Discussion on Construction Technology and Welding Deformation of High-Rise Steel Frame Structure

Because of urbanization,land resources in China’s cities has become increasingly scarce.Therefore,modern buildings are becoming taller,making high-rise steel frame structures the new favorite of the construction industry.However,the construction of high-rise steel frame structures requires advanced technology.If the construction technology is effectively implemented and the welding techniques of the construction personnel align with the requirements for high-rise steel frame structures,it can help mitigate deformations in the steel structure,thus preserving the overall construction quality of high-rise steel frame structures.To enhance the applicability of steel frame structures in high-rise buildings,this paper focuses on analyzing the optimization path for the construction process of high-rise steel frame structures.It introduces a tailored approach to control welding-induced deformations in steel frame structures,aiming to make a valuable contribution to the advancement of China’s construction industry.

Effect of welding sequence on residual stress and deformation of 6061-T6 aluminium alloy automobile component

Four different welding sequences of double-pulse MIG welding were conducted for 6061-T6 aluminum alloy automobile bumpers by using nonlinear elastoplasticity finite element method based on ABAQUS software.The post-welding residual stress and deformation were definitely different among the four welding sequences.The results showed that the highest temperature in Solution A was approximately 200℃higher than the melting point of base metal.High residual stress was resulted from this large temperature gradient and mainly concentrated on the welding vicinity between beam and crash box.The welding deformation primarily occurred in both of the contraction of two-ends of the beam and the self-contraction of crash box.Compared with other welding sequences,the residual stress in Solution A was the smallest,whereas the welding deformation was the largest.However,the optimal sequence was Solution B because of the effective reduction of residual stress and good assembly requirements.

Numerical simulation of the welding deformation for the side sill of the bogie frame based on local-global method

Considering the limitation of computational capacity, a new finite element solution is used to simulate the welding deformation of the side sill of railroad car＇ s bogie frame based on the local-global method. Firstly, a volumetric heat source defined by a double ellipsoid is adopted to simulate the thermal distributions of the arc welding process. And then, the local models extracted from the global model are computed with refined meshes. On these bases, the global distortions of the subject studied are ascertained by transferring the inner forces of computed local models to the global model. It indicates that the local-global method is feasible for simulating the large welded structures by comparing the computed results with the corresponding actual measured values. The work provides basis for optimizing the welding sequence and clamping conditions, and has theoretical values and engineering significance in the integral design, manufacturing technique selection of the bogie frame, as well as other kinds of large welded structures.

Sequence optimization of hull structure assembly based on prediction of welding deformation

Optimization of assembly process is significant for ship construction, thus reducing the time and related costs of construction. Welding Structure Deformation Analysis （Weld-sta） was used to predict welding deformation of a hull block. After the reliability of simulation was proved by comparing with measured results, four kinds of welding sequences was determined. By considering welding deformation and assembly process with the e]ficieney of automation, decreasing the overturn times （times of turning the erections upside down during welding） and working hours etc, one of the welding sequences is assumed to be the most reasonable one. The study shows this method is very useful in optimal assembly program determination of practical engineering structures.

Numerical simulation of residual stress and deformation for submerged arc welding of Q690D high strength low alloy steel thick plate

The finite element simulation software SYSWELD is used to numerically simulate the temperature field,residual stress field,and welding deformation of Q690D thick plate multi-layer and multi-pass welding under different welding heat input and groove angles.The simulation results show that as the welding heat input increases,the peak temperature during the welding process is higher,and the residual stress increases,they are all between 330–340 MPa,and the residual stress is concentrated in the area near the weld.The hole-drilling method is used to measure the actual welding residual stress,and the measured data is in good agreement with the simulated value.The type of post-welding deformation is angular deformation,and as the welding heat input increases,the maximum deformation also increases.It shows smaller residual stress and deformation when the groove angle is 40°under the same heat input.In engineering applications,under the premise of guaranteeing welding quality,smaller heat input and 40°groove angle should be used.

A time-dependent measuring system for welding deformation

In this paper the establishment and application of a time dependent measuring system for welding deformation are presented which is established with high quality sensors shielded from strong welding interference. By using this system, vertical and horizontal displacements of the high temperature area are surveyed at the same time. And this system is also used for monitoring and controlling the deformation of real welded structures.

