Search Results (1,665)

Wire-based laser metal deposition is an additive manufacturing process that can be used in the efficient manufacturing of complex structures. This paper utilizes a three-beam coaxial laser wire system to explore the effect of process parameters on the resultant deposition density. The reduction in or elimination of defects is important to the mechanical properties of the additively manufactured material and the widespread adoption of additive manufacturing processes. In this work, two-bead-wide walls were deposited under varying experimental conditions, including the traverse feed rate and workpiece illumination proportion. A method for calculating the bead pitch and layer height increment based on the geometry of the deposited material was developed. The deposited samples were micro-CT-scanned to characterize internal defects at a high resolution. The volume of the detected defects was measured and compared to the total sample volume to calculate a defect rate for each run of the experiment. The traverse feed rate and defocusing level were found to have a significant impact on the output defect rate. As these process parameters were increased, the defect rate decreased. Across the experimental levels, the defect volume percentage was reduced from 1.021% to 0.062%. This reduction in internal defect size enhances the material’s mechanical performance and ensures its suitability for aerospace applications. Full article

SiC matrix composites are widely used in high-temperature structural components of aircraft engines and nuclear reactor materials because of their excellent properties such as their high modulus, high strength, corrosion resistance, and high-temperature resistance. However, the bonding of SiCf/SiC composites poses significant challenges in practical engineering applications, primarily due to residual stresses, anisotropy in composite properties, and the demanding conditions required for high-performance joints. This work reviews various bonding technologies for SiC ceramics and SiC matrix composites. These include solid-state diffusion bonding, NITE phase bonding, direct bonding without filling materials, MAX phase bonding, glass ceramic bonding, polymer precursor bonding, metal brazing bonding, and Si-C reaction bonding. Key results, such as the highest bending strength of 439 MPa achieved with Si-C reaction bonding, are compared alongside the microstructural characteristics of different joints. Additionally, critical factors for successful bonding, such as physical mismatch and metallurgical incompatibility, are discussed in detail. Future research directions are proposed, emphasizing the optimization of bonding techniques and evaluation of joint performance in harsh environments. This review provides valuable insights into advancing bonding technologies for SiC composites in aerospace and nuclear applications. Full article

Stiffened panels are extensively used in aerospace applications, particularly in wing and fuselage sections, due to their favorable strength-to-weight ratio under in-plane loading conditions. This research employs the commercial finite element software Ansys-19 to analysis the critical buckling and ultimate collapse load of an aluminum stiffened panel having a dimension of 1244 mm (Length) × 957 mm (width) × 3.5 mm (thickness), with three stiffener blades located 280 mm away from each other. Both the critical buckling load and post-buckling ultimate failure load of the panel are validated against the experimental data found in the available literature, where the edges towards the length are clamped and simply supported, and the other two edges are free. For nonlinear buckling analysis, a plasticity power law is adopted with a small geometric imperfection of 0.4% at the middle of the panel. After the numerical validation, the investigation is further carried out considering four different lateral pressures, specifically 0.013 MPa, 0.065 MPa, 0.085 MPa, and 0.13 MPa, along with the compressive loading boundary conditions. It was found that even though the pressure application of 0.013 MPa did not significantly impact the critical buckling load of the panel, the ultimate collapse load was reduced by 18.5%. In general, the ultimate collapse load of the panel was severely affected by the presence of lateral pressure while edge compressing. Three opening shapes—namely, square, circular, and rectangular/hemispherical—were also investigated to understand the behavior of the panel with openings. It was found that the openings significantly affected the critical buckling load and ultimate collapse load of the stiffened panel, with the lateral pressure also contributing to this effect. Finally, in critical areas with higher lateral pressure load, a titanium panel can be a good alternative to the aluminum panel since it can provide almost twice to thrice better buckling stability and ultimate collapse load to the panels with a weight nearly 1.6 times higher than aluminum. These findings highlight the significance of precision manufacturing, particularly in improving and optimizing the structural efficiency of stiffened panels in aerospace industries. Full article

To address the manufacturing demands of large-scale aerospace composite components, this study systematically investigates the coordinated motion characteristics of multi-axis systems in fiber placement equipment. This investigation is based on the structural features and process specifications of the equipment. A comprehensive motion control scheme for grid-based fiber placement machines was developed using the Siemens 840D CNC system, integrating filament-winding and tape-laying functionalities on a unified control platform while enabling 10-axis synchronous motion. To mitigate thermal-induced errors, a compensation method incorporating a BP neural network optimized by a genetic algorithm with an enhanced fitness function (GA-BP) was proposed. Experimental results demonstrate significant improvements: the maximum thermal errors of the Z-axis and X3-axis were reduced by 36.7% and 53.3%, respectively, while the core mold placement time was reduced to 61% of the specified duration, with notable enhancements in trajectory accuracy and processing efficiency. This research provides a technical framework for the design of multi-axis cooperative control systems and thermal error compensation in automated fiber placement equipment, offering critical insights for advancing manufacturing technologies in aerospace composite applications. The proposed methodology highlights practical value in balancing precision, efficiency, and system integration for complex composite component production. Full article

