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Numerical analysis of temperature profile and weld dimensions in laser ＋ GMAW hybrid welding of aluminum alloy t-joint

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China Welding 2013年第3期22卷 51-55页

作者：胥国祥武传松秦国梁王旭友 Key Laboratory of Advanced Welding technology of Jiangsu Province Jiangsu University of Science and Technology Zhenjiang 212003 Institute for Materials Joining Shandong University Jinan 250061 Harbin Welding Institute Harbin 150025

the temperature fields in the transient state and weld dimensions in laser ＋ gas metal arc welding （GMAW） hybrid welding of aluminum alloy t-joint for different welding conditions were calculated using the developed heat source model, and the effect of welding speed on them was analyzed. the results show that the temperature field for the first weld pass only shows the feature of GMAW and the one for the second weld pass has the characteristics of both laser welding and GMAW. Welding speed can affect greatly weld dimensions and temperature distribution. When welding speed reaches 3.5 m/min, the fusion zones of two weld passes are separated and the maximum peak temperature of thermal cycle on the workpiece surface decreases largely.

关键词： hybrid welding aluminum alloy temperature field t-joint numerical simulation

Formation, microstructure and mechanical properties of double-sided laser beam welded ti-6Al-4V t-joint

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transactions of Nonferrous Metals Society of China 2016年第3期26卷 729-735页

作者：马旭颐巩水利张久兴芦伟杨璟北京工业大学材料科学与工程学院北京100124 北京航空制造工程研究所高能束流加工技术重点实验室北京100124

the t-joints of ti?6Al?4V alloy were manufactured by double-sided synchronized laser beam welding with the homologous filler wire. the formation, microstructure and mechanical properties of welded joints as well as the correlations of each other were investigated. the results indicate that the quality of weld seams is good without defects such as discontinuity, beading, visible cracks or porosity, which is linked to the steady molten pool behavior and droplet transition. the morphologies of the heat affected zone (HAZ) located on the skin and stringer are disparate. the microstructure of the HAZ and fusion zone (FZ) is mainly comprised of acicular martensiticα′ phases. the microhardness of the HAZ and FZ is higher than that of the base metal (BM) and reaches a maximum value at the HAZ near FZ on the stringer. the tensile specimens along the skin and stringer fractured at the BM with ductile fracture surfaces.

关键词： ti-6Al-4V alloy double-sided laser beam welding t-joint high-speed photography microstructure mechanical property

Experimental and Finite Element Analysis of a t-joint Welding

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Journal of Mechanics Engineering and Automation 2012年第7期2卷 411-421页

作者： Rabih Kamal Kassab Henri Champliaud Ngan Van Le Jacques Lanteigne Marc thomas Mechanical Engineering Department Ecole de Technologie Superieure Montreal QC H3C 1K3 Canada Institut de Recherche d'Hydro Quebec Varennes QC J3X1S1 Canada

this paper presents the Finite Element （FE） modeling of a two-seam welding process for a t-joint with a V chamfer preparation： the aim of the model is to predict the deformations, distortions and residual stresses resulting from the welding of the plates and experiments have been carried out in order to compare to the FE model. the ＂birth and death＂ method is used in ANSYS to simulate the filler metal deposition and the heat generation and weld pool simulation are conducted accordingly with the double ellipsoid configuration as proposed by Goldak et al. the model takes into consideration the temperature dependent non-linear material properties and uses a new formulation to compute the temperature dependent combined coefficient of heat loss. Improvements in the calculation are achieved by combining two types of meshing. the FE simulation is divided into two consecutive parts： the thermal simulation followed by the structural simulation. the results of the numerical model are compared to experiments.

关键词： Welding t-joint finite element modeling residual stresses.

Multi-objective optimization of gas metal arc welding parameters and sequences for low-carbon steel (Q345D) t-joints

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Journal of Iron and Steel Research International 2017年第5期24卷 544-555页

作者： Qing Shao tao Xu tatsuo Yoshino Nan Song School of Mechanical Science and Engineering Jilin UniversityChangchun 130022JilinChina

Q345D high-quality low-carbon steel has been extensively employed in structures with stringent weld- ing quality requirements. A multi-objective optimization of welding stress and deformation was presented to design reasonable values of gas metal arc welding parameters and sequences of Q345D t-joints. the optimized factors included continuous variables （welding current （I）, welding voltage （U） ahd welding speed （V）） and discrete variables （welding sequence （S） and welding direc- tion （D））. the concepts of the pointer and stack in Visual Basic （VB） and the interpolation method were introduced to optimize the variables. the optimization objectives included the different combina- tions of the angular distortion and transverse welding stress along the transverse and longitudinal dis- tributions. Based on the design of experiments （DOE） and the polynomial regression （PR） model, the finite element （FE） results of the t-joint were used to establish the mathematical models. the Pareto front and the compromise solutions were obtained by using a multi-objective particle swarm optimization （MOPSO） algorithm. the optimal results were validated by the corresponding results of the FE method, and the error between the FE results and the two-objective results as well as that be-tween the FE results and the three-objective optimization results were less than 17.2% and 21.5%, respectively. the influence and setting regularity of different factors were discussed according to the compromise solutions.

关键词： t-joint Welding parameter Welding sequence Multi-objective optimization Pareto front Gas metal arc welding Q345D

Progressive Failure Evaluation of Composite Skin-Stiffener joints Using Node to Surface Interactions and CZM

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Computer Modeling in Engineering & Sciences 2018年第5期115卷 281-294页

作者： A.Sane P.M.Padole R.V.Uddanwadiker Department of Mechanical Engineering Visvesvaraya National Institute of TechnologyNagpur440010India

t shaped skin-stiffener joint are one of the most commonly used structures in aerospace *** has been proven in various studies that these joints are susceptible to failure when loaded in pull out conditions however,in specific applications these joints undergo pull ***-lamination/de-bond nucleation and its growth is one of the most common failure mechanisms in a fiber reinforced composite *** growth takes place due to the induced interlaminar normal and shear stresses between different structural constituents when a load is *** this study,Finite Element Analysis has been performed using cohesive contact interactions on a composite t-joint to simulate the pull out test conditions.A simplified shell based model coupled with CZM is proposed,which can evaluate the failure initiation and progression accurately with lesser computational *** final failure occurred at a displacement of 4.71 mm at the computed failure load of 472.57 kgf for basic *** Failure load for the padded configuration is 672.8 kgf and corresponding displacement is 4.6 *** results obtained by the proposed numerical model are validated by experimental results and it is observed that predicted failure displacements and failure load calculated were correlating reasonably well with the experiment.

关键词： Carbon fiber composite FE analysis t-joint cohesive zone modeling node to surface interactions

Hybrid laser/arc welding of thick high-strength steel in different configurations

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Advances in Manufacturing 2018年第2期6卷 176-188页

作者： M. Mazar Atabaki N. Yazdian R. Kovacevic Research Center for Advanced Manufacturing (RCAM) Southern Methodist University Dallas TX 75205 USA

In this investigation, hybrid laser/arc welding （HLAW） was employed to join 8-mm-thick high-strength quenched and tempered steel （HSQtS） plates in the butt- and t-joint configurations. the influences of welding parame- ters, such as laser power, welding speed, stand-off distance （SD） between the arc of gas metal arc welding, and the laser heat source on the weld quality and mechanical properties of joints, were studied to obtain non-porous and crack-free fully-penetrated welds. the weld microstructure, cross- section, and mechanical properties were evaluated by an optical microscope, and microhardness and tensile tests. In addition, a finite element model was developed to investigate the thermal history and molten pool geometry of the HLAW process to join the HSQtS. the numerical study demon- strated that the SD had a paramount role in good synergy between the heat sources and the stability of the keyhole. For the butt-joint configuration, the results showed that, at a higher welding speed （35 mm/s） and optimum SD between the arc and laser, a fully-penetrated sound weld could be achieved. A non-porous weld in the t-joint configuration was obtained at a lower welding speed （10 mm/s）. Microstructural evaluations indicated that the formation of residual austenite and the continuous network of martensitic structure along the grain boundary through the heat affected zone were the primary reasons of the softening behavior of this area. this was confirmed by the sharp hardness reduction and failure behavior of the tensile coupons in this area.

关键词： Hybrid laser/arc welding - Butt-joint t-joint Steel

Using thermoelastic Stress Analysis to Detect Damaged and Hot Spot Areas in Structural Components

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Journal of Mechanics Engineering and Automation 2015年第11期5卷 623-634页

作者： Freire J. L. F. Waugh, R. C. Fruehmann, R. Dulieu-Barton, J. M. Mechanical Engineering Department Pontifical Catholic University of Rio de Janeiro PUC-Rio Rio de Janeiro 22453-900 Brazil Faculty of Engineering and Environment University of Southampton Southampton SO17 1BJ UK

this paper discusses the suitability of using tSA （thermoelastic stress analysis） as an advanced tool to detect damaged areas and highly stressed （hot spot） areas in structural components. Such components can be, for example, parts of large structural panels built of welded metallic or composite materials. Besides detecting hot spot areas, it is expected that stresses in these areas can be suitably quantified and processed in order to predict crack initiation and propagation due to in-service loads. the paper starts with references to selected review and application articles on the subject. two simple laboratory experiments are presented which illustrate the quality of the results that can be achieved using tSA. In the first experiment, a stainless steel t-joint designed to model a welded structural component is analysed. the t-joint had a machine-notched crack-like flaw close to the component＇s weld toe. the qualitative and quantitative experimental results determined along four specified areas of the t-joint model showed that tSA can indeed be used as a tool to detect loaded cracks and hot spots in large metallic structures, and that stresses can be accurately evaluated. In the second experiment, a prismatic bar made of CFRE （carbon fibre-reinforced-epoxy） was tested to locate three subsurface areas of damage introduced beforehand into the component. two of these inside damaged areas were detected to be 3.1 mm and 7.1 mm from the observed surface. the positive results achieved with the two lab experiments, along with a review of the selected research publications, indicate that tSA application can be extended to the real-world field of structural components. topics to be addressed in this research field should have to do with components that work under random or quasi-cyclic service loading, problems where adiabatic conditions do not prevail, and reduction of the cost of infra-red cameras.

关键词： tSA stress distribution NDt stress distribution stress concentration crack t-joint infra-red.