Welding Assembly Research Articles

Characterization of adhesion within structural materials by means of guided elastic waves

Assembly methods in industry have improved considerably during last decades and mechanical fastening is increasingly abandoned in favor of structural bonding and/or welding methods. The need for improved nondestructive testing and evaluation (NDT&E) methods becomes therefore important particularly for thermoplastic composites welding. Indeed, the latter welding process generates subtle defects (Kissing Bonds) that can hardly be detected, hence the need to develop specific well-calibrated techniques. In addition to bonding testing which is based on the existing contrast between high and weak bonded areas, it remains necessary to determine the adhesion quality, particularly in the case of multi-layered materials. In this contribution a nondestructive quantification method of the adhesion strength corresponding to welded assemblies is presented. The work is based on the use of an ultrasonic contactless experimental device based on air-coupled ultrasound propagating within welded composites. The work takes advantage of the existing interaction between the generated guided waves and the composite structure along the propagating distance in order to locate defects and evaluate the adhesion of the tested thermoplastic welded assemblies. This rely on the basis of an inverse method based on the dispersion curves of Lamb waves, which revealed to be sensitive to the deterioration in adhesion quality.

Welded Gold Nanoparticle Assemblies Defined Plasmonic Coupling.

Nanoparticle assemblies with interparticle ohmic contacts are crucial for nanodevice fabrication. Despite tremendous progress in DNA-programmable nanoparticle assemblies, seamlessly welding discrete components into welded continuous three-dimensional (3D) configurations remains challenging. Here, we introduce a single-stranded DNA-encoded strategy to customize welded metal nanostructures with tunable morphologies and plasmonic properties. We demonstrate the precise welding of gold nanoparticle assemblies into continuous metal nanostructures with interparticle ohmic contacts through chemical welding in solution. We find that the welded gold nanoparticle assemblies show a consistent morphology with welded efficiency over 90%, such as the rod-like, triangular, and tetrahedral metal nanostructures. Next, we show the versatility of this strategy by welding gold nanoparticle assemblies of varied sizes and shapes. Furthermore, the experiment and simulation show that the welded gold nanoparticle assemblies exhibit defined plasmonic coupling. This single-stranded DNA encoded welding system may provide a new route for accurately building functional plasmonic nanomaterials and devices.

Optimizing environmental costs and economic benefits in new energy vehicle production: A case study of FAW Hongqi in China

This study focuses on the environmental cost accounting and economic benefit optimization of China’s FAW Hongqi New Energy Vehicle manufacturing enterprise under uncertain conditions, within the context of the emission permit system This study calculates the pollution situation throughout the manufacturing and production process of FAW Hongqi new energy vehicles, and constructs a multi-level environmental cost evaluation system for FAW Hongqi new energy vehicle manufacturing projects. Through the interval fuzzy model of FAW Hongqi new energy vehicle manufacturing projects, the maximum economic benefits of the enterprise are simulated. The research results indicate that the pollution emissions of enterprises are mainly concentrated in the three processes of welding, painting, and final assembly. Enterprises use their own exhaust gas and wastewater treatment devices to meet the standards for pollution emissions. At the same time, solid waste generated during the automobile manufacturing process is handed over to third-party companies for treatment. Secondly, based on the accounting results of enterprise pollution source intensity and a multi-layer environmental cost evaluation system, the environmental costs of enterprises are accounted for, and the environmental costs are represented in interval form to reduce uncertainty in the accounting process. According to the accounting results of enterprise environmental costs, the main environmental costs of enterprises are environmental remediation costs caused by normal pollution discharge and purchase costs of environmental protection facilities. Pollutant emission taxes and routine environmental monitoring costs are relatively low. Enterprises can adopt more scientific solutions from the aspects of environmental remediation and environmental protection facilities to reduce environmental costs. After optimization by the fuzzy interval uncertainty optimization model, the economic benefits of the FAW Hongqi new energy vehicle manufacturing project were [101,254.71, 6278.5413] million yuan. Compared with the interval uncertainty optimization model, the lower bound of economic benefits increased by 57.68%, and the upper bound decreased by 12.08%, shortening the results of the economic benefits interval. Clarify the current environmental pollution situation of FAW Hongqi’s new energy vehicle manufacturing enterprise, provide data support for sustainable development of the enterprise, and provide reasonable decision-making space for enterprise decision-makers.

