Abstract The present study deals with laser beam welding (LBW) and friction stir welding (FSW) applied to high-strength aluminum alloys used in aircraft industry and displays their advantages compared with the riveting technique regarding structural integrity, weight and material savings. First of all, it is shown with respect to different applications and strength levels which high-strength aluminum alloys represent the state-of-the-art and which aluminum alloys are proposed as substitutes in the future. Furthermore, the respective joining process principles are described and demonstrated on different joint configurations, whereby mechanical and microstructural properties of laser beam- and friction-stir-welded joints are discussed and compared. The current study clearly demonstrates that these two joining techniques are not competing but complementary joining techniques in the aircraft industry. FSW, as a solid-state joining process, has the advantage that the joining is conducted at temperatures below the melting point of the materials to be joined. Therefore, improved mechanical performance of joints is expected compared to that of fusion joining processes such as LBW. Furthermore, better mechanical properties can be obtained when heat input during joining is reduced by employing stationary shoulder FSW and/or external cooling. On the other hand, LBW offers several advantages such as low distortion, high strength of the joint, and high welding speeds due to its low localized-energy input. Thus, LBW - as a high-speed and easily controllable process - allows the welding of optimized complex geometrical forms in terms of mechanical stiffness, strength, production velocity, and visual quality. Both joining processes have advantages and disadvantages, depending on joint geometries and materials. They both have the potential to reduce the total weight of the structure. The FSW process (particularly lower heat input stationary shoulder FSW process) is more advantageous in producing long-distance straight-line butt joints or overlapped joints of aircraft structures, whereas the high-speed and easily controllable LBW process allows the joining of complex geometrical forms due to its high flexibility, particularly in the new generation high strength Al-alloys (such as AA2198), the strengthening phases of which are more heat resistant.
Abstract The integration of high strength, high toughness, and excellent flame retardancy in polymer materials is highly desirable for their practical applications in the industry. However, existing material design strategies often fail to realize such a performance portfolio because of mutually exclusive mechanisms between strength and toughness, and low flame retardancy efficiency of nanofillers in polymers. Here, we reported the preparation of a multifunctional nanohybrid, Ti3C2Tx@MCA, by engineering the surface of titanium carbide nanosheets (Ti3C2Tx, MXene) with melamine cyanurate (MCA) via hydrogen bonding interactions, and subsequent thermoplastic polyurethane (TPU)/Ti3C2Tx@MCA nanocomposites. The resultant TPU nanocomposite containing 3.0 wt% of Ti3C2Tx@MCA shows a high tensile strength of 61.5 MPa, a toughness as high as 175.4 ± 7.9 MJ m−3 and a high strain at failure of 588%, and 40% reduction in the peak of heat release rate. Such extraordinary mechanical and fire retardant performances are superior to those of its previous counterparts. Interfacial hydrogen bonding in combination with the “labyrinth” effect and catalytic action of 2D Ti3C2Tx nanosheets are responsible for the outstanding mechanical and fire retardancy properties of TPU nanocomposites. This work provides a new paradigm for integral design of high-performance polymeric materials with excellent mechanical and fire-safe performances portfolio.
Ultrasound is composed of mechanical sound waves that originate from molecular movements that oscillate in a propagation medium. The waves have a very high frequency, equal to approximately 20 kHz, are divided into two categories (i.e., low-intensity and high-intensity waves) and cannot be perceived by the human ear. Nature has created the first ultrasound applications. Bats use ultrasound to navigate in the dark, and many cetaceans use echolocation to detect prey or obstacles using ultrasound produced by their vocal system. Ultrasound is commonly associated with the biomedical field. Today, ultrasound-based methods and equipment are available to detect organs, motion, tumour masses, and pre/post-natal handicaps, and for kidney stone removal, physiotherapy, and aesthetic cures. However, ultrasound has found multiple applications in many other fields as well. In particular, ultrasound has recently been used in the food industry to develop various effective and reliable food processing applications. Therefore, this review summarizes the major applications of ultrasound in the food industry. The most common applications in the food industry include cell destruction and extraction of intracellular material. Depending on its intensity, ultrasound is used for the activation or deactivation of enzymes, mixing and homogenization, emulsification, dispersion, preservation, stabilization, dissolution and crystallization, hydrogenation, tenderization of meat, ripening, ageing and oxidation, and as an adjuvant for solid-liquid extraction for maceration to accelerate and to improve the extraction of active ingredients from different matrices, as well as the degassing and atomization of food preparations.
