Aerospace Applications Research Articles

Investigating the Effect of Carbon Nanotubes Decorated SmVO4-MoS2 Nanocomposite for Energy Storage Enhancement via VARTM-Fabricated Solid-State Structural Supercapacitors Using Woven Carbon Fiber.

Traditional supercapacitors are cumbersome and need separate enclosures, which add weight and reduce space efficiency. In contrast, structural supercapacitors combine energy storage with load-bearing materials, optimizing space and weight for automotive and aerospace applications. This study investigates the synthesis of SmVO4-MoS2 and SmVO4-MoS2-CNT nanocomposites, focusing on optimizing CNT concentration in SmVO4-MoS2-CNT for high-performance supercapacitors. The optimal concentration of SmVO4-MoS2-CNT is identified and used to fabricate structural supercapacitor devices via the vacuum-assisted resin transfer molding (VARTM) technique. The results indicate that the specific capacitance of Sm-Mo-C5, using a three-electrode system, reached 1.01Fcm-2 at a current density of 2.187mAcm-2. The performance improvement is attributed to the synergistic interaction among SmVO4, MoS2, and CNTs, collectively enhancing conductivity and active site availability. The practical application of this study is demonstrated by synthesizing Sm-Mo-C5 on woven carbon fiber (WCF) and subsequently fabricating a structural supercapacitor device (SSD) using the VARTM. The SSD, produced via VARTM, exhibited a specific capacitance of 0.287Fcm- 2 at a current density of 2Acm-2. The device showcased exceptional cyclic stability, maintaining 72.5% of its initial capacitance after 50,000 charge-discharge cycles. Additionally, it achieved a maximum energy density of 79.86Whkg-1 at a power density of 1017.69Wkg-1.

Investigation into the Suitability of AA 6061 and Ti6Al4V as Substitutes for SS 316L Use in the Paraplegic Swivel Mechanism

SS 316L, a low-carbon 316 Stainless Steel, has been used to manufacture swivel mechanisms for paraplegic patients, but its weight is relatively high compared to a few materials in its range of properties. Aluminum alloy 6061 and Titanium alloy (Ti6Al4V) offer lightweight and incredible strength-to-weight ratio, hence their use for medical, aerospace, and automotive applications. This study, therefore, seeks a replacement for SS 316L. A 3D model of a swivel mechanism was developed to compare the performance of the swivel mechanism made with SS 316L, AA 6061, and Ti6Al4V. The kinematic analysis of the mechanism based on a range of weights: 1kN, 1.1 kN, 1.2 kN, 1.3 kN, 1.4 kN, and 1.5 kN was carried out to generate the inputs for the simulation. The 3D model was made with SolidWorks, and the results of the kinematic analysis were used to define the simulation parameters for the mechanism. Two scenarios generated depicted the full collapse of the mechanism and the full extension. The results showed that AA 6061 and Ti6Al4V outperformed SS 316L with higher yield strength and factor of safety. Therefore, swivel plates made with AA 6061 and Ti6Al4V have higher yield strength than those made with SS 316L, adding to the advantage that they have a higher strength-to-weight ratio. From this analysis and known knowledge of the cost of these materials, the optimal replacement considering cost with yield strength is AA 6061. However, Ti6Al4V is a better alternative for the strength-to-weight ratio for SS 316L.

