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For the automatic drilling and riveting in panel assembly, gaps between the skin and strangers are inevitable and undesirable. At present, the determination of pre-joining schemes relies on workers’ experience, introducing excessive number and inappropriate locations of pre-joining. This paper aims to present a new method for the evaluation of residual clearances after pre-joining and the pre-joining scheme optimization, providing operation guidance for the workers in panel assembly workshop.

In this paper, an equivalent gap assembly model for pre-joining is proposed on the basis of the mechanism of variation. This model retains the essential elastic behavior of the key features during the pre-joining operation and calculates the residual clearances in the view of the potential energy. Subsequently, this method is embedded into a Pareto optimality-based genetic algorithm, and the optimal pre-joining schemes are achieved with the consideration of the total residual clearances and the permissive tolerances.

The equivalent gap assembly model has the capability to predict an acceptable degree of accuracy of the residual clearances and achieve the optimized pre-joining schemes with less number of pre-joining at the same level of residual clearances.

The optimized pre-joining schemes are given in the form of Pareto optimality set, and workers can select suitable results according to their inclination to the quality and efficiency.

The paper is the first to propose the equivalent gap assembly model for the pre-joining operation, which provides for the simplification of the calculation of residual clearances based on the constrained variation principles.

An ongoing revolution in the development and implementation of new materials has placed new demands on the ability to join these materials into devices, parts and components, and devices, parts and components into packages, assemblies and structures for both electrical and mechanical applications. Looks at the past successes and shortcomings of traditional joining technologies. Presents some obvious and some not‐so‐obvious directions as one attempt at prognostication of the needs for new joining technologies for the forthcoming new century.

From when we, as humans, first lashed a pointed stone to a split straight stick to make a more effective spear for hunting to now when we fasten and bond ablative ceramic tiles to the frail metal skin of the Space Shuttle to allow safe re‐entry from manned excursions into space, joining has been a pragmatic, albeit critically important, fabrication process. As we move beyond the Industrial Age to the ages of Information Technology, Nanotechnology, and Biotechnology, joining must move from a secondary process for manufacturing objects or articles from pre‐synthesized and pre‐shaped materials to a primary process for combining materials into fundamental structures as these structures and even materials are being synthesized; where the boundary between the materials and the structure becomes blurred. This paper attempts to catch a glimpse of the future where joining comes of age to become an enabling technology practiced as much or more by technicians or physicians than as a trade practiced by helmeted welders or hard‐hatted riveters.

The purpose of this paper is to propose a new model for optimizing pre-joining processes quickly and accurately, guiding workers to standardized operations. For the automatic riveting in panel assemblies, the traditional approach of determination of pre-joining processes entirely rests on the experience of workers, which leads to the improper number, location and sequence of pre-joining, the low quality stability and the high repair rate in most cases.

The clearances computation with the complete finite element model for every process combination is time-consuming. Therefore a fast pre-joining processes optimization model (FPPOM) is proposed. This model treats both the measured initial clearances and the stiffness matrices of key points of panels as an input; considers the permissive clearances as an evaluation criterion; regards the optimal number, location and sequence as an objective; and takes the neighborhood-search-based adaptive genetic algorithm as a solution.

A comparison between the FPPOM and complete finite element model with clearances (CFEMC) was made in practice. Further, the results indicate that running the FPPOM is time-saving by >90 per cent compared with the CFEMC.

This paper provides practical insights into realizing the pre-joining processes optimization quickly.

This paper is the first to propose the FPPOM, which could simplify the processes, reduce the degrees of freedom of nodes and conduct the manufacturers to standardized manipulations.

Three-dimensional (3D) printing, one of the important technological pillars of Industry 4.0, is changing the landscape of future manufacturing. However, the limited build volume of a commercially available 3D printer is one inherent constraint, which holds its acceptability by the manufacturing business leaders. This paper aims to address the issue by presenting a novel classification of the possible ways by which 3D-printed parts can be joined or welded to achieve a bigger-sized component.

A two-step literature review is performed. The first section deals with the past and present research studies related to adhesive bonding, mechanical interlocking, fastening and big area additive manufacturing of 3D printed thermoplastics. In the second section, the literature searches were focused on retrieving details related to the welding of 3D printed parts, specifically related to friction stir welding, friction (spin) welding, microwave and ultrasonic welding.

The key findings of this review study comprise the present up-to-date research developments, pros, cons, critical challenges and the future research directions related to each of the joining/welding techniques. After reading this study, a better understanding of how and which joining/welding technique to be applied to obtain a bigger volume 3D printed component will be acquired.

The study provides a realistic approach for the joining of 3D printed parts made by the fused deposition modeling (FDM) technique.

This is the first literature review related to joining or welding of FDM-3D printed parts helping the 3D printing fraternity and researchers, thus increasing the acceptability of low-cost FDM printers by the manufacturing business leaders.

The purpose of this paper is to join an anodized aluminium alloy AA6061 sheet with high-density polyethylene (HDPE) using friction spot process.

The surface of AA6061 sheet was anodized to increase the pores’ size. A lap joint configuration was used to join the AA6061 with HDPE sheets by the friction spot process. The joining process was carried out using a rotating tool of different diameters: 14, 16 and 18 mm. Three tool-plunging depths were used – 0.1, 0.2 and 0.3 mm – with three values of the processing time – 20, 30 and 40 s. The joining process parameters were designed according to the Taguchi approach. Two sets of samples were joined: the as-received AA6061/HDPE and the anodized AA6061/HDPE.

Frictional heat melted the HDPE layers near the lap joint line and penetrated it through the surface pores of the AA6061 sheet via the applied pressure of the tool. The tool diameter exhibited higher effect on the joint strength than processing time and the tool-plunging depth. Specimens of highest and lowest tensile force were failed by necking the polymer side and shearing the polymer layers at the lap joint, respectively. Molten HDPE was mechanically interlocked into the pores of the anodized surface of AA6061 with an interface line of 18-m width.

For the first time, HDPE was joined with the anodized AA6061 by the friction spot process. The joint strength reached an ideal efficiency of 100 per cent.

Joining, while first and foremost a pragmatic undertaking, concerned more with needs and results than with theory, will likely have to change with the dawn of the twenty‐first century to a true science. As materials become ever‐more sophisticated in their chemical composition, molecular morphology, micro‐ and nano‐structure, and macro‐structural arrangement to provide ever‐better functionally specific properties, a more complete and precise understanding of how such materials can be joined for optimal effectiveness and efficiency will become essential. Traditional options for joining will surely evolve – sometimes to provide unimagined capabilities. But, in addition, totally new methods will almost certainly emerge as evolution of materials gives way to revolution to meet unimagined new designs and design demands. This paper takes a glance at the past and a hard look at the present in the hope of catching a glimpse of the future.

The purpose of this paper is to design a reasonable joining path and achieve assembly automation for multiple arc-shaped panels. A fuselage panel is primarily composed of skins, stringers, frames and clips. Both inserted and nested structures are adopted in the panels to improve the strength and hermeticity of the fuselage. Due to the complex structures and relationships, it is a challenge to coordinate the arc-shaped panels in the assembly process.

A motion sequence model which achieves arc approximation based on the relative motion of multiple panels is established. The initial position of the panels is obtained by decomposing the computer-aided design model of the panels. Two translation rules, i.e. progressively decreasing translation and limited deformation translation, are applied to determine the moving path of the panels. If a panel is not at its path node, a search algorithm is used to find the nearest path node. Finally, the key algorithms are implemented in an integration system to promote joining automation of multiple panels.

The zigzag path is effective for the joining of multiple panels with complex mating relationships. The automation of the join–separate–rejoin operations is time-saving and safety-assuring. The proposed method is demonstrated in practical engineering and a good efficiency is obtained.

This method has been used in a middle fuselage assembly project. The practical results show that the zigzag path is convenient to be stored and reused, and the synchronous movements of multiple curved panels are precisely realized. Additionally, the posture accuracy of panels is significantly improved, and the operating time is reduced considerably.

This paper gives a solution including path planning and process integration to solve the joining problem of multiple panels. The research will promote the automation of fuselage assembly.

The purpose of this paper is to join sheets of an aluminium alloy together with pre-holed carbon steel via friction spot technique.

An AISI 1006 steel sheet was a pre-holed with a 4.8 mm diameter and put under AA5052 sheet with a lap joint configuration. The joining process was carried out by extruding the aluminium through the steel hole using a rotating tool of 10 mm diameter. Furthermore, three process parameters (pre-heating time, rotating speed and plunging depth of the tool) with three values for each parameter were used to study their effects on the joints quality. In order to join samples, nine experiments were designed according to a Taguchi method. Shear strength, microstructure and X-ray diffraction tests of the joint were carried out.

The joining mechanism occurred by a mechanical interlock of the extruded aluminium with the inner surface of the steel hole. The tool plunging depth had a significant effect on the shear strength of the joint. The shear strength of two joints exceeded the shear strength of the wrought material (AA5052). All samples failed with two modes: pull-out and shearing of the extruded aluminium.

For the first time, the extrusion technique was used to join AA5052 sheet together with pre-holed carbon steel, with a perfect joint efficiency.

Clinching is, due to its characteristics, a joining method with several advantages. The high joining forces, which require heavy process equipment are a major disadvantage. The Fraunhofer Institute has developed clinching methods which reduce the joining forces considerably to make clinching applicable for further developments and new application areas.