Joining Method Research Articles

Flexural and vibration behaviour of co-cured CFRP composite joints with MWCNT-modified adhesive

Among the diverse adhesive-bonded joining methods, the co-curing technique offers several advantages for fusing structural components. Co-curing technique effectively enhances specific strengths and ensures more equitable stress distribution. This research investigated the multi-walled carbon nanotubes (MWCNTs) incorporated with varying wt.% in carbon fibre-reinforced polymeric (CFRP) composite joints through co-cure bonding techniques. The effects of flexural and vibration behaviour in CFRP composite joints were evaluated using the three-point bending and free vibration tests. Experimental results revealed that the epoxy adhesive containing 0.5 wt.% nanofiller demonstrated the highest flexural strength and modulus. These values were significantly superior to pure epoxy adhesive, exhibiting increases of 270 and 120%, respectively. However, the 1.0 wt.% of nanofiller exhibited the maximum natural frequency under three vibration modes, which is 29, 17, and 14% higher than the pure epoxy adhesive. The statistical analysis of the results was examined using an ANOVA, ensuring the reliability of the findings. Optimisation and prediction were done with the Levenberg-Marquardt artificial neural network, further reinforcing the confidence in the outcomes. The overall coefficient (R) mean square error of 0.99844 is within the acceptable range, indicating that both outcomes are reliable and in agreement.

A Block-chain Based Mechanism for Securely Storing Data on Cloud and IOT

The burgeoning paradigm of cloud computing has made a number of tools available to researchers. It is a cutting-edge technology that keeps revolutionizing many sectors in every imaginable method. It is a promising technology that gives users and researchers new perspectives, development, and many amazing factors. The integration of cloud and block-chain technology and internet of things (IOT). The benefits both service providers and customers by enabling the use of resources that can be authenticated while protecting anonymity. This joining method is distinct and environmentally. This cooperative method sheds light on the different paths or facets of computers that can solve issues other than security-related ones. The primary problem at the moment is cloud security. For service providers, it's critical to protect client privacy and avoid data loss. Using client data privacy solutions, the current review study focused on block-chain with combination of IOT and data security. In order to strengthen security and expand the power or utility of cloud systems, a comprehensive examination is also carried out. Block-chain technology has the ability to increase speed and anonymity while providing numerous advantages to cloud-based and IOT based applications.

Physical Heat Cycle Measurement of Resistance Spot Welding

Resistance spot welding (RSW) is still the ideal joining method in the automotive industry. Mostly steel sheets are used in the car body, so overlap and layering are required for welding or riveting, as spot welding provides simultaneous clamping force with interfacial welding to ensure the required strength and quality. A fundamental understanding of heating and cooling rates in thermal distributions is essential for predicting microstructure formation in the weld and the heat-affected zones (HAZ) of RSW joints. The ability to measure the heat cycle in the RSW process can be valuable in weld control and welding parameter optimization. RSW parameters can be optimized through tensile shear tests and microscopic investigations. Heat cycle measurement (HCM) demonstrates the welding consequences in terms of the change in mechanical properties and microstructural formations. The accuracy of cooling rate measurements including t8/5 cooling time is very important to predict the microstructural evolution in the HAZ, however, the thermocouple measurement raises numerous challenges due to the high temperature gradient and small weld and HAZ size. During our investigations heat cycle measurement has been conducted experimentally by a K-type thermocouple. The data logger is connected to the output of the thermocouple for recording the voltage to measure the temperature distributions as a function of both time and position during the welding process. Measurement results of 1 mm thick martensitic MS1400 steel overlapped RSW joints are discussed, and the HCM curve of heating and cooling rates of the spot-welding process is presented. The heat cycle during RSW was measured with two different welding parameter combinations. In addition to welding current, welding time, and electrode force, pulsation has shown disparate curves. Numerous experiments have been attempted to measure the heat cycle in HAZ sub-zones due to the difficulty of positioning the thermocouple accurately, uppercritical HAZ, intercritical HAZ, and subcritical HAZ were investigated and measured in both welding parameter combinations. Difficulties were encountered in the experimental work as a result of the instantaneous welding time and the vibration resulting from the passage of alternating electrical current between the two electrodes. A magnetic field is generated that affects the thermocouple measurement and appears as a noisy curve that is filtered out and smoothed. Joule heat, interfacial heat generation, and cooling effects of electrodes are also considered in the experiment.

