The growing demand for lightweight, high-strength materials in marine and aerospace structures has promoted the use of friction stir welding (FSW) for welding dissimilar aluminum alloys. However, tensile residual stresses and microstructural heterogeneities often degrade weld integrity. This study investigates the combined impact of base material positioning, single- and double-pass FSW, and post-weld shot peening (SP) on the metallurgical and mechanical properties of AA6061–AA2017 joints. Five welding configurations were examined to evaluate how varying base material positions on the advancing and retreating sides affect material flow and mechanical behavior. Post-weld SP effectively presented compressive residual stresses, reduced surface defects, and refined surface grains. The average grain size in the stir zone was reduced from 5.2 μm (single-pass) to 2.0 μm (double-pass U-turn) after SP, confirming significant grain refinement through dynamic recrystallization. Mechanical testing revealed that double-pass FSW with opposite weld direction (U-turn) followed by SP achieved the highest performance, with ultimate tensile strength (UTS) improving from 246 MPa to 289 MPa (≈17% increase) and tensile elongation rising from 8.78% to 9.41%. Microhardness in the heat-affected zone improved up to 127 VHN, countering thermal softening effects. The synergistic effect of double-pass welding and SP enhanced homogeneity, fatigue resistance, and surface integrity. The results establish SP as an efficient post-FSW treatment for dissimilar aluminum joints, offering quantifiable improvements in strength and ductility, making the process highly suitable for demanding marine and aerospace structural applications.
Accurate prediction of load distribution in multi-bolt metal–composite joints relies heavily on high-fidelity modeling of single-bolt joint stiffness. Current models, however, inadequately capture the complex effects of bolt–hole clearance, including delayed load take-up and reduced bearing chord stiffness, as well as multi-interface friction interactions. To overcome these limitations, quasi-static tests were conducted on single-bolt, single-lap aluminum–CFRP joints with varying clearances. By integrating experimental findings with an analysis of the load-transfer mechanisms, we identified five distinct loading states and formulated corresponding analytical load-deformation equations along with explicit transition criteria, culminating in a novel piecewise-linear stiffness model. Enhancements over traditional tri-linear models encompass: (a) subdivision of the transition region into separate local and global slip phases, facilitating an accurate representation of asynchronous slip initiation at different frictional interfaces and (b) the implementation of a nonlinear correction approach to quantify the reduction in bearing chord stiffness induced by clearance. The proposed model exhibits excellent agreement with experimental observations across all clearance settings, affirming its predictive accuracy. Consequently, it offers a robust theoretical basis for improving load distribution prediction and facilitating design optimization in multi-bolt M-C joints. Furthermore, the methodology presented here shows considerable potential for adaptation to composite–composite joints.
For centuries, steel has been a cornerstone material for structural construction; by contrast, adhesive joining is a relatively nascent technology, particularly in heavy structural applications. The present article aims to provide the reader a review of the applications of adhesive joining in steel-based applications. Steel being a popular material in many industries due to its excellent mechanical properties, but traditional joining methods might have certain limitations viz. ability to withstand vibrations or movement, distortion, difficult to repair, and the like. Adhesive joining provides an alternative approach that offers advantages like reduced weight, improved corrosion resistance, enhanced aesthetics, ability to join multi-materials, ability to resist vibrations to a certain limit, and the like. This article examines the use of steel within the automotive and construction industries, intentionally narrowing its scope from steel’s broader range of applications. This article tries to provide the reader an overview of some of the applications and focuses on the relevant principles of adhesive joining, types of adhesives used, surface preparation techniques, joining methods, and the mechanical properties of adhesive joints. Finally, the article examines current challenges and outlines future research trends in the field of adhesive joining, with a focus on similar applications.
The present review evaluates recent advances in the development of Welding-Based Additive Manufacturing (WBAM) technologies using arc, high-energy density, solid-state, and hybrid welding systems by providing an interdisciplinary assessment of technological aspects, sensing, process optimization, and multi-process strategies. It is concluded that, in spite of considerable progress in process optimization and control, there exist numerous paradoxes associated with relationships among process conditions, structure, and properties, especially those related to heat input effects on material microstructure and performance. An important finding is the fragmentation of predictive modeling approaches, where physics-based and data-driven methods remain inadequately integrated, limiting generalizability and accuracy. Another important conclusion is related to the dominance of the effect of thermal history and multi-physical phenomena on the mechanical performance of the material produced by WBAM technologies. Besides, the complexity and contradiction in defect generation mechanisms, monitoring, and evaluation methodologies restrict the development of process standardization and certification. New directions in intelligent fabrication based on artificial intelligence and digital twins are identified.