Study on welding deformation of the side beam based on numerical simulation method

The welding deformation is a key factor affecting the production quality of the side beam of the subway bogie frame. A major issue is how to control the welding deformation during the manufacturing processes. Based on the ＂Local- Global＂ method, the thermal cycle and the stress of a local model extracted from the global side beam model were simulated. The simulated strain result was mapped into the global model as an initial load to simulate the welding assembly deformation. Then the deformation distribution of the side beam was obtained by elastic finite element method, and compared with the measurement results. Furthermore, the welding deformation under different welding sequences and constraints was simulated. The influence of the welding sequences and constraints on the side beam deformation was analyzed. The results indicate that the deformation is the smallest when the sequence is symmetrical and decreases with the increase in constraints.

Prediction of Welding Deformation of Underframe

An inherent strain method was applied to the welding deformation analysis of left girder of GM’s Buick’s chassis underframe assembly. Three models are used in the calculation. Model 1 takes into account the longitudinal and transverse inherent strains; model 2 considers only longitudinal inherent strain; model 3 also takes into account the longitudinal and transverse inherent strains, but inherent strains are taken according to the function instead of the constant, for simulating the variation of the girder’s stiffness during welding process. The result shows the deformation of model 2 is less than that of the model 1, the error is less than 10% of the absolute displacement. So the longitudinal inherent strain is the main factor determining boxes-girder’s welding deformation. The deformation of model 3 is also less than that of the model 1, because the inherent strains of the model 3 are less than that of the model 1. At last, the welding deformation of the whole underframe was analyzed. The analysis results can be taken as references not only for the choices of welding sequence, welding parameters and fixture’s location, but also for welding deformation prediction of other car chassis.

Impact Strength Analysis of Plate Panels with Welding-Induced Residual Stress and Deformation

The paper describes the simulation of impact loads applied on plate panels with welding-induced residual stresses and deformation (WSD). Numerical simulations using FEM are carried out to study the influence of welding-induced residual stresses and deformation on the impact strength of plate panels. Welding is simulated using a three dimensional thermal mechanical coupled finite element method. The welding stress and deformation are taken as the initial imperfections in the impact strength analysis and their influence on the behavior of plate panels subjected to impact loadings. The impact loadings from the three directions, the lateral direction and two in-plane directions of the plate panels are studied. Results show a certain reduction in the impact strength due to the existence of welding stress and deformation in the plate panels. It is found that the reduction of impact force is strongly influenced by the welding deformation and the impact directions in the plate panels. This reduction is more significant when the impact force is in the lateral direction.

Welding deformation control of medium-thickness structures made by advanced high strength steel

In order to investigate the residual angular deformation in fillet welding of T-joint of HG785 high strength steel with a medium thickness plate, both detailed thermo-mechanical finite element simulation and conventional gas metal arc welding experiment were carried out in the present study. In-process deformation control method using backheating method to reduce the residual deformation was discussed.

Specular reflection based sensing surface deformation of gas tungsten arc weld pool

A sensing system is developed to measure the weld pool boundary and pool suoface deformation in gas tungsten arc welding. LaserStrobe technique is used to eliminate the strong arc light inteoference, and specular reflection from the pool suoface is sensed to describe the relation between the deformed stripes and pool surface depression. Clear images of both the pool boundary and the deformed stripes edges are obtained during gas tungsten arc welding process, which lays foundation for realtime monitoring the pool suoface depression and weld penetration.

Prediction and controlling for welding deformation of propeller base structure

Welding deformation often brings about manufacturing problems such as dimensional inaccuracies during assembly and reduces fabrication efficiency.Prediction and controlling welding deformation can help to improve the quality of welded structures.In this paper,the welding deformation of propeller base struc-tures is predicted by means of numerical approaches and mechanical constraints are proposed to control deformations in welding process.Thermal elasto-plastic finite element method(TEP FEM)is employed to simulate welding process of the base structure.Computed accuracy of welding deformation by TEP FEM analysis is verified by comparing with experimental data of tee joint welding.Results show that welding deformations of the base mainly comprise out-of-plane distortion of ring fringe and radial distortion of cylindrical plate.Exerting mechanical constraints of fixed points at fringe and rigid supports inside cylin-der can decrease out-of-plane and radial distortions effectively.The numerical approach adopted in this article can serve as an effective tool to optimize welding process planning in integrated design method.

