Aerospace Components Research Articles

INVESTIGATION ON THE ELECTRICAL DISCHARGE MACHINING OF Cu-SHAPE MEMORY ALLOY: A STUDY ON MACHINABILITY AND SURFACE TOPOGRAPHY ASPECTS

Shape memory alloys (SMAs) are an excellent material for producing components for a wide range of industrial applications, such as orthopedic implacers, micro-equipment, actuators, fittings, and screening components, as well as military equipment, aerospace components, bio-medical equipment, and fabrication requirements. Despite its remarkable qualities, the production of SMAs is a problem for investigators all over the globe. The purpose of this research is to evaluate the effects of altering the [Formula: see text], [Formula: see text], [Formula: see text], and GV while processing copper-based SMA in an electrical discharge machining process on the material removal rate (MRR) and surface roughness (SR). The major runs were designed using a central composite design. SEM was also utilized to examine the micro-structure of EDM-processed electrode tools and work samples. SEM scans indicated the presence of debris, micro-cracks, craters, and a newly formed recast layer on the electrode tool and workpiece surface. High [Formula: see text] and prolonged [Formula: see text] provide huge spark energy simply at the work sample-tool contact, resulting in debris production. The experimental results reveal that the least and highest MRR values are 10.333 and 185.067[Formula: see text]mm3/min, respectively, while the minimum and maximum SR values are 3.07 and 7.15[Formula: see text][Formula: see text]m. The desirability technique, teacher learning based optimization (TLBO), and the Jaya algorithm were also utilized to optimize the studied solutions (i.e. MRR and SR) on a single and multi-objective basis. The best MRR and SR were determined using the desirability approach, the Jaya Algorithm, and the TLBO to be 152.788[Formula: see text]mm3/min and 4.764[Formula: see text][Formula: see text]m; 240.0256[Formula: see text]mm3/min and 1.637[Formula: see text][Formula: see text]m; and 240.0257[Formula: see text]mm3/min and 1.6367[Formula: see text][Formula: see text]m.

Climbing robots for manufacturing.

Robotized intelligent manufacturing is a growing trend in the manufacturing of large and complex components in aviation, aerospace, marine engineering and other industries. With their expansive workspaces and flexible deployment, climbing manufacturing robots can create a revolutionary manufacturing paradigm for large and complex components. This paper defines the climbing manufacturing robot based on the application status of climbing robots and then analyzes four key technical requirements: adhesion, locomotion, localization and control. Subsequently, the current research status of climbing robots in these four areas is classified and reviewed, along with a clarification of the research frontiers and trends in each area, and the applicability of the relevant research to manufacturing-oriented climbing robotic systems is analyzed. Finally, by concluding the development trends of robotized intelligent manufacturing equipment in terms of manufacturing dimension and scale, environmental adaptability and cluster collaboration capability, we clarify the major challenges for climbing manufacturing robots in terms of adhesion principles, motion mechanisms, positioning technology and control methods, and propose future research directions in these fields.

Hot-Pressing Furnace Current Monitoring and Predictive Maintenance System in Aerospace Applications.

This research combines the application of artificial intelligence in the production equipment fault monitoring of aerospace components. It detects three-phase current abnormalities in large hot-pressing furnaces through smart meters and provides early preventive maintenance. Different anomalies are classified, and a suitable monitoring process algorithm is proposed to improve the overall monitoring quality, accuracy, and stability by applying AI. We also designed a system to present the heater's power consumption and the hot-pressing furnace's fan and visualize the process. Combining artificial intelligence with the experience and technology of professional technicians and researchers to detect and proactively grasp the health of the hot-pressing furnace equipment improves the shortcomings of previous expert systems, achieves long-term stability, and reduces costs. The complete algorithm introduces a model corresponding to the actual production environment, with the best model result being XGBoost with an accuracy of 0.97.