Effect of Preheating Parameters on Extrusion Welding of High-Density Polyethylene Materials

High-density polyethylene (HDPE) has emerged as a promising alternative to fiber-reinforced plastic (FRP) for small vessel manufacturing due to its durability, chemical resistance, lightweight properties, and recyclability. However, while thermoplastic polymers like HDPE have been extensively used in gas and water pipelines, their application in large, complex marine structures remains underexplored, particularly in terms of joining methods. Existing techniques, such as ultrasonic welding, laser welding, and friction stir welding, are unsuitable for large-scale HDPE components, where extrusion welding is more viable. This study focuses on evaluating the impact of key process parameters, such as the preheating temperature, hot air movement speed, and nozzle distance, on the welding performance of HDPE. By analyzing the influence of these variables on heat distribution during the extrusion welding process, we aim to conduct basic research to derive optimal conditions for achieving strong and reliable joints. The results highlight the critical importance of a uniform temperature distribution in preventing defects such as excessive melting or thermal degradation, which could compromise weld integrity. This research provides valuable insights into improving HDPE joining techniques, contributing to its broader adoption in the marine and manufacturing industries.

Microstructure and mechanical properties of ultrasonically welded aluminum to Zn–Mg–Al coated and uncoated mild steels

The gaining popularity of aluminum alloys in the automotive industry demand the development of energy efficient joining methods of Al with other metals such as steel. Among such joining methods, ultrasonic welding is advantageous because it is cost effective and prevents metallurgical defects because of the low welding energy involved. This study evaluates the microstructural changes and mechanical properties of dissimilar ultrasonic welding of Al to Zn–Mg–Al-coated and uncoated mild steels. Various intermetallic compounds (IMCs), such as FeAl3, and Fe2Al5 with different thicknesses and morphologies were observed at the joint interfaces. The Al-to-Zn-Mg-Al-coated steel exhibited mechanical properties that are superior to those of Al-to-uncoated mild steel. The results are discussed in terms of microstructure evolution, joint characteristics, and interfacial reactions in the welds. This study contributes to the understanding of the mechanisms behind strong ultrasonic welding of dissimilar metals.

Ultraviolet Irradiation Surface Treatment to Enhance the Bonding Strength of Polyamide-Based Carbon Fiber-Reinforced Thermoplastic Polymers.

Adhesive bonding is a suitable joining method to satisfy the increasing industrial demand for carbon fiber-reinforced polymers without the need for a machining process. However, thermoplastic-based carbon fiber-reinforced polymers have small adhesive strength with structural thermoset adhesives. In this study, an ultraviolet irradiation surface treatment was developed to improve the adhesive bonding strength for polyamide-based carbon fiber-reinforced polymer. The type of ultraviolet wavelength, irradiation distance and irradiation time were optimized. Surface treatment with simultaneous UV irradiation of 185 nm and 254 nm wavelength generated unbound N-H stretching that was capable of chemical bonding with epoxy adhesives through a photo-scission reaction of the amide bond of polyamide matrix. Therefore, ultraviolet irradiation treatment improved the wettability and functional groups of the polyamide-based carbon fiber-reinforced polymers for adhesive bonding. As a result, the adhesive strength of the polyamide-based carbon fiber-reinforced polymers was increased by more than 230%.