Recent Advances in Hybrid Nanocomposites for Aerospace Applications

Hybrid nanocomposites have emerged as a groundbreaking class of materials in the aerospace industry, offering exceptional mechanical, thermal, and functional properties. These materials, composed of a combination of metallic matrices (based on aluminum, magnesium, or titanium) reinforced with a mixture of nanoscale particles, such as carbon nanotubes (CNTs), graphene, and ceramic nanoparticles (SiC, Al2O3), provide a unique balance of high strength, low weight, and enhanced durability. Recent advances in developing these nanocomposites have focused on optimizing the dispersion and integration of nanoparticles within the matrix to achieve superior material performance. Innovative fabrication techniques have ensured uniform distribution and strong bonding between the matrix and the reinforcements, including advanced powder metallurgy, stir casting, in situ chemical vapor deposition (CVD), and additive manufacturing. These methods have enabled the production of hybrid nanocomposites with improved mechanical properties, such as increased tensile strength, fracture toughness, wear resistance, and enhanced thermal stability and electrical conductivity. Despite these advancements, challenges remain in preventing nanoparticle agglomeration due to the high surface energy and van der Walls forces and ensuring consistent quality and repeatability in large-scale production. Addressing these issues is critical for fully leveraging the potential of hybrid nanocomposites in aerospace applications, where materials are subjected to extreme conditions and rigorous performance standards. Ongoing research is focused on developing novel processing techniques and understanding the underlying mechanisms that govern the behavior of these materials under various operational conditions. This review highlights the recent progress in the design, fabrication, and application of hybrid nanocomposites for aerospace applications. It underscores their potential to revolutionize the industry by providing materials that meet the demanding requirements for lightweight, high-strength, and multifunctional components.

Surface integrity and mechanical properties of small elements fabricated through LPBF and post-processed with heat treatment and abrasive machining

AbstractThe present research analyzes the impact of heat treatment atmosphere followed by finishing surface machining of small elements of Inconel 939 fabricated through laser powder bed fusion (LPBF). The analysis involved annealing in two gas mediums, solution treatment, and aging to achieve the desired microstructure and mechanical properties. The finishing surface was performed using various variants of abrasive machining. A more than fivefold reduction in the average roughness height Ra from 5.6 µm to 1.15 µm was achieved using metal balls as an abrasive, which was required for further processing. Residual stress tests have shown that due to heat and abrasive treatment, tensile stresses change into compressive ones. After printing, samples are characterized by tensile residual stresses on the surface (+ 428 MPa), while after heat treatment, compressive stresses occur (− 179 MPa). Abrasive machining with metal balls increases the value of compressive stresses to − 464 MPa. In addition, the impact of post-processing on the microstructure of Inconel 939 was discussed in terms of mechanical properties. The yield strength of 1184 MPa and elongation values of 19.3% were obtained for samples after HT in an argon atmosphere and abrasive machining with a ceramics roller. These studies provide valuable new information on the effective heat treatment and optimization of the finishing machining of Inconel 939, especially in achieving the desired surface roughness, microstructure, and mechanical properties for aerospace applications.

The Effect of Modifiers on the Strength and Impact Toughness of Carbon Fiber Reinforced Plastics

This study utilized epoxy resin, three types of fabric (carbon fiber, glass fiber, and Kevlar), and two plasticizers – tricresyl phosphate (TCP) and oleic acid (OA) – to enhance the impact toughness of carbon fiber-reinforced plastics (CFRP). The polymer matrix used in the experiments was a hot-cured epoxy compound "Etal Inject-T" consisting of two components: A – epoxy resin and B – hardener, in a mass ratio of 100:49.9. For the fabrication of CFRP plates, both manual and vacuum molding techniques were employed. Combined reinforcement of carbon fiber was achieved using one of two types of fabrics: Ortex 360 glass fiber or Kevlar. Accordingly, two compositions were prepared for the experiments: carbon fiber/glass fiber and carbon fiber/Kevlar. Layer stacking in each composition was performed at ratios of 10:10 and 14:6, consisting of 20 layers in total. The greatest strengthening effect for CFRP in the case of carbon fiber/glass fiber was observed with a layer ratio of 14:6 and matrix modification using 10% TCP plasticizer. The strength of the CFRP increased from 425 to 451 MPa, and the impact toughness (α) improved from 192 to 280 kJ/m². A key feature of this technology is the achievement of high-performance dual-purpose CFRP. This enables the reduction of CFRP structures in aerospace applications by 3 to 5 times, while simultaneously enhancing resistance to impact loads.

FRICTION STIR PROCESSED MAGNESIUM MATRIX SURFACE COMPOSITES: A COMPREHENSIVE REVIEW

Abstract Nowadays modern materials are tailored using different manufacturing techniques. Usually, material surface is modified by even distribution of reinforcement particles/ fibres up to a certain depth. The developed surface metal matrix composites (MMCs) exhibit superior metallurgical, mechanical and electrochemical properties in contrast to base materials. These surface MMCs have potential applications in biomedical, automotive, aerospace and power industries. Many techniques have been used to develop these surface MMCs, however, the friction stir processing (FSP) has gained wide popularity. This review paper summarizes the effects of different FSP parameters on the metallurgical, mechanical and electrochemical properties of developed surface composites. Furthermore, the effects of secondary phase particles on the Magnesium-matrix surface composites are also comprehensively discussed.

Effect of various notch shape on Lamb wave scattering behaviour in a bent plate

Abstract The application of guided waves to investigate commonly used plate shapes in the aerospace, mechanical and civil industries are plates with bend shapes. This paper investigates the interaction of fundamental Lamb waves with notches in bent plates, commonly found in aerospace, mechanical, and civil engineering applications. These areas are particularly susceptible to failure due to defects such as cracks and notches, which often manifest as semi-circular corrosion patches or 900 notches. The presence of notches affects stress distribution, necessitating thorough analysis to prevent accidents. Accordingly, this paper focus on the interaction of fundamental Lamb waves through two types of notches that could be present inside a bent metal plate section. To explore this, a hybrid numerical framework is employed which combines Semi-Analytical Finite Elements (SAFE) with the Finite Element Method (FEM). A bent plate sections with various notch types is simulated using FEM, while SAFEs facilitate the definition of wave propagation through healthy regions of the plate. The study analyses the scattering behaviour of Lamb waves for different notch configurations and examines both fundamental modes over a specified frequency range. With a change in the interrogation signal parameters, there is a noticeable difference in the sensitivity of scattered waves with different notch types. Formulating a strategy for identifying and locating a notch inside a bent plate may need careful consideration of the important conclusions drawn. Understanding these interactions, aim of the paper is to enhance the integrity assessment of structural components subject to such defects.

Comparison of the ablative performance of silicone rubber‐based composites by analyzing a large number of samples

AbstractSilicone rubber‐based materials are important thermal protection materials for high‐temperature applications. In this work, a holistic analysis of silicone rubber‐based materials was conducted with an aim to comparatively study the ablative performance of different rubber matrices using the oxyacetylene flame. Six types of silicone rubber‐based composites were prepared in large quantities using a customized device, and the relationship between the ablative properties and influencing factors was elucidated, which was useful in guiding the design and preparation of flexible ablative materials for thermal protection purpose. The expansion and ceramicization of char layer, which was realized by introducing expandable graphite and alumina was found helpful in reducing line ablation rate. The increase in the thickness of char layer and the decrease in surface roughness indicated a successful implementation of the above strategy, which led to a significant decrease in line ablation rate and an increase in thermal insulation performance of the studied system. Moreover, a thermal ablative composite with excellent moldability after ablation process was prepared which showed a promising application as a reusable thermal protection material. This work provided guidelines for developing flexible thermal ablative composites, which can be targeted for practical applications in aerospace and fire protection sectors.

Vertical z-axis discontinuous carbon fibers for improved lightning strike performance of continuous fiber-reinforced polymer composites

Effective lightning strike protection for critical aerospace and wind applications requires high electrical conductivity to dissipate current efficiently. However, polymer matrix composites face a challenge due to their inherently insulating nature. While conventional carbon fiber-reinforced composites (CFRP) exhibit electrical conductivity in the planar direction, achieving through-thickness conductivity remains an ongoing challenge. In this work, we have undertaken the fabrication of CFRP interleaved with vertically oriented carbon fibers (Z-fiber) to impart higher electrical conductivity along the thickness direction. Two Z-fiber composite variations are prepared: Z-1 with a single layer of Z-fiber and Z-5 with five interleaved layers and compared with no Z-fiber layer (Z-0) composite. The composite panels were subjected to lab-scale lightning strike tests with a current magnitude of 100 kA. To emulate real-world service conditions, an aerospace-grade paint coating was applied to the composite laminates. Comparative analysis shows Z-1 reduces damage diameter to ∼22 mm compared to Z-0 (∼26 mm), while Z-5 exhibits the least damage (∼16.7 mm), confirmed by optical microscopy. Z-5 demonstrates nine times higher through-thickness electrical conductivity than Z-0, reducing electrical anisotropy substantially. Thermal-electric finite element damage modeling predicts surface damage within 6% of experimental values for both Z-0 and Z-5 composites. Flexural tests post-lightning reveal Z-5 retains 66% flexural strength and 86% modulus, significantly better than Z-0, which retains less than 40% for both properties. This study highlights the efficacy of Z-fiber composites in lightning strike protection, offering improved through-thickness conductivity and mechanical property retention.

Continuous fiber printing path generation based on Euler diagram division

Continuous fiber printed structures are widely used in aerospace applications because of their excellent performance and high design freedom. Existing path planning methods optimize the continuous fiber printing direction by stress lines or discrete angles, but these methods are far from perfect printing paths and lack planning for connectivity relations. In this study, a planning method for continuous fiber printing paths based on constructing Eulerian circuits from a weighted undirected graph is proposed. The principal stress lines are transformed into a weighted undirected graph, which divides the Eulerian subgraph by splitting the common nodes to plan the continuous fiber printing path circuit. Subsequently, the printing structure parameters are optimized based on simulation analysis. The experimental results, taking MBB (Messerschmitt-Bolkow-Blohm) beams as an example, show that the printing path designed in this paper improves the structural strength by 52.9% and the structural stiffness by 81.7% compared with the conventional printing path.

Enhancing performance through friction welding of dissimilar aluminium 2014 and 7075 hybrid metal-matrix composite: insights into material characterization, crystallographic texture, and mechanical properties

Abstract Welding high-strength, age-hardenable aluminium alloys from the 2XXX and 7XXX series poses challenges when using fusion-based welding processes. Common issues such as hydrogen porosity, hot cracking, stress corrosion cracking, and solidification cracking can lead to a reduction in mechanical properties due to the loss of strengthening precipitates and alloying elements. Consequently, friction stir welding (FSW) has emerged as a promising solid-state welding technique for joining dissimilar aluminium alloys and composites, particularly in aerospace applications where a combination of strength, corrosion resistance, and other desirable properties is required. This study investigates the FSW of dissimilar aluminium alloys, specifically AA2014 and a hybrid metal-matrix composite of AA7075 reinforced with silicon carbide and graphite particles. The microstructural and mechanical properties of the welded joints were characterized, revealing an average grain size of 2.39 μm ± 1.2 in the stir zone (SZ). A high angle grain boundary volume fraction of 47.25% was observed in the SZ, compared to 2.01% in the AA7075 composite and 15.03% in the AA2014 base metal. The presence of shear textures and the distribution of cube, S, and H textures indicate a homogeneous mixing of the base materials and a high shear strain rate during welding. The hardness of the SZ increased by 13%, and the ultimate tensile strength, yield strength, and elongation of the joint were measured at 251 MPa, 183 MPa, and 6.44%, respectively. The flexural strength of the joints improved significantly, with the CW13 sample showing a 67% increase compared to CW1. The dissimilar joint CW13, welded at 12.5 mm min−1, achieved a maximum joint efficiency of 95%.

Crystal Chemistry at Interfaces Between Liquid Al and Polar SiC{0001} Substrates

Silicon carbide (SiC) has been widely added into light metals, e.g., Al, to enhance their mechanical performance and corrosion resistance. SiC particle-reinforced metal matrix composites (SiC-MMCs) exhibit low weight/volume ratios, high strength/hardness, high corrosion resistance, and thermal stability. They have potential applications in aerospace, automobiles, and other specialized equipment. The macro-mechanical properties of Al/SiC composites depend on the local structures and chemical interactions at the Al/SiC interfaces at the atomic level. Moreover, the added SiC particles may act as potential nucleation sites during solidification. We investigate local atomic ordering and chemical interactions at the interfaces between liquid Al (Al(l) in short) and polar SiC substrates using ab initio molecular dynamics (AIMD) methods. The simulations reveal a rich variety of interfacial interactions. Charge transfer occurs from Al(l) to C-terminating atoms (Δq = 0.3e/Al on average), while chemical bonding between interfacial Si and Al(l) atoms is more covalent with a minor charge transfer of Δq = 0.04e/Al. The prenucleation at both interfaces is moderate with three to four recognizable layers. The information obtained here helps increase understanding of the interfacial interactions at Al/SiC at the atomic level and the related macro-mechanical properties, which is helpful in designing novel SiC-MMC materials with desirable properties and optimizing related manufacturing and machining processes.

Recent Advances in Near‐β Titanium Alloys: Microstructure Control, Deformation Mechanisms, and Oxidation Behavior

Near‐β titanium alloys are used as promising structural materials for aerospace, biomedical, and other advanced applications due to their excellent combination of high specific strength and superior corrosion resistance. Precise control of the microstructure and mechanical properties through thermomechanical processing and heat treatment is paramount for exploiting the full potential of these alloys. This review article provides a comprehensive and critical assessment of the state‐of‐the‐art research on the microstructure evolution, deformation mechanisms, and oxidation behavior of near‐β titanium alloys. Furthermore, the challenges and emerging opportunities in the development of near‐β titanium alloys have also been identified, ranging from alloy design and processing optimization to multiscale characterization and integrated computational materials engineering. This review article provides a timely and comprehensive roadmap for the research and development of near‐β titanium alloys, paving the way for unlocking their full potential in critical industries.

3D printing molding of UV‐curing liquid silicone rubber by UV follow curing

AbstractSilicone rubber is renowned for its excellent mechanical properties and high biocompatibility. 3D printing enables the realization of more complex structures and the development of more flexible and diverse functions, providing more opportunities and a more comprehensive range of applications in aerospace, biomedical, flexible wearable, soft robotics, and other fields. However, silicone rubber is often hindered by poor rheology and low curing efficiency, which significantly affects the forming performance of the parts. Therefore, this study introduces a UV‐follow curing method for direct ink writing (UFC‐DIW) utilizing UV‐curable silicone rubber. First, a kind of liquid silicone rubber (UV‐LSR) capable of rapid curing under UV light was synthesized, both its curing kinetics and rheological behavior were thoroughly investigated. Then, UV‐LSR inks with lower shear stress were printed using the UFC‐DIW method. A comparative analysis was conducted between the overall structure produced via UFC‐DIW and parts molded through postprinting integral curing methods. The results show that while parts cured postprinting exhibit deformation correlated with printing height, those fabricated using UFC‐DIW maintain structural integrity without deformation. It demonstrates that the UFC‐DIW method can effectively improve the formability of the parts.

State-of-the-art Advances in the Ignition Selay Reduction of N,N-dimethylethanamine

Propellant is a core fuel in defense and aerospace applications. However, conventional hydrazine fuel is highly volatile, toxic, and carcinogenic, resulting in huge threats to the human body and environment. N,N-dimethylethanamine (DMAZ) is a green, high-energy fuel with a low freezing point, high density, high specific impulse, and high combustion rate, and it is a promising substitute of conventional hydrazine fuel. Nevertheless, the industrial application of DMAZ is limited by long ignition delay. In this study, the mechanism of ignition of DMAZ was explored by summarizing current methods to reduce the ignition delay of DMAZ, including the addition of catalyst, fuel formulation, and tuning molecular structure. This study provides references for applications of amine azide.

Taguchi, Grey Relational Analysis, and ANOVA Optimization of TIG Welding Parameters to Maximize Mechanical Performance of Al-6061 T6 Alloy

This study presents a comprehensive investigation into optimizing Tungsten Inert Gas (TIG) welding parameters to enhance the mechanical performance of the widely used Al-6061 T6 alloy, specifically in a double V joint configuration with a plate thickness of 6 mm, for aerospace applications. The Taguchi method was employed to design the experiments, providing a robust framework for analyzing the influence of the electrical current, voltage, and gas flow rate on weld quality. Additionally, a Grey Relational Analysis (GRA) and an Analysis of Variance (ANOVA) were used to validate the optimal welding parameters and quantify the significance of each factor. The optimized parameters were determined to be an amperage of 180 A, a voltage of 18 V, and a gas flow rate of 10 L/min, resulting in significant improvements of up to 40% in tensile strength and 23% in hardness, demonstrating the effectiveness of the optimized conditions. The findings provide valuable insights into welding metallurgy, offering practical guidelines for enhancing high-performance welded joints in critical industrial applications. This study underscores the potential of combining Taguchi, GRA, and ANOVA methodologies to achieve superior mechanical properties and reliability in welded structures.

Mechanical and microstructural characteristics of Al-Li2099-graphene MMCs for aerospace applications

ABSTRACT Aluminium-Lithium (Al-Li) alloys are known for its properties that are superior to conventional ones. The inclusion of graphene reinforcements to the metal matrix improved strength, stiffness, density reduction, tensile properties, wear, creep, and fatigue resistance. This study examined the combined result of graphene nanoparticles (GNP) and the Al-Li2099 alloy with an ultrasonic-aided stir-casting process. The nano-particulate metal matrix composites with various weight percentages (wt. %) of GNP were fabricated and investigated for physical, mechanical, and microstructural properties. The nanocomposites’ mechanical properties were examined in detail, and significant improvements in hardness, tensile, and compressive strength were observed with higher wt. % of GNP. Theoretical and empirical densities were measured, revealing that the nanocomposite’s densities decrease with the increase in wt. % of nano-reinforcements. Material characterisation of the composites was carried out using XRD, EDAX, SEM, and Fourier-Transformation Infrared Spectroscopy (FTIR). SEM and EDAX confirmed the presence of GNP particulates in the matrix microstructure and elemental composition. The XRD results confirmed the presence of GNP particulates in the Aluminium Alloy (AA) 2099 and the composite, and no other intermetallic elements were detected. The results demonstrated that the GNP addition to the AA2099 significantly enhanced the mechanical and microstructural characteristics of the nanocomposite.

Numerical investigation on the heat transfer and pressure loss characteristics of precooler under negative pressure

Precoolers have garnered considerable attention owing to their applications in aerospace and industrial fields. Nonetheless, there is a paucity of research concerning the performance of precoolers under conditions of extremely low pressure. This study conducts a numerical analysis of the heat transfer and pressure loss characteristics of a plate-fin precooler operating under negative pressure, considering the coupled heat transfer interactions among the hot fluid, solid wall, and cooling fluid. The comprehensive performance and flow field on each side of the precooler are investigated. Moreover, the impact of negative pressure on the heat transfer and pressure recovery performance of the hot fluid in the rectangle channel is evaluated. The results show that, even under operating conditions with pressures below 30 kPa and inlet temperatures exceeding 1100 K, the precooler attains a pressure recovery coefficient greater than 95.6 % and achieves a temperature drop exceeding 43.2 % for the hot fluid as the mass flow rate ranges from 0.205 kg/s to 0.564 kg/s. Additionally, the heat transfer coefficient of the hot fluid is less than 1/40 that of the cooling fluid, resulting in increased thermal resistance between the hot fluid and the wall. Consequently, a distinct thermal boundary layer develops between the hot fluid and the wall, which is not present between the cooling fluid and the wall. Furthermore, the performance of heat transfer and pressure recovery for the hot fluid exhibits considerable variability with changes in static pressure at a constant inlet velocity. However, a turning point is observed when these parameters are evaluated in terms of the inlet Reynolds number. At low Reynolds numbers, both the heat transfer coefficient and the friction factor remain relatively stable, notwithstanding fluctuations in static pressure. Conversely, at higher Reynolds numbers, a reduction in static pressure negatively influences these factors. For instance, when the static pressure is 10 kPa, the associated Reynolds number is 500. Nevertheless, the Reynolds number at which this turning point occurs escalates with an increase in static pressure.

Efficient conversion of Euler angles to quaternion for practical aerospace applications

Abstract Current methods for converting Euler angles to a rotation quaternion are computationally intensive and have limited practical applications in aerospace. This study introduces an efficient approach that directly converts Euler angles in any desired sequence to a rotation quaternion, eliminating the need for intermediate Euler angle transformation matrices, which leads to a significant improvement in computational efficiency. Moreover, it is general because it works with all 12 possible sequences of rotations. A case study is presented, demonstrating the application of the algorithm in converting between the launch frame and the missile frame of a vertical takeoff vertical landing (VTVL) rocket. The results show more than a ninefold improvement in computational efficiency compared to the classical Euler angle method while maintaining consistency of results.

Measuring and Extracting the Complex Permittivity of Porous Ceramic Materials in the Y-Band

ABSTRACT 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.