Computational Models for Resistance Spot Welding

2012 ◽  
Author(s):  
Pierluigi Mollicone ◽  
Martin Muscat ◽  
Matthew Said
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Spot Welding ◽  
Large Scale ◽  
Computational Models ◽  
Computational Modelling ◽  
Welding Process ◽  
Stress Fields ◽  
Modelling Technique ◽  
Hole Drilling

Spot welding is a very important joining process for many industries. Structural integrity of a spot welded joint is however compromised by the formation of residual stress fields, which arise due to the thermal loadings imposed on the material during this welding process. Experimental investigation of these effects is possible but often costly, especially in complex and large-scale applications. Computational models, through the application of advanced Finite Element Analysis (FEA) techniques, are hence of interest for the prediction, analysis and assessment of these effects. The computational modelling required to assess these effects is however relatively complex due to the interaction of thermal and structural solution fields. It follows that many decisions must be taken with regards to the modelling technique to adopt in these scenarios. This work presents a modelling technique for the prediction of spot welding induced residual stresses, validated with experimental measurements for the temperature and residual stress fields. The simulations, carried out in ANSYS, are aimed at using a general-purpose solver to predict residual stresses whilst the validation is carried out through transient thermocouple measurements and residual stress measurements done using the hole drilling method. Comparison of experimental and FEA model results highlight which parts and assumptions of the computational model are to be considered valid and hence its boundary for use in industry.

Measurement and Simulation of Residual Stresses of Electron Beam Welding Joint of Pure Aluminum

2012 ◽  
Vol 184-185 ◽  
pp. 649-652
Author(s):  
Gui Fang Guo ◽  
Shi Qiong Zhou ◽  
Liang Wang ◽  
Li Hao ◽  
Ze Guo Liu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Residual Stresses ◽  
Electron Beam Welding ◽  
Pure Aluminum ◽  
Research Result ◽  
Welding Process ◽  
Hole Drilling ◽  
Longitudinal Residual Stress

The effects of electron beam welding on the residual stresses of welded joints of pure aluminum plate 99.60 are studied by through-hole-drilling and blind-hole-drilling method. Meanwhile, based on the thermal elastic-plastic theory, and making use of ANSYS finite element procedure, a three - dimensional finite element model using mobile heat source of temperature and stresses field of electron beam welding in pure aluminum is established. The welding process is simulated by means of the ANSYS software. The results show that the main residual stress is the longitudinal residual stress, the value of the longitudinal residual stress is much larger than the transverse residual stress. But the residual stress in the thickness is rather small. And in the weld center, the maximum value of residual stresses is lower than its yield strength. The simulation results about the welded residual stresses are almost identical with the experimental results by measuring. So the research result is important to science research and engineering application.

Measurement of residual stresses in T-plate weldments

2003 ◽  
Vol 38 (4) ◽  
pp. 349-365 ◽  
Author(s):  
R. C Wimpory ◽  
P. S May ◽  
N. P O'Dowd ◽  
G. A Webster ◽  
D J Smith ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Plastic Zone ◽  
Residual Stresses ◽  
Plate Thickness ◽  
Welding Process ◽  
Plastic Zone Size ◽  
Hole Drilling ◽  
Stress Distributions ◽  
Premature Failure

Tensile welding residual stresses can, in combination with operating stresses, lead to premature failure of components by fatigue and/or fracture. It is therefore important that welding residual stresses are accounted for in design and assessment of engineering components and structures. In this work residual stress distributions, obtained from measurements on a number of ferritic steel T-plate weldments using the neutron diffraction technique and the deep-hole drilling method, are presented. It has been found that the residual stress distributions for three different plate sizes are of similar shape when distances are normalized by plate thickness. It has also been found that the conservatisms in residual stress profiles recommended in current fracture mechanics-based safety assessment procedures can be significant—of yield strength magnitude in certain cases. Based on the data presented here a new, less-conservative transverse residual stress upper bound distribution is proposed for the T-plate weldment geometry. The extent of the plastic zone developed during the welding process has also been estimated by use of Vickers hardness and neutron diffraction measurements. It has been found that the measured plastic zone sizes are considerably smaller than those predicted by existing methods. The implications of the use of the plastic zone size as an indicator of the residual stress distributions are discussed.

Determination of Residual Stresses on a Centrifugal Compressor Impeller

2011 ◽  
Author(s):  
Hector Delgado ◽  
Jeff Moore ◽  
Augusto Garcia Hernandez
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Centrifugal Compressor ◽  
Welding Process ◽  
Hole Drilling ◽  
Residual Tensile Stress ◽  
Scanning Method ◽  
Stress Measurements ◽  
Hole Drilling Method ◽  
Compressor Impeller

This paper reports a comparison of two methods to perform residual stress measurements. The specimens tested by each method were two blades from a shrouded centrifugal compressor impeller. The first method is the conventional hole drilling strain gage method which was used to predict residual stresses across the blade surface. The residual stresses are released by drilling a hole in the blade. The second method is called the nonlinear harmonic (NLH) scanning method and is based on the principal that the magnetic domains of ferrous materials vary in a non-linear way relative to internal stress. The effects of residual stress may be either helpful or harmful, depending on the magnitude of the residual with respect to the operating stresses. If not adequately relieved by heat treatment, residual tensile stress that develops in the welding process of shrouded impellers, will add to the stress developed by rotation which moves the point to the right on the Goodman diagram and reduces allowable alternating stress. The results showed comparable residual stress measurements of the NLH method compared to the conventional hole drilling method.

