Prediction of weld-induced distortion of large structure using equivalent load technique

2016 ◽  
Vol 232 (3) ◽  
pp. 499-512 ◽  
Author(s):  
Arpan Kumar Mondal ◽  
Anche Lohit ◽  
Pankaj Biswas ◽  
Swarup Bag ◽  
Manas Das
Keyword(s):  
Welding Process ◽  
Residual Deformation ◽  
Computation Time ◽  
Mechanical Analysis ◽  
Angular Distortion ◽  
Computational Time ◽  
Large Structure ◽  
Welded Structure ◽  
Weld Structure ◽  
Equivalent Load

Angular distortion in fusion welded joints is an alarming issue which affects the stability and life of the welded structures, occurs due to the changes in the temperature gradient during the welding process. This degrades the dimensional quality of a large structure during assembly which leads to rework the products and hence decreases the productivity. Predicting the weld-induced residual deformation before the production saves the valuable time and resources for rework. The conventional coupled transient, nonlinear, elasto-plastic thermo-mechanical analysis involves huge computational time. Computing a weld sample of small size with single pass itself takes several hours, which will be a huge amount of time in case of large structures consisting of several welding passes; thus, there is a real need of an efficient alternative technique to predict the post-weld distortions. In this work, an attempt has been made to determine the deformation in a submerged arc welded structure using equivalent load technique which reduces the total analysis time by one-third of the conventional techniques in case of a small weld structure. In this proposed method, the transient nonlinear elasto-plastic structural analysis part which is the major time-consuming part of analysis has been almost eliminated. So, this method can effectively use to predict the weld-induced distortion of very large structure with a computation time almost equal to the time required for transient thermal analysis of a small weld structure only. It is not feasible to analyze such a large welded structure with conventional coupled transient, elasto-plastic, nonlinear thermo-mechanical analysis. The predicted results of distortions have been validated with the experimental as well as published results and good agreements have been found.

scholarly journals Modified Equivalent Load Method for Welding Distortion Analysis

2020 ◽  
Vol 8 (10) ◽  
pp. 794
Author(s):  
Jaemin Lee ◽  
Hyun Chung
Keyword(s):  
Shell Element ◽  
Angular Distortion ◽  
Computational Time ◽  
Welding Distortion ◽  
Distortion Analysis ◽  
Equivalent Load Method ◽  
Inherent Deformation ◽  
Longitudinal Bending ◽  
Equivalent Load ◽  
Improved Accuracy

In this study, modified equivalent load method for welding distortion analysis is suggested to improve its accuracy. To avoid the excessive computational time for welding distortion analysis of large welded structures, shell element-based elastic analysis methods are widely used, applying the inherent deformation approach. Equivalent nodal forces are commonly used in common FE (Finite Element) codes to enter these inherent deformation values. However, the conventional method cannot estimate precise longitudinal bending following the conventional equation. In this study, the problem of the existing equivalent load method is analyzed by a case study, and the modified equivalent load method that can estimate angular distortion, transverse shrinkage, and longitudinal bending is presented based on the FEM principle. The results show that by applying the proposed method, the shell element-based elastic FE approach for the welding distortion analysis can be achieved with improved accuracy.

Numerical Study on the Effectiveness of Fixture and Pre-Strain for Reduction of Welding Distortion

2008 ◽  
Vol 580-582 ◽  
pp. 401-404
Author(s):  
Lin Jie Zhang ◽  
Jian Xun Zhang ◽  
Wei Liang ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Numerical Study ◽  
Residual Deformation ◽  
Angular Distortion ◽  
Welding Distortion ◽  
Work Piece ◽  
Fe Model ◽  
Structure Comparison ◽  
Welded Structure ◽  
Simulation Results ◽  
Appreciable Reduction

An in-house developed FE code, based on the idea of Iterative Substructure Method, was used to evaluate the effectiveness of fixture and pre-strain for reduction of welding distortion in a fillet welded structure. Comparison between the simulation results and experimental results has been performed to validate the basic FE model. Effects of two fixture conditions and various prestrain schemes were analyzed. The simulation results show that appropriate fixture can greatly reduce angular distortion of the work-piece and results in an appreciable reduction in residual deformation and the application of pre-strain can significantly reduce the residual distortion.

scholarly journals Structure Analysis and Design of Automobile plastic clutch pump body based on friction welding

2020 ◽  
Vol 316 ◽  
pp. 02001
Author(s):  
Jing Sheng ◽  
Aamir Sohail ◽  
Mengguang Wang ◽  
Zhimin Wang
Keyword(s):  
High Temperature ◽  
Structural Design ◽  
Friction Welding ◽  
Room Temperature ◽  
Welding Process ◽  
Structure Type ◽  
Mechanical Analysis ◽  
Analysis And Design ◽  
Technical Requirements ◽  
Design Requirements

In order to realize the need for lightweight automobiles through replacing steel with plastics, the research and development of the plastic clutch pump body based on the friction welding was carried out. For the clutch pump body connected by friction welding process between the upper pump body and the lower pump body, the technical requirements of pressure 14 MPa and durability (high temperature 7.0 × 104 times, room temperature 7.0 × 105) are required. The structure type of the upper and lower pump bodies of the end face welding type was proposed. Through the static analysis of the pump body and weld and the mechanical analysis under the working condition, the structure of the clutch pump body (upper and lower pump body) was determined. According to the established welding process, the pressure of the clutch pump body is more than 15 MPa, and the number of high-temperature durable circulation and the number of room temperature durable circulation also reached 7.2×104 and 7.3×105 times respectively. The results show that the structural design of a clutch pump body meets the design requirements.