Evaluation of alternative joining methods in softshell fabric types

Parameters such as high performance, durability and comfort are very important in protective and sports clothing produced to increase the technical or functional properties of clothing products, as well as aesthetic and decorative features. Fabrics that provide comfort to the user by regulating body temperature, protect against harsh weather conditions, and are waterproof and windproof, as well as breathable, are used for these purposes. One of the most important fabrics with these features is the fabric called ‘softshell’. Softshell is a fabric specially created to release moisture and regulate body temperature. Therefore, the outer layer of the softshell is not waterproof, but water-repellent, ensuring that it remains dry and protective while a person is wearing it. Creating a three-dimensional product from a two-dimensional fabric with these features is achieved through the sewing process. As traditional methods are used in the sewing process, an alternative joining method called ‘ultrasonic joining’ can also be used. While alternative joining methods provide joining without sewing thread, these methods do not create holes in the fabric surfaces since there is no sewing needle. Joining processes with thermal, laser and ultrasound energy are based on the principle of melting, fusing and cooling the joined surfaces. In this study, it was aimed to analyze the change in the physical properties of different softshell fabrics as a result of joining them with classical and innovative sewing/joining methods. In this context, lockstitch, lockstitch & tape welding, ultrasonic welding, and ultrasonic welding & tape welding are applied to the softshell, ripstop softshell and Lycra softshell fabrics used in the market. The thickness, air permeability, seam strength and elongation at break properties of the bonded fabrics were examined. Within the scope of this study, obtaining successful results in softshell fabric types, which is one of the bulky fabrics, contributes to the idea that the usage area of ultrasonic welding will expand day by day.

АНАЛІЗ РОЗПОДІЛУ КОНТАКТНИХ НАПРУЖЕНЬ У ДВОЗРІЗНОМУ БОЛТОВОМУ З'ЄДНАННІ КОМПОЗИТНИХ ТА МЕТАЛЕВИХ ЕЛЕМЕНТІВ

Bolted joining technique is the dominant joining method for CFRP load-carrying structures in aircraft. However, the weak point of such structures are the areas located in the vicinity of the fastener holes, which are the areas of increased stress concentration. In addition, drilling the holes results in structural discontinuities due to cutting material fibers. Among all failure modes of composite bolted joint, bearing failure is one of the most common type of damage. This failure is caused by the local compressive stresses acting normal to the contact surface, that leads to delamination of material due to insufficient strength of matrix. Therefore, it is extremely important to optimize the design of composite bolted joints in order to enhance the entire composite structure. To increase the load-carrying capacity of the composite joint structural parts and protect the hole walls from damage, a method for installing titanium bushing with glue into the holes of composite plate is proposed. The paper presents the results of numerical analysis of the impact of stacking sequence on the distribution of contact stresses in a double-shear bolted joint of composite plate to steel cover plates. Using the finite element method and ANSYS Workbench 2019 R3 software, a three-dimensional finite element model of a double-shear bolted joint was created, which enables to analyze the impact of the stacking sequence on the distribution of contact stresses at the bolts to titanium bushings interface in the case of uniaxial tension of the middle composite plate at the level of tensile stresses in the gross section of 100 MPa. The obtained result explains the fundamental difference in the behavior of composite and metal materials: due to the change in the orientation and sequence stacking, the stiffness of the composite element of the joint changes, which affects the ovalization of the holes and the level of local deformations of the bushings, which in turn leads to a change in the maximum contact stresses and their concentration. By optimizing stacking sequence, it was possible to reduce the level of maximum contact stresses by 1.1 times. At the same time, the degree of unevenness of the distribution of contact stresses decreased by 1.21 times. The optimal stacking sequence was one in which 37.5% of the fibers oriented at an angle of 0°, 50% of the fibers oriented at angles of ±45°, and 12.5% of the fibers oriented at an angle of 90°

Generalized cycle joining method and its application to the construction of long-period Galois NFSRs

Generalized cycle joining method and its application to the construction of long-period Galois NFSRs

A Comparative Study of Microwave Welding Using Multiwalled Carbon Nanotubes and Silicon Carbide Nanowhiskers as Microwave Susceptors

