Impact of Welding Sequence on the CRDM Nozzle-to-Vessel Weld Stress Analysis

2004 ◽  
Author(s):  
Yaoshan Chen ◽  
David Rudland ◽  
Gery Wilkowski
Keyword(s):  
Computing Time ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Three Dimensional Model ◽  
Control Rod ◽  
Moving Source ◽  
Welding Sequence ◽  
Significant Difference ◽  
Three Dimensional Finite Element

A three-dimensional finite element model is presented to simulate the welding process of the side-hill control-rod-drive-mechanism (CRDM) nozzle to the vessel head. Emphasis is given to how the weld is laid out in the analysis so that accurate residual stress results can be obtained while the required computing time is viable. In the order of complexity, three approaches are examined in this study: a) the simultaneous approach, i.e., the weld bead (therefore the heat associated with it) is put in the model in a uniform fashion; b) the piece-by-piece approach, i.e., the weld is laid out segment by segment; c) the moving-source approach where the analysis is done by simulating the moving heat source. It is found that there is a significant difference between the stress results by the uniform approach and the piece-by-piece approach. While the moving source method gives the closet representation of the welding process, the computing time for such a multi-pass, three-dimensional model is still prohibitive. The natural choice is therefore the piece-by-piece approach, with the number of segments for the weld dependent on the weld parameters and the geometries of the nozzle and vessel head.

Assessment of the Influence of Welding Parameters on Distortion

2014 ◽  
Vol 597 ◽  
pp. 208-212
Author(s):  
Fábio Renck Locatelli ◽  
Walter Jesus Paucar Casas ◽  
Ricardo Frederico Leuck Filho
Keyword(s):  
Welding Speed ◽  
Three Dimensional ◽  
Welding Process ◽  
Physical And Mechanical Properties ◽  
Element Model ◽  
Welding Parameters ◽  
Welding Sequence ◽  
Dimensional Finite Element ◽  
Definition Of ◽  
Three Dimensional Finite Element

The welding involves the transfer of high localized heat flow, which results in residual stresses in the welded body. The impossibility of relieving these stresses generates welding distortions that become a problem in dimensional setting of welded structures. This study aims to evaluate the influence of some parameters in the welding process in a T-type joint. Due to the complexity of the welded joint and the deposition rate, a three-dimensional finite element model was developed for the solution of the temperature field and distortions. The transient thermal analysis used the Goldak equation for definition of the heat flux transferred to the part. The nonlinear characteristics of the phenomenon as well as the dependence of physical and mechanical properties with the temperature were considered in this work. The parameters studied were the welding speed, welding sequence and cooling time between weld beads. The results suggest that the higher welding speed, the welding sequence forward and back and with cooling interval between beads present themselves as the best parameters for welding with lower distortions.

Numerical Study of Welding Sequence on the Residual Stress Field in a Thick-Walled Tee Joint

2011 ◽  
Vol 219-220 ◽  
pp. 1211-1214
Author(s):  
Wei Jiang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Field ◽  
Factors Affecting ◽  
Welding Sequence ◽  
Welding Sequences ◽  
Three Dimensional Finite Element

Finite element simulation is an efficient method for studying factors affecting weld-induced residual stress distributions. In this paper, a validated three-dimensional finite element model consisting of sequentially coupled thermal and structural analyses was developed. Three possible symmetrical welding sequences, i.e. one-welder, two-welder and four-welder sequence, which were perceived to generate the least distortion in actual welding circumstances, were proposed and their influences on the residual stress fields in a thick-walled tee joint were investigated. Appropriate conclusions and recommendations regarding welding sequences are presented.

Three-Dimensional Analysis of Continuously Reinforced Concrete Pavements

2000 ◽  
Vol 1730 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Seong-Min Kim ◽  
Moon C. Won ◽  
B. Frank McCullough
Keyword(s):  
Reinforced Concrete ◽  
Three Dimensional ◽  
Drying Shrinkage ◽  
Nonlinear Effects ◽  
Element Model ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Transverse Steel ◽  
Three Dimensional Finite Element

Continuously reinforced concrete pavement (CRCP) performance depends primarily on early-age cracks that result from changes in temperature and drying shrinkage. Presented is the behavior of the CRCP due to the temperature change obtained by using a three-dimensional finite element model. The nonlinear effects of the bond-slip between concrete and steel and between concrete and base have been studied. Modeling for the curling effect and for the viscoelastic material characteristics also has been considered. The results from the two-dimensional and three-dimensional models have been compared to verify the possibility of using a two-dimensional model. From this study, it was found that crack width and concrete stress are dependent on the transverse steel arrangement near the edge (longitudinal joint), but they are almost independent in the interior of the slab. The tensile stress occurring at the top of the edge on the transverse steel location can be higher than that occurring at the top of the slab center. This represents the possibility of forming a transverse crack from the edge on the transverse steel location. The twodimensional model with the plane stress element gives results very close to those of the three-dimensional model, except near the edge.

