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Porous ceramics find extensive applications in aerospace and other fields, and the measurement of their electromagnetic parameters is helpful in optimization of material properties and device designs. In this paper, a free-space 8f quasi-optical measurement system consisting of a vector network analyzer, a 325–500 GHz frequency expansion module, and four off-axis parabolic mirrors have been established to measure the transmission parameter S21 of porous ceramics. The complex permittivity was extracted according to the Newton-Raphson iterative method utilizing its measured S21 parameters based on flat mode. The porous ceramics with different porosity and density were measured and the relationships between their permittivity and porosity and density was established, respectively. These results are beneficial to the quality evaluation and application design of porous ceramic materials in the aerospace field. [ABSTRACT FROM AUTHOR]

The emphasis has shifted away from synthetic fibres and towards natural fibres as a result of the increased industrial demand for environmentally friendly products. Natural fibres are suitable candidates for use in modern industrial applications since they are biodegradable, lightweight, affordable, and environmentally beneficial. One fibre that has very good mechanical properties is abaca fibre. This paper reviews the literature on abaca fibres as a reinforcing material. The composition and properties of abaca fibres are discussed, along with various studies on abaca-reinforced composites. Abaca reinforced composite's difficulties and future work are therefore investigated. Research shows that pre-treating abaca fibres improves the composite's mechanical characteristics. Also, there have been attempts to improve the mechanical characteristics and environmental performance of current synthetic composites by adding abaca fibres. Abaca is anticipated to become one of the most effective sources of reinforcing fibre for use in the building of a variety of components, including aerospace and automotive materials. [ABSTRACT FROM AUTHOR]

The increasing need for lightweight, high strength and cost-effective materials for automotive and aerospace industries worked as the impetus for this investigation. E-glass fibers are layered with 3K-carbon fibers in proportions of 7:6 & 6:7 for fabricating hybrid fiber reinforced polymer (FRP) composites. First stage of the study involves the identification of the optimized fiber stacking pattern. Later, nanocomposites were made for further enhancement of tensile properties by infusing titanium dioxide (TiO2) nanoparticles to hybrid FRP composite ‘C2G3C3G3C2’ with optimized stacking pattern. The TiO2 nanoparticles are equally disseminated in the epoxy resin using ultrasonication with five different wt. % of 0, 1.25, 2.5, 3.75, and 5. The peak load, ultimate tensile strength (UTS), tensile modulus, and % elongation at break were examined as per ASTM D3039 tensile testing. The UTS of optimized hybrid FRP composite, carbon non-hybrid FRP composite, and nanocomposite (at 2.5 wt. % TiO2 nanoparticles) were 424.98 MPa, 429.0 MPa, and 478.51 MPa, respectively. Further, the cost of optimized hybrid FRP composite and nanocomposite (at 2.5 wt. % of TiO2 nanoparticles) is approximately 36.93% and 21.51% less than most expensive carbon non-hybrid FRP composite. The morphological analysis revealed that TiO2 added composites up to 2.5 wt. % exhibit fewer defects, indicating a better interaction between the matrix and the fibers. [ABSTRACT FROM AUTHOR]

Innovative high-performance composite materials are the need of the hour required by modern manufacturing techniques such as 3D printing due to less weight with high mechanical and thermal properties-based materials required. The application domain of 3D-printed high-performance composite materials includes aerospace, automobile, tissue engineering, soft robotics, sensors, and actuator applications. In this regard, the combination of metal-reinforced polymer composites has emerged as one of the most innovative sources for 3D printing applications in such sectors. The present study detailed the state-of-the-art review of the metal reinforcement in the polymer's matrix fit for 3D printing applications. The reinforcement of the metal in the polymers tunes the mechanical, thermal, chemical, morphological, electrical, and sensing properties that are very crucial for high-performance applications. The main outcomes of this study are to determine the best suitability of composite materials in accordance with requirements. In this study, the high-performance metals reinforcement materials such as Ag, Al, Cu, and Au have been discussed with their potential applications (medical, electronics, household, sports, communications, military, business, industry, marine, energy, civil, aerospace, and the automobile) as per required properties. This study is supported by the direction of future studies for extending the innovations and applications. [ABSTRACT FROM AUTHOR]