Rapid assembly bolt connection design method for TBM disc cutter box based on AHP

With the TBM disc cutter box as the subject of investigation, this study addresses the intricate and labor-intensive nature of the assembly process in TBM disc cutter box welding assembly. In order to expedite the assembly of the cutter-head and disc cutter box, an alternative approach utilizing combined bolt connections is implemented in place of welding assembly. Therefore, this article proposes a TBM disc cutter combination bolt connection design method based on AHP. Initially, a hierarchical analysis model is constructed, taking into account the actual conditions of the TBM disc cutter box combined bolt connections. Subsequently, from the array of factors influencing bolted connection performance, five experimental variables were chosen, and an orthogonal experimental layout was devised to examine the stress dispersion in the TBM disc cutter box under conditions of bolted assembly, employing finite element analysis. By conducting extreme difference analysis, the study examined the effects of each experimental factor on the bolt connection performance, and determined the order of importance of each factor more objectively. Thus, the comprehensive weights of each factor were calculated, and the optimal solution of the bolt connection scheme was selected by synthesizing the effects of multiple factors.

High-biobased polymerizable deep eutectic solvents for sustainable DLP printing: assembly welding and reprintable printing

A series of high bio-based, reprocessable, and reprintable Polymerizable deep eutectic solvents (PDES), named CDAG, based on citric acid (CA) and glycerol (Gly), has been developed for sustainable 3D printing.

Digital twin and parameter correlation-enabled variant design of production lines

ABSTRACT The rapid transformation of production lines into a new design scheme is the key to improving the market competitiveness of enterprises. The production line is a complex manufacturing system with a complex structure. There are multidisciplinary correlation networks between different design dimensions, such as causality, mapping, and transfer. Clarifying these correlative relations is the key to the design of production line correlation. In this paper, a descriptive system is built for the production line configuration model, the motion model, the control model, and the optimization model, and the design content of production lines is clarified. A design framework of production line correlation based on the digital twin technology is proposed, and an optimization system of design schemes is built in the form of hierarchical iteration. Polychromatic sets are used to identify the relationship between different dimensions. The high-fidelity simulation ability of the digital twin technology is taken advantage of to verify the proposed four-in-one variant design method in the mobile phone welding assembly line.

Digital twin-driven parameter change propagation path optimization for production line variant design

ABSTRACT Current mass individualization requires that production lines for processing products be able to quickly vary to adapt to product changes. The variation and propagation of parameters have a central role in the variation process of a flexible production line, which increases the complexity of the design due to the non-unique propagation path of the variation. Obtaining the optimal variant design scheme has become a major challenge for designers. This paper aims to develop a method to determine optimal paths of change propagation. The digital twin-driven framework of parameter correlation path instantiation is presented. The high-fidelity simulation capability of digital twinning will contribute to the fast variant design of flexible production lines at low cost of trial and error. Then, a parameter variation search algorithm based on multi-fork tree has been proposed. The optimal variation design scheme has been achieved for the optimal propagation path of parameter variation from the perspectives of cost, time and complexity. A prototype verification system of production line design based on digital twin is developed to support the instantiation design of parameter change propagation path. An example of mobile phone welding assembly lines was taken to verify the effectiveness of the method.

Ergonomic Embedded in Designing Welding Assembly Tool for Automotive Manufacturing Process

Ergonomics focuses on understanding how workers interact with their work environment, tools, and equipment. The proper ergonomics consideration in tool design will impact worker safety and productivity. Ergonomics-embedded knowledge is critical in designing welding assembly tools for automotive manufacturing. The study aims to improve the ergonomic issues faced by the automotive assembly welders. The methodology involves studying the existing welding assembly process in automotive manufacturing regarding RULA scores and simulating the postures using CATIA analysis. Based on the simulation, critical ergonomics issues should be identified and analyzed. Finally, the welding process is improved by designing the hand support for the workers to assemble parts. The results revealed that the RULA scores have improved from 7 (high risk at the existing condition) to 3 (medium risk) for both worker's hands after the support of the assembly tool. In conclusion, ergonomic embedding in welding assembly tool design has improved the automotive assembly worker's well-being. The findings of this study contribute to the growing body of knowledge on integrating ergonomics into automotive manufacturing processes, providing valuable insights for industry practitioners and researchers alike.

Bending deformation control in a laser-welded long straight structure by elastic pre-bending technique

Longitudinal bending deformation is the most typical mode of welding deformation in long-straight welded structures with asymmetric cross-sections. It is very critical for manufacturing accuracy to control the longitudinal bending deformation during the welding assembly stage. The objective of this study is to propose an elastic pre-bending technique to control the longitudinal bending deformation induced by welding heat input. Both numerical simulation technology and experimental method are employed to investigate the longitudinal bending deformation in a large-straight structure made of SUS304 stainless steel. In the current study, the effectiveness of the proposed elastic pre-bending method is verified by experiment. Simulation results show that the longitudinal bending deformation caused by welding could be reduced by >90 % by setting an appropriate value of pre-bending deformation. In addition, based on theoretical analysis and simulation results, the control mechanism of longitudinal bending deformation is clarified.