Recently, microwave welding has arisen as an advanced joining method due to its versatility and rapid heating capabilities. Among others, microwave susceptors play a crucial role in microwave welding, as different classes of microwave susceptors have distinct microwave heating mechanisms. In this work, polypropylene (PP) was utilized as a thermoplastic substrate and two types of microwaves susceptors, namely multiwalled carbon nanotubes (MWCNTs) and silicon carbide nanowhiskers (SiC NWs), were studied for microwave welding. The susceptor was first dispersed in acetone to form susceptor suspension. Next, the susceptor suspension was deposited onto the targeted area on substrate and paired with another bare PP substrate. The paired sample was then exposed to 800 W microwave radiation in a microwave oven. Afterward, the welded joint was evaluated using a tensile test and scanning electron microscopy to determine its joint strength and cross-section microstructure. The results showed that the joint strength increased as the heating duration increased. The welded joint formed using MWCNTs achieved a maximum strength of 2.26 MPa when 10 s was used, while the SiC NWs-formed welded joint achieved a maximum strength of 2.25 MPa at 15 s. This difference in duration in forming a complete welded joint can be attributed to the higher microwave heating rates and thermal conductivity of MWCNTs. However, increasing the heating duration to 20 s caused severe deformation at the welded joint and resulted in low joint strength. Overall, this study highlights the significance of understanding the microwave heating mechanism of different susceptors and provides essential insight into the selection of a microwave susceptor for microwave welding.

Joining SiC ceramics with CaO-Al2O3-SiO2 mixed powder/glass based on induction heating

CaO-Al2O3-SiO2 mixed powder and glass were used as the joining materials to join SiC ceramics by induction heating in a joining temperature range of 1400–1600 °C under pressureless condition with heating and cooling rates of 100 °C/min. The joint prepared with CaO-Al2O3-SiO2 mixed oxide powder as joining material has the highest shear strength of 60.09 ± 6.22 MPa at joining temperature of 1500 °C, which contains triclinic CaAl2Si2O8 crystalline phase generated by chemical reaction in the holding process. In contrast, the joint produced with CaO-Al2O3-SiO2 glass powder at 1500 °C also has the highest shear strength of 75.76 ± 2.34 MPa, which contains hexagonal CaAl2Si2O8 and quartz generated through crystallization in the holding process due to rapid cooling rate of induction heating. In this study, the feature of mixed powder and glass joining by the induction heating technology was discussed to provide an effective and economic method for ceramic joining.

Expanding Lightweight Design Potential by Hybrid Joining of Aluminum Sheets with Aluminum Casting Through Compound Sand Casting and Induction Heating

Combining light metals like aluminum to produce lightweight structures offers a high weight‐saving and contributes to a circular economy in automotive car body construction. Compound casting is a promising process for producing car body parts. Difficulties arise in creating metallic continuity between insert and casting. Insert coatings are used to remove the oxide layer and thereby improve the wettability of the melt. This study uses a hybrid joining method to improve the metallic bond between insert and casting. Induction heating differently influences the strength properties of age‐ and nonage‐hardenable inserts. Compression shear tests characterize the metallic bond strength. Microscopic images show the influence of the process variables on the compound quality. Reproducible sound metallic bonding with low scattering is achieved by enhancing the compound casting process through induction and no insert coating. Cast wall thicknesses down to 4 mm contribute to further lightweight potential as they have the same strength level as the reference sample. A decisive factor is the insert temperature in the compound zone. Thereby, insert preheating conditions play a crucial role. Additional heat treatment of hardenable compounds leads to a further increase in metallic bond strength.