The inferior creep ductility of Inconel 718 (IN718) fabricated by selective laser melting (SLM), which is unable to meet aerospace material specification (≥4%), limits its engineering application. Despite persistent optimization efforts in the SLM process and post-heat treatment, this issue remains unresolved. This study involved SLM fabrication of the modified IN718 with trace amounts of LaB6 and/or P, followed by homogenization and double aging heat treatment. The addition of trace LaB6 notably influenced the recrystallized grain structure and carbide precipitation at grain boundaries, while trace P addition had minimal impact. All samples exhibited similar γ′ and γ″ strengthening precipitates. Creep tests conducted at 650°C/690 MPa revealed that the individual modification of LaB6 showed limited improvement in creep performance and P showed no improvement, but the combined addition of LaB6 and P led to a substantial enhancement in creep performance, especially reaching as high as 8.6% creep strain. This remarkable improvement in creep ductility is unlikely to arise from the altered grain structure and grain boundary precipitates induced by LaB6 but predominantly arises from the synergistic effect of P and B in enhancing resistance to crack propagation during the third stage of creep. [ABSTRACT FROM AUTHOR]

Segmented grinding wheels, with active abrasive regions and passive slots, have been reported as a promising choice for controlling the grinding force via an intermittent cutting scheme. With an appropriate selection of feed and other operating variables, segmented grinding could mark its merits of improved thermal performance and grinding efficiency, typically in difficult-to-machine aerospace materials. However, the formation of a boundary layer around a rotating grinding wheel is always a barrier to effective cutting fluid delivery in the grinding zone. This article attempts to investigate the boundary layer characteristics of segmented grinding wheels, typically with a comparison of 8-segmented and 32-segmented grinding wheels with a non-porous electroplated structure and its comparison with traditional porous grinding wheel configuration. The regression model proposed in this article can predict boundary layer thickness and tangential air velocity in the grinding zone during the rotation of the wheel. A closer look at flow aspects has been covered using computational fluid flow modeling/simulation, followed by experimental assessments through particle image velocimetry and shadowgraphs. The influence of segmentation and its configuration (typically the number of segments) have been illustrated through a case study of wet grinding on Ti6Al4V. [ABSTRACT FROM AUTHOR]

The incorporation of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPMS) modified Nb2C into graphene oxide (GO) results in the GO-AEAPMS/Nb2C nanofillers which are dispersed in the epoxy resin (EP). Electrochemical techniques, such as scanning electrochemical microscopy (SECM) and Electrochemical impedance spectroscopy (EIS) were used to assess the protective effects of EP coating on AA8019 in the presence of various amount of GO/AEAPMS-Nb2C in seawater. It was established that 0.6 was the optimal weight percentage of GO-AEAPMS/Nb2C in the epoxy matrix, resulting in an excellent coating performance. The coating resistance of EP-GO/AEAPMS-Nb2C was over 70.6 times greater than plain coating. Even after spending 960 h exposed in seawater, the EP-GO/AEAPMS-Nb2C nanocomposite demonstrated improved coating resistance (10,366 kΩ·cm2) according to EIS tests. The least amount of Al3+ ions were discharged (1.1 I/nA), according to SECM measurements, at the scratch of the EP-GO/AEAPMS-Nb2C coating due to the coated substrate's better resistance to anodic dissipation. The corrosion resistance of the substrates was increased by carbide coatings, however, due to the porosity of the EP-Nb2C coatings and the roughness of the coating-substrate interface, the corrosion resistance of these layers reduced after 960 h of exposure to the seawater. According to Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM/EDX) investigation, the Nb2C was discovered in the rusted components, generating an exceptional inert coating at the surface. The results showed that the newly formed EP-GO/AEAPMS-Nb2C composite has enhanced barrier capabilities and hydrophobic qualities with water contact angle (WCA) of 157°. When GO-AEAPMS/Nb2C was introduced, the epoxy matrix's mechanical properties are improved (Adhesion strength: 27.3 MPa) and (Microhardness: 3990 MPa). The EP-GO/AEAPMS-Nb2C nanocomposite may therefore be utilized as a coating material in aerospace industries. [ABSTRACT FROM AUTHOR]

Nowadays, adhesive joints are largely applied in the automotive, aircraft and aerospace, civil, and naval industries. Although several applications involve flat (plane) adherends, curved joints play an important role in many engineering applications like civil and aircraft construction. This work aims to investigate three structural adhesives, ranging from brittle to ductile, applied in curved joggle-lap joints between carbon fibre reinforced polymer adherends and subjected to internal pressure, to validate a robust design procedure and provide project guidelines for this complex structural, geometrical, and loading system, which constitute the main novelty of the proposed work. A numerical cohesive zone model parametric analysis was undertaken by varying the overlap length, thickness of the adherends, and adherends' curvature, including the evaluation of peel and shear stresses in the adhesive, failure mode comparison, maximum load, and energy dissipated after failure. Validation of the cohesive zone model technique was initially performed using flat single-lap joint under tensile loads. A significant effect of the overlap length and thickness of the adherends on the maximum load was found, while the adherends' curvature effect on the maximum load was negligible. Ductile adhesives, although less strong, generally performed better in terms of maximum load and dissipated energy. [ABSTRACT FROM AUTHOR]