Effects of electric welding on hearing loss and respiratory damage

Objective: To investigate the occupational health status of electric welding workers and explore the effects of electric welding on hearing loss and respiratory damage. Methods: From August to December 2021, the cluster sampling method was used to select workers from an automobile manufacturer in Guangzhou City as research subjects: 636 welding workers in the welding workshop as the welding group, 757 assembly workers in the engine workshop and the final assembly workshop exposed to pure noise as the assembly group. Occupational disease hazard factors were detected for welding positions and assembly positions, and occupational health examination was carried out for research subjects. The occupational health status, the trends of hearing loss and respiratory abnormalities with working age were compared and analyzed between the two groups. Binary logistic regression was used to analyze the association between hearing loss and respiratory abnormalities in welding workers. Results: The excess rates of welding fumes, manganese and its compounds in the welding position were both 9.68% (3/31). Its noise exposure intensity [ (85.36±2.68) dB (A) ] and excess rate [48.39% (15/31) ] were not significantly different from those in the assembly position [ (84.86±3.28) dB (A) and 43.24% (16/37) ] (P>0.05). The results of the occupational health examination showed that the detection rates of hearing loss, digital radiography (DR) chest X-ray abnormality, alanine aminotransferase abnormality, deazelaic aminotransferase abnormality and white blood cell count abnormality of workers in the welding group were higher than those in the assembly group (P<0.05). The detection rates of hearing loss, DR chest X-ray abnormality, pulmonary ventilation abnormality in the welding group and the detection rate of hearing loss in the assembly group increased with the working age of the workers (P<0.05). The hearing loss detection rate and DR chest X-ray abnormality detection rate of the workers with ≥9 years working age in the welding group were both higher than those in the assembly group workers with same working age (P<0.05). The binary logistic regression analysis showed that abnormal pulmonary ventilation and abnormal DR chest X-ray were the risk factors for hearing loss in welding workers (OR=10.83, 95%CI: 7.31-16.06; OR=16.59, 95%CI: 5.72-48.10; P<0.05) . Conclusion: Hearing loss and respiratory damage are prominent problems among welding workers, and the detection rates of abnormality increase with the working age of the workers. Hearing loss in welding workers is associated with abnormal pulmonary ventilation and abnormal DR chest X-ray.

Robotic friction stir welding in lightweight battery assembly of extrusion-cast aluminium alloys

The present study focuses on developing lightweight assembly of two different aluminium alloys extruded and high pressure die cast (HPDC) for battery frame assembly in BEV. The goal is to produce defect-free welds in lap configuration with smooth surface finish. Stationary shoulder friction stir welding (SSFSW) was employed with welding speeds of 3–15 mm/s. EBSD analysis revealed two groups of grains in the stir zone (SZ) due to dynamic recrystallization. Moreover, the grain size of the SZ significantly decreased compared to both alloys. The cast alloy contains large iron particles, and that were broken by the rotating probe, and the stirred material consisted of fine dispersed precipitates. Tensile-shear test found the fracture location at the hook area near to cast, and a model representing fracture behavior is also discussed. With increasing welding speed from 3 to 5 mm/s, the tensile strength found ∼95 and ∼100 MPa, respectively without any significance difference in the fracture behavior and location. Overall, this study provides valuable insights such as materials mixing, grain refinement, and joint strength in dissimilar joining using SSFSW. The findings could be useful in developing optimized welding parameters and improving the overall quality and productivity of the SSFSW process for battery pack assembly in BEV.

Fabrication of the Fermilab Pre-Series Cold Mass for the HL-LHC Accelerator Upgrade Project

Fermilab is fabricating ten full length cold masses for the high-luminosity Large Hadron Collider Accelerator Upgrade Project (HL-LHC AUP). One practice assembly and one pre-series assembly have been completed. This paper summarizes the construction details. Topics include incoming inspection, bus assembly, component machining, shell forming, beam tube insertion, bus expansion loop installation, instrumentation installation, electrical testing, heat exchanger installation and final assembly welding. In-process surveys, alignment measurements and testing are presented and explained. Problems encountered during construction and their solutions are discussed.