Effect of particle size on additive manufacturing of complex architecture of silicon carbide

The high-temperature stability, chemical inertness, and enhanced mechanical strength of SiC are utilized for the fabrication of space components. Here, environment-friendly water-based SiC ceramic inks were developed using different size SiC powders. The relation between the SiC particle size and rheological properties is established. The additive manufacturing conditions for SiC are optimized which shows the compressive strength of ∼1.21 MPa. This strength was obtained in the green state for SiC having an average particle size of ∼0.5 μm. As the milling time increases, particle size decreases which make better dispersion in the ink system and it shows good shear-thinning characteristics. The optimum sintering temperature (1400 °C) results in improved compressive strength of ∼80 MPa with a relative density of ∼81%. The current printing method can produce complex ceramic components which can be utilized for manufacturing complex aerospace components.

Rapid Printing of High-Temperature Polymer-Derived Ceramic Composite Thin-Film Thermistor with Laser Pyrolysis.

Polymer-derived ceramic (PDC)-based high-temperature thin-film sensors (HTTFSs) exhibit promising applications in the condition monitoring of critical components in aerospace. However, fabricating PDC-based HTTFS integrated with high-efficiency, high-temperature anti-oxidation, and customized patterns remains challenging. In this work, we introduce a rapid and flexible selecting laser pyrolysis combined with a direct ink writing process to print double-layer high-temperature antioxidant PDC composite thin-film thermistors under ambient conditions. The sensitive layer (SL) was directly written on an insulating substrate with excellent conductivity by laser-induced graphitization. Then, the antioxidant layer (AOL) was written on the surface of the SL to realize the integrated manufacturing of double-functional layers. Through characterization analysis, it was shown that B2O3 and SiO2 glass phases generated by the PDC composite AOL could effectively prevent oxygen intrusion. Therefore, the fabricated PDC composite thermistors exhibited a negative temperature coefficient in the temperature range from 100 to 1100 °C and high repeatability below 800 °C. Meanwhile, it has excellent high-temperature stability at 800 °C with a resistance change of only 2.4% in 2 h. Furthermore, the high-temperature electrical behavior of the thermistor was analyzed. The temperature dependence of the conductivity for this thermistor has shown an agreement with the Mott's variable range hopping mechanism. Additionally, the thermistor was fabricated on the surface of an aero-engine blade to verify its feasibility below 800 °C, showing the great potential of this work for state sensing on the surface of high-temperature components, especially for customized requirements.

Determining the laser absorptivity of Ti-6Al-4V during laser powder bed fusion by calibrated melt pool simulation

Additive manufacturing processes such as laser powder bed fusion (LPBF) are now routinely used for advanced medical and aerospace components. However, moving from these bespoke applications to high-volume commercial manufacturing requires higher levels of predictability and control of part properties. Detailed simulations of the LPBF process can assist this transition by providing understanding of defect mechanisms and guiding paths to improvement. An accurate value of laser absorptivity for the material is critical for LPBF simulation but the published literature contains surprisingly little absorptivity data applicable to actual LPBF operating conditions. Here we determine the in-situ laser absorptivity of the alloy Ti-6Al-4V during LPBF to be 0.27 +/- 0.03, for a laser wavelength of 1.07 μm. Our technique involves calibrating melt pool CFD simulations against single-track experiments conducted over a range of energy densities and can be extended to other materials. The simulations incorporate multiple laser reflections and cover the transition from conduction to keyhole mode. We also discuss physical mechanisms that may be responsible for changes in the absorption behaviour at high laser energy density which are observed in this and other work.

Compressive resistance of the bio-inspired cuttlebone-like sandwich structure under quasi-static load

Inspired by cuttlebone, this study proposes a bioinspired metallic sandwich structure with matrix material of Ti-6Al-4V prepared by selective laser melting method. The bioinspired cuttlebone-like sandwich (CLS) structure is evaluated in terms of compression resistance and energy-absorbing capacity, thereby examining the influential dimensional parameters and the underlying collapse mechanisms of the core of CLS structure which are asymmetrical corrugated walls. Then, Parametric investigation of CLS structure demonstrates that the amplitude of the asymmetrical corrugated walls plays a significant role in the compression performance compared with other structural parameters. Besides, the collapse analysis of the corrugated walls revealed that the local buckling around Y-direction followed by progressive folding is expected for high energy absorption. And the optimal design strategy for the CLS core is summarized. Moreover, bionic CLS structure is confirmed with high strength and great energy dissipation by experiment and simulation methods, and is validated superior to other typical sandwich structures. This CLS metallic structure shows the potential of applying in protective energy-absorbing components in aerospace, armament and medical industry. And this study can be conducive to the development of novel energy-absorbing structural metallic materials.