An in-plane honeycomb sandwich structure used in aerospace applications has been modeled, in order to study the structural-acoustic performances of the sandwich panel using a finite element analysis software. A modal and steady state analysis were conducted to investigate the vibro-acoustic and sound transmission characteristics of the sandwich panel. Several materials used in aerospace composite structures were tested to compare their acoustic performances and to deduce which material have a good acoustic insulation property. Two different cases of structural acoustic design, were performed in this research taking into account the effect of changing material, thickness of skins and the total mass on the sound transmission characteristics of the sandwich panel through varying the effective properties without compromising the mass of the panel in case of the first design. In case of the second design, we consider the thickness of skins as constant. The results reveals that the glass fiber reinforced polymer (GFRP) cores with fiber-reinforced plastic (FRP) facing materials have a better vibro-acoustic and sound transmission characteristics comparing to all other design cases presented in this article. GFRP cores with an FRP facing can replace the aluminum materials without affecting the acoustic performances of the panel with a mass reduction of the panel. [ABSTRACT FROM AUTHOR]

Due to low density and high mechanical and physical properties, magnesium matrix composites are prospective materials for diverse aerospace and defence applications. Specific strength, stiffness, damping behaviour, and wear behaviour can all be improved. The installation of reinforcing components has a substantial impact on creep and fatigue parameters compared to traditional engineering materials, into the metallic matrix. This paper describes the outline of impacts of various reinforcement into the magnesium and its alloy, featuring their advantage and disadvantage alongside the performance of magnesium metal matrix composites under mechanical testing like hardness, ductility, stiffness, corrosion, biocompatibility other significant properties to make them suitable for human implant. It additionally depicts various processes with which magnesium metal composites can be manufactured alongside their benefits and drawbacks. Finally, this publication highlights the researchers' findings as well as prospects for magnesium-based composites. [ABSTRACT FROM AUTHOR]

Titanium alloys are the most appealing material for aerospace, biomedical, and chemical applications due to their high specific strength and fracture resistance. Drilling of titanium alloy is required in the bolt/rivet assembly of aerospace components and bone plate, fracture bone for biomedical applications. The main objective of this study is to explore the drill rate, surface roughness and drill time during abrasive water jet machining (AWJM) of Ti6Al4 V alloy. Water jet pressure (WJP), standoff distance (SOD), abrasive flow rate (AFR) and feed rate (FR) are input variables, and the output responses are surface roughness (Ra), drill rate (DR) and drill time (DT). Experiments were carried out using the Taguchi L27 orthogonal array. Analysis of variance (ANOVA) was used to investigate the most influential factor for DR, DT, and Ra. The most influential factor in reducing DT and enhancing DR is FR. WJP, SOD, and AFR are the most important factors influencing Ra. With increasing WJP, SOD, and FR selected cutting conditions, Ra was observed to increase. Increased FR results in higher DR for AWJM of Ti6Al4 V alloy. The surface morphology of an optimized AWJM sample was investigated. An EDS (energy-dispersive spectroscopy) result reveals the presence of carbon and oxygen on the machined surface. Grey relational grade is used to find the best AWJM process parameters for machining the Ti6Al4 V alloy. The AWJ machined surface was investigated with SEM to assess the quality of the optimized setting through GRA. [ABSTRACT FROM AUTHOR]