Effect of post-welding coating process on the organization and properties of MIG-welded T-joints of 6063-T6 aluminum alloy

Abstract With the rapid development of the precision industry, aluminum alloy structural parts have been widely used. However, in the welding process of aluminum alloy, there are problems such as welding deformation and weld tumor defects due to the special physical characteristics of aluminum alloy. Therefore, this paper mainly focuses on 6063-T6 aluminum alloy as the research object to analyze the effect of the coating process on the organizational properties of MIG welded T-joints of 6063-T6 aluminum alloy. First, based on the Simufact welding finite element analysis platform, the establishment of a three-dimensional welding simulation model, the simulation calculations and test results for comparison, the peak temperature and temperature change trend of each measurement point between the two. Secondly, according to the T-joint welding process, welding numerical simulation of 6063-T6 aluminum alloy rear compartment structural parts to obtain the rear compartment assembly welding residual stress is mainly concentrated in the vicinity of the weld. Finally, the impact of welding current on the organization and properties of T-shaped welded joints of 6063-T6 aluminum alloy was discussed. The results show that the coating process has a good strengthening effect on the mechanical properties of welded joints. Compared with the pre-coating process, the welded joint tensile strength increased by 14.93%, and the welding coefficient of 73% of the parent material heat-affected zone microhardness increased by 21.82% compared to the pre-coating process. In this paper, the finite element theory of the coating process and MIG welding, T-joint organization between the found welding heat-affected zone after the coating process can make Mg, and Si atoms continue to be enriched, and mechanical properties strength is enhanced.

Tensile Behaviors and Mechanical Property Analyses of T-Welded Joint for Thin-Walled Parts in Consideration of Different TIG Welding Currents Using Multiple Damage Models and Fracture Criterions: Numerical Simulation and Experiment Validation.

In order to deeply investigate the tensile properties and fracture behaviors that are obtained by tensile tests of welded joints, constitutive and damage models are imperative for analyzing the tensile behaviors. In this work, the tensile tests are conducted on the T-welded joint specimens of aluminum alloy 6061-T6, which were cut from the T-welded joints of thin-walled parts under different welding currents of Tungsten Inert Gas Welding (TIGW). A modified Johnson-Cook (J-C) model based on the original J-C equation, Swift model, Voce model, and Hockett-Sherby (H-S) model, their linear combination model, and fracture failure model are constructed and applied to simulate tensile behaviors, combined with tensile test data. What is more, the finite element (FE) simulation of tension tests is executed with the VUMAT and VUSDFLD subroutines. Compared to those results simulated with different fracture criteria and tensile experiments, the tensile strength and yield strength of T-welded joint thin-walled parts under different welding currents were achieved, and their best mean errors were only about 1%. Furthermore, the accuracy of different fracture criteria is also evaluated by the correlation coefficient and mean squared error. The results show that the combination model can accurately predict the tensile properties and fracture behaviors of T-welded joints better than the single model, especially the results simulated with the Swift-H-S model and H-S-Voce model, which are in good agreement with tensile test results, which will provide an analysis foundation for enhancing the welding assembly quality and preventing fracture failure for complex thin-walled antenna structures.

Формообразование зданий на основе стержневых арок с изменяемой геометрией

Introduction. Spatial core structures of coatings are used for more efficient industrial production of building structures, which reduces the costs of their mass production, specialization of production and rationality of design solutions. When designing spatial coverings, unique designs of single execution are used, which help to solve grandiose architectural and functional tasks. But coatings that are based on standard elements that help to create various architectural forms are also in great demand. Materials and methods. The subject of the study is a spatial architectural and structural system that is capable of implementing various design tasks, being fast-built, lightweight and having unified elements that exclude assembly welding. Such arches will find wide application from sports to exhibition complexes, thanks to their quick installation. The arch can take the shape of a circle, an ellipse, a parabola or bending in two directions, the arch can take the form of an arbitrary curve with the conjugation of curves curved in different directions. Results. The spatial arch is assembled according to the principle of a crystallographic triangulation scheme, where the upper and lower belts, braces and rods can be distinguished. A new universal joint connecting element connecting from six to twelve standard rods is proposed, which allows achieving a minimum number of standard sizes and performing ground-based manual assembly of enlarged structural elements, the spatial rigidity of the system is ensured when they are articulated together. Conclusions. The results of the present study allow us to consider such a variant of the rod spatial arch as a promising solution, as a result of the theoretical study, it was found that the main direction of improvement of spatial rod structures is the development of new nodal connections.

