In this study, Ni was bonded with steels having various microstructures to investigate the effect of various microstructures in steels on the bonding strength evolution by ultrasonic welding. It is ...found that at Ni/ferrite interface having similar hardness, the bonding can be produced by flattening of wear particles generated from the abrasion during ultrasonic welding to obtain a higher degree of plastic deformation, which is positive to bonding strength evolution. As for Ni/pearlite and Ni/martensite interfaces having dissimilar hardness, the bonding formation is difficult due to the presence of hard phases that limit the degree of plastic deformation near the interface, and Ni fragments are attached on the steel side. As a result, lower bonding strength evolution is correspondingly obtained due to slower increment of bonded area, whereas longer time is required for bonding formation between attached Ni fragments and the base metal Ni.
Ultrasonic metal welding has advantages over other joining technologies due to its low energy consumption, rapid cycle time and the ease of process automation. The ultrasonic welding (USW) process is ...very sensitive to process parameters, and thus can be difficult to consistently produce strong joints. There is significant interest from the manufacturing community to understand these variable interactions. Machine learning is one such method which can be exploited to better understand the complex interactions of USW input parameters. In this paper, the lap shear strength (LSS) of USW Al 5754 joints is investigated using an off-the-shelf Branson Ultraweld L20. Firstly, a 33 full factorial parametric study using ANOVA is carried out to examine the effects of three USW input parameters (weld energy, vibration amplitude & clamping pressure) on LSS. Following this, a high-fidelity predictive hybrid GA-ANN model is then trained using the input parameters and the addition of process data recorded during welding (peak power). Once trained, the predictive model is tested against seven unseen parameter combinations specimens. Analysing the experimental data shows that the LSS performance envelop is non-linear with respect to the process variables of clamping pressure, vibration amplitude and welding energy. Vibration amplitude is the dominant input parameter affecting the LSS of the joints. At a fixed welding energy, the LSS can be increased by increasing vibration amplitude. However, the effect of clamping pressure on LSS is dependent on the level of welding energy. The resultant GA-ANN model accurately predicts the LSS of unseen test data producing a mean absolute percentage error of 7.51% with a Pearson's correlation coefficient of 0.96 for all data. It is demonstrated that including process data in a closed loop reduces the mean prediction error from 13.17% to 7.51%.
•A hybrid machine learning approach was developed to predict the quality of ultrasonically welded Al 5754 lap joints.•Vibration amplitude was identified as the dominant parameter affecting the lap shear strength.•Clamping pressure exceeding 0.45 MPa produces surface cracks in the Al 5754 substrate due to excessive plastic strain.•When formulating predictions, the inclusion of measured processing data reduced the prediction error from 13.17% to 7.51%.
In this study, a new hybrid artificial intelligence approach is proposed to model the ultrasonic welding of a polymeric material blend. The proposed approach is composed of an ensemble random vector ...functional link model (ERVFL) integrated with a gradient-based optimizer (GBO). First, welding experiments were conducted on acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) blends produced by the injection molding method. The experiments were designed according to the L27 orthogonal array considering three process factors (applied pressure, welding time, and vibration amplitude) and two responses (average temperature and joint strength). Then, the obtained experimental data were used to train the developed model. To verify the accuracy of the model, it was compared with standalone ERVFL in addition to two fine-tuned ERVFL models (ERVFL-SCA and ERVFL-MRFO) in which ERVFL is incorporated with sine cosine algorithm (SCA) or Manta ray foraging optimization (MRFO). The four models were evaluated using five statistical tools. ERVFL-GBO has the highest coefficient of determination and the lowest root mean square error, mean relative error mean absolute error, and coefficient of variance compared with other models which indicate its high accuracy over other tested models.
The ultrasonic welding (UW) technique is an ultra-fast joining process, and it is used to join thermoplastic composite structures, and provides an excellent bonding strength. It is more ...cost-efficient as opposed to the conventional adhesive, mechanical and other joining methods. This review paper presents the detailed progress made by the scientific and research community to date in the direction of the UW of thermoplastic composites. The focus of this paper is to review the recent development of the ultrasonic welding technique for thermoplastic composites to thermoplastic composites, and to dissimilar materials. Different ultrasonic welding modes and their processing parameters, namely, weld time, weld pressure, amplitude, type of energy directors (EDs) affecting the welding quality and the advantages and disadvantages of UW over other bonding techniques, are summarized. The current state of the ultrasonic welding of thermoplastic composites and their future perspectives are also deliberated.
Ultrasonic welding (UW), a most promising solid-state welding technique, is being developed for the automotive industry, more specifically, for joining components in electric vehicle batteries. It ...has also been used in rare-earth barium copper oxide (REBCO)-based superconductors, which have different stabilizing materials. At present, challenges remain when using UW to join aluminum (Al) and copper (Cu) in either application, and research in these areas are undeniably important for the future use of fully in-line UW applications. This paper provides a review of the current status of UW for joining Al and Cu, specifically in electric vehicle batteries and REBCO-based superconductors. Important issues about process characteristics and critical concerns about weld parameter optimization, joint structure morphology, temperature measurements, joint mechanical properties, and quality of the joints are addressed. Modeling and simulations using the finite element method in predicting the physical phenomena in the dynamic UW process are discussed. The status of electromechanical behaviors in ultrasonically welded joints in superconductors is detailed. Lastly, guidelines and valuable knowledge for the integration of Al and Cu UW in electric vehicle battery assembly and superconductors are provided as a basis for future research directions in these fields.
