Residual Stress Analysis by Simplified Inherent Strain at Welded Pipe Junctures in a Pressure Vessel

1999 ◽  
Vol 121 (4) ◽  
pp. 353-357 ◽  
Author(s):  
M. Mochizuki ◽  
M. Hayashi ◽  
T. Hattori
Keyword(s):  
Residual Stress ◽  
Pressure Vessel ◽  
Welded Joint ◽  
Three Dimensional ◽  
Small Diameter ◽  
Welding Residual Stress ◽  
The Finite Element Method ◽  
Diameter Pipe ◽  
Welded Pipe ◽  
Inherent Strain

We present a new and simplified method of estimating residual stress in welded structures by using inherent strain. The method makes use of elastic analysis by means of the finite element method and is used to calculate the residual stress in complicated three-dimensional structures efficiently. The inherent strain distribution in a welded joint of a small-diameter pipe penetrating a pressure vessel was assumed to be a simple distribution, and the residual stress was calculated. Inherent strain distributions were inferred from those of welded joints with simple shapes. The estimated residual stress using these inferred inherent strains agrees well with the measurements of a mock-up specimen. The proposed method is a simple way to estimate welding residual stress in three-dimensional structures of complicated shapes.

Measurement of Through-Thickness Residual Stress in Primary Piping of Girth Welded Joint

2008 ◽  
Vol 580-582 ◽  
pp. 577-580
Author(s):  
Masahito Mochizuki ◽  
Shigetaka Okano ◽  
Gyu Baek An ◽  
Masao Toyoda
Keyword(s):  
Residual Stress ◽  
Direct Measurement ◽  
Welded Joint ◽  
Strain Analysis ◽  
Residual Stress Distribution ◽  
Welding Residual Stress ◽  
Thickness Direction ◽  
Welded Pipe ◽  
Inherent Strain ◽  
Pipe Joint

The welding residual stress of a butt-welded pipe joint is evaluated, using inherent strain analysis. The residual stress distribution is obtained in detail along the thickness direction. The residual stresses are similar to values obtained by direct measurement on the specimen surface; as if though direct measurement is not used for the inherent strain analysis. These results indicate that inherent strain analysis is effective in evaluating through-thickness residual stress in primary piping of girth welded joint.

Numerical Analysis of Welding Residual Stress and Its Verification Using Neutron Diffraction Measurement

1999 ◽  
Vol 122 (1) ◽  
pp. 98-103 ◽  
Author(s):  
Masahito Mochizuki ◽  
Makoto Hayashi ◽  
Toshio Hattori
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Surface Stress ◽  
Welded Joint ◽  
Strain Analysis ◽  
Evaluation Methods ◽  
Welding Residual Stress ◽  
Diffraction Measurement ◽  
Stress Distributions ◽  
Inherent Strain

Direct measurements and computed distributions of through-thickness residual stress in a pipe butt-welded joint and a pipe socket-welded joint are compared. The analytical evaluation methods used were inherent strain analysis and thermal elastic-plastic analysis. The experimental methods were neutron diffraction for the internal residual stress, and X-ray diffraction and strain-gauge measurement for the surface stress. The residual stress distributions determined using these methods agreed well with each other, both for internal stress and surface stress. The characteristics of the evaluation methods and the suitability of these methods for each particular welded object to be evaluated are discussed. [S0094-4289(00)01501-2]

Inherent-Strain-Based Theory of Measurement of Three-Dimensional Residual Stress Distribution and Its Application to a Welded Joint in a Reactor Vessel

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Keiji Nakacho ◽  
Naoki Ogawa ◽  
Takahiro Ohta ◽  
Michisuke Nayama
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Strain Distribution ◽  
Measurement Method ◽  
Welded Joint ◽  
Three Dimensional ◽  
Reactor Vessel ◽  
Residual Stress Distribution ◽  
Stress Distributions ◽  
Inherent Strain

The stress that exists in a body under no external force is called the inherent stress. The strain that is the cause (source) of this stress is called the inherent strain. This study proposes a general theory of an inherent-strain-based measurement method for the residual stress distributions in arbitrary three-dimensional bodies and applies the method to measure the welding residual stress distribution of a welded joint in a reactor vessel. The inherent-strain-based method is based on the inherent strain and the finite element method. It uses part of the released strains and solves an inverse problem by a least squares method. Thus, the method gives the most probable value and deviation of the residual stress. First, the basic theory is explained in detail, and then a concrete measurement method for a welded joint in a reactor vessel is developed. In the method, the inherent strains are unknowns. In this study, the inherent strain distribution was expressed with an appropriate function, significantly decreasing the number of unknowns. Five types of inherent strain distribution functions were applied to estimate the residual stress distribution of the joint. The applicability of each function was evaluated. The accuracy and reliability of the analyzed results were assessed in terms of the residuals, the unbiased estimate of the error variance, and the welding mechanics. The most suitable function, which yields the most reliable result, was identified. The most reliable residual stress distributions of the joint are shown, indicating the characteristics of distributions with especially large tensile stress that may produce a crack.