The reliability of welded joints is a vital factor in modern manufacturing, directly affecting product performance and durability. This study investigates methods to enhance the mechanical and metallurgical quality of butt joints in AISI 304L stainless steel welded by the gas tungsten arc (GTA) process. A systematic experimental design was implemented using the Taguchi method with an L9 orthogonal array, considering welding current, gas flow rate, and travel speed as the main parameters. To determine overall weld performance, the joints were characterized by measuring ultimate tensile strength (UTS), yield strength, percentage elongation, and examining their microstructural morphology. An experimental strategy based on the Taguchi approach has been implemented. The welding performance of the material was investigated, and the process parameters were optimized using multiresponse optimization through principal component analysis (PCA), incorporating an orthogonal array design, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA). C1G1S3—the predicted optimal parameter combination—is the ideal factor configuration as determined by PCA (welding current = 100 A, gas flow rate = 10 L/min, travel speed = 2 mm/sec). Results demonstrate that precise control of process parameters significantly enhances weld quality. The methodology also provides a systematic framework that engineers and practitioners can apply to produce reliable stainless steel welds with improved accuracy and predictability.
Friction stir welding (FSW) of Al 6063 alloy plates of 6 mm thickness was investigated in the present study for exploring the mechanical attributes of the welded joints. The tool profile significantly influences the quality of joints produced by FSW. In the current study, the influence of tool profile and FSW process parameters on the FSW weld characteristics of similar joining of Al 6063 plates has been investigated. The effect of FSW tool rotational speed (TRS) and tool travel speed on the FSW weld properties, mainly microstructure characteristics, microhardness, and ultimate tensile strength (UTS), have been studied. Comparison of two different tool profiles, namely taper and cylindrical tool, has also been examined. The effect of transient temperature distribution has also been studied for varying FSW process parameters. When increasing the tool’s rotational speed from 800 to 1200 rpm at a fixed traverse speed of 80 mm/min, a rise in peak temperature is observed. Conversely, increasing the traverse speed from 80 to 100 mm/min while keeping the rotational speed constant at 1200 rpm results in a decrease in the peak temperature. Expanding the TRS from 800 to 1200 rpm—while keeping the welding speed constant at 80 mm/min—leads to a wider FSW weld nugget zone. Under the same welding conditions, the average microhardness of the nugget zone decreases as a result of this increase in TRS. Additionally, as the TRS increases from 800 to 1000 rpm at a steady traverse speed of 80 mm/min, the UTS improves and reaches a peak of about 235 MPa, which is close to the strength of the base material. When the rotational speed is further increased to 1200 rpm, the UTS drops to approximately 150 MPa, likely due to overheating, which may cause grain coarsening or softening in the welded region.
This article aims to estimate the high-cycle fatigue (HCF) behavior of a circumferential notched A357-T6 cast aluminum alloy based on the affected depth (AD) approach. This technique is applied as a useful way to anticipate the fatigue life of notched components using the multiaxial fatigue criterion proposed by Crossland. Simulations of the cyclic finite element (FE) calculations in Abaqus involve implementing an elastic–plastic combined Chaboche model. Calculations lead to determining the Kitagawa–Takahashi diagram for this type of defect under the load ratio Rσ = 0.1, showed good agreement with the experimental data. The study provides a clear quantification of the effect of the notch on fatigue resistance. The fatigue limit of the notched specimen decreases by about 16% when the radius of the notch is equal to 3 m. This cast aluminum alloy has revealed a low sensitivity to notches. The notch sensitivity factor (q) was estimated for different defects and conditions, indicating that a factor value closer to zero suggests the material is insensitive to the notch. Additionally, the findings of Takaji’s coarse microstructures are contrasted with the evaluation of the notch sensitivity factor q for fine microstructures. The findings show that the fatigue resistance of notched A357-T6 specimens is not significantly impacted by the microstructural scale, suggesting that fatigue initiation in this alloy is primarily controlled geometrically.