Machine learning can be as good as maximum likelihood when reconstructing phylogenetic trees and determining the best evolutionary model on four taxon alignments

Phylogenetic tree reconstruction with molecular data is important in many fields of life science research. The gold standard in this discipline is the phylogenetic tree reconstruction based on the Maximum Likelihood method. In this study, we present neural networks to predict the best model of sequence evolution and the correct topology for four sequence alignments of nucleotide or amino acid sequence data. We trained neural networks with different architectures using simulated alignments for a wide range of evolutionary models, model parameters and branch lengths. By comparing the accuracy of model and topology prediction of the trained neural networks with Maximum Likelihood and Neighbour Joining methods, we show that for quartet trees, the neural network classifier outperforms the Neighbour Joining method and is in most cases as good as the Maximum Likelihood method to infer the best model of sequence evolution and the best tree topology. These results are consistent for nucleotide and amino acid sequence data. We also show that our method is superior for model selection than previously published methods based on convolutionary networks. Furthermore, we found that neural network classifiers are much faster than the IQ-TREE implementation of the Maximum Likelihood method. Our results show that neural networks could become a true competitor for the Maximum Likelihood method in phylogenetic reconstructions.

Statistical analysis of adhesive rod-tube joints under tensile stress for structural applications

Adhesive bonding has been replacing traditional joining methods such as welding, bolting, and riveting in the design of mechanical structures in the automotive, aerospace and aeronautic industries. This joining method has several advantages over traditional methods such as ease of manufacture, lower costs, ease of joining different materials, higher fatigue resistance, and high corrosion resistance. Although tubular adhesive joints have varying applications, such as in truss structures and vehicles, machine axles, and piping, different joint configurations exist, such as rod-tube joints (RTJ), which are not conveniently addressed in the literature. This work compares the tensile performance of adhesively bonded RTJ between aluminium alloy components (AW6082-T651), considering the variation of the main geometric parameters: overlap length (LO), tube thickness (tS), rod diameter (d), adhesive fillet angle (f), and type of adhesive. The Taguchi’s method was employed in the elaboration of the applied design of experiments (DoE). To compare the RTJ behaviour, a numerical analysis was carried out through finite element analysis (FEA) and cohesive zone modelling (CZM). Peel (σy) and shear (τxy) stresses in the adhesive layer were initially obtained by applying purely elastic models. CZM modelling made possible to obtain the damage evolution in the adhesive layer, the maximum load (Pm) and dissipated energy (U) at Pm of the adhesive joints. As a result of applying the Taguchi method, the adhesive joint that showed the best overall performance used the adhesive Araldite® AV138, LO = 40 mm, d = 20, and tS = 3 mm.

Friction weldability of ultrafine-grained titanium grade 2

The paper presents the results of an experimental study of the friction weldability of Titanium Grade 2 with ultrafine-grained (UFG) microstructure obtained by hydrostatic extrusion and rotary swaging (HE+RS). High-speed friction welding with different rotational speed (n) values was used as a joining method. The best properties were obtained for n=7000 rpm. Metallographic observations confirmed the formation of a continuous friction joint with a changed microstructure of the base material in the thermal-mechanical affected zone (TMAZ) and a friction weld (FW). The results of the mechanical properties showed the greatest decrease in hardness in the TMAZ. The friction welded joint had an 18 % lower tensile strength value than initial state UFG Titanium Grade 2 after the HE+RS process (with UTS=1050 MPa).

Numerical Evaluation of Hydroformed Tubular Adhesive Joints under Tensile Loads

Adhesive joints are widespread in the aerospace, aeronautics, and automotive industries. When compared to conventional mechanical joints, adhesive joints involve a smaller number of components, reduce the final weight of the structure, enable joining dissimilar materials, and resist the applied loadings with a more uniform stress state distribution compared to conventional joining methods. Hydroformed tubular adhesive joints are a suitable solution to join tubes with identical cross-sections, i.e., tubes with the same dimensions, although this solution is seldom addressed in the literature regarding implementation feasibility. This work aims to numerically analyze, by cohesive zone modelling (CZM), hydroformed tubular adhesive joints between aluminum adherends subjected to tensile loads, considering the variation of material parameters (type of adhesive) and geometrical parameters. Initially, a validation of the proposed CZM approach is carried out against experimental data. Next, the aim is to numerically evaluate the tensile characteristics of the joints, measured by the maximum load (Pm) and energy of rupture (ER), considering the main geometrical parameters (outer tube diameter of the non-hydroformed adherend or dENHA, overlap length or LO, tube thickness or tAd, and joggle angle or q). CZM validation was successfully performed. The numerical study determined that the optimal geometry uses the adhesive Araldite® AV138, higher dENHA and LO highly benefit the joint behavior, tAd has a moderate effect, and q has negligible influence on the results.

