Welding Metallurgy of

Thermoplastic–epoxy interactions and their potential applications in joining composite structures – A review Part A Applied science and manufacturing

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.

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Advances in Ultrasonic Welding of Thermoplastic Composites: A Review

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.

Modeling ultrasonic welding of polymers using an optimized artificial intelligence model using a gradient-based optimizer

Laser transmission welding of polymers – A review on process fundamentals, material attributes, weldability, and welding techniques

Experimental and Numerical Procedure for studying strength and heat generation responses of Ultrasonic Welding of Polymer Blends

This research paper attempts to investigate the performance of blended PC/ABS joints using the ultrasonic material joining process. The key focus is on examining the thermal aspects during the joining of PC/ABS blends using ultrasonic welding and the subsequent mechanical testing to determine the strength of the weldments. Thermal behavior of the blends during welding may govern or alter the mechanical properties and integrity of the joints. Hence, investigations on thermal characteristics involved in PC/ABS blends when subjected to high vibrational heat generated during the ultrasonic welding process is imperative. DSC is used to measure the glass transient temperature (Tg) after subjecting it to welding. Mass loss is calculated with TGA. TGA and DSC results indicate change in Tg which are attributed to the molecular alignment occurring when the specimens are subjected to ultrasonic vibrations. Initially, two step mass losses occur that is contributed by ABS in which long single chains are associated and alters PC. SEM images reveal the absence in intermolecular compounds or impurities that tend to weaken weld joints. The diffusion of these molecules is uniform in the welded region. The amorphous nature enhances the integrity of weld joints. Molded part illustrates the higher strain rate in comparison with the welded specimens. The RSM model proposed is sufficient and has limited possibility for violating the independence or the assumption of constant variance.

Experimental Studies on Thermo-Mechanical Behavior of Ultrasonically Welded PC/ABS Polymer Blends

The physics underlying the polymer joining is autohesion. The formation of stable bonds between two surfaces of specimens in contact is known as autohesion process. Restriction to the peeling of the welded parts at the primary contact surface is offered by the bonds formed. Autohesion method is initially reported in the year of 1935–7 (Dodin MG: The Journal of Adhesion 12 (2):99–111, 1981)[1].

Polymer Welding Techniques and Its Evolution

Ultrasonic welding of polymers is an economically viable joining technique which eludes the addition of solvents or adhesives but causes localized heating at the interface by using relatively short cycle times [1]. Ultrasound welding is a high-frequency continuous joining technique. It is appropriate for joining small and larger regions in a sequential manner [2]. It is the technique that offers a good alternative to automotive, medical, packaging, appliance, textile, electronics, and others. The merits of ultrasonically assembled parts reveal clean and reliable bonds to the components. Ultrasonic welding is a swift process wherein a frequency in the range of 18–70 kHz is being used. Output value differs from hundreds of watts to a few kilowatts. Ultrasonic welding machine comprises a booster, transducer, horn, and electrical power supply (generator). The transducer (process controller) receives the electrical signal supply from the generator. Transducer converts electrical signal into mechanical longitudinal vibrations which are transmitted to horn to bond the interface of the material.

Ultrasonic Welding of Polymers

Elemental segregation leads to hot fissuring in the Incoloy 20. The present investigation examines the possibility of lessening the elemental segregation in the conventional arc welding techniques. In the present investigation, Incoloy 20 plates were fused by continuous current gas tungsten arc welding (CCGTAW) and pulsed current gas tungsten arc welding (PCGTAW) with two different nickel-based filler wires (ERNiCrMo-2 and ERNiCrMo-3). The result of the macroexamination shows that steady fluid flow with crack-free welding was succeeded in all the weldments. Optical and scanning electron microscope proves the columnar and cellular structure in CCGTAW specimens and fine equiaxed dendritic structure in PCGTAW specimens. Energy-dispersive spectroscopy (EDS) and X-ray diffraction results exhibit that the weld joint produced by CCGTAW ERNiCrMo-2 shows Cr segregation that leads to the formation of M23C6 phases in the interdendritic regions, whereas ERNiCrMo-3 shows the presence of NbC instead of M23C6. The elemental segregation is suppressed when it comes to PCGTA weldments in both filler wires. Electron backscatter diffraction analysis shows that the CCGTA weldments show coarser grain structure in the heat-affected zone (HAZ). In all the cases, the formation of secondary phases affects the strength of the weld joints at HAZ. Refined microstructure obtained in the PCGTAW in both filler wires shows the marginally higher ultimate tensile strength and toughness compared to the corresponding CCGTA weldments. From the corrosion study, PCGTAW specimens exhibit higher corrosion resistance than the CCGTAW specimens for both filler wires.

Influence of Filler Wires to Suppress the Microsegregation and to Improve Mechanical Properties of Conventional Arc-Welded Nickel-Based Superalloy Incoloy 20

M. Natesh

Papers

Experimental and Numerical Procedure for studying strength and heat generation responses of Ultrasonic Welding of Polymer Blends

Experimental Studies on Thermo-Mechanical Behavior of Ultrasonically Welded PC/ABS Polymer Blends

Polymer Welding Techniques and Its Evolution

Ultrasonic Welding of Polymers

Influence of Filler Wires to Suppress the Microsegregation and to Improve Mechanical Properties of Conventional Arc-Welded Nickel-Based Superalloy Incoloy 20