In this work, the microstructure and mechanical behavior of AL7079 metal matrix composites (MMCs) mixed with zirconia and quarry dusts are analyzed. The high-strength Al7079 can be further improved by the addition of zirconia particulates and quarry dust particles, a cost-effective reinforcement. Composite samples with different weight fractions of zirconia (2%, 4%, and 6%) and quarry dust (2%) were produced via a stir-casting technique. Scanning electron microscope (SEM) was engaged to examine the microstructure of the composites, which showed that the reinforcements were well integrated and bonded perfectly to the matrix material. A simple mechanical test of hardness, tensile, and impact strength revealed enrichment in hardness and tensile strength in comparison to the Al7079 alone, whereas the impact strength decreased. Composite containing 6% zirconia and 2% quarry dust improved both the hardness (95 BHN) and tensile strength (186 MPa) by 7%, outperforming the remaining composition thus an effective novel material for automotive sector.
The utilization of Inconel 718 is increasing daily in stringent operating conditions such as aircraft engine parts, space vehicles, chemical tanks, and the like due to its physical properties such as maintaining strength and corrosion resistance at higher temperature conditions. Besides, Inconel 718 is one of the difficult materials for machining because of maintaining its strength at elevated temperature, which generates higher cutting force leading to observed multiple tool wear mechanisms that affect the surface quality; lower thermal conductivity of materials produces high temperature generation that impacts the tool performance by reducing tool life. In addition, the presence of carbides and high hardness of IN 718 affects the machining performance. Therefore, in this view, this article describes the effect of cutting environments and machining parameters on the machining of Inconel 718 and optimizes the cutting conditions for sustainable machining. Three input parameters namely cutting speed, feed rate, and depth of cut as well as three cutting environments such as flood cooling, MQL (minimum quantity lubrication), and NMQL (nano minimum quantity lubrication) were considered for the experimentation. Experimental runs were designed based on the Taguchi method, which had a total of 27 runs performed on the CNC turning. TiAlN-coated triangular-shaped cutting inserts were used for all experimental runs. This research study addresses three output parameters namely surface roughness, tool wear, and cutting temperature. Finally, the cutting condition was optimized by using the Taguchi method and predicting the relationship between the input parameters and the output parameter using the RSM method. Experimental results observed that the NMQL cutting environment shows better machining performance than the MQL and flood cooling due to the presence of nanoparticles in the base fluid, which act as heat carriers. Whereas minimal surface roughness 0.4 μm and lower cutting temperature (85°C) were observed at low cutting speed, feed rate, and depth of cut (78.54 mm/min, 0.1 mm/rev, 0.1 mm) combination and minimum tool wear was found in moderate cutting speed conditions (117.81 mm/min, 0.1 mm/rev, 0.1 mm). Whereas highest cutting temperature and tool wear such as 130°C and 0.3 mm, respectively, observed in flood cooling environment at the cutting speed (157.08 mm/min, 0.3 mm/rev, 0.3 mm). Using the Taguchi method optimum condition was found in the NMQL cutting environment, at the combination of cutting speed 78.54 m/min, feed 0.1 mm/rev, and depth of cut 0.1 mm. From the ANOVA results, develop the predictive model whose results match with the experimental result. Finally, regression model was developed between the response variable and input parameters.
Composite sandwich beams are widely favored for their high strength-to-weight ratio, so understanding their vibration characteristics is important for optimizing designs in critical industries. This study investigates, through experimental and statistical analyses, the impact of core geometry on the vibration characteristics of epoxy/carbon fiber composite sandwich beams featuring sinusoidal and trapezoidal cores. Modal tests were conducted to determine natural frequencies, damping ratios, and mode shapes. The height and angle of the cores were treated as key independent factors influencing the beams’ vibration characteristics. In both of the cores the damping ratio values increased about 25% and 35% with increasing the height and angle of the sinusoidal and trapezoidal cores, respectively. Additionally, response surface methodology (RSM) was used for statistical analysis of these input parameters’ effects on damping properties, and the optimal values of core’s geometries were determined. Finally, finite element analysis was performed to calculate the vibration properties of the composite sandwich panel that showed good agreement with the experimental results demonstrating strong agreement.
Composite materials are increasingly utilized in industries such as automotive and aerospace due to their lightweight nature and high strength-to-weight ratio. Understanding how strain rate affects the mechanical and crashworthiness properties of CFRP composites is essential for accurate impact simulations and improved safety performance. This study examines the strain rate sensitivity of CFRP composites through mechanical testing and finite element analysis (FEA). Experimental results confirm that compressive strength increases by 100%–200% under dynamic loading, while stiffness decreases by up to 22% at a strain rate of 50 s−1, consistent with trends observed in previous studies. A sled test simulation using LS-Dyna demonstrated that the CFRP crash box sustained an average strain rate of 46.5 s−1, aligning with realistic impact conditions. Incorporating strain rate–dependent material properties into the FEA model significantly improved correlation with experimental crashworthiness data, reducing discrepancies in peak acceleration, mean acceleration, and displacement by 6.5%, 5.9%, and 6.3%, respectively. These findings reinforce the necessity of accounting for strain rate effects in crash simulations and composite structure design, ensuring more accurate predictions of impact performance and structural integrity in safety-critical applications.
