Application of elastic-plastic analysis method in high pressure heater tubesheet design

AbstractThe transient thermal process of a thin-wall beam with CO2 Gas Metal Arc Welding (GMAW) is analyzed by Finite Element Analysis Method (FEA). The thermal input is simplified as transient section body heat sources and loaded as its actual sequence in the analysis. The transient temperature field obtained can represent the basic characteristics of the real welding process and can be used as the foundation of thermal elastic-plastic analysis. Based on the temperature field, thermal elastic-plastic FEA is performed on the thin-wall beam. The distribution and change of the welding deformation, stress and strain are obtained and compared with the experiment results. Also an improvement can be presented on the inherent strain method. Using the inherent strain method, the welding deformation of the thin-wall beam is calculated. The temperature loading method is developed to load the variable inherent strain value expediently. The loading of inherent strain value on spatial welding line that is unparallel to the global coordinate axis is achieved with the application of element coordinate system. Comparison with the experiment results shows that both the thermal-elastic-plastic analysis and inherent strain analysis method can be used to predict the welding deformation effectively, the results calculated by both the thermal-elastic-plastic analysis and inherent strain analysis are close to the test measure results.

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

10.1115/pvp2021-61367 ◽

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.

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Study on Piping Response Under Multiple Excitation Validation for Elastic-Plastic Analysis of Piping

Volume 8: Seismic Engineering ◽

10.1115/pvp2014-28675 ◽

2014 ◽

Author(s):

Satoru Kai ◽

Tomoyoshi Watakabe ◽

Naoaki Kaneko ◽

Kunihiro Tochiki ◽

Makoto Moriizumi ◽

...

Keyword(s):

Plastic Deformation ◽

Seismic Response ◽

Nuclear Power ◽

Time History ◽

Large Earthquake ◽

Response Analysis ◽

Analysis Method ◽

Elastic Plastic ◽

History Analysis ◽

Plastic Analysis

Piping in a nuclear power plant is usually laid across several floors of a single building or adjacent buildings, and is supported at many points. As the piping is excited by a large earthquake through multiple supporting points, seismic response analysis by multiple excitations within the range of plastic deformation of piping material is necessary to obtain the precise seismic response of the piping. The verification of the dynamic analysis method of piping under an elastic domain, which is excited by multiple seismic inputs, was performed in our study last year and the correspondence of a piping response between an analysis and an experiment have been confirmed [17][18]. However, few experiments under plastic deformation conditions have been performed to verify the validity of multiple excitation analysis under a plastic deformation range. To obtain better understanding of the behavior of piping under a large seismic input, it is important to investigate the seismic response by multiple excitations and to verify the validity of the analytical method by multiple excitation experiments. This paper reports the validation results of the seismic elastic-plastic time history analysis of piping compared with the results of the shaking test of a 3-dimensional piping model under a plastic deformation range using triple uni-axial shake table. Three directional strains from the analysis and the experiments were compared in order to validate the analysis method. As a result, it is confirmed that the elastic-plastic analysis by time history excitation shows good agreement with the test results.

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Simplified Elastic-Plastic Analysis Method Using Ke Factors Obtained for the Real Structural Model

Journal of Pressure Vessel Technology ◽

10.1115/1.1522416 ◽

2003 ◽

Vol 125 (1) ◽

pp. 59-64 ◽

Cited By ~ 2

Author(s):

Asao Okamoto ◽

Yasuhiro Ohtake

Keyword(s):