Prediction by Genetic Algorithm and Measurement by Center Hole Drilling of Residual Stresses of MAG Weldment

2009 ◽  
Vol 83-86 ◽  
pp. 738-745
Author(s):  
G.H. Farrahi ◽  
G.H. Majzoobi ◽  
A. Fadaee
Keyword(s):  
Genetic Algorithm ◽  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Growth Rates ◽  
Welding Process ◽  
Fatigue Tests ◽  
Hole Drilling ◽  
Grinding Operations ◽  
Crack Growth Rates

In the present work, specimens were cut out from St-37 plates with 19 mm thickness. The thickness of plates was reduced to 12.5 mm by milling and grinding operations. Then a standard V-shaped fillet was made on one edge of the plates. Two plates were butt-welded by standard metal arc gas (MAG) welding process. Residual stresses induced by welding were measured on 20 specimens by centre hole drilling. Load controlled axial fatigue tests were carried out to determine the fatigue life of specimens. Crack growth rates were obtained from experiment. Fractography of specimens was performed. Genetic Algorithm (GA) was employed for prediction of residual stress value in weldments using the crack growth rates obtained from experiments. The results show that, by using the measured crack growth rates and GA model, residual stresses can be estimated with a good approximation.

The Application of the Hole Drilling Method to Define the Residual Stress of Dissimilar Laser Welded Components

2007 ◽  
Vol 7-8 ◽  
pp. 133-138 ◽  
Author(s):  
E.M. Anawa ◽  
Abdul Ghani Olabi
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Laser Welding ◽  
Power Plants ◽  
Welding Process ◽  
Hole Drilling ◽  
Welding Parameters ◽  
Heating Process ◽  
Hole Drilling Method ◽  
Drilling Method

Dissimilar metal welds between Ferritic steel and Austenitic steel (F/A)are commonly used in power plants, food industry, pharmaceutical industry and many other applications. There are many issues/problems associated with the joining of dissimilar materials, depending on the materials being joined and the process selected. During the laser welding process, residual stresses are introduced by a rise in temperature during the melting or heating process followed by a very quick cooling of the weld and the surrounding material. In this study, CO2 continuous laser welding has been successfully applied for joining 316 stainless steel with AISI 1009 low carbon steel F/A. Design of Experiment techniques (DOE) has been used for some of the selected welding parameters (laser power, welding speed, and focus position) to model the dissimilar F/A joints in terms of its residual stresses. The Hole-Drilling Method technique was use for measuring the residual stress of dissimilar welded components. Taguchi approach for selected welding parameters was applied and the output response was the residual stresses. The results were analysed using analysis of variance (ANOVA) and signal-tonoise (S/N) ratios for the effective parameters combination.

Reduce the Residual Stress of Welded Structures by Post-Weld Vibration

2005 ◽  
Vol 490-491 ◽  
pp. 102-106 ◽  
Author(s):  
De Lin Rao ◽  
Zheng Qiang Zhu ◽  
Li Gong Chen ◽  
Chunzhen Ni
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Mechanical Vibration ◽  
Welding Process ◽  
Hole Drilling ◽  
Welded Structures ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Before And After

The existence of residual stresses caused by the welding process is an important reason of cracking and distortion in welded metal structures that may affect the fatigue life and dimensional stability significantly. Heat treatment is one of the traditional methods to relieve the residual stresses. But it is often limited by the manufacturing condition and the size of the structures. In this paper a procedure called vibratory stress relief (VSR) is discussed. VSR is a process to reduce and re-distribute the internal residual stresses of welded structures by means of post-weld mechanical vibration. The effectiveness of VSR on the residual stresses of welded structures, including the drums of hoist machine and thick stainless steel plate are investigated. Parameters of VSR procedure are described in the paper. Residual stresses on weld bead are measured before and after VSR treatment by hole-drilling method and about 30%~50% reduction of residual stresses are observed. The results show that VSR process can reduce the residual stress both middle carbon steel (Q345) and stainless steel (304L) welded structures effectively.

Analysis of Welded Joint Under Residual Stresses

2014 ◽  
Author(s):  
H. P. Jawale ◽  
Rahul Singh
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joint ◽  
Weld Zone ◽  
Welding Process ◽  
Fatigue Behaviour ◽  
Hole Drilling ◽  
Building Structures ◽  
Residual Stress Field ◽  
Stress Relieving

Welded joint is most commonly used for building structures and machine components. Welding process involves heating followed by uneven cooling causing residual stress field. In conjunction with stresses due to external loads, in-service behaviour is affected due to residual stress in welded components. It induces defects, also alters crack initiation life, fatigue behaviour, breaking strength, corrosion resistance and increases the susceptibility of structure to failure by fracture. The residual stress is function of cooling rate and the size of weld. The role of residual stress associated with welding is therefore very important while designing mechanical parts. Conventional methods like heat treatment and shot-peening techniques becomes difficult to be applied for reduction of residual stress in general purpose applications. The work presented in this paper describes the measurement of residual stress using stress relieving method, based on hole-drilling technique. Subsequently, residual stresses are relived and measured using strain rosette near the weld zone. These strains value is converted in to stress value. Residual stress is quantified with respect to yield strength, making it possible to be considered for safe designing of weld components.