Due to the increasing precision requirements for stainless steel castings in the current industrial field, we take stainless steel as the object, use numerical simulation to analyze the manufacturing process of castings, and explore the mechanism of related defects and preventive measures. The results indicate that in the process optimization of small castings, the maximum shrinkage and porosity of the conventional scheme, the optimization scheme with the addition of cold iron and insulation riser, and the optimization scheme with the improved pouring system combined with the optimal parameters are 1.83%, 1.64%, and 1.42%, respectively. The optimal pouring temperature, pouring speed, and shell preheating temperature of medium- and large-sized castings are: 1620°C, 1.5 kg/s, and 1100°C, respectively. According to the aforementioned findings, the study raises the standard of precision production for stainless steel, and fuel the growth of the precision casting sector.
The efficiency and performance of lithium-ion batteries are highly influenced by the quality of laser cutting of electrode materials. The laser cut quality of thin foils is often measured by amount of kerf width and heat-affected zone (HAZ). This article adopts a novel approach that involves pre-cooling of thin copper foils prior to the laser cutting process. The impact of laser conditions and foil temperature were analyzed on HAZ and kerf width induced during laser cutting experiments conducted based on L27 orthogonal array. Teaching-learning-based optimization (TLBO) technique was employed to identify the optimal laser parameters. ANOVA results indicated that the temperature was the most significant factor influencing kerf width and HAZ. The optimized laser parameters identified through TLBO technique were 16 W laser power, 69.47 mm/s scanning speed, and 20 kHz pulse frequency at dry ice conditions. A reduction of 50.76% kerf width and a decrease in 7.6% HAZ were observed when the foils were cut at dry ice conditions. The quality of cut surfaces were further examined using scanning electron microscope.
The escalating weight of main battle tanks (MBTs) has compelled designers to innovate with Ultrahigh hard armor (UHA) steel against the current generation rolled homogenous armor (RHA). This study delves into investigating the experimental and numerical ballistic performance of 15 mm-thick UHA steel and 15 mm-thick RHA steel against a 7.62 mm armor-piercing (AP) small-arm projectile. Finite element (FE) simulations were executed using ANSYS software, incorporating the Johnsons Cook model and shock Rankine-Hugoniot equations. The outcomes highlight that the UHA steel arrests the projectile's advancement at a depth of penetration (DoP) of 3 mm, where the mode of failure is projectile break-up with cleavage failure. Conversely, the RHA base metal demonstrates perforation accompanied by ductile hole growth as the mode of failure. This perforation is attributed to plastic deformation and material extrusion, aligning well with the FE model. In the second scenario, the ballistic limit of a 7.62 mm AP projectile on RHA plate is explored by increasing the plate thickness to 18 mm. At this thickness, the projectile comes to a halt, creating a smooth bulge. Notably, UHA steels exhibit a projectile break-up mode of failure and an 81.5% reduction in weight compared to RHA steels. An intriguing correlation is identified between hardness and thickness, as elevated hardness and thickness shift the failure mode from ductile hole growth to projectile break-up.
Polymer composites, such as fiber-reinforced plastics (FRPs), are widely used in shipbuilding, aerospace, and automobile industries due to their lightweight and high strengths. In real-world conditions, ship hulls are exposed to harsh environmental factors, including variations in moisture and salinity. FRPs tend to absorb water and moisture, leading to an increase in weight and a reduction in strengths over time, which is undesirable for ship and aircraft structures. This study investigates the reduction in energy absorption and specific energy absorption of glass FRPs (GFRP) and aluminum honeycomb sandwich composites (AHSC) due to exposure to moisture and salinity. Experimental analysis was conducted by immersing the materials in saline and non-saline water. A comparative assessment of the percentage reduction in specific energy absorption (SEA) of GFRP and AHSC is presented. Additionally, the influence of honeycomb parameters such as cell size (CS), foil thickness (FT), and core height (CH) on SEA has been analyzed. Results indicate a 27% reduction in SEA for GFRP and a 7% reduction for AHSC due to water absorption. Furthermore, SEA in AHSC can be improved by changing honeycomb parameters, with foil thickness having the most significant impact on SEA enhancement.