Waste from non-degradable plastics is becoming an increasingly serious problem. Therefore, more and more research focuses on the development of materials with biodegradable properties. Bio-polymers are excellent raw materials for the production of such materials. Bio-based biopolymer films reinforced with nanostructures have become an interesting area of research. Nanocomposite films are a group of materials that mainly consist of bio-based natural (e.g., chitosan, starch) and synthetic (e.g., poly(lactic acid)) polymers and nanofillers (clay, organic, inorganic, or carbon nanostructures), with different properties. The interaction between environmentally friendly biopolymers and nanofillers leads to the improved functionality of nanocomposite materials. Depending on the properties of nanofillers, new or improved properties of nanocomposites can be obtained such as: barrier properties, improved mechanical strength, antimicrobial, and antioxidant properties or thermal stability. This review compiles information about biopolymers used as the matrix for the films with nanofillers as the active agents. Particular emphasis has been placed on the influence of nanofillers on functional properties of biopolymer films and their possible use within the food industry and food packaging systems. The possible applications of those nanocomposite films within other industries (medicine, drug and chemical industry, tissue engineering) is also briefly summarized.
Abstract The market size of fresh and minimally-processed fruits and vegetables (MPFVs) have grown rapidly in the last years as a result of consumer attitudes change due to their increasing use in prepared mixed salad for fresh, healthy and convenient food. Handling and mechanical operations of cutting and peeling induce injures and release of on-site cellular contents which promote the growth of harmful microbes. Chlorine has been widely adopted in fresh and MPFVs disinfection in washing due to its low cost and high efficacy against a broad spectrum of microorganisms; but, continuous replenishment of chlorine into high organic wash water can promote the formation of suspected carcinogenic compounds. There is a real need to find new alternatives to chlorine to preserve MPFVs quality for longer time. Although several methods and chemicals can be used to achieve similar reduction of microorganism counts without the production of harmful compounds, nor compromising the quality of MPFVs produce, fewer amount of them have gained widespread acceptance by the food industry. The challenge of this work was to give an upgraded level of understanding for producers and retailers to underpin future research directions for a modern food industry in order to resolve existing issues that limit fresh-cut quality and shelf-life. This paper covers a comprehensive review to improve shelf-life and quality of MPFVs, from the traditional technologies toward the most promising advancements.
Binder jetting is an additive manufacturing process utilizing a liquid-based binding agent to selectively join the material in a powder bed. It is capable of manufacturing complex-shaped parts from a variety of materials including metals, ceramics, and polymers. This paper provides a comprehensive review on currently available reports on metal binder jetting from both academia and industry. Critical factors and their effects in metal binder jetting are reviewed and divided into two categories, namely material-related factors and process-related parameters. The reported data on density, dimensional and geometric accuracy, and mechanical properties achieved by metal binder jetting are summarized. With parameter optimization and a suitable sintering process, ten materials have been proven to achieve a relative density of higher than 90%. Indepth discussion is provided regarding densification as a function of various attributes of powder packing, printing, and post-processing. A few grades of stainless steel obtained equivalent or superior mechanical properties compared to cold working. Although binder jetting has gained its popularity in the past several years, it has not been sufficiently studied compared with other metal additive manufacturing (AM) processes such as powder bed fusion and directed energy deposition. Some aspects that need further research include the understanding of powder spreading process, binder-powder interaction, and part shrinkage.