In previous studies, a valveless piezoelectric pump with arc-shaped tubes (VPPAST) based on the Coriolis Effect was proposed. To promote the application of VPPAST in the field of navigation and guidance, it is vital to further explore the influences of the layout and structural parameters of arc-shaped tubes on the flow rate. Accordingly, in this study, the analysis of flow characteristics of fluid in arc-shaped tubes was conducted, and the velocity difference between the clockwise and counterclockwise flow of the liquid was reduced. Eventually, the flow equations of three layout modes of arc-shaped tubes were established. VPPAST with anomalous-direction arc-shaped tubes, single-arc-shaped tube, and same-direction arc-shaped tubes were produced using 3D printing technology. In addition, the valveless piezoelectric pump with the anomalous-direction arc-shaped tubes (VLPPADA) with different parameter flow tubes were also fabricated. Based on the resultant flow rates of each piezoelectric pump, it was demonstrated that the flow rate of the VLPPADA was the highest under the same driving conditions, and the flow rate can be determined as 1.72 mL/min when the driving voltage was set as 160 V at 14 Hz. It indicated that the pump flow rate of VLPPADA was directly proportional to the base radius and width of the arc-shaped tube. Full article

High-strength and high-modulus epoxy resins are key elements for preparing carbon-fiber-reinforced polymer composites, which play an irreplaceable role in aerospace. In this study, five optimal epoxy systems were developed utilizing the reverse design strategy. The reverse design strategy was based on the ideal resin and curing agent structures offered by the AI polymer platform, and the rules were summarized to create an optimum resin formulation. The formulations used m-phenylenediamine (MPD) as the principal curing agent, which was modified with 10 wt% diethyltetramethylenediamine (DETDA), 10 wt% 4,4′-diaminodiphenylmethane (DDM), or 10 wt% triethylenetetramine (TETA) to establish multiple crosslinking networks. Systematic characterization using differential scanning calorimetry (DSC) and rheological analysis revealed that the optimized activation energy was 55.95–63.42 kJ/mol, and the processing viscosity was ≤500 mPa·s at 80 °C. A stepwise curing protocol (3 h@80 °C, 2 h@120 °C, and 3 h@180 °C) was established to achieve a complete crosslinking network. The results showed that the system with 10% DDM had a tensile strength of 132.6 MPa, a modulus of 5.0 GPa, and a glass transition temperature of 253.1 °C. This work advances the rational design of epoxy resins by bridging molecular architecture with macroscopic performance, offering a paradigm for developing a next-generation matrix tailored to accommodate extreme operational demands in high-end engineering sectors. Full article

To address the insufficient bonding performance between TC4 (Ti-6Al-4V) coating and carbon fiber-reinforced thermoplastic (CFRP) matrices that limits engineering applications of composite structures, TC4 coatings were fabricated on CFRP polymer composites via laser cladding and analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to examine the interface morphology, microstructure, and phase composition. The influence of laser processing parameters on the cladding quality was assessed based on the mechanical performance of the TC4 coating. The findings revealed that insufficient laser power (<230 W) or excessive scanning speed (>1.4 m/min) led to incomplete melting of TC4 powder, preventing the formation of intermetallic compound (IMC) layers. Conversely, excessive laser power (>270 W) or a low scanning speed (<1.0 m/min) caused thermal decomposition of the CFRP due to its limited thermal resistance, leading to interfacial defects such as cracks and pores. The interface between the CFRP and TC4 coating primarily comprised granular TiC and acicular α′ martensite, with minor TiS₂ detected. Optimal mechanical performance was achieved at a laser power of 250 W and a scanning speed of 1.2 m/min, yielding a maximum interfacial shear strength of 18.5 MPa. These findings provide critical insights for enhancing the load-bearing capacity of TC4/CFRP aeronautical composites, enabling their reliable operation in extreme aerospace environments. Full article