Numerical investigation on the effect of welding speed and heat input on the residual stress of multi-pass TIG welded stainless steel pipe

2020 ◽  
pp. 095440542098133
Author(s):  
Parviz Asadi ◽  
Samaneh Alimohammadi ◽  
Omid Kohantorabi ◽  
Ali Soleymani ◽  
Ali Fazli
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Numerical Investigation ◽  
Welding Speed ◽  
Heat Input ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Stress States ◽  
Three Dimensional Finite Element

A numerical investigation is provided to study the residual stress states in multi-pass TIG welding of stainless steel SUS304 pipe. An uncoupled thermomechanical three-dimensional finite element model is developed using the ABAQUS software for a circular weld design around the pipe. The effects of weld pass numbers, electrode moving speed, and heat input on the internal and external surface tensions of the pipe are investigated. The simulation results show that by increasing the welding speed, the axial tensile stresses decrease on the pipe surfaces. In the case of hoop stress, as the welding speed raises, the tensile and compressive stresses are increased for both two- and three-pass welding. However, the width of the stress zone becomes narrower in higher welding speeds. The hoop stresses, in comparison with the axial stresses, are more strongly influenced by the welding speed and the heat input. Furthermore, using the three-pass welding process results in much lower stresses in comparison with the two-pass one.

scholarly journals FATIGUE LIFE ESTIMATION OF A BUTT WELDED JOINT BY S-N APPROACH

2012 ◽  
pp. 95-99
Author(s):  
VINOD M. BANSODE ◽  
N.D. MISAL
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Welding Process ◽  
Life Time ◽  
Element Model ◽  
Simulation Software ◽  
Surface Machining ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A failure analysis based on stress life approach may be useful for predicting the life time of weld in the structure. This study presents an upcoming methodology in new three dimensional Finite Element Model to calculate the fatigue life of weld. Ansys 12.1 simulation software uses stress-life method, based on a static non-linear Structural analysis. The weld material S-N curve were experimentally determined by the Fatigue testing of the dumbell specimen as per 7608 standard. This study assumes that a flaw exist in weld due to welding process, material in-homogeneity, air voids, slugs or impurities in weld, improper surface machining and many more. This material curve is used in simulation to get more accurate results. Thus the fatigue life prediction with the material curves from experimentation will give us more accurate and close to actual failure results.

Simulation of a New Solid State Joining Process Using Single-Shoulder Two-Pin Tool

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
S. Mukherjee ◽  
A. K. Ghosh
Keyword(s):  
New Technology ◽  
Local Heating ◽  
Reaction Force ◽  
Three Dimensional ◽  
Welding Process ◽  
Tool Material ◽  
Element Model ◽  
Tool Design ◽  
Friction Stir ◽  
Three Dimensional Finite Element

In friction stir welding (FSW) process, heat is generated by friction between the tool and the workpiece. The conventional tool design employs a cylindrical shoulder with a single profiled pin. A new process has been designed that uses two-pin tool under the same shoulder to increase shear deformation within workpiece that can enhance local heating where joining occurs. The design employs two closely spaced pins rotating in the same direction within the workpiece under a separately controlled shoulder. The process is distinctly different from the Twin-stir™ variant of FSW in which each pin performs an independent function and non-interacting. Prior to gathering considerable experimental data with new equipment, a fully coupled themomechanical three-dimensional finite element model has been developed to compare the existing single-pin technology with new technology of friction driven stitch welding process. The computational results for the two-pin tool show considerable shearing along the joining interface, enhanced local heating, and a reduced reaction force on the pins, which are described in this paper. The results of this study indicate that the two-pin tool design with a separate shoulder, with the same direction of pin rotation, can be a superior design in comparison to the conventional single-pin FSW tool and could minimize damage to tool material.

Numerical Simulation and Experiment Analysis of MIG Welding for Aluminum Alloy Extrusion

2012 ◽  
Vol 430-432 ◽  
pp. 1311-1314
Author(s):  
Zheng Zhi Luo ◽  
Yi Su Pan
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Mig Welding ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Welding Processes ◽  
Aluminum Alloy Extrusion

Welding characteristics of MIG welding for aluminum alloy extrusions are studied. In this article, the aluminum alloy is EN AW-6005A. The welding heat source and the welding processing of aluminum alloy extrusions are discussed. A three dimensional finite element model has been developed to dynamically simulate the welding process. The investigations focus on the comparison the welding heat resource of simulation and section of the experiments parts. And the residual stress of numerical simulation and tests are compared. It’s help to optimize the MIG welding processes and improve the welding quality for aluminum alloy extrusion.

A Fracture Mechanics Evaluation of an Indication in an RPV Vertical Shell Weld Produced by the Upjohn Welding Technique

2004 ◽  
Author(s):  
Hardayal S. Mehta ◽  
Wade F. Miller ◽  
M. A. Brooks
Keyword(s):  
Three Dimensional ◽  
Infinite Plate ◽  
Welding Process ◽  
Element Model ◽  
K Value ◽  
Heavy Plate ◽  
Asme Code ◽  
Three Dimensional Finite Element ◽  
Renewal Period ◽  
Welding Technique

A reactor pressure vessel (RPV) manufacturer used the Upjohn welding technique to fabricate the longitudinal and meridional seam welds in a number of RPVs. The Upjohn welding process allowed fabrication of heavy plate sections without the use of positioning devices. With this welding technique, the major dimension of fabrication flaws extends through the weld thickness rather than parallel to the thickness as with other fabrication welding techniques. One vertical weld seam of a RPV fabricated using the Upjohn weld process was examined by ultrasonic techniques consistent with PDI requirements. Flaws were detected during the ASME Code required in-service inspection. After the application of the flaw proximity rules, one indication was characterized as a planar flaw 4.24 inches long (along the weld thickness direction) and 2-inches wide. One end of the indication was located 0.7 inch from the ID surface, which included a clad thickness of 5/16 inch. The use of Section XI flaw characterization and proximity rules would have required the characterization of this flaw as a large surface flaw. Therefore, a three-dimensional finite element model, including crack tip elements, was developed to determine the increase in the theoretical infinite plate K value due to the edge effect. The flaw evaluation was based on the guidelines of Appendix A of ASME Section XI. The allowable K values considered adjusted reference temperature (ART) based on cumulative fluence from operation to end of design life, which included a 20-year license renewal period. Because the calculated values of K were less than the allowable values of K, it was concluded that the indication is not expected to become a surface indication during future operation. Discussion on recommendations for RPVs with Upjohn welds, suggested changes to ASME Section XI Paragraph IWB-3610 and a comparison with the RPV flaw database is also provided.

scholarly journals An Efficient Dynamic Modeling Technique for a Central Tie Rod Rotor

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jingze Liu ◽  
Qingguo Fei ◽  
Shaoqing Wu ◽  
Zhenhuan Tang ◽  
Sanfeng Liao ◽  
...  
Keyword(s):  
High Efficiency ◽  
Experimental Testing ◽  
Research Work ◽  
Three Dimensional ◽  
Element Model ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Mass Model ◽  
One Dimensional ◽  
Three Dimensional Finite Element

Compared with the three-dimensional rotor model for a central tie rod rotor, an equivalent one-dimensional model can greatly improve the computational efficiency in rotor dynamics analysis with a certain accuracy. However, little research work can be found on improving the modeling accuracy of one-dimensional models using experimental data. In this paper, a one-dimensional discrete mass model considering pretightening force is proposed for central tie rod rotors to achieve the purpose of both efficient and accurate modeling. Experimental testing and three-dimensional model analysis are used as reference and verification approaches. A sensitivity-based method is adopted to update the proposed one-dimensional model via minimizing the error in the critical speed comparing with the corresponding three-dimensional finite element model which has been verified by a modal test. Prediction of damped unbalanced response is conducted to show the practicality of the updated one-dimensional model. Results show that the method presented in this research work can be used to simulate a complex preloaded rotor system with high efficiency and accuracy.

Influence of Elastic Deformations of Turbo-Generator Tilting Pad Bearings on the Static Behavior and on the Dynamic Coefficients in Different Designs

1989 ◽  
Vol 111 (2) ◽  
pp. 364-371 ◽  
Author(s):  
D. Brugier ◽  
M. T. Pascal
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Operating Conditions ◽  
Three Dimensional Model ◽  
Static Loads ◽  
Turbo Generator ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Tilting Pad Bearings ◽  
Three Dimensional Finite Element

The load on the larger tilting pad bearing can be as high as 106 N. With such high static loads, pad and pivot distortions and thermal effects in the lubricant cannot be neglected. This paper analyzes the influence of the deformation of the pads and pivots on the static and dynamic behavior of typical turbo-generator tilting pad bearings used in actual operating conditions. Thermal and pressure distortions are compared. The hydrodynamic pressures and lubricant temperatures are computed with a three-dimensional model. Thermal and elastic pad and pivot distortions are obtained with a three-dimensional finite element model.

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