Information in existing ASME Code stress reports should be sufficient to determine the new Ke factor. The proposed methodology is applicable to structural materials including austenitic stainless steel and nickel based alloys, carbon steel and low alloy steel. Comparison of the proposed methodology with detailed elastic-plastic finite element analysis shows that the new Ke factors are conservative but offer relief from the excessive conservatism in the Code Ke values. This paper provides the technical basis for an ASME draft Code Case for Alternative Approaches for ASME Code Simplified Elastic-plastic Analysis being pursued through the Section III ASME Code Committees.

The Application of ABAQUS in Cast-Steel Joints Elastic-Plastic Analysis

2013 ◽  
Vol 351-352 ◽  
pp. 854-859 ◽  
Author(s):  
Fan Wang ◽  
Zhi Feng Luo ◽  
Sheng Hao Mo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cast Steel ◽  
Element Analysis ◽  
Elastic Plastic ◽  
The Finite Element Analysis ◽  
Plastic Analysis ◽  
Reticulated Shell Structure ◽  
Steel Joints ◽  
Cast Steel Joint

The article introduces the application of the large universally used finite element analysis software ABAQUS in elastic-plastic analysis of the cast-steel joints in building structure. Using the cast-steel joint of a large reticulated shell structure in Shenzhen as an example, the article explains how to import the joint model into ABAQUS and start the finite element analysis, and finally get the elastic-plastic analysis results, thus provide the reference for engineering design, analysis and optimize design of cast-steel joints.

Twice-Yield Method Abaqus Implementation With Application to a Thermally Shocked Stepped Pipe

2021 ◽  
Author(s):  
Steven M. Smith ◽  
David N. Hutula
Keyword(s):  
Finite Element Analysis ◽  
Material Properties ◽  
Structural Response ◽  
Analysis Method ◽  
Load Range ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Lehigh University ◽  
Plastic Analysis ◽  
Technical Basis

Abstract The Twice-Yield method is an elastic-plastic finite element analysis (FEA) pioneered by Professor Arturs Kalnins at Lehigh University which approximates the stabilized cyclic response that would otherwise be obtained from a cycle-by-cycle elastic-plastic FEA. The Twice-Yield method is used to evaluate the load range conditions which occur between any two load states from the stabilized cyclic structural response. The rigorous implementation of the Twice-Yield method requires special handling of material properties. In particular, the method requires the average of the properties corresponding to the two load states. This paper documents a detailed technical basis of the Twice-Yield method’s implementation in Abaqus including the special handling of material properties. An assessment of the Twice-Yield method is performed based on analyzing a thermally shocked stepped pipe. Included in the assessment are comparisons of the cycle-by-cycle elastic-plastic FEA results and the Twice-Yield method elastic-plastic FEA results. The comparisons show the efficacy of the Twice-Yield method as a viable cyclic elastic-plastic analysis method.

Overview of Code Case on Alternative Design Methodology by Using Elastic-Plastic Finite Element Analysis for Class 1 Vessels in the JSME Rules on Design and Construction

2010 ◽  
Author(s):  
Seiji Asada ◽  
Takashi Hirano ◽  
Tetsuya Nagata ◽  
Naoto Kasahara
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Methodology ◽  
Evaluation Method ◽  
Plastic Collapse ◽  
Element Analysis ◽  
Alternative Design ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Design And Construction

An alternative design methodology by using elastic-plastic finite element analysis has been developed and published as a code case of the JSME Rules on Design and Construction for Nuclear Power Plants (The First Part: Light Water Reactor Structural Design Standard). This code case applies elastic-plastic analysis to evaluation of such failure modes as plastic collapse, shakedown, thermal ratchet and fatigue. Advantages of this evaluation method are no use of stress linearization/classification, consistent use of Mises equivalent stress and applicability to complex 3-dimentional structures which are hard to be treated by the conventional stress classification method. The evaluation method for plastic collapse consists of the Lower Bound Approach Method, Twice-Elastic-Slope Method and Elastic Compensation Method. Cyclic Yield Area (CYA) criterion based on elastic analysis is applied to screening evaluation of shakedown limit instead of secondary stress evaluation, and elastic-plastic analysis is performed when the CYA screening criterion is not satisfied. Strain concentration factors can be directly calculated based on elastic-plastic analysis.