Zero-emission joining methods for low-load automotive structural components

Zero-emission joining methods for low-load automotive structural components

Design of a welding table as a medium for determining elbow points and joints

Welding is a method of joining two or more metals with electrode extension media using current heating and voltage according to the variation in the thickness of the iron material used. Welding is one of the connection media with a patent system, meaning that the results of the process can be changed by damaging the results of the welding process. From looking at several welding workshops, almost all of them to do welding are under or on the ground so many workers complain that they tend to be more tired and the welding results are less than optimal, especially for symmetrical or straightness of the connection results. The method used in this research is to design a welding table that is adjusted to the level of needs, especially for the height of the table and the centric axis to combine so that the results of the connection process are completely straight and reduce the results of welding defects. The purpose of designing this welding table is to use it as a method for working on the welding process so that the welding results are really strong and straight according to the design drawing. From the results of the design process, a welding table is obtained with iron material as a table base to place the workpiece to be cut. using borders of iron with a thickness of approximately 120 x 240 x 40cm using Material: Iron plate about 5-6 mm thick. In addition, the results of the design process also reduce the welding process time for blunt joints from 85 seconds to 48 seconds, overlap joints from 85 seconds to 60 seconds, and T joints from 88 seconds to 81 seconds. The quality of the welding results is visually better, the results of welding defects are smaller and straighter or symmetrical

Uncertainty Analysis of Tensile Strength of Scarf Adhesive Joints using Numerical Method and Validation through Experimentation

Adhesive joints represent a significant advancement in material bonding technology, offering benefits such as reduced weight and uniform stress distribution, which distinguish them from conventional joining methods. Among the various adhesive joints, the scarf adhesive joint stands out due to its mechanical advantages and potential for high-strength applications. This research investigates the impact of key parameters on the strength of scarf adhesive joints, including scarf angle, surface roughness, adhesive type, and adhesive layer thickness. By systematically varying these parameters and employing a design of experimentation (DOE) methodology, we aim to identify the optimal conditions that maximize joint strength. A series of scarf adhesive joint specimens with diverse parameter combinations will be fabricated and tested to evaluate the resultant joint strength. Statistical analysis of the experimental data will facilitate the understanding of how each parameter influences joint performance and contribute to the development of optimized adhesive joint designs. The findings of this study are expected to advance the application of scarf adhesive joints in various high-performance engineering fields, providing insights into the critical factors that govern their strength and reliability. Key Words: Scarf Adhesive Joint, Adherend Material, SS 304 Stainless Steel, Finite Element Analysis (FEA), Tensile Strength, Max von Mises Stress, Scarf Angle, Design of Experiments (DOE), Adhesive Properties, Surface Roughness.

QUALITY ASPECTS IN THE WELDING OF SOME ELEMENTS OF MICRO-MOTORS IN AUTOMOTIVE AND HOUSEHOLD APPLIANCES INDUSTRY

In the automotive and household appliances industry, there is a permanent concern to find fast and efficient welding methods and technologies, pressure welding being one of the usual joining methods, due to the minimum qualification requirements, cheap equipment, ease of control, high speed of operation, repeatability and suitability for automation or robotization for inclusion in high production assembly lines. In the paper, quality aspects are described in spot welding of some elements of micro-motors in the automotive industry and household appliances by using tools that allow highlighting the fact that the process is controllable from a statistical point of view, concerning two micro-motors from the production flow.