The structural, mechanical, dislocation, and electronic properties of the Sc₃AlC MAX phase under applied pressure are investigated in detail using first-principles calculations. Key parameters, including lattice parameter ratios, elastic constants, Young’s modulus, bulk modulus, shear modulus, brittle-to-ductile behavior, Poisson’s ratio, anisotropy, Cauchy pressure, yield strength, Vickers hardness, and energy factors, are systematically analyzed as a function of applied pressure. The results demonstrate that the Sc₃AlC MAX phase exhibits remarkable mechanical stability within the pressure range of 0 to 60 GPa. Notably, applied pressure markedly improves its mechanical properties, such as resistance to elastic, bulk, and shear deformations. The B/G ratio suggests a tendency toward ductile behavior with increasing pressure, and the negative Cauchy pressure indicates the directional characteristics of interatomic bonding in nature. Vickers hardness and yield strength increase under pressures of 0 to 10 GPa and then decrease sharply above 50 GPa. High pressure suppresses dislocation nucleation due to the increased energy factors, along with twinning deformation. Furthermore, electronic structure analysis confirms that high pressure enhances the interatomic bonding in the Sc₃AlC MAX phase, while the enhancement effect is not substantial. This study offers critical insights for designing MAX phase materials for extreme environments, advancing applications in aerospace and electronics fields. Full article

This study investigates the application of carbon nanotube (CNT)-enhanced epoxy adhesives for localised Joule heating-based curing in composite bonding. The electrical, thermal, and mechanical properties of epoxy with 0.25–1 wt% CNT loadings were evaluated. A simple CNT alignment method using DC voltage showed improved electrical conductivity, greatly reducing the percolation threshold. Transient thermal analysis using finite element modelling of representative volume elements revealed that aligned CNTs led to increased localised temperatures near the CNT clusters. The model was validated with infrared thermal imaging analysis, which also showed similar non-linear heat distribution and more uniform heating under higher CNT loading. Additionally, power distribution mapping was evaluated through inverse modelling techniques, suggesting different conductivity zones and cluster distribution within the single-lap joint. The numerical and experimental results demonstrated that CNT alignment significantly enhanced localised conductivity, thereby improving curing efficiency at lower voltages. The lap shear test results showed a peak shear strength of 10.16 MPa at 0.5 wt% CNT loading, 9% higher than pure epoxy. Scanning electron microscopy analysis confirmed the formation of aligned CNT clusters, and how CNT loading affected the failure modes, transitioning from cohesive to void-rich fracture patterns at a higher wt%. These findings establish CNT-enhanced Joule heating as a viable and scalable alternative for efficient composite bonding in aerospace and structural applications. Full article

Polyether ether ketone (PEEK) is a high-performance thermoplastic widely used in aerospace, automotive, and medical applications due to its exceptional strength, heat resistance, and chemical stability. However, warpage and mechanical property variations remain significant challenges in 3D printing PEEK parts. This study investigates the effect of key printing parameters, including nozzle temperature, layer thickness, platform temperature, and infill rate, on the mechanical properties and warpage of 3D-printed PEEK components. By systematically analyzing tensile and compressive loading conditions, this research aims to optimize printing settings to improve dimensional accuracy and structural integrity. The experimental results indicate that mechanical properties, such as tensile and compressive stress at break, vary significantly with printing conditions. The highest tensile strength and compressive strength achieved were 71.4 MPa and 167 MPa, respectively. Meanwhile, the lowest tensile (45.36 MPa) and compressive strengths (72.5 MPa) were also recorded. Higher nozzle and platform temperatures, coupled with increased infill rates, enhance layer adhesion, leading to improved tensile and compressive strength. However, a nozzle temperature of 400 °C, platform temperature of 130 °C, and 60% infill rate lead to optimal bonding between layers and thus a reduction in warpage. Considering warpage in all four corners and mechanical properties, a 400 °C nozzle temperature, 0.16 mm layer thickness, and 130 °C platform temperature, coupled with a 60% infill rate, provide optimal printing conditions. The 10% carbon fiber-reinforced PEEK composites exhibit an improved tensile strength that is 1.68 times higher compared to pure PEEK. To emphasize the importance of thermal and structural settings, the findings highlight the crucial role of printing parameters in minimizing warpage and enhancing mechanical properties in 3D-printed PEEK parts, which were analyzed by the multi-objective optimization method. Scanning electron microscopy analyses were carried out to analyze fracture morphology and printing layer orientation. Full article

Boron phosphide (BP), an emerging III–V semiconductor, has garnered significant interest because of its exceptional structural stability, wide bandgap, high thermal conductivity, and tunable electronic properties. This review provides a comprehensive analysis of BP, commencing with its distinctive structural characteristics and proceeding with a detailed examination of its exceptional physicochemical properties. Recent progress in BP synthesis is critically examined, with a focus on key fabrication strategies such as chemical vapor deposition, high-pressure co-crystal melting, and molten salt methods. These approaches have enabled the controlled growth of high-quality BP nanostructures, including bulk crystals, nanoparticles, nanowires, and thin films. Furthermore, the review highlights the broad application spectrum of BP, spanning photodetectors, sensors, thermal management, energy conversion, and storage. Despite these advances, precise control over the growth, morphology, and phase purity of BP’s low-dimensional structures remains a critical challenge. Addressing these limitations requires innovative strategies in defect engineering, heterostructure design, and scalable manufacturing techniques. This review concludes by outlining future research directions that are essential for unlocking BP’s potential in next-generation electronics, sustainable energy technologies, and multifunctional materials. Full article