MAX phase materials a new family of ternary layered carbide and nitride compounds are represented by the general formula of Mn+1AXn, where n = 1 ∼ 3, M stands for early transition metal, A express A-group elements, and X is either nitrogen or carbon. As early as 1960s, this materials had been paied much attention due to their unique physical properties combination of metals and ceramics such as machinability, low hardness, excellent electrical, good thermal conductivity, damage tolerance, thermal shock resistance, high elastic moduli, oxidation and corrosion resistance. Therefore, MAX phase ceramics can be used as structural and functional materials, and is regarded as an ideal strengthening phase for metal matrix composites. Researchers have recognized the potentially technologically important application of this emerging material in the fields of aerospace, high-speed rail, nuclear industry, gas igniter, heat exchanger, high thrust rocket nozzle, electric brush, kiln furniture, metal refining electrode and high-temperature seal. In recent years, a new research caused heightened concerns on MAX phase, as the feasibility of attaining MXenes via selectively etching these and removing of the A-group element. In this review, the development of MAX phase and th e characteristics and applications of its derivative of MXenes are introduced in the first place. Next, the structure, morphology, electronic structure and diversity of the MAX phase are described. Thirdly, the different preparation methods and related applications of MAX phase films, bulk materials and powder materials are systematically introduced according to the current preparation technologies. Finally, the future development potential of MAX phase and the related improvement of the research subject are prospected. It aims to provide theoretical guidance and new ideas for synthesizing and creating new and excellent MAX phase materials, so that this new type of material can be put into social production and application in large quantities. [ABSTRACT FROM AUTHOR]

Bacteria biofilm formation and its complications are of special concern in isolated structures, such as offshore stations, manned submarines and space habitats, as maintenance and technical support are poorly accessible due to costs and/or logistical challenges. In addition, considering that future exploration missions are planned to adventure farther and longer in space, unlocking biofilm formation mechanisms and developing new antifouling solutions are key goals in order to ensure spacecraft's efficiency, crew's safety and mission success. In this work, we explored the interactions between Cupriavidus metallidurans, a prevalently identified contaminant onboard the International Space Station, and aerospace grade materials such as the titanium alloy TiAl6V4, the stainless steel AISI 316 (SS316) and Polytetrafluoroethylene (PTFE) or Teflon. Borosilicate glass was used as a control and all surfaces were investigated at two different pH values (5.0 and 7.0). Biofilms were almost absent on stainless steel and the titanium alloy contrary to Teflon and glass that were covered by an extensive biofilm formed via monolayers of scattered matrix-free cells and complex multilayered clusters or communities. Filamentous extracellular DNA structures were observed specifically in the complex multilayered clusters adherent to Teflon, indicating that the employed attachment machinery might depend on the physicochemical characteristics of the surface. [ABSTRACT FROM AUTHOR]

The goal of this study was production of an Al–15%Mg2Si metal matrix composite (MMC) containing 3 wt.% copper and also study microstructural and hardness properties. For this, pure Al, Mg, Si and Cu ingots were used to make composite via in situ route. The composite was characterised by X-ray diffraction, optical microscope (OM) and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (EDX) analysis. Microstructural observations explored that Mg2Si particles form all over the Al matrix. According to the OM characterisation, the size of primary Mg2Si particles was estimated to be ~20 μm. This amount could be decreased to ~7 μm (65% reduction) due to the presence of copper, mostly because of the formation of Cu-rich intermetallic phases during solidification, as detected by EDX analysis. Further results showed that these phases lead to an MMC with more hardness compared to the counterpart without Cu. In addition, because of Mg2Si phases in these systems which are even lighter than Al, it has high specific stiffness and strength. Therefore, it could be widely used as a lightweight material in aerospace and automobile fields, such as safety-belt pretensioner, steering wheel frame, crossbeams, wheel rims, car frame and shock absorbing cover. [ABSTRACT FROM AUTHOR]

Latest generation of Al-Li alloys are considered as a futuristic material for aerospace industries. Friction stir welding process has been emerged as a suitable joining process for these materials. In this paper, a heat-assisted backing plate is proposed for preheating the workpiece to enhance the quality of weld joint in friction stir welding. A heating element is employed just beneath of the welded line to preheating the material. It was found that the tensile strength has increased after the application of preheat in friction stir welding. It was also observed that the tool wear rate reduces by preheating and thus life of tool enhanced. [ABSTRACT FROM AUTHOR]

Phenylethynyl-terminated polyimide resin/carbon fiber composites become ideal structure materials for aerospace vehicle because of excellent mechanical properties and high-temperature thermal stability. However, the curing temperature of the polyimide resin/carbon fiber composite was higher than 370 °C, which caused much thermal stress that would inevitably deteriorate the performance of the composite and restrict its application. In this paper, a compound catalyst of isopropyl peroxide and cobalt naphthenate was used to catalyze the cross-linking reaction of phenylethynyl-terminated polyimide resin and decrease the curing temperature of the polyimide/carbon fiber composite. The result showed that the phenylethynyl characteristic absorption peak at cm−1 was still existed in the polyimide resin without catalyst and disappeared for the catalystic polyimide resin when curing temperature was 300 °C, in which the spectrum was the same as that of the polyimide resin cured at 370 °C without catalyst. The inter-laminar shear strength and flexure strength of the catalytic polyimide/carbon fiber composite were 96.8 MPa and 2080.0 MPa, there were increases of 28.8% and 23.8% compared to that of the composite without catalyst cured 370 °C. All these results demonstrate that the compound catalyst of radical initiator and coordination catalyst could efficiently decrease the curing temperature of phenylethynyl terminated polyimide resin and increase the mechanical properties of the polyimide resin/carbon fiber composite. [ABSTRACT FROM AUTHOR]