Evaluation of through-thickness residual stresses and microstructure in SA516 Gr. 70 steel welds

2021 ◽  
pp. 095440542199012
Author(s):  
Pradeeptta Kumar Taraphdar ◽  
Manas Mohan Mahapatra ◽  
Arun Kumar Pradhan ◽  
Pavan Kumar Singh ◽  
Kamal Sharma ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Nuclear Power ◽  
Three Dimensional ◽  
Welding Process ◽  
Influential Factors ◽  
Stress Fields ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Steel Welds

The critical working condition of nuclear power plant equipment necessitates meticulous determination of the welding process and parameters. In this work, some major influential factors of welding were investigated to observe their effects on the through-thickness residual stress distribution in multipass pressure vessel steel welds. In this regard, experiments were conducted to find the characteristics of residual stresses dispersed in SA516 Grade 70 steel welds of different groove geometries with distinct welding conditions. Three-dimensional finite element models of the weldments were developed considering a moving heat source with temperature-dependent material properties to simulate the welding thermal cycles and corresponding residual stress fields. Effects of weld groove geometry, number of weld passes, external constraints, and preheating on the through-thickness residual stress fields were studied. Additional attention was given to the evaluation of the heterogeneous microstructure and microhardness across the weld cross-section associated with their weld thermal history. Finally, the evolution of the through-thickness residual stresses attributed to subsequent weld passes was elaborated.

Influence of the Welding Sequence on Residual Stresses in Laser Welded T-Joints of an Airframe Aluminium Alloy

2008 ◽  
Vol 571-572 ◽  
pp. 375-380 ◽  
Author(s):  
Winulf Machold ◽  
Peter Staron ◽  
Funda S. Bayraktar ◽  
Stefan Riekehr ◽  
Mustafa Koçak ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welding Process ◽  
Base Plate ◽  
Stress Fields ◽  
Stress Concentrations ◽  
T Joints ◽  
Element Simulation ◽  
Welding Sequence ◽  
Welding Sequences

The effect of different welding sequences between a 4.5 mm thick AA 6156 T6 base plate and a 2 mm thick AA 6013 T6 clip – resembling a skin-clip joint of an airframe – using a 3.3 kW Nd:YAG laser is investigated. Under cyclic loading the breakdown of such T-joints happens at one end of the clip, which is due to local residual stress concentrations. Recent measurements indicated that tensile stresses could be lower at the run-in than at the run-out locations. For a deeper investigation of this effect sheets with different welding sequences were produced. One welding sequence was made with two starting points in the centre, and a second with starting points at the clip ends. Temperature measurements were made using thermocouples to verify the heat conditions for a finite element simulation of the welding process, which is used for predictions of the residual stress distribution. Actual values of the residual stress fields were determined by neutron diffraction. The influences of the welding sequence on the measured temperatures and the residual stresses are discussed.

scholarly journals Residual Stress Study for Sustainable Structural Integrity Assessment

2019 ◽  
Author(s):  
S Hossain ◽  
MD Salim Miah ◽  
B Fakhim
Keyword(s):  
Residual Stress ◽  
Hydrostatic Pressure ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Welding Process ◽  
Surface Measurement ◽  
Hole Drilling ◽  
Near Surface ◽  
Integrity Assessment ◽  
Welding Processes

Marine structures are susceptible to failure mechanism due to presence of both external and internal loads. A submarine is manufactured with several circular hull sections welded together and forming an entire hull. A hull section consists of several bowed metal sheets welded together and strengthened by T-section rings which are welded at repeated spaces. T-section rings are fabricated using numerous web and flange plates and curved correctly by plastically bending before welding. Fatigue life of a submarine hull is dependent on load produced from hull contraction due to surrounding hydrostatic pressure, as well as residual stress present without any applied load. Numerical simulation can be used to calculate stresses generated from hydrostatic pressure. However, predicting residual stresses resulting from bending and welding processes can be more involved. Moreover, the predicted stresses need to be validated by measurement. Incremental centre-hole drilling (iCHD) is broadly applied technique to measure residual stress. The iCHD technique however is limited to near surface measurement which can contribute to misleading structural integrity assessment. On the other hand an over-conservative estimate of stress due to welding process can lead to reduced life estimate. It is thus imperative to analyse residual stresses accurately and deep into metal parts in order to move away from decade old conservative estimates. This paper reviews various techniques available for analysing residual stress field and considers multiple techniques with an aim to provide an optimum solution.

Sign in / Sign up

Export Citation Format

Share Document