The bio-integrated electronics industry is booming and becoming more integrated with biological tissues. To successfully integrate with the soft tissues of the body (eg. skin), the material must possess many of the same properties including compliance, toughness, elasticity, and tear resistance. In this work, we prepare mechanically and biologically skin-like materials (PSeD-U elastomers) by designing a unique physical and covalent hybrid crosslinking structure. The introduction of an optimal amount of hydrogen bonds significantly strengthens the resultant elastomers with 11 times the toughness and 3 times the strength of covalent crosslinked PSeD elastomers, while maintaining a low modulus. Besides, the PSeD-U elastomers show nonlinear mechanical behavior similar to skins. Furthermore, PSeD-U elastomers demonstrate the cytocompatibility and biodegradability to achieve better integration with tissues. Finally, piezocapacitive pressure sensors are fabricated with high pressure sensitivity and rapid response to demonstrate the potential use of PSeD-U elastomers in bio-integrated electronics. Designing biodegradable and biocompatible polymers to mimic both mechanical and biological properties of skins for emerging electronic devices remains a challenge. Here, the authors propose PSeD-U skin-like elastomers with both mechanical and biological properties for bio-integrated electronics.
Abstract In this study, silver nanoparticles (AgNPs) and anthocyanin-rich purple corn extract (PCE) were incorporated into chitosan to develop active and intelligent food packaging films. The structural, physical and functional properties of chitosan/AgNPs/PCE films were compared with those of chitosan, chitosan/AgNPs and chitosan/PCE films. Spectroscopic analysis showed seven kinds of anthocyanins were present in PCE. Some particles and spots appeared on the surfaces and cross-sections of composite films. Fourier transform infrared and X-ray diffraction analyses suggested the interactions between chitosan and AgNPs were based on coordination effect, whereas the interactions between chitosan and PCE were mainly established through hydrogen bonds. The incorporation of PCE and/or AgNPs remarkably promoted the light and water vapor barrier ability, mechanical strength, antioxidant and antimicrobial properties of chitosan film. Notably, chitosan/AgNPs/PCE film exhibited the highest barrier, mechanical, antioxidant and antimicrobial properties due to synergistic effect between PCE and AgNPs. Besides, chitosan/PCE and chitosan/AgNPs/PCE films could change their colors in different pH buffers because of abundant anthocyanins in PCE. Our results suggested chitosan/AgNPs/PCE film could be used as novel active and intelligent food packaging material in food industry.
A. C. Martins, J. Carvalho, Laís Cristina Barbosa Costa
et al.
Abstract Steel slags are by-products generated in high volumes in the steel industry. Their main constituents are calcium, silicon, ferric, aluminum, and magnesium oxides. Larnite, alite, brownmillerite, and ferrite are also found. The presence of expansive compounds cause concern when used in cement-based composites; however, mitigating routes have been proposed. Activation techniques improve the binding properties of steel slag powder, potentiating its use as a supplementary cementitious material (SCM). As an aggregate, steel slag presents good morphological and mechanical properties. Promising mechanical and durability performances in cement-based composites encourage further research to promote the use of steel slag.
Abstract This article reviews, for the first time, the mechanical behaviour of functionally graded structures at small-scale levels. Functionally graded nanoscale and microscale structures are an advanced class of small-scale structures with promising applications in nanotechnology and microtechnology. Recent advancements in fabrication techniques such as the advent of powder metallurgy, made it possible to tailor the mechanical properties of structures at small-scale levels by fabricating them out of functionally layerwise mixture of two or more materials; this class of structures, called functionally graded (FG), can be used to improve the performance of many microelectromechanical and nanoelectromechanical systems due to their spatially varying mechanical and electrical properties. The increasing number of published papers on the mechanical behaviours of FG nanoscale and microscale structures, such as their buckling, vibration and static deformation, employing scale-dependent continuum-based models, has proved their importance in academia and industry. Generally, the nonlocal elasticity-based models have been used for FG nanostructures whereas modified versions of couple stress and strain gradient theories have been utilised for FG microstructures. In this review paper, first, various scale-dependent theories of elasticity for FG small-scale structures are explained. Then, available studies on the mechanical behaviours of FG nanostructures such as FG nanobeams and nanoplates are described. Moreover, available investigations on the mechanics of microstructures made of FG materials are reviewed. In addition, in each case, the most important findings of available studies are reviewed. Finally, further possible applications of advanced continuum mechanics to FG small-scale structures are inspired.