Due to ever increasing use of polymer composites and rising environmental concerns throughout the world, greater attention is being paid to the incorporation of lingo-cellulosic materials as filler in polymer matrices instead of synthetic materials in the field of aerospace and automobile industry. In this work, polystyrene composites using wheat husk, rice husk and mustard husk as fillers are synthesised using in-situ polymerisation technique. Three different filler loading (5, 10 and 15 %) and three different filler sizes (250–355 µ, 355–500 µ, 500–710 µ) were utilised for the studying the effect of these compositions on different mechanical properties of the synthesised composites. The results have shown that the filler size 250–355 µ and 5% loading give the maximum values for tensile strength, flexural strength and hardness for all the three types of fillers. While in case of water absorptivity the lower the size/loading, lesser would be the water absorbed. The SEM analysis is done to study the fractured surface of the specimen. [ABSTRACT FROM AUTHOR]

CFRP plates are important advanced material used in the aerospace field, high-quality and high-efficiency drilling is the main application processing demand of CFRP. In this paper, a 532 nm nanosecond fiber laser with adjustable pulse duration is used and the scanning path was planned as Z-direction up-bottom incremental cutting, and X-Y direction concentric circle cutting scanning mode to realize the CFRP plates hole drilling, and obtain high drilling performance. The mechanisms of material removal for CFRP plates hole drilling under 532 nm nanosecond laser is explored, and it is mainly attributed to thermal evaporation accompanied by certain heating carbonization. The results show that a narrow width of HAZ can be obtained with short pulse duration, the minimum value of HAZ width at hole entrance edge is 18.74 µm, and the matrix material damage near the HAZ becomes small. Reducing the pulse duration also helps to decrease the drilling taper (minimum taper value 0.046), the taper of the drilling hole is smaller than that of the drilling dicing. But the drilling efficiency is reduced due to the low pulse energy with short pulse duration. [ABSTRACT FROM AUTHOR]

Superalloy is one of the most important material in aerospace, shipbuilding and nuclear power industries. However, due to its excellent structure, its machinability is very poor. High pressure cooling is a new cooling technology, which provides technical support for cutting superalloy and other difficult-to-cut materials. Therefore, in view of the problem of poor machinability of superalloys, a cutting test on nickel-based superalloy GH4169 is conducted based on the high pressure cooling cutting technology in this paper. It is mainly to study the effects of different cutting parameters and coolant pressure on surface roughness and tool life. The results show that the feed has the greatest influence on surface roughness, followed by cutting depth and coolant pressure, and the least influence is cutting speed. Among the influences on tool life, cutting speed has the greatest influence on tool life, followed by feed and coolant pressure, and the least influence is cutting depth. Based on the adaptive genetic method, the prediction models of machined surface roughness and tool life of cutting GH4169 under high pressure cooling are established respectively, and the process optimization analysis is carried out with the goal of tool life, machined surface roughness and cutting efficiency. The optimal parameter combination is obtained as vc=163.75 m/min, f = 0.14 mm/r, ap=0.52 mm, P = 50.46 bar. The above research results can provide certain technical support for improving the machinability of superalloys. [ABSTRACT FROM AUTHOR]

Composites are key materials in the aerospace and aeronautics industry. However, a disadvantage is their susceptibility to interlaminar fracture because of poor adhesion at fiber surface andmatrix interface. Carbon nanotube (CNT) growth onto carbon fiber (CF) surface is a promising method to increase CF--matrix adhesion. This work studies interlaminar properties of unidirectional CF composites and thermoset matrix, with CNT deposition on CF surface. CNT growth goes along in chemical vapor deposition with a floating catalyst of ferrocene and flow of CO2 and C2H2 precursors. Tensile strength tests on single-filament and CF tow showed the preservation of tensile properties after preparation and growth. Results of the interlaminar shear strength study presented a 35% increase in shear strength and a 15% increase in fracture toughness at the initial delamination crack. An overall analysis reveals an improvement in the interlaminar interface on mechanical tests; however, fracture toughness analysis is limited by fragile pathways in intralaminar regions. [ABSTRACT FROM AUTHOR]

From the last few decades, the piezoelectric materials are playing a vital role in the field of aerospace engineering. One of the major factors to reduce an aircraft's malfunctioning is its health monitoring. In doing so multiple types of sensors are required to be designed specifically for an aircraft. A large amount of energy source is required for operating all those sensor therefore harvesting techniques are made. This paper discusses the use of piezoelectric materials in health monitoring, aircraft's sensors and energy harvesters. It gives an elaborated idea of how piezoelectric materials can be used in various stages at aerospace industries. [ABSTRACT FROM AUTHOR]

Importance of this present investigation is to identify the influence of modified tool (tool with texturing) on the process of orthogonal turning of Ti-6Al-4V work material. To achieve the enhanced turning conditions, four different types of textures (plain conventional, cross, perpendicularly textured and parallel textured tool to the chip flow direction) were fabricated on the rake face of the tool insert and the lubricant used during the machining process is molybdenum disulfide (MoS2). Machining forces (the force of cutting and feed), angle of shear, chip morphology, temperature distribution between tool and chip were measured. Shear strain and strain rate were also computed and compared with all type of cutting tools. Experimental results revealed that the cross-textured cutting tool exhibit an effective reduction in cutting force, friction, shear strain and strain rate. The favorable metal removal condition of curling chip with low diameter was achieved through cross-textured tool. [ABSTRACT FROM AUTHOR]

This paper reviews literatures and information on Abaca fibers (Musa textilis Nee) as reinforcing material for aerospace composite materials. Characterization of Abaca as well properties of Abaca reinforced composites and its applications were discussed. Therefore, challenges and future works for Abaca Reinforced composites were explored. Studies reveal that Abaca fiber pre-treatment helps in improving the mechanical properties of the composite. In addition, there have been efforts in combining Abaca fibers to existing mixture of synthetic composites to improve its mechanical properties and environmental performance. The future of Abaca is seen as one of the potent sources of reinforcing fiber for various material construction including aerospace materials. [ABSTRACT FROM AUTHOR]

Adhesive bonding is one of the most promising joining technologies for composite aircraft. However, to comply with current aircraft certification rules, current safety-critical bonded joints, in which at least one of the interfaces requires additional surface preparation, are always used in combination with redundant mechanical fasteners, such as rivets and bolts. This lack of trust in bonded structures is mostly linked to the fear of lack of adhesion or a “weak bond”. The aim of this paper is to tackle this challenge by assessing the ability to use composite peel tests and acoustic emission (AE) technique to assess adhesion quality and distinguish a good bond quality from a “weak bond”. Composite Bell Peel (CBP) tests and Double-Cantilever-Beam (DCB) tests were performed on contaminated and non-contaminated CFRP bonded specimens. The results show that peel strength drops significantly at the location of the contaminated interface that has led to weak adhesion, as a result from adhesive failure. The AE signals obtained during DCB tests show different features for cracks growing at the interface (“weak bonds”) and inside the adhesive layer (cohesive failure). In addition to this, scattering of the AE signals were observed in the contaminated specimens with “weak bonds”. [ABSTRACT FROM AUTHOR]

The need for cost-effective energy-efficient materials that can accommodate the diverse industrial demands has stimulated the advancement of magnesium-based materials. One such recently-reported advancement is magnesium-based hybrid composites in which more than one reinforcement phase is added to the base matrix. Hybrid composites offer wide flexibility in terms of the selection of reinforcing phases as well as in terms of the processing routes. Thus, these composites have potential applications in aerospace and automotive sectors. Magnesium-based hybrid composites also exhibit superior mechanical and tribological properties over their lightweight counterparts. Based on the available literature, this paper attempts to review current developments associated with magnesium-based hybrid composites in terms of processing techniques, metallurgical characteristics, and mechanical properties. [ABSTRACT FROM AUTHOR]

The small punch (SP) test is a widely accepted methodology for obtaining mechanical property information from limited material quantities. Much research has presented the creep, tensile and fracture responses of numerous materials gathered from small-scale testing approaches. This is of particular interest for alloy down selection of next-generation materials and in situ mechanical assessments. However, to truly understand the evolution of deformation of the miniature disc specimen, an accurate and detailed understanding of the progressive damage is necessary. This paper will utilise the SP test to assess the tensile properties of several Ti-6Al-4V materials across different temperature regimes. Fractographic investigations will establish the contrasting damage mechanisms and finite element modelling through DEFORM software is employed to characterise specimen deformation. [ABSTRACT FROM AUTHOR]

Titanium-based metal composites (TMCs) are showing great potential to replace existing traditional materials in aerospace, automotive, and other high temperature engineering applications. This is due to their excellent mechanical, thermal, and physical properties and improved strength to weight ratio. Weight savings in the aerospace industry results in higher efficiency. Carbon nanotubes (CNTs), because of their low density and high Young's modulus, are considered to be an excellent reinforcement for metal matrix composites (MMCs). In the last 20 years extensive research has been carried out to investigate the combination of carbon nanotubes with aluminum, nickel, copper, magnesium, and other metal matrices. The production techniques such as mechanical alloying through powder metallurgy routes and their effects on the mechanical properties of CNT reinforced TMCs are reviewed in this article. The role of the volume fraction of carbon nanotubes and their dispersion into the metal matrix are highlighted. Governing equations to predict the mechanical and tribological properties of CNT reinforced titanium matrix composites are deduced. With the help of this initial prediction of properties, the optimal processing parameters can be optimized. Successful development of CNT reinforced TMCs would result in better wear and mechanical behavior and enhance their ability to withstand high temperature and structural loading environments. [ABSTRACT FROM PUBLISHER]

The isothermal forging process of a typical aviation component with complex shape of high ribs and thin webs was simulated based on the finite-element method, aiming to obtain a set of optimal process parameters. According to the simulation results, the aviation component was successfully formed with a good surface quality by the isothermal forging process. Metallographic analysis shows that recrystallization took place all over the cross section of the forging. The grain size of different areas is basically the same. As indicated by the transmission electron microscope micrographs, dislocations at the surface of the forging have almost the same distribution as those at the core, whereas the dislocations at the surface of the billet by hot forging process are much denser than those at the core. Moreover, the precipitates in the forging by the isothermal forging process were basically of the same small size. On the contrary, larger precipitates were formed at the grain boundaries than in the matrix of the billet through the hot forging process. In one word, uniform grain size and homogeneous distribution of dislocations and precipitates were found in the aviation component by the isothermal precise forging process. [ABSTRACT FROM PUBLISHER]

Drilling of holes in difficult-to-cut aerospace materials with desired surface finish and accurate geometry is beyond the capability of conventional twist drills. Nonconventional machining methods which have the capabilities to offset the cutting difficulties of twist drills are currently being used for making holes in hard materials under the terminology of advanced machining processes (AMPs). Electrical discharge machining (EDM) is one such AMP which has been used in the present experiment for making holes in high nickel alloy with slight modification in sinking EDM machine. The concept of tool rotation is incorporated in sinking EDM machine and authors have termed it as electrical discharge drilling (EDD). The main objective of this experimental study is to study and analyze the impact of introduced tool rotation in EDD. Present experiment confirms that tool rotation has substantive effect on surface roughness (Ra) and average circularity (Ca) of the hole made by EDD process. Micrograph results of two samples of machined workpiece also substantiates with output results of introductory concept of tool rotation in EDM machine. [ABSTRACT FROM AUTHOR]

Single-point incremental forming (SPIF) is relatively a novel sheet forming process to produce small lots with low cost. In this article, guidelines for tool size selection for SPIF of an aerospace grade alloy (AA-2024) are presented. The role of tool size, with respect to sheet thickness employed, on the formability in SPIF (i.e., spifability) is clarified. The response surface method is employed in order to study the significance of sheet thickness (to) and tool radius (r) on the spifability. The results of analysis of variance (ANOVA) show that the sheet thickness and tool radius are not significant individually, however, a strong interaction between these parameters exists. Moreover, for a particular sheet thickness, there exists only oner/tovalue at which the spifability can be maximized under a given set of conditions. Furthermore, for a given sheet thickness, if a tool with radius lesser than a particular value is used (i.e.,r/to < 2) the material squeezes out from the tool/sheet interface. And, such a condition adversely affects the material spifability. FEA using LS-DYNA has also been carried out. [ABSTRACT FROM PUBLISHER]