Thermomechanical Model of Spot Welding for Calculating Residual Stresses

2003 ◽  
Author(s):  
Lijun Xu ◽  
Jamil A. Khan
Keyword(s):  
Residual Stresses ◽  
Heat Generation ◽  
Spot Welding ◽  
Welding Process ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Thermomechanical Model ◽  
Faying Surface ◽  
Proposed Model ◽  
Electrode Interface

A comprehensive axisymmetric model of the coupled thermal-electrical-mechanical analysis predicting weld nugget development and residual stresses for the resistance spot welding process of Al-alloys is developed. The model estimates the heat generation at the faying surface, the workpiece-electrode interface, and the Joule heating of the workpiece and electrode. The phase change due to melting in the weld pool is considered. The contact area and its pressure distribution at both the faying surface and the electrode-workpiece interface are determined from a coupled thermal-mechanical model using a finite element method. The knowledge of the interface pressure provides accurate prediction of the interfacial heat generation. For the numerical model, temperature dependent thermal, electrical and mechanical properties are used. The proposed model can successfidly calculate the nugget diameter and thickness, and predict the residual stresses and the elastic-plastic deformation history. The calculated nugget shape and the deformation of sheets based on the model are compared with the experimental data. The computed residual stresses approach the distribution of experimental measurement of the residual stress.

Residual Deformation of a Hard-Coated Valve Seat Subjected to Thermal Shocks

2010 ◽  
Author(s):  
Jean-Philippe Mathieu ◽  
Jean-Franc¸ois Rit ◽  
Je`roˆme Ferrari ◽  
David Hersant
Keyword(s):  
Welding Process ◽  
Residual Deformation ◽  
The Body ◽  
Dominant Effect ◽  
Welding Temperature ◽  
Physical Test ◽  
Physical Testing ◽  
A Chain ◽  
Globe Valve ◽  
Thermal Shocks

Most safety related valves in EDF’s nuclear plant must prove their ability to sustain thermal shocks of approximately 240K amplitude. This paper evaluates the simulation of a globe valve tested for thermal shocks. Since the physical test campaign showed inadequate internal sealing, the simulation focuses on the residual deformation of the hard alloy, planar seat, welded on successive body designs. This deformation is the result of the thermal loadings first induced by the welding process, then by fluid flow inside the valve. A chain of 3D simulations successively computes: a welding temperature transient in the body, the resulting strain hardening — especially in the seat vicinity —; temperature transients in the flow and the valve parts, and the resulting strains in the body causing a bump deformation of the seat surface. This end result agrees with measurements on the tested valve specimen. We show that inaccurate results are obtained on simpler assumptions, such as no welding, and we give insights on the dominant effect of the first hot, cold, hot transient over other profiles. Finally, the agreement we obtain on deformation predictions is toned down by an unsatisfactory sealing prediction, as well as the complexity and duration of the simulation chain compared with physical testing.

A Method to Define the Best Weld Sequence Using a Limited Number of Welding Simulation Analysis

2015 ◽  
Author(s):  
Mahyar Asadi ◽  
Ghazi Alsoruji
Keyword(s):  
Simulation Model ◽  
Surrogate Model ◽  
Simulation Analysis ◽  
Combinatorial Problem ◽  
Fem Analysis ◽  
Simulation Models ◽  
Computational Time ◽  
Optimal Sequence ◽  
Welded Structure ◽  
Welding Sequence

Weld sequence optimization, which is determining the best (and worst) welding sequence for welding work pieces, is a very common problem in welding design. The solution for such a combinatorial problem is limited by available resources. Although there are fast simulation models that support sequencing design, still it takes long because of many possible combinations, e.g. millions in a welded structure involving 10 passes. It is not feasible to choose the optimal sequence by evaluating all possible combinations, therefore this paper employs surrogate modeling that partially explores the design space and constructs an approximation model from some combinations of solutions of the expensive simulation model to mimic the behavior of the simulation model as closely as possible but at a much lower computational time and cost. This surrogate model, then, could be used to approximate the behavior of the other combinations and to find the best (and worst) sequence in terms of distortion. The technique is developed and tested on a simple panel structure with 4 weld passes, but essentially can be generalized to many weld passes. A comparison between the results of the surrogate model and the full transient FEM analysis all possible combinations shows the accuracy of the algorithm/model.