With the increasing application of fiber-reinforced thermoplastic (FRTP) in the industry, many researchers are focusing on the welding of metal/FRTP hybrid structures. Ultrasonic welding is an ...efficient and cost-effective method for metal/FRTP dissimilar joining. This paper summarizes the current understanding of metal/FRTP ultrasonic welding from four aspects: welding process, joining mechanism, mechanical properties, and galvanic corrosion. It shows that the physical mechanisms, especially the chemical bonding mechanism underlying ultrasonic welding of metal/FRTP are still unclear. Modeling and numerical simulation of metal/FRTP ultrasonic welding is currently lagging behind due to the lack of formulating the metal/FRTP interface interaction. Making macroscopic or microscopic grooves and protrusions on the metal surface is the main method to improve the metal/FRTP joint strength, however, the effect is unstable and quantitative analysis on these grooves and protrusions is required. Overall, the research on metal/FRTP ultrasonic welding still has a lot of space for development.
Ultrasonic welding (USW) of Titanium (Ti) sheets presents several challenges, notably crack formation due to sliding friction. To overcome this problem, the present study applied USW to pure α-Ti ...sheets both with and without different interlayer metals (Al, Ni, and Fe). Al interlayer improved the strength at room temperature significantly to cause base metal fracture (1700 N) by inducing concentrated plastic deformation, facilitating bonding with Ti while minimizing damage. However, its strength decreased significantly at 150–300 °C, suggesting the limitation of using Al interlayer at elevated temperatures. Conversely, the Ni and Fe interlayers led to a two-phase strength development. This enhancement was due to β-phase transformation, which reduces the interfacial defects and generates a more pronounced β-stabilization effect. The Ni interlayer, which has a higher β-transus point (765 °C) and lower molybdenum equivalency, required a higher welding energy (1800 J) and longer diffusion time into Ti, resulting in a gradual increase in strength due to a slower β-Ti transformation. On the other hand, the Fe interlayer with a lower β-transus point relative to Ti (595 °C) achieved peak strength at a lower welding energy of 1200 J. Both Fe and Ni interlayers displayed only a slight decrease in strength (1500–1600 N) at 300 °C with base metal fracture, revealing better joint performance at higher temperatures. These insights suggest a strategical interlayer selection based on the operation temperature, where Al interlayers were advantageous for low-energy welding at room temperature application, Fe and Ni interlayers offer sufficient strength at elevated temperatures by facilitating the β-Ti formation.
Ultrasonic metal welding has been applied for joining aluminum AA5754 sheets to a thermoset matrix composite consisting in a carbon fiber reinforced epoxy resin (CF/epoxy). To overcome the ...limitations of thermosetting resins, that, unlike thermoplastic polymers, cannot melt due to their chemical structure, a thermoplastic film of Polyamide 6 (PA6) has been used as a surface layer of the CF/epoxy stack before curing. The functional surface created on the thermoset matrix composite enables a fast welding with a metallic sheet. By a proper selection of welding energy and force, an average adhesion strength of 34.8MPa has been obtained on CF/epoxy-PA6-AA5754 ultrasonically welded joints.
The morphological characterization has revealed that the aluminum-composite interface is characterized by carbon fibers in a direct contact or even embedded in aluminum, whose surface presents pores and crevices due to the pronounced plastic deformation of the Al interfacial area.
•Ultrasonic welding (USW) is applied in joining of less ductile hexagonal close-packed metals.•The intrinsic brittleness of α-Ti inhibited the increase in joint strength in USW.•A deposition of a ...thin Fe interlayer purposefully introduced an α-to-β transformation.•A β-Ti layer formed by Fe diffusion without obvious Fe–Ti intermetallics after USW.•A strong Ti/Ti bond was obtained with a continuous α/β/α interfacial microstructure.
We investigated ultrasonic welding (USW) of pure α-Ti sheets, which exhibited an insufficient weldability due to the extensive formation of cracks caused by sliding friction during the USW. To overcome this issue, an α/β/α heterogeneous interfacial microstructure was designed by introducing a thin Fe interlayer, a beta stabilizer, between α-Ti sheets. The diffusion of Fe interlayers triggered the formation of a continuous β-Ti thin layer (⁓1–2 μm) without Fe–Ti intermetallics near the bonding interface after USW. The continuous thin β-Ti layer exhibited a significant improvement in the joining of the brittle α-Ti, where the bonding strength was increased from 350 to 1700 N. This study provides a potential approach to design an interfacial microstructure that promotes the formation of a deformable phase, overcoming the inherent brittleness of hexagonal close-packed metals and enabling production of strong joints.
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