Research on Voids Deformation Welding Condition for Manufacturing of Heavy Forgings

Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings.The healing result depends on many factors during the forging process,such as stress,temperature,deformation and type of material,while the void diffusion welding condition is still not well known at the present.This paper is concerned with the deformation welding condition of the closed void interface in heavy ingot during the hot forging process.A void crushing experiment is carried out to recognize the microstructure of the closed void interface.According to the healing mechanism at high temperature,a new physical simulation model is setup to study the deformation welding process of the closed void interface based on the theory of atom diffusion and the interface contact mechanics prototype.Compared with the experimental results,the influence of deformation degree,forming temperature and holding time on the welding quality is discussed,and then the deformation welding condition of closed void interface is presented.The proposed condition helps to improve forging technology and product quality.

Identification of Connection Flexibility Effects Based on Load Testing of a Steel-Concrete Bridge

In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper.

Mechanical performance of 22SiMn2TiB steel welded with lowtransformation- temperature filler wire and stainless steel filler wire

TX-80 low-transformation-temperature(LTT)welding wire was used to replace the traditional ER 307Si welding wire to realize the connection of 22SiMn2TiB armor steel in manual overlay welding.The previously existing issues,such as welding cracks,large welding deformation,and severe welding residual stress,were solved to ensure good strength and ductility requirements.In particular,with the same welding conditions,TX-80 LTT wire eliminates welding cracks.It reduces the welding deformation no matter the base pretreatment of pre-setting angle or no pre-setting angle.By comparison,it was found that the microstructure at the TX-80 weld is mainly composed of martensite and a small amount of retained austenite.In contrast,the microstructure of the ER 307Si weld consists of a large amount of austenite and a small amount of skeleton-like ferrite.The variation trend of residual stress and microhardness from the weld to the base were investigated and compared with the mechanical properties of base materials.The TX-80 and the ER 307Si tensile samples elongation is 6.76%and 6.01%,while the ultimate tensile strengths are 877 and 667 MPa,respectively.The average impact toughness at room temperature of the ER 307Si weld is 143.9 J/cm^(2),much higher than that of the TX-80 weld,which is only 36.7 J/cm^(2).The relationship between impact and tensile properties with microstructure species and distribution was established.In addition,the fracture surface of the tensile and the impact samples was observed and analyzed.Deeper dimples,fewer pores,larger radiation zone,and shear lips of TX-80 samples indicate better tensile ductility and worse impact toughness than those of ER 307Si weld.

Computational fluid dynamics simulation of friction stir welding:A comparative study on different frictional boundary conditions

Numerical simulation based on computational fluid dynamics （CFD） is a useful approach for quantitatively investigating the underlying thermal-mechanical conditions during FSW, such as temperature field and material deformation field. One of the critical issues in CFD simulation of FSW is the use of the frictional boundary condition, which represents the friction between the welding tool and the workpiece in the numerical models. In this study, three-dimensional numerical simulation is conducted to analyze the heat transfer and plastic deformation behaviors during the FSW of AA2024. For comparison purposes, both the boundary velocity （BV） models and the boundary shear stress （BSS） models are employed in order to assess their performances in predicting the temperature and material deformation in FSW. It is interesting to note that different boundary conditions yield similar predictions on temperature, but quite different predictions on material deformation. The numerical predictions are compared with the experimental results. The predicted deformation zone geometry by the BSS model is consistent with the experimental results while there is large difference between the predictions by the BV models and the experimental measurements. The fact that the BSS model yields more reasonable predictions on the deformation zone geometry is attributed to its capacity to automatically adjust the contact state at the tool/workpiece interface. Based on the favorable predictions on both the temperature field and the material deformation field, the BSS model is suggested to have a better performance in numerical simulation of FSW than the BV model.

Fixture Locating Modelling and Optimization Research of Aluminum Alloy Sidewall in a High-Speed Train Body

The high-speed train body is welded with aluminum alloy assemblies or parts.Due to the material properties,the welding deformation is much significant.In order to control the welding deformation,this paper takes the sidewall welding of a high-speed train body as the research objective,and carries out the fixture locating modelling and optimization research of the aluminum alloy sidewall.Firstly,a finite element model of the sidewall is established and verified by the comparison between the analysis results and the actual measurement data.Then the residual stress and deformation of the sidewall after welding are analyzed.By selecting the longitudinal parameters of different fixture locating layouts for welding analysis,models describing the relat ionship between the maximum welding residual stress and maximum welding deformation and the longitudinal fixture locating distance of the sidewall are established.Finally,the fixture locating model of welding deformation is used to optimize the longit udinal fixture locating distance.And the transverse fixture locating distance is also optimized by comparing different locating positions.The result shows that the welding residual stress and the welding deformation have been decreased in the optimal fixture locat ing layout.