Attia Khushi, Mushtaq K. Abdalrahem, Muhammad Habib Ullah Khan
et al.
Nanofluids are at the forefront of research on enhanced HT fluids, which has a significant impact. They are widely applied across heat exchangers, mechanical systems, chemical processing, and other industries that demand superior HT capabilities. The present study addresses a Sakiadis flow configuration utilizing the advanced tetra-NF (Al2O3/MgO/Cu/Ag−H2O), owing to its improved thermal characteristics relative to previous NF formulations. This formulation utilizes recently developed characteristics alongside appropriate transformation functions. In addition, the energy equation is modified to include nonlinear radiation, dissipation, and convective heating effects, making it more applicable to thermal systems. The PDEs are transformed into ODEs using similarity variables. LBP-ANNs are used to create and explain a framework for entropy generation analysis. ANNs are used to graphically analyze temperature, velocity and entropy rate. These gradients are all represented graphically. In recent work, LBP-ANNs is used to discussed the solution behavior of Sakiadis flow by using tetra-NF on a flat moving surface with entropy generation impact. To deduced the solution behavior of f′(η) , β(η) and NS(η), the number of parameters likes; Rd, Ec, Pr and ϕ1 varied. In each case, ANNs are used to display the graphical results of MSE, EH, TSF, FSF, RGN-A, solution evaluation, and AE findings. The f′(η) profile rises up when there is an increase in ϕ1. The β(η) profile tends to decline with increasing difference of Rd, while it increases with increasing values of Ec& Pr. The entropy generation NG(η) profile rises up with rising values of Rd, while it declines with rising values of Ec& Pr. The MSE consequences (testing, training, validation) for tetra-NF flow on a flat moving sheet lies between 10−10to1000. The values of performance grids are lies between 10−09to10−11, while gradients values lie around 10−08to10−07 by using ANNs. The EHA range recorded around 10−08to10−05 for all seven scenarios of tetra-NF flow on a moving flat sheet. The R-squared value is equal to 1 for all data sets of tetra-NF flow on a moving flat sheet. The AE is noted between 1×10−05to10×10−05 for all seven scenarios.
Dr. Arun Kumar Sharma, R. Bhandari, A. Aherwar
et al.
Abstract Materials are continuously developed with the time being due to the necessity of human civilization and therefore advancement of each material in its highest classes is the best research necessity. The search for new and advanced materials is always an important subject for contemporary technological requirements and to make a product at optimum cost which is a basic consumer demand. New materials are continually developed and materials properties improved in line with existing technological developments in order to meet safety and operational standards. Composites have developed continuously from its early to the advanced stages. The need and consumption of metal matrix composites (MMCs) continuously increasing worldwide with the time because of its high applications. A continuous need observed in industries which make the path to develop stronger lightweight material which having high efficiency and performance across a wide variety of industries. The product manufacturers are generally in need of lightweight, medium strength and less cost, for them aluminum metal matrix composites (AlMMCs) is an asset. AlMMCs for many engineering applications are seen as new generation potential materials. AlMMCs offer great promise for producing composites with the required properties for certain applications with a wide variety of reinforcing materials. The AlMMCs are evolved to obtain good mechanical and tribological characteristics with lightweight, based on specification and application requirements. In this article, various aspects and analysis of applications fields of AlMMCs discussed in brief.
Abstract The growing concerns surrounding the rising carbon emissions have impelled the leaders around the world to make efforts to prevent catastrophic manifestations of climate change and global warming. This has led to the resurrection of vegetal concrete building materials using biomass, which have the added benefits of carbon sequestration apart from low embodied energy and renewability. Vegetal concretes are made up of an organic or inorganic binder, and biomass originating from agro-forestry industries such as rice husk, straw bale, hemp, kenaf, cork, and so on. Hemp concrete, a variety of vegetal concrete has been widely researched and is arguably one of the most researched building materials in current times. This paper presents a review of the state-of-the-art of hemp concrete research, with a view to identifying research gaps that shall guide future research for its implementation in the fast-growing green buildings industry. The reviewed aspects of hemp concrete include properties of hemp relevant to construction, binder characteristics, mechanical properties, durability, hygric and thermal properties, environmental credentials, manufacturing processes, and current applications. Several research gaps with regards to the hydraulicity of the binder, strength and durability, and fire resistance of hemp concrete were identified. It was also established that hemp concrete has very low embodied carbon and embodied energy, making it ideal for green building applications. The paper ends with a discussion outlining the need and direction for future research on improving the manufacturing processes and mechanical performance of hemp concrete for wider adoption by the construction industry.
Ganesan Subbiah, Manjunath Channappagoudra, Deepak Bhanot
et al.
The growing demand for sustainable alternatives in textile and biomedical industries has spurred interest in natural fibers. This study aimed to evaluate the potential of Solanum nigrum stem fibers as a renewable material through comprehensive physicochemical and biological characterization. Raw fibers were extracted via water retting and subjected to a series of analyses. Structural properties were examined using X-ray diffraction and Fourier Transform Infrared spectroscopy, while thermal stability was assessed through thermogravimetric analysis. Morphological features were investigated using scanning electron microscopy, and mechanical performance was evaluated through tensile testing. Biological activity was analyzed using antibacterial assays and biofilm inhibition studies. The fibers showed moderate crystallinity (78.43 %), good thermal resistance up to 320 °C, and a fibrous morphology favourable for composite applications. Mechanical tests revealed a tensile strength of 9.53 MPa and Young’s modulus of 6.41 GPa. Antibacterial tests against Escherichia coli exhibited a 13 mm inhibition zone, with 72.6 % biofilm reduction, highlighting the fiber's potential for antimicrobial use. Overall, the results suggest that Solanum nigrum fibers are a viable, eco-friendly option for developing sustainable textile products and biomedical materials.
Ágatha Missio da Silva, Erick Gabriel Ribeiro dos Anjos, Thaís Ferreira da Silva
et al.
Abstract Antistatic packaging prevents electrostatic discharge (ESD) damage, protecting electronic components during storage and transport, ensuring reliability in industries like electronics and aerospace. This study develops heterophasic ethylene-propylene copolymer (HEPC) composites reinforced with recycled aircraft graphite for antistatic applications. HEPC composites with 1, 5, and 10 wt% recycled graphite were prepared via twin-screw extrusion and injection molding. Morphological, thermal, rheological, mechanical, and electrical properties were analyzed. Adding 5 wt% graphite increased the elastic modulus by 21.3% and Shore D hardness by 6.1%. Electrical conductivity improved significantly, with a nine-order magnitude increase for 5 wt% graphite, enabling effective electrostatic dissipation. This sustainable approach enhances material performance while promoting circular economy practices by upcycling aerospace waste into high-value functional materials.
Abstract Hydrate-based carbon dioxide (CO2) sequestration (HBCS) technology utilizes naturally occurring high-pressure and low-temperature marine conditions to convert CO2 into solid hydrates within marine sediments, offering a promising complementary pathway for carbon emission reduction and large-scale marine sequestration. This review examines the current developments and challenges of HBCS from both scientific and engineering perspectives. First, we present the fundamental principles of HBCS, with particular emphasis on key mechanisms such as phase transition and pore sequestration. Then, we explore the mechanisms of hydrate nucleation and growth that influence core processes, as well as multi-scale stability characteristics from the microscopic to the macroscopic level. Furthermore, we systematically assess thermodynamic and kinetic factors affecting sequestration efficiency, including but not limited to marine reservoir types, injection strategies, and environmentally friendly additives. Subsequently, based on an integrated evaluation of environmental, social, and economic dimensions, we assess the development potential of HBCS technology. Finally, the primary challenges currently faced are identified, and future research directions are proposed. Overall, this review provides a comprehensive overview of the progress and challenges associated with HBCS, emphasizes its potential role in global carbon reduction efforts, and offers theoretical guidance for future industrial applications. Graphical Abstract
Energy industries. Energy policy. Fuel trade, Renewable energy sources