Experimental Estimation of Energy Absorbed and Impact Strength of Kevlar/Basalt-Epoxy Interwoven Composite Laminate Added with Al2O3 Nanoparticles after High-Velocity Bullet Impact

The use of composites has increased exponentially in most industries, especially in the aerospace industry; the usage of composites has increased by almost 40% in the last 15 years. Aerospace components are often subject to high-impact loads, so it is important to use impact-resistant materials. Kevlar is known for its high-impact resistance and is commonly used as a fiber with various resins to achieve the desired properties. This paper mainly focuses on weaving Kevlar with basalt fiber in plain weave type by the traditional handloom weaving method. The epoxy resin, along with the harder, is then mixed with the aluminum oxide nanoparticles (Al2O3) in different percentages [1%-KB1, 3%-KB2, and 5%-KB3] to form the matrix. The laminate fabricated is then subjected to the high-velocity bullet impact of around 250 m/s. A steel hemispherical head projectile was used in the testing, and it was found to be penetrated through all the specimens making holes. The impact strength for all the different specimens was then estimated by calculating the bullet damage area and energy absorbed. The plate added with 3% Al2O3 nanoparticle was found to have improved impact strength when compared with the other two specimens. This plate can be used for bulletproof and other high-velocity impact applications.

Prediction of cutting forces including tool wear in high-feed turning of Nimonic® C-263 superalloy: A geometric distortion-based model

The hottest parts of aerospace components are often made of heat-resistant materials. Due to the high requirements in such parts and accelerated wear rates, machining is a challenging task. Recently, new high-feed machining strategies were launched by tool developers. The main idea is ​​using extremely low side cutting edge angles Kr so that high feeds and low chip thicknesses are both possible. These tools are supposed to be decisive for greater productivity rates. However, tool wear’s traceability is the key in order to replace them before dramatic failure. Additionally, the machining of such aggressive materials must be assisted by high pressure cooling. To reduce the environmental footprint, cryogenic techniques look promising. This work proposes a prediction cutting model for high feed turning of Nimonic© C-263 superalloy including tool wear. It allows to consider the geometric tool deterioration, which is the key mechanism in the evolution of cutting forces on this superalloy. The concept of reducing side cutting edge angle and its benefit on productivity is also explored. Besides, oil emulsion and CO2 cryogenic conditions are also compared. The wear prediction model showed good agreement with the experimental results by obtaining relative errors of less than 5 % using cutting speeds lower than 100 m/min and less than 14 % for higher speeds. The benefit of reducing the side cutting edge angle on tool life 8 (from 90° to 30°) was also demonstrated by increasing tool life x3 (from 8 to 24 min). Notches were removed. In contrast, using cryogenic conditions do not seem to be a clear advantage over this type of superalloy. Finally, optimum conditions were found: using vc = 70 m/min, f = 0.2 mm/rev and = 1 mm, good surface finish, chip control and tool life can be satisfied.