Joining of dissimilar metals has various automotive, aerospace, nuclear, chemical, and cryogenic applications. The present study focuses on friction stud welding of aluminum and mild steel. Experiments had been conducted by varying the process parameters and the strength of the friction welded joints was evaluated. Experimental results show that the speed of rotation, friction time, and axial shortening distance have significant effect on the impact strength of the welded joints. The dissipation of frictional heat from the weld center results in temperature gradient across the welded joint, causing different zones with different microstructures. Scanning electron microscope (SEM) micrograph reveals the presence of three distinctive regions in the heat-affected zone, namely, fully plasticized deformed zone, partially deformed zone, and unaffected base metal zone. The microhardness values were measured across the welded joint. At the interfacial region, there is an increased plastic deformation. This is due to the rise in heat input during friction stage and applied upsetting load in the forging stage. Consequently, there is an increase in hardness at the interfacial region of the welded joint. [ABSTRACT FROM AUTHOR]

It has been observed that considerable attention has been given to the use of cBN and/or ceramic tools for achieving better performance in the machining of superalloy Inconel 718. However, their cost limits the use in the engineering applications. In this article, the performance of multicoated TiN/TiAlN (PVD) coated and TiN/Al2O3/TiCN (CVD) coated tungsten carbide tools were investigated while high speed turning (HST) of superalloy Inconel 718. The effect of coating materials on cutting force, cutting temperature, vibration, and acoustic emission were recorded, analyzed, and reported. From the experimental results it has been found that TiN/Al2O3/TiCN (CVD) coated tool outperformed the TiN/TiAlN (PVD) coated tool in terms of machinability parameters such as cutting force and cutting temperature. From the fast Fourier transform (FFT) analysis of the vibration signals it was observed that the vibrations were less in case of the CVD coated tool than in case of the PVD coated tool. [ABSTRACT FROM AUTHOR]

European governments dreamed in the 1990s of creating a genuine defence-aerospace industrial champion, but were thwarted. The proposed merger between EADS and BAE Systems, though facing significant hurdles, would finally bring about this goal. It would be a natural reaction to the prospect of shrinking defence-equipment markets. [ABSTRACT FROM PUBLISHER]

An advanced casting simulation based optimisation approach was applied in this study to assist in the improvement of the mould design of aerospace components made of A356 alloy. By using this approach, mould filling and solidification related defects (including macroshrinkage and shrinkage porosity) were significantly minimised and hence it helped in cost reduction, performance enhancement and quality assurance of complex A356 cast parts. An experimental validation and detailed calibration procedures of the models for prediction of macroshrinkage and shrinkage porosities were performed using A356 plates cast in furan-silica sand moulds using the Prometal rapid casting technology (RCT) mould printing technology. Correlations between Niyama values and the pore percentage were also developed. Therefore, the severity level of shrinkage porosity can be determined via the Niyama criterion. Predictions were then compared with the macroshrinkage and porosity measurements in plates of various plate thicknesses and in other commercial A356 casting components. [ABSTRACT FROM AUTHOR]

In this study, silica aerogel saturated with erythritol as phase change materials (PCMs) was prepared by melt infiltration. The properties of the composite were determined by scanning electronic microscope (SEM), Fourier transformation-infrared spectroscope (FT-IR) and differential scanning calorimeter (DSC). In the novel composite, erythritol with high latent heat of fusion was used as PCM for thermal control, whereas nanoporous silica aerogel was prepared as the phase change matrix to provide structural strength and prevent leakage of the melted erythritol. Nitrogen gas adsorption curves and SEM analysis indicate that the pore structure of silica aerogel was porous and connected with each other. FT-IR analysis showed that the composite formation of silica aerogel and erythritol were physical, whereas DSC analysis showed that the melting point and heat storage capacity of the composite were 123.8°C and 289.92 kJ/kg, respectively. The thermal protection properties of phase change composites were designed under laboratory conditions using a thermal measurement setup of a simulated thermal environment of an aircraft. The phase change composite produced by the study can be used for thermal protection applications. Compared with the paraffin–silica aerogel composite, the erythritol–silica aerogel composite could rapidly control the rising temperature by absorbing heat under high thermal environments. [ABSTRACT FROM PUBLISHER]

The article offers information on several engineering tools including the Earthmine mapping tool from Atkins Global, the aerospace products Kalrez Aerosol and Vespel ASB-0670 from DuPont, and the Nitron Flight multi-layer coatings from Wallwork Group.

The article offers information on several engineering tools including the Earthmine mapping tool from Atkins Global, the aerospace products Kalrez Aerosol and Vespel ASB-0670 from DuPont, and the Nitron Flight multi-layer coatings from Wallwork Group.