Influence of the Welded Joint on the Mechanical Behavior of Steel Piles during Static and Dynamic Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Welded Joint ◽  
Dynamic Deformation ◽  
Three Dimensional ◽  
Steel Structures ◽  
Residual Stress Distribution ◽  
Dynamic Mechanical Behavior ◽  
Steel Piles

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results

scholarly journals Residual Stress Improvement on Inside Wall of Small-Diameter Pipe by Underwater Laser Ablation

2002 ◽  
Vol 122 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Yuji Sano ◽  
Masaki Yoda ◽  
Naruhiko Mukai ◽  
Mitsuaki Shimamura ◽  
Yoshiaki Ono ◽  
...  
Keyword(s):  
Residual Stress ◽  
Laser Ablation ◽  
Small Diameter ◽  
Diameter Pipe ◽  
Underwater Laser ◽  
Inside Wall

scholarly journals Study on Residual Stress of Welded Hoop Structure

2020 ◽  
Vol 10 (8) ◽  
pp. 2838
Author(s):  
Wenbo Ma ◽  
Heng Zhang ◽  
Wei Zhu ◽  
Fu Xu ◽  
Caiqian Yang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Speed ◽  
Weld Seam ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Forming Process ◽  
Maximum Residual Stress

Residual stress is inevitable during welding, which will greatly affect the reliability of the structure. The purpose of this paper was to study the residual stress of the hoop structure caused by the cooling shrinkage of the weld when the outer cylinder was wrapped and welded under the condition of the existing inner cylinder. In this paper, the “method of killing activating elements” of ANSYS was used to simulate the three-dimensional finite element of the hoop structure. In the case of applying interlayer friction, the welding-forming process and welding circumferential residual stress of the hoop structure were analyzed. The blind hole method was used to test the residual stress distribution of the hoop structure, and the test results were compared with the finite element simulation results to verify the reliability of the simulation calculation method and the reliability of the calculation results. Then, the influence factors of the maximum welding residual stress of the hoop structure were studied. The results show that the maximum residual stress of the outer plate surface of the hoop structure decreases with the increase of the welding energy, the thickness of the laminate, the width of the weld seam, the welding speed, and the radius of the container. Based on the results of numerical simulation, the ternary first-order equations of the maximum residual stress of the hoop structure with respect to the welding speed, the thickness of the laminate, and the width of the weld seam were established. Then, the optimal welding parameters were obtained by optimizing the equations, which provided an important basis for the safe use and optimal design of the welding hoop structure.

Numerical Simulation of Residual Stress in Multi-Pass Butt-Welded Stainless Steel Pipe

2009 ◽  
Author(s):  
S. Kasa ◽  
M. Mouri ◽  
M. Tsunori ◽  
D. Takakura
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Three Dimensional ◽  
Structural Response ◽  
Welding Residual Stress ◽  
Steel Pipe ◽  
Inelastic Behavior ◽  
Axisymmetric Model ◽  
Stiffness Method ◽  
Stainless Steel Pipe

It is necessary to obtain an accurate welding residual stress distribution for the evaluation of stress corrosion cracking (SCC) behavior. However, a welding residual stress simulation for pipes is often performed by a two dimensional axisymmetric model because this type of simulation requires significant time to analyze the complicated inelastic behavior. This approximation deteriorates the modeling accuracy since the welding heat input and the structural response are approximated by axisymmetric responses although they are originally three dimensional. The authors propose “a virtual additional stiffness method” in order to improve the accuracy of the axisymmetric model. With this method, the difference between the axisymmetric model and a three dimensional behavior was greatly reduced. The virtual additional stiffness method was used to reproduce three dimensional constraints that were not taken into account in the axisymmetric model. In the case of the axisymmetric model, an unrealistic large thermal expansion was observed because of simultaneous heating along a hoop direction of the whole pipe. In order to compensate this unrealistic deformation, a virtual additional stiffness was added in axial and radial directions on the axisymmetric model. This stiffness was added by using spring elements whose positions and spring constants were determined by comparing the two and three dimensional models. Results obtained by this new method in the multi-pass butt-welded stainless steel pipe were in very good agreement with measurements of the mock-up specimens.

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