Although Ti-6Al-4V alloy offers high strength-to-weight ratio, corrosion resistance, and biocompatibility properties, its machining is challenging due to low thermal conductivity, high hardness, and chemical reactivity. This study examines turning of Ti-6Al-4V under minimum quantity lubrication (soybean oil). Cutting speed (CS), feed rate (FR), and depth of cut (DOC) are considered as the input parameters. On the other hand, material removal rate (MRR), tool wear rate (TWR), surface roughness (SR), and cutting force (Fc) are treated as the responses. Optimization of the said process is carried out using the mixed aggregation by comprehensive normalization technique (MACONT), a recently developed multi-criteria decision-making (MCDM) method. The optimal parameters are identified as CS = 72.26 m/min, FR = 0.022 mm/rev, and DOC = 0.2 mm, achieving high MRR with low TWR, SR, and Fc. The effects of different turning parameters on the responses are also investigated. Sensitivity analysis confirms robustness, and comparative evaluation with other MCDM tools validates accuracy of the adopted approach. The results demonstrate MACONT’s effectiveness in optimizing turning of hard-to-machine alloys, supporting greener and sustainable machining practices.
Gears are essential components in industrial machinery, and their design needs to be optimized to ensure the proper functioning of mechanical systems across various industrial applications. In this study, an optimization approach is proposed to determine the optimal design of a spur gear. This approach is based on an improved Jaya algorithm, which features a straightforward formulation without any algorithm-specific control parameters. Utilizing a simple and parameter-free updating mechanism, the strength of this algorithm lies in its iterative ability to enhance candidate solutions by moving them toward the best solution while avoiding the worst one, providing a flexible framework for optimization. However, since the original Jaya algorithm was primarily designed for continuous optimization problems, this research incorporates adjustments to adapt it effectively for mixed-variable optimization problems and to manage multi-objective functions. The effectiveness of the proposed algorithm is evaluated through examples of constrained problems taken from previous research and case studies on spur gear design, which were refined in this study. The optimum solutions obtained using the improved Jaya are compared with other metaheuristic optimization algorithms. Results exhibit promising results regarding objective function value, solution robustness, and statistical results.
Friction stir surfacing is an advance surface modification technique, which is functionally evolved from the friction stir welding process. However, the fundamental reason behind the joining of Al/ steel is difficult due to the formation of hard and brittle intermetallic compounds (IMC). To address the problem of IMC formation, the current study suggested an alternate production technique with solid-state friction surfacing deposition. In this work, the adhesion mechanism and metallurgical properties of solution-treated AA6061-T6 aluminum alloy cladding over a low-carbon steel IS2062 substrate were investigated. Impact procedural factors (axial frictional force, spindle speed, table traverse speed, consumable rod diameter, and substrate roughness) were examined. Push-off and hardness tests were used to inspect the mechanical properties of cladded samples. 67-77 +/- HV hardness is observed at the interface of the cladded cross-section. A push-off strength of 9 kN was achieved, indicating effective bonding between the AA6061-T6 alloy and the low-carbon steel substrate. Microexamination indicated that there is clear bonding through broken asperities, which are due to mechanical interlocking. The suggested approach can likewise be used with other dissimilar combinations that are mutually intractable.
NiCoCrAlY powders were thermally sprayed by combustion flame spray (CFS) and high-velocity oxygen fuel (HVOF) processes on IN 718 alloy substrates. Experimental parameters were fixed to manufacture coatings with a thickness about 200 μm. Microscopy and X-ray diffraction analyses were performed to reveal microstructural characteristics of both developed CFS and HVOF coatings, and it was observed that they were formed by a lamellar morphology composed of β and γ phases. The analyses also revealed lower porosity in the coatings produced by HVOF process while was compared with CFS process. While a microstructure composed of like-deformed powder was developed in HVOF process, in the case of CFS a building layer-by-layer was characteristic. Vickers hardness tests were also performed, and it was found that coating developed by HVOF process showed quite higher hardness values compared with those measured on the coatings developed with the CFS process, nonetheless this difference was small. Hence, the results showed that the coatings by CFS process are very promising for industrial applications, with negligible manufacture costs and very appropriate to be applied in situ.
