The Experts below are selected from a list of 11934 Experts worldwide ranked by ideXlab platform
Chao Wang - One of the best experts on this subject based on the ideXlab platform.
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artificial thermal strain method a novel approach for the analysis and fast prediction of the thermal distortion
Journal of Materials Processing Technology, 2021Co-Authors: Chao Wang, D T Pham, Jaewoong Kim, Zhenqian JinAbstract:Abstract Understanding the thermal distortion induced by arc welding, laser, or induction heating is a challenge in academia and industry. This study presents the artificial thermal strain (ATS) method which was modified from strain as boundary (SDB) method, based on inherent strain theory, and its equivalent mechanical model to analyse the distortion mechanism. Experiments and numerical simulation of multi-pass laser bending of alloy 304 L were conducted, wherein the various kinds of inherent strain distributions and the boundary of effective inherent strain were examined. Further, the mechanism of bending angle reduction under lower line energy was evaluated by considering the inherent strain redistribution at each pass. The results indicate that the bending angle reduction in multi-pass laser scanning is determined by the size of the inherent strain area at low line energy. Moreover, a simplified plastic finite element model based on the ATS method was developed to predict the welding deformation of plate curvature induced by parallel laser scanning. Additionally, only 210 elements and 7 s was cost to perform with the deformation analysis, which indicates that the ATS model is effective in predicting thermal distortion. Meanwhile, the ATS method can provide theoretical guidance and fast prediction for the actual thermal processing in large Welded Structure and additive manufacturing in the future.
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numerical modelling of welding distortion redistribution due to the change of self constraint in a t joint Welded Structure
Journal of Mechanical Science and Technology, 2016Co-Authors: Chao WangAbstract:Finite element method (FEM) is a powerful tool for analysing the potential deformation during a material removal process. After the removal of material, re-establishment of equilibrium within the remaining part of the Structure causes distortion due to the relief of residual stress in the removed materials. In this study, commercial FEM software (MSC.Marc) was used to simulate material removal, and the accuracy was evaluated by comparison with results from machining experiments. The effect of cutting height on the distortion redistribution and the kerf width in a T-joint Welded Structure is discussed, and the distortion differences at the centre line of the bottom were compared between the calculated and experimental results. The results demonstrate that the developed model is useful and efficient for simulating the redistribution of welding distortion due to material removal.
Boutabout Benali - One of the best experts on this subject based on the ideXlab platform.
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3 d finite element analysis of stress concentration factor in spot Welded joints of steel the effect of process induced porosity
Computational Materials Science, 2011Co-Authors: Farida Bouafia, Serier Boualem, Mecirdi Mohamed El Amin, Boutabout BenaliAbstract:The work presented in this paper utilises a numerical analysis for the computation of stress concentration factor generated by the presence in the weld nugget of a pore formed during the welding process. Welded Structure containing porosity is subjected to uniaxial tensile stress. The effects of geometrical parameters of the pore and the interaction pore-defect on the stress concentration factor variation have been analyzed.
Radovan Kovacevic - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation and experimental validation of residual stress and welding distortion induced by laser based welding processes of thin structural steel plates in butt joint configuration
Optics and Laser Technology, 2018Co-Authors: Ehsan Dezhparvar Derakhshan, Nima Yazdian, Blake Craft, Steve Smith, Radovan KovacevicAbstract:Abstract Thin plates are extensively used in automotive, shipbuilding, and railway industries. Welding technology is the main assembling method to manufacture thin plate Structures because of its high productivity and ease of use. Consequently, residual stress and distortion induced by welding are an inevitable part of the manufacturing process in welding thin plate Structures. Relatively low stiffness, and a high amount of heat input are the main reasons for distortion of the Welded Structures. In order to decrease the heat input, laser-based welding processes that generate highly localized heat with a very high intensity can be a good choice as an alternative to traditional fusion welding. To predict residual stress and distortion in welding thin plate Structures, a three dimensional, thermo-metallurgical-mechanical finite element method was developed. The results of three different laser-based welding processes including aspects of Autogenous Laser Welding (ALW), Cold Wire Assisted Laser Welding (CWLAW), and Hybrid Laser-Arc Welding were compared with traditional Submerged Arc Welding (SAW) from both predicted and experimental perspectives. SYSWELD commercial code was used for the simulations in which both large and small deformation theories were employed to predict the residual stress and the final deformation. Experiments were executed to verify the simulation results. A digital high-resolution microscope was used to visualize and measure the weld cross- sectional shape and bead geometry. To measure the residual stress, an X-ray diffractometer was employed. A digital Vernier Caliper and a 3D laser-handheld scanner were used to measure displacement in the z-direction. Moreover, the mechanical properties of welds obtained by different welding processes were also verified by tensile and micro-hardness tests. It was concluded that lower heat input can markedly influence the final distortion of the Welded Structure. This conclusion can strongly support the idea of replacing traditional arc welding method with a laser-based one. Simulation and experimental results were matched fairly.
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joining of advanced high strength steel to aa 6061 alloy by using fe al structural transition joint
Materials & Design, 2015Co-Authors: Wei Liu, Mazar M Atabaki, Radovan KovacevicAbstract:Abstract Joining steel plates and aluminium plates by means of using Fe/Al structural (Triclad) transition joints has been well-received in the shipbuilding industry, but is rarely applied in other industries. In this work, 12.7 mm thick plates of advanced high-strength steel and AA 6061 alloy were successfully joined by using hybrid laser-arc welding with the help of Triclad transition joints. The parameters were optimized for welding dissimilar steels (A516 to advanced high-strength steel) and welding dissimilar aluminium alloys (AA 5456 to AA 6061). The optimization controlled the total heat input and kept the Al/Fe interface of the Triclad transition joint below the maximum allowable temperature of 315.56 °C in order to minimize the growth of brittle intermetallic phases and retain the mechanical properties of the Triclad transition joint. A finite element model was developed to study the temperature evolution at the Triclad interface and the heat distribution along the Welded Structure. A “4:1” ratio was used between the width of the Triclad transition joint and the thickness of the webs. This ratio improved the load-bearing property of the Triclad transition joint and compensated for the microcracks and brittle Al-rich intermetallic phases observed at the Triclad interface. Tensile strength of 220 MPa was achieved at the Welded Structure. The fracture occurred at the heat affected zone of the AA 5456-to-AA 6061 weld.
Chang Qi - One of the best experts on this subject based on the ideXlab platform.
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an adaptive multi step varying domain topology optimization method for spot weld design of automotive Structures
Structural and Multidisciplinary Optimization, 2019Co-Authors: Shu Yang, Chang QiAbstract:Spot welds are widely used to join metal stamping parts in the automotive industry. The number and layout of spot welds have direct impacts on both the mechanical performances of the vehicle and the manufacturing cost. The traditional methods including the 0–1 programming method, the size optimization method, the direct optimization method, and the single-step topology optimization (SSTO) method all have major drawbacks and are not suitable or efficient for spot weld layout design of an automotive Structure. In this work, we propose a new method called multi-step varying-domain topology optimization (MVTO) method for spot weld design of automotive Structures to balance structural performance and manufacturing cost. Based on a multi-step topology optimization framework with adaptive and varying design domains, the MVTO method can find a better layout design of the spot welds in a more efficient way compared to the existing methods. Limited engineering experiences are required and adverse human factors are eliminated in the spot weld design process with MVTO. To assist the application of MVTO method and to realize design automation, a new modeling approach is also developed to connect the continuous connection elements (CCEs) of the spot welds to the shell elements of the Welded Structure. Two case studies involving a simple single-hat beam and an automotive B-pillar show that the proposed MVTO method is reliable and effective for spot weld design of automotive Structures. It has also been demonstrated that the MVTO method is superior to the direct optimization method and the SSTO method in terms of spot weld number reduction and Welded Structure performances, thus has a great potential for spot weld design of complicated automotive Structures.
Ari Niemela - One of the best experts on this subject based on the ideXlab platform.
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fatigue strength of thin laser hybrid Welded full scale deck Structure
International Journal of Fatigue, 2017Co-Authors: Ingrit Lillemae, Sami Liinalampi, Heikki Remes, Antti Itavuo, Ari NiemelaAbstract:Abstract The fatigue behavior of a 4-mm thick laser-hybrid Welded Structure was studied using small- and full-scale specimens. The aim of the work was to understand the response and fatigue strength of large thin Welded Structures. The difference and similarity between small- and full-scale specimens, which is crucial in order to transfer fatigue test results into fatigue design, was carefully studied. The experiments included accurate optical geometry measurements and constant amplitude fatigue testing under axial loading. The fatigue test results were analyzed in terms of structural hot spot stress. The results showed that when initial distortion shape and geometrical nonlinearity are properly considered, the small- and full-scale specimens have equal fatigue strength with small scatter and the same S-N curve slope close to m = 5. In addition, the measured fatigue strength is considerably higher in comparison to IIW structural stress design curve FAT100. This indicates that high fatigue strength can be achieved in thin laser-hybrid Welded Structures, given that the shape and the magnitude of initial distortion as well as the weld quality are controlled.