Finishing the surface micro-layer of additively manufactured TiAl alloy using electro-thermal discharge assisted post-processing

Selective laser melting (SLM) of titanium–aluminium (TiAl) alloy components has gained significant attention in the modern industrial world. The flexibility of the SLM process in producing complex shapes with minimum utilization of material and energy makes it dominant over other manufacturing techniques. As aerospace and biomedical industries demand complex-shaped TiAl alloy components, part fabrication using SLM becomes the ultimate solution. However, the unacceptable level of surface integrity and anisotropic behavior of SLM components demand post processing operations such as laser polishing, chemical polishing, and conventional polishing methods. In this study, a recently developed polishing method called wire electrical discharge polishing (WEDP) is performed on TiAl alloys for obtaining a smooth and defect-free surface. This study aims to investigate the micro-layer modification occurring to the WEDP-processed surface in detail. The experimental results establish the effectiveness of WEDP method in terms of improved surface integrity. The surface finish (Sa) got enhanced by ~88% after WEDP processing. In addition, the thickness of recast layer formed by WEDP was found to be minimum. Moreover, post-processing of TiAl alloy resulted in better surface morphology specifically at lower settings of peak current. It is noteworthy that the migration of wire material was minimum with zinc-coated brass electrode compared to the normal brass electrode. Hence, coated wire electrodes are recommended for WEDP process. In short, an excellent surface integrity can be achieved using WEDP process through favorable surface modification aided by lower peak current and coated wire electrodes. Furthermore, less electrode wear observed in WEDP process enables the deployment of lower feed rates leading to minimal electrode consumption.

Digital Thread Roadmap for Manufacturing and Health Monitoring the Life Cycle of Composite Aerospace Components

This paper provides a detailed review of a digital thread for composite aerospace components. The current state of the digital thread continues to progress and at an ever-accelerating rate due to advancements in supporting technologies such as AI, data capture/processing/storage, sensors, simulation, and blockchain. While the individual steps that make up the digital thread have made manufacturing innovation and benefits possible, the connection points of the thread are not consistently solid, with many experiments and proof-of-concepts being conducted, but with few full digital threads in deployment. Key gaps include the ability to handle such large and continuous amounts of data, the infrastructure needed to capture and process them for insight, and the AI-based analytics to build and scale enough to obtain the expected exponential benefits for life cycle insight and manufacturing optimization. Though some of these gaps may take specific technology innovations to advance, there is a specific roadmap that can be deployed immediately in order to obtain “rolling ROI” benefits that will scale in value as this cycle is repeated across the product line.

Influence of preload on the tribological performance of MoS2/GO composite lubricating coating

Lubrication is one of the key factors to ensure the reliable operation of sliding parts for some critical components in aerospace. The most favorable lubrication performance of the lubricating film is always achieved after the initial period or the pre-running-in period. In this work, the influence of preloads varying from 0.5 to 15 N on the tribological performance of molybdenum disulfide/graphene oxide (MoS2/GO) composite lubricating coating was studied. It was found that the coefficient of friction (COF) during the running-in period decreased from 0.17 at 0.5 N to 0.14 at 5 N, and stabilized at 0.14 with further increasing the normal load, indicated that the optimal stable COF was obtained at 5 N and negligible changes when load is further increased from 5 to 15 N. In contrary to the widely reported coatings that their tribological results deteriorate at high applied loads, the MoS2/GO composite lubricating coating here exhibits much lower COF under higher loads, with the COF decreased from 0.14 at 5 N to 0.03 at 100 N. The results suggests that the preload had a positive effect on the tribological performance of the MoS2/GO composite coating, the COF of the composite coating decreased with the increase of the preload, which further improved the tribological properties and even achieved the optimized lubrication condition, and the optimum preload was equal to or slightly higher than the steady-state load. This work provides a guiding idea for the selection strategy of the preload for optimal tribological performance of the solid lubricating coating.

Comparison of differences between agro-waste sand mold additives effects on the hardness and microstructural views of recycled aluminum alloy cooling in various coolants

This paper described some mechanical properties of aluminum alloy using agro-waste materials such as sawdust, groundnut shell, and eggshell. The sand-casting method was adopted to produce the alloy with 5, 15, 25, and 35% wt. additives. The microstructure of the various samples produced after quenched in water, palm oil, and engine oil was examined while hardness properties were determined. The result obtained shows that hardness values increased with an increase in the addition of sand mold Agro-waste ashes. Samples cast with eggshell ash additive and quenched in water coolant had the highest hardness value of 82.4 at 25% wt. additive when compared with sawdust ash and groundnut shell ash additives. sand-casting enhances the hardness of the specimens and thus, can be used in many engineering applications such as engine blocks and wheels in automotive parts and aerospace components.