The increasing demand for fully recyclable composites has spurred extensive research on thermoplastics, valued for their recyclability and excellent mechanical properties. High-performance thermoplastics such as PEEK and PPS have been widely adopted in aerospace applications due to their outstanding load-bearing capabilities, which are well documented. Recently, thermoplastic polymer blends have gained attention for their enhanced recyclability and sustainability, as well as their ability to improve thermal stability, viscosity, and manufacturability. However, limited data are available on the mechanical characterization of composites that incorporate these blends, particularly when recycled thermoplastics are used. In this study, we first examine the stress–strain behavior of the following three polymer blends relevant for structural applications: PES/PEEK, PPS/PEEK, and HDPE/PP. We then perform a numerical analysis to predict the mechanical performance of unidirectional fiber-reinforced composites using each blend as the matrix. This involves a micromechanical Representative Volume Element (RVE) approach combined with an advanced polymer model previously validated against experimental data. The findings are discussed to critically assess the suitability of these blends for producing fully matrix-recycled composites. Full article

High-entropy alloys (HEAs) are a novel class of metallic materials composed of five or more principal elements in near-equimolar ratios. This unconventional composition leads to high configurational entropy, which promotes the formation of solid solution phases with enhanced mechanical properties, thermal stability, and corrosion resistance. Phase stability plays a critical role in determining their structural integrity and performance. This study provides a focused review of HEA phase transitions, emphasizing the role of lattice gas models in predicting phase behavior. By integrating statistical mechanics with thermodynamic principles, lattice gas models enable accurate modeling of atomic interactions, phase segregation, and order-disorder transformations. The combination of computational simulations (e.g., Monte Carlo, molecular dynamics) with experimental validation (e.g., XRD, TEM, APT) improves predictive accuracy. Furthermore, advances in data-driven methodologies facilitate high-throughput exploration of HEA compositions, accelerating the discovery of alloys with optimized phase stability and superior mechanical performance. Beyond structural applications, HEAs demonstrate potential in functional domains, such as catalysis, hydrogen storage, and energy technologies. This review brings together theoretical modeling—particularly lattice gas approaches—and experimental validation to form a unified understanding of phase behavior in high-entropy alloys. By highlighting the mechanisms behind phase transitions and their implications for material performance, this work aims to support the design and optimization of HEAs for real-world applications in aerospace, energy systems, and structural materials engineering. Full article

In this study, we propose a robust artificial intelligence (AI) model for vibration monitoring of rotating equipment to support reliable operation across various industries, including manufacturing, power plants, and aerospace. The reliability and completeness of sensor data are essential for early detection of anomalies in equipment and for performing predictive maintenance. While AI-based predictive maintenance and condition-monitoring technologies have advanced in recent years, the issue of data loss caused by sensor failures remains a significant challenge that leads to performance degradation of AI models. In particular, for equipment utilizing multiple sensors, the complete loss of data from a single sensor significantly diminishes the predictive maintenance capability of AI models, thereby reducing their reliability. To address this issue, this study introduces topological data analysis (TDA) to develop a robust AI model. TDA analyzes the topological structure of sensor data to generate consistent feature vectors that capture the intrinsic characteristics of the data. This enables stable predictions even when certain channels of multi-sensor data are entirely missing. The proposed method demonstrates high performance resilience under conditions of partial sensor data loss, thereby contributing to enhanced reliability of AI-based predictive maintenance systems and the establishment of efficient maintenance strategies in the future. Full article

Magnesium–lithium alloys, currently the lightest metallic structural materials, exhibit exceptional specific strength, superior damping capacity, and remarkable electromagnetic shielding properties. These characteristics endow them with significant potential for engineering applications in automotive, aerospace, satellite, and military industries. However, their poor corrosion resistance severely restricts practical implementation. This review systematically examines recent advances in surface engineering techniques for magnesium–lithium alloys, with a focus on corrosion protection strategies. Key approaches are critically analyzed, including chemical conversion coatings, electroless plating, anodization, and advanced coating technologies. Furthermore, emerging hybrid methods combining multiple surface treatments are highlighted. Finally, future research directions are proposed to address existing challenges in surface protection of magnesium–lithium alloys. Full article