Provably Secure Authentication Approach for Data Security in Cloud Using Hashing, Encryption, and Chebyshev-Based Authentication

2022 ◽  
Vol 16 (1) ◽  
pp. 0-0
Keyword(s):  
Data Security ◽  
Security Analysis ◽  
Data Communication ◽  
Computation Time ◽  
Computational Time ◽  
Security Issues ◽  
Authentication Mechanism ◽  
Cloud Server ◽  
Secure Authentication ◽  
Provably Secure

Secure and efficient authentication mechanism becomes a major concern in cloud computing due to the data sharing among cloud server and user through internet. This paper proposed an efficient Hashing, Encryption and Chebyshev HEC-based authentication in order to provide security among data communication. With the formal and the informal security analysis, it has been demonstrated that the proposed HEC-based authentication approach provides data security more efficiently in cloud. The proposed approach amplifies the security issues and ensures the privacy and data security to the cloud user. Moreover, the proposed HEC-based authentication approach makes the system more robust and secured and has been verified with multiple scenarios. However, the proposed authentication approach requires less computational time and memory than the existing authentication techniques. The performance revealed by the proposed HEC-based authentication approach is measured in terms of computation time and memory as 26ms, and 1878bytes for 100Kb data size, respectively.

Experimental and numerical simulation of thermomechanical phenomena during a TIG welding process

2004 ◽  
Vol 120 ◽  
pp. 697-704
Author(s):  
L. Depradeux ◽  
J.-F. Jullien
Keyword(s):  
Numerical Simulation ◽  
Numerical Models ◽  
Welding Process ◽  
Central Zone ◽  
Mechanical Analysis ◽  
Tig Welding ◽  
General Ability ◽  
Reduced Dimensions ◽  
Simple Geometry ◽  
A Tig Welding

In this study, a parallel experimental and numerical simulation of phenomena that take place in the Heat Affected Zone during TIG welding on 316L stainless steel is presented. The aim of this study is to predict by numerical simulation residual stresses and distortions generated by the welding process. For the experiment, a very simple geometry with reduced dimensions is considered: the specimens are disks, made of 316L. The discs are heated in the central zone in order to reproduce thermo-mechanical cycles that take place in the HAZ during a TIG welding process. During and after thermal cycle, a large quantity of measurement is provided, and allows to compare the results of different numerical models used in the simulations. The comparative thermal and mechanical analysis allows to assess the general ability of the numerical models to describe the structural behavior. The importance of the heat input rate and material characteristics is also investigated.

scholarly journals Improving ozone profile retrieval from spaceborne UV backscatter spectrometers using convergence behaviour diagnostics

2010 ◽  
Vol 3 (6) ◽  
pp. 1555-1568 ◽  
Author(s):  
B. Mijling ◽  
O. N. E. Tuinder ◽  
R. F. van Oss ◽  
R. J. van der A
Keyword(s):  
Cross Sections ◽  
A Priori ◽  
Computation Time ◽  
External Input ◽  
Computational Time ◽  
Ozone Profile ◽  
Global Performance ◽  
Convergence Behaviour ◽  
Low Cloud ◽  
Average Computation Time

Abstract. The Ozone Profile Algorithm (OPERA), developed at KNMI, retrieves the vertical ozone distribution from nadir spectral satellite measurements of back scattered sunlight in the ultraviolet and visible wavelength range. To produce consistent global datasets the algorithm needs to have good global performance, while short computation time facilitates the use of the algorithm in near real time applications. To test the global performance of the algorithm we look at the convergence behaviour as diagnostic tool of the ozone profile retrievals from the GOME instrument (on board ERS-2) for February and October 1998. In this way, we uncover different classes of retrieval problems, related to the South Atlantic Anomaly, low cloud fractions over deserts, desert dust outflow over the ocean, and the intertropical convergence zone. The influence of the first guess and the external input data including the ozone cross-sections and the ozone climatologies on the retrieval performance is also investigated. By using a priori ozone profiles which are selected on the expected total ozone column, retrieval problems due to anomalous ozone distributions (such as in the ozone hole) can be avoided. By applying the algorithm adaptations the convergence statistics improve considerably, not only increasing the number of successful retrievals, but also reducing the average computation time, due to less iteration steps per retrieval. For February 1998, non-convergence was brought down from 10.7% to 2.1%, while the mean number of iteration steps (which dominates the computational time) dropped 26% from 5.11 to 3.79.

Accelerated plane-wave destruction

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. V1-V9 ◽  
Author(s):  
Zhonghuan Chen ◽  
Sergey Fomel ◽  
Wenkai Lu
Keyword(s):  
Plane Wave ◽  
Iterative Algorithm ◽  
Field Experiments ◽  
Computation Time ◽  
Computational Time ◽  
Iterative Estimation ◽  
Local Slope ◽  
Slope Estimation ◽  
Correct Estimation ◽  
Wave Filter

When plane-wave destruction (PWD) is implemented by implicit finite differences, the local slope is estimated by an iterative algorithm. We propose an analytical estimator of the local slope that is based on convergence analysis of the iterative algorithm. Using the analytical estimator, we design a noniterative method to estimate slopes by a three-point PWD filter. Compared with the iterative estimation, the proposed method needs only one regularization step, which reduces computation time significantly. With directional decoupling of the plane-wave filter, the proposed algorithm is also applicable to 3D slope estimation. We present synthetic and field experiments to demonstrate that the proposed algorithm can yield a correct estimation result with shorter computational time.

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