Fault Diagnosis for Body-in-White Welding Robot Based on Multi-Layer Belief Rule Base

Fault diagnosis for body-in-white (BIW) welding robots is important for ensuring the efficient production of the welding assembly line. As a result of the complex mechanism of the body-in-white welding robot, its strong correlation of components, and the many types of faults, it is difficult to establish a complete fault diagnosis model. Therefore, a fault diagnosis model for a BIW-welding robot based on a multi-layer belief rule base (BRB) was proposed. This model can effectively integrate monitoring data and expert knowledge to achieve an accurate fault diagnosis and facilitate traceability. First, according to the established fault tree, a fault mechanism was determined. Second, based on the multi-layer relationship of a fault tree, we established a multi-layer BRB model. Meanwhile, in order to improve the accuracy of the model parameters, the projection covariance matrix adaptive evolutionary strategy (P-CMA-ES) algorithm was used to optimize and update the parameters of the fault diagnosis model. Finally, the validity of the proposed model was verified by a simulation experiment for the BIW-welding robot.

A Wideband Cavity-Backed Dual-Polarized Antenna for X-Band Applications

In this letter, a cavity-backed dual-polarized antenna operating in X-Band (8–12 GHz) is presented. The antenna is composed of a metal cavity with a circular slot, a dual-polarized feeding balun structure printed on a single-layer substrate, and a loaded dielectric block. The units of the antenna are fixed by screws, and no additional welding assembly is required. By setting notches structure on the dual-polarized planar feeding probes, the port isolation and polarization purity of the proposed antenna have been significantly improved. A prototype with the compact size of 0.44 × 0.44 × 0.39 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength at 10 GHz) is fabricated and measured. Measured results demonstrate the return losses are lower than 10 dB and the isolations are greater than 23 dB from 8 to 12 GHz, the measured bore-sight gains vary from 4.5 to 5.8 dBi, and the cross-polarization levels less than −20 dB are obtained within the operational band.

The Seamless Collaborative Operation Technology of Integrating Equipment Control for Intelligent Laser Welding Assembly Unit

The Seamless Collaborative Operation Technology of Integrating Equipment Control for Intelligent Laser Welding Assembly Unit

Planning and Multi-Objective Optimization of Production Systems by means of Assembly Line Balancing

The ever-shorter time to market demanded by customers and an increasing number of variants lead to high-frequency product development and production system planning cycles. This article therefore presents an approach that aims at increasing efficiency in the repetitive planning of variant-specific assembly systems. Compared to the state-of-the-art manual, document-based planning prevailing in industry, formal optimization methods have the potential of considering multiple optimization criteria. This article therefore proposes an approach for assigning individual process steps to stations for a given customer cycle time while minimizing the number of stations as well as optimizing additional criteria such as increasing the production system flexibility, achieving good ergonomics or reducing the deviation within provided tolerances. The solution space of the optimization is constrained by the mathematical modeling of a limited number of stations. The operations research (OR) model developed for this purpose considers given assembly precedence graphs as an input and includes variables, parameters, objective function and constraints. Especially the latter considers the process precedence relations in terms of the Assembly Line Balancing (ALB) problem as well as a divisibility of process steps. The approach is applied to the variant-specific planning of a highly automated welding assembly in the automotive supplier industry as use case. The results show its applicability and potential in reducing planning time.

Supply Chain Management of Outsourcing Module Components Decision-Making using Analytical Hierarchy Process and Visual Basic Application in Automotive Body-in-White Welding Assembly Line

Supply Chain Management (SCM) has gained the attention of business organizations as it affects corporate efficiency and competitive advantage. Component outsourcing is an important element of SCM practices and is considered to be a multi-criteria decision-making problem (MCDM) in vendor selection processes. However, decision-making on the selection of vendors is crucial, as the outsourcing program is influenced by multiple technical and commercial criteria of vendors. Developing an Excel-based Analytic Hierarchy Process (AHP) model for vendor selection therefore helps to simplify selection processes. In this paper, a Visual Basic Application (VBA) Excel-based AHP model was developed, which multiple criteria, sub-criteria and vendors and simultaneously compared with multiple main criteria, sub-criteria and alternatives for vendor selection. The model was validated with a case study of selecting a vendor for module components of body-in-white (BIW) in automotive industry as industrial application. As a result, vendor A is the best vendor since it has the highest overall score of 0.35206. Whereas vendor B is 0.239, vendor C is 0.126, vendor D is 0.146 and vendor E 0.135. In addition, the model is capable of resolving other MCDM problems. This paper provides resources such as AHP methodology, validating method and VBA code programming to readers in developing their own VBA Excel-based model.