Evaluation Method ◽

Structural Model ◽

Practical Case ◽

Analysis Method ◽

Axisymmetric Nozzle ◽

Element Analysis ◽

The Real ◽

Elastic Plastic ◽

Wide Range ◽

Plastic Analysis

This paper describes a new simplified elastic-plastic analysis method, which utilizes a plastic strain multiplication factor (Ke factor) obtained from elastic-plastic finite element analysis (FEA) results for the same structural model in the design stress calculation. ASME Code, Sec. III specifies a simplified elastic-plastic analysis method which can be used when PL+Q intensity exceeds the 3Sm limit, provided that the rules to prevent thermal stress ratchet are satisfied. The conventional method requires using Ke factors given by a closed-form equation having a value of PL+Q intensity as a variable. The elastically calculated peak stresses need be multiplied by the Ke factors, before performing the fatigue analysis. The Ke factors in the Code were derived from strain multiplication factors calculated for rather simple structural elements, which are assumed to cover a wide range of structural components. Consequently, although the rule can be applied safely to most of the cases, the results are usually too conservative. On the other hand, when PL+Q intensities are near 3Sm level, it has been pointed out based on experiments and analyses that the current Ke has a lack of margin. We propose to use the Ke factors obtained by FEA of the real structural model, in order to avoid the foregoing overconservatism and the lack of margin. The procedure also makes it unnecessary to extract PL+Q category, which is necessary in the conventional evaluation method. Elastic and elastic-plastic FEAs were performed for the axisymmetric nozzle in a vessel, and the effectiveness of the proposed procedure was shown in a practical case. Generalization of the procedure is also discussed.

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Nonlinear Computational Welding Mechanics for Large Structures

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4041395 ◽

2018 ◽

Vol 141 (2) ◽

Cited By ~ 1

Author(s):

Kazuki Ikushima ◽

Masakazu Shibahara

Keyword(s):

Thin Plate ◽

Conventional Method ◽

High Speed ◽

Large Scale ◽

Steel Structures ◽

Welding Deformation ◽

Analysis Method ◽

Plate Structures ◽

Elastic Plastic ◽

Plastic Analysis

In the construction of thin plate steel structures, including ships, welding is widely used to join parts. Welding inevitably causes deformation in thin plate structures, which may cause various problems. In the present study, an analysis method is developed to realize the prediction of deformation during the construction of large-scale structures based on the thermal elastic plastic analysis method. The developed method uses the idealized explicit finite element method (IEFEM), which is a high-speed thermal elastic plastic analysis method, and an algebraic multigrid method (AMG) is also introduced to the IEFEM in order to realize an efficient analysis of large-scale thin plate structures. In order to investigate the analysis accuracy and the performance of the developed method, the developed method is applied to the analysis of deformation on the welding of a simple stiffened structure. The developed method is then applied to the prediction of welding deformation in the construction of a ship block. The obtained results indicate that the developed method has approximately the same analysis accuracy as the conventional method, and the computational speed of the developed method is dramatically faster than that of the conventional method. The developed method can analyze the welding deformation in the construction of the ship block structure which consists of more than 10 million degrees-of-freedom and is difficult to solve by the conventional method.

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Analysis on Seismic Behavior of Structures Supported by Foundations with Different Locations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.824 ◽

2013 ◽

Vol 690-693 ◽

pp. 824-828

Author(s):

Li Ping Wang ◽

He Ping Zhong ◽

Lin Qing Huang

Keyword(s):

Seismic Design ◽

Seismic Behavior ◽

Internal Force ◽

Distribution Characteristic ◽

Analysis Method ◽

Distribution Law ◽

Elastic Plastic ◽

Plastic Analysis ◽

Displacement Angle ◽

Plastic Displacement

In order to know more about the seismic behavior of structures supported by foundations with different locations, using the elastic and static elastic-plastic analysis method, the research is respectively from the aspects of the distribution characteristic of elastic inter-story displacement angle, the distribution law of story shear, and the distribution characteristic of elastic-plastic displacement angle and the sequence of plastic hinges. In the end, it is got that the characteristics of force and deformation of structures supported by foundations with different locations. It is found that the position of weak story would change along with the change of story stiffness. In order to guarantee the structures supported by foundations with different locations to have good seismic behavior, it needs to take the necessary internal force adjust measures and details of seismic design.

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