Thermal Elastic-Plastic Stress Analysis of Structural Elements With Creep

2005 ◽  
Author(s):  
R. Sarala ◽  
B. Sutharson ◽  
D. Jaya Kanth
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Kinematic Hardening ◽  
Transient State ◽  
Structural Elements ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Plastic Stress

Finite element analysis of thermo-mechanical problems is reported here. From the literature, it may be seen that the thermal-elastic plastic analysis of structural elements has continued to remain a research topic for a couple of decades. No one computationally verified the thermal elastic plastic stress analysis with creep using triangular elements or quadrilateral elements. Finite element analysis code TSAP (Thermal Structural Analysis Programme) was developed in FORTRAN to handle the elastic-plastic stress analysis on two-dimensional planar or three dimensional axisymmetry structures subjected to combined thermal and mechanical loads. In this work, thermo elastic plastic analysis is extended to creep support. A triangular or quadrilateral element has been used to analysis of structures with inclusion of creep. The formulation is based on isotropic or kinematic hardening rule. The validation checks on the program are carried out using results available in the literature. The parameters are considered while analyses are (1.) Type of materials used (2.) Type of elements used (3.) Structure geometry (axisymmetry, plane stress or plane strain) (3.) Type of analysis (steady state or transient state) (4.) Type of loading (5.) Various boundary conditions (conductive or heat flux boundary) (6.) Effect of creep inclusion.

A Simplified Approach on the Elastic-Plastic Analysis of Threaded Connectors

1986 ◽  
Vol 108 (1) ◽  
pp. 15-19
Author(s):  
L. Y. Chen ◽  
M. R. Williams
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Analysis ◽  
Element Analysis ◽  
Manufacturing Costs ◽  
Simplified Approach ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Improve Cost Effectiveness ◽  
Improve Cost

The design of threaded connectors based on an elastic analysis appears overly conservative. This, in turn, will result in unnecessary material and manufacturing costs. To improve cost effectiveness, the design of connectors from the elastic-plastic viewpoint is warranted. This paper presents a simplified approach on the elastic-plastic finite element analysis of connectors. This approach would save tremendous computer costs which may be incurred in conducting a regular elastic-plastic analysis of threaded connectors.

Numerical Investigation on Plastic Strain Correction Factor in Simplified Elastic-Plastic Fatigue Analysis

2016 ◽  
Vol 853 ◽  
pp. 226-230
Author(s):  
Qian Hua Kan ◽  
Su Juan Guo ◽  
Jian Li ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Plastic Strain ◽  
Correction Factor ◽  
Stress Range ◽  
Secondary Stress ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Design Stress

A plastic strain correction factor is used in a simplified elastic-plastic fatigue analysis of nuclear power plant components. Numerical investigation on the plastic strain correction factor is presented for the case of the primary and secondary stress range exceeding three times the design stress intensity value under thermal-mechanical loadings. The plastic strain correction factor was computed separately by following the RCC-M code and applying the elastic-plastic finite element analysis. The influence of loading ratio, loading controlled mode and ambient temperature on the plastic strain correction factor was discussed. It was shown that the plastic strain correction factor computed from the RCC-M code is not as conservative as that from the complete elastic-plastic finite element analysis when the primary plus secondary stress range is close to three times the design stress intensity value. However, it is too conservative when the primary plus secondary stress range is more than three times the design stress intensity value multiplying parameter m (use in RCC-M code). Additionally, a new formula of plastic strain correction factor was proposed to provide a complete envelope curve to the entire primary plus secondary stress range.

scholarly journals Elastic-Plastic Analysis of the PVRC Burst Disk Tests With Comparison to the ASME Code Primary Stress Limits

2000 ◽  
Vol 122 (2) ◽  
pp. 146-151 ◽  
Author(s):  
D. P. Jones ◽  
J. E. Holliday
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
High Strength ◽  
High Ductility ◽  
Test Results ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Primary Stress ◽  
Asme Code

This paper provides a comparison between finite element analysis results and test data from the Pressure Vessel Research Council (PVRC) burst disk program. Testing sponsored by the PVRC over 20 yr ago was done by pressurizing circular flat disks made from three different materials until failure by bursting. The purpose of this reanalysis is to investigate the use of finite element analysis (FEA) to assess the primary stress limits of the ASME Boiler and Pressure Vessel Code (hereafter the Code), and to qualify the use of elastic-plastic (EP-FEA) for limit-load calculations. The three materials tested represent the range of strength and ductility found in modern pressure vessel construction and include a low-strength, high-ductility material, a medium-strength, medium-ductility material, and a high-strength, low-ductility, low-alloy material. Results of elastic and EP-FEA are compared to test data. Stresses from the elastic analyses are linearized for comparison of Code primary stress limits to test results. Elastic-plastic analyses are done using both best-estimate and elastic-perfectly plastic (EPP) stress-strain curves. Both large strain-large displacement (LSLD) and small strain-small displacement (SSSD) assumptions are used with the EP-FEA. Analysis results are compared to test results to evaluate the various analysis methods, models, and assumptions as applied to the bursting of thin disks. The test results show that low-strength, high-ductility materials have a higher burst capacity than do high-strength, low-ductility materials. Linearized elastic FEA stresses and ASME Code primary stress limits provide excessive margins to failure for the burst disks for all three materials. The results of these studies show that LSLD EP-FEA can provide a best-estimate analysis of the disks, but the accuracy depends on the material stress-strain curve. This work concludes that SSSD EPP analysis methods provide a robust and viable alternative to the current elastic linearization method of satisfying the primary stress limits of the Code. [S0094-9930(00)01602-4]

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