Refining microstructure of medium-thick AA2219 aluminium alloy welded joint by ultrasonic frequency double-pulsed arc

The increasing demand for achieving high-efficiency and high-quality medium-thick aluminium alloy welded structures, especially for large scale aerospace components, presents an urgent challenge to the conventional TIG arc welding process. This work proposed a novel double-pulsed variable polarity tungsten inert gas (DP-VPTIG) arc, in which the variable polarity square wave current was simultaneously modulated into ultrasonic frequency (20–80 kHz) and low frequency (0.5–10 Hz) pulses. Full penetration welds of 6 mm thick AA2219 aluminum alloy were successfully obtained by using this process. The microstructure and mechanical properties of the weld produced by DP-VPTIG arc were investigated, taking the conventional VPTIG arc as a comparative study. Results show that the microstructure of weld zone by DP-VPTIG arc showed an alternating distribution of fine equiaxed grain band and slightly coarse equiaxed grain band. Compared to VPTIG arc, the grain structure was effectively refined in the weld zone with DP-VPTIG arc, showing a significant reduction of average grain size by 51.2% along transverse section and 61.3% along longitudinal section. The morphology of α-Al+θ-CuAl2 eutectics transformed from continuously distributed netlike shape to separately distributed granular shape, and segregation of Cu solute element was obviously improved. The average microhardness of weld zone was increased by about 8.7% and 5.6% along transverse section and along longitudinal section. The tensile properties of ultimate tensile strength, yield strength and elongation were increased by 6.6%, 10.6% and 20.5%, respectively. The results provide a valuable basis for improving welding efficiency and joint quality through a hybrid pulsed arc.

Facile manipulation of mechanical properties of Ti-6Al-4V through composition tailoring in laser powder bed fusion

Ti-6Al-4 V alloy when processed by laser powder bed fusion (LPBF) is a useful material which can be used for the manufacture of complex 3D components for aerospace and medical applications. LPBF fabricated Ti-6Al-4 V typically shows high tensile strength (>1200 MPa) but poor ductility (<10%), explained by the characteristic microstructures that form under high cooling rates and multiple thermal cycles. Here, the composition of the feedstock Ti-6Al-4 V powder was modified via the addition of commercially pure Ti (CP Ti) to achieve improved ductility of LPBF parts through an in-situ modified composition, while maintaining good strength. The LPBF printed Ti alloy (with nominal composition Ti-3Al-2 V) showed a tensile strength of ∼1000 MPa, with improved ductility (∼13%), comparable to wrought Ti-6Al-4 V. These properties are thought to be explained by the decreased c/a ratio (where c and a are the lattice parameters of the titanium hexagonal close-packed phase) resulting in enhanced dislocation slip. Good relative density was also achieved using the modified composition under the same processing parameters. Some non-uniform regions were seen in the developed alloys, as well as evidence of increased martensite α′ thickness. It is proposed that with optimized parameters, further enhancements may be achieved. This work has shown that microstructural and mechanical properties can be facilely manipulated with proper CP Ti addition.

Dynamical analysis and vibration estimation of a flexible plate with enhanced active constrained layer damping treatment by combinatorial neural networks of surrogates

The effective estimation of the vibration of spacecrafts are frontier issues in the aerospace industry. But the vibration of aerospace components such as space solar panels and flexible manipulators under large overall rotating motion is usually very complex due to strong nonlinearity and often requires a lot of repetitive and burdensome calculations. Artificial neural network (ANN) is composed of interconnected neurons, and a surrogate model can be established to effectively predict the mechanical characteristics. In addition, the computational efficiency will be greatly improved if the object is changed from the model that is established by commercial finite element method (FEM) software or numerical calculations to the surrogates. However, the stochasticity of the estimation by single neural network is inevitable, and some neural networks much rely on the initial weight and threshold. This paper will implement a new combinatorial strategy that relