Journal of Advanced Joining Processes最新文献

This paper is focused on multi-planar hybrid busbars made from copper and aluminum for electric energy distribution systems. The objective is to provide an overview of its assembly by injection lap riveting in multidirectional tools and to compare the electrical performance of its joints against that of conventional (in-plane) busbars.

The injected lap riveted joints require a dovetail ring hole and a countersunk hole to be first machined in the overlapped copper and aluminum sheets and then to inject the semi-tubular rivets by compression through the lined-up holes in order to fix the sheets in position. In this work, the injection of the semi-tubular rivets was carried out in a laboratory multidirectional tool set that converts the vertical press stroke into two-orthogonal horizontal movements by means of cam slide units consisting of compression punch holders and sliding wedge actuators attached to the upper bolster.

Experimental results obtained for a multi-planar, three-conductor, rake-shaped elbow of a hybrid busbar system allow concluding that while the required compression force is proportional to the number of injected lap riveted joints, the electrical performance is non-proportional due to changes in the distribution of electric current density. Numerical simulation with finite elements gives support to the discussion and allows readers to recognize the pitfalls of designing busbar joints exclusively based on mechanical requirements.

In present study, a wall structure of SS309L was constructed through Gas metal arc welding based Wire-arc additive manufacturing process. The wall structure of SS309L underwent investigation for microstructure and mechanical properties at three positions along the horizontal deposition direction. Mechanical assessments, including microhardness testing, impact testing, tensile testing, and fractography, were conducted at three positions of walls. Microstructure study has shown a fine granular structure in addition to colony of columnar dendrites in bottom section, a columnar dendrites in middle section, and a mix of dendritic structure with even coarser structures in top section. The mean microhardness values were observed to be 159 ± 4.21 HV, 162 ± 3.89 HV, and 168 ± 5.34 HV for the top, middle, and bottom sections, respectively. Results of impact testing for the wall structure indicated greater strength compared to wrought SS309L. The tensile strength of the built structure showed average values of yield strength, ultimate tensile strength, and elongation to be 409.33 ± 7.66 MPa, 556.66 ± 6.33 MPa, and 39.66 ± 2.33 %, respectively. In comparison, wrought 309 L steel typically exhibits tensile strengths in the range of 360–480 MPa for yield strength, 530–650 MPa for ultimate tensile strength, and 35–45 % elongation. Thus, the obtained tensile strength results for the wall structure fall within the range of tensile strength observed in wrought 309 L steel. Fractography of the tensile and impact specimens, as obtained through Scanning Electron Microscopy, revealed the superior ductility of the fabricated component. This study contributes valuable insights into the manufacturing of wall structure and their analysis regarding mechanical characteristics.

Functionally graded composites offer impressive promise in overcoming the inherent weaknesses of Metal-polymer hybrid structures. In this study, functionally graded 5083 aluminum (Al5083) and high-density polyethylene (HDPE) tri-laminated composites were fabricated by colding-assisted friction stir additive manufacturing (CA-FSAM) and friction stir additive manufacturing (FSAM). Functionally graded laminate composites have been used to overcome these drawbacks by varying the thickness of the raw laminate. The thickness changes in the user sheets were functionally 0.75 mm compared to the previous laminate. Finally, the initial sheets were transformed to three thicknesses: 3, 2.25, and 1.5 mm. The bond strength between the sheets was measured using the T-peel test. In the T-peel test, the initial crack length was 25 mm and the length of the weld zone was 111 mm. The results showed that the bond strength between the laminates improved with cooling after the CA-FSAM process. The bond strength is essentially determined by the amount of covalent bonding, which, in turn, is a function of the density on the treated surface. Dislocation forest at the surface of the tri-laminate composite can be considered a consequence of T-peel test. The joining mechanism could be ascribed to mechanical interlocking, adhesion bonding at the interface of the Al5083 alloy and HDPE polymer, and metal-chip reinforcement in HDPE of the stir zone. The maximum force (F_max) obtained in the FSAM and CA-FSAM specimens were 1057.58 and 1254.20 N, respectively. Average force of T-peel test (F_{avg peel}) obtained in the FSAM and CA-FSAM specimens was 984.36 and 1024.32 N, respectively.

Because of their excellent lightweight properties, aluminium alloys are processed in industries across the mobility sector. A suitable and efficient process for joining structural components made of aluminium sheet metal is solid self-piercing riveting (SSPR). It eliminates the need for time-consuming preparatory work, such as the insertion of pilot holes, while making the joining process highly automatable.

Due to the process technology, the rivet itself first acts as a punching tool and then as a fastener to transfer the load of the joint. This leads to high requirements for the rivet in terms of strength and ductility.

In this paper, a new rivet design will be presented that focuses on adjusting the rivet geometry, as well as the material, to enable sufficient functionality in the installation and operational phase. Consequently, aluminium sheet metal can be joined in a wider range of applications using aluminium-based SSPR. With this newly developed aluminium rivet, it is possible to join the aluminium alloy EN AW-6111 PX, which is widely used in the automotive industry, up to a total sheet thickness of 3.1 mm for the first time. This development contributes to aluminium-based lightweight structures and ensures a good recyclability.

Joining is a key part of the manufacturing process including automobile, household appliances, aircraft manufacture, and medical sectors. Vibration welding (VW), also known as linear friction welding, is the most used technique to join thermoplastic components and composites mostly due to its simplicity, controllability, versatility of applications, and cost-effectiveness in terms of thermal efficiency, compared to conventional adhesive, mechanical fastening, and other fusion bonding techniques. This review aims to provide a comprehensive overview of the recent advances in understanding the multiple factors affecting vibration weld strength of thermoplastic polymers and their composites. The key process parameters such as weld pressure, frequency, amplitude and time are discussed along with their influence on weld strength of various materials. The effects of material characteristics like crystallinity, fiber reinforcement, and nanoparticles are summarized. Furthermore, the impact of joint design factors like thickness and geometry on mechanical performance is reviewed. The current challenges and future research directions for optimizing vibration weld strength through process, material, and design selections are highlighted. The overall goal is to present updated understanding on achieving strong vibration welded joints by considering the complex interplay between processing, structure, and properties.

The joining of new and dissimilar materials in the transportation sector, to meet the demands for lighter structures, requires the use of alternative joining processes. However, it is not clear how different types of structural joints compare in terms of their contribution to the vibration and damping of structures. The present work aims to provide a comprehensive experimental and numerical analysis on the contribution of three structural joints – butt friction stir welding, single lap adhesive joint and hole hemmed joint – to the vibration and damping of two joined aluminium sheets. For this purpose, experimental analysis is performed to study the free-free vibration of the three structural joints. In addition, finite element models are developed to better understand the behaviour of these joints and discuss the challenges of the numerical modelling procedure. The first four natural frequencies, experimentally obtained for each structure, suggest that the adhesive joint has significantly higher natural frequencies, due to the thickness increase at overlap, while the hole hemmed joint presents the most significant contribution to damping, owing to sliding at the overlap region. The numerical models show a very good agreement with the experimental results in terms of the natural frequencies and mode shapes, with simple modelling providing accurate results. In conclusion, the main findings are that the adhesive joints allow for a stiffer structure, with the natural frequencies increasing with the overlap dimension, while hole hemming enhances damping. The butt-butt friction stir welding has a small effect on the structural behaviour, showing a similar dynamic stiffness and damping when compared to a solid sheet of the same dimension.

In this study, a center-driven double-sided linear friction welding (LFW) process was employed to join three dissimilar materials: A7075-T6, S45C, and pure Ni. High pressure was applied to the A7075-T6 side, as it was intended to be joined at a low temperature, while low pressure was applied to the S45C side, which needed to be joined at a high temperature. By setting the applied pressure on the A7075-T6 side to 300 MPa, which corresponds to the intersection in the graph of the strength dependence of A7075-T6 and pure Ni on temperature, the joint with a joining efficiency of 92% was obtained. SEM and TEM observations were carried out on the joint, confirming the absence of the welding defects at both the A7075-T6/Ni and Ni/S45C interfaces. A thin intermetallic compound layer of approximately 100 nm thick was formed at the A7075-T6/Ni interface.

This paper is focused on hybrid busbar joints with a twofold objective of understanding the differences in electrical resistance under service conditions and evaluating their performance when subjected to hazardous high voltages. Three different types of joints fabricated by conventional bolting, friction stir spot welding and injection lap riveting are selected and two different experimental setups are used to allow the hybrid busbars to be tested up to high voltage electrical discharges of 30 kV. The work is an enhancement of previous experimental and numerical investigations of the authors in the field with results showing no signs of damage or catastrophic failure when the different types of busbars are subjected to high voltage electrical discharges. Results also confirm the good overall performance and advantages of injection lap riveted hybrid busbar joints against bolted and friction stir spot welded.

Laser transmission welding of injection moulded thermoplastics is commonly used in industrial applications such as electronic packaging, textiles, biomedical devices, windows, signs, food and medical packaging, visual displays and automotive components due to very precise control of the process parameters, including the amount of energy delivered and its location, which results in high joint quality. In this article, the influence of laser transmission contour welding parameters and geometry of welding rib on joint force is investigated. Velocity with which the laser beam moves on the sample, temperature applied, clamp force, laser beam size and number of laser passes were studied for various dimensions of the rib with rectangular and triangular cross section. Samples of different thermoplastic materials, PMMA and PC/ABS, were produced and then joined by transmission laser welding and after that were subjected to tensile tests, in order to measure strength of the joint between the plastic parts. Initially, optimal welding conditions were found for each studied rib and their influence on the force of the joint was analysed. Afterwards, a comparison between the best results obtained for each rib was performed, in order to define the dimensions of the rib that result in the highest joint force. It was observed that samples with triangular ribs achieved higher joint strength. For both studied geometries of rib cross section, an increase of the width of the ribs improves the joint strength, while an increase of the height worsens it.

In the present study, the Gas metal arc welding (GMAW) based Wire-arc additive manufacturing (WAAM) process was preferred for the fabrication of multi-layered structures and their investigations of mechanical properties on metal core wire. Based on literature work, preliminary trials, machine limits, travel speed (TS), voltage (V), and gas mixture ratio (GMR) were identified as machining parameters along with output factors of bead width (BW), bead height (BH), and depth-of-penetration (DOP). Experiments were conducted by following the Box-Behnken design. The feasibility of the generated non-linear regression models has been validated through the statistical analysis of variance and residual plots. The multi-layered structure has been successfully fabricated at the optimized parametric settings of TS at 24 mm/s; the voltage at 24 V, and GMR at 1 which was obtained through the heat transfer search (HTS) algorithm. The fabricated structure was observed to be uniform. The structure exhibited uniform bead-on-bead deposition for the deposited layers. The fabricated multi-layered structure underwent a detailed microstructural and mechanical examinations. Microstructural examination revealed dense needles at the bottom section of the structure as compared to the top section, as the bottom section undergoes multiple heating and cooling cycles. When comparing the multilayer structure to the metal core wire, all the properties exhibited favorable tensile characteristics. The obtained strength from the impact test results highlights the impressive ductility of the multi-layer deposition. Fractography of tensile and impact test specimens has shown the occurrences of larger dimples and suggested a ductile fracture. Lastly, the hardness value in all the sections of the built structure was observed to be uniform, suggesting uniform deposition across the built multi-layer structure. The authors consider the current work will be highly beneficial for users in fabricating multi-layer structures at optimized parametric settings and their investigations for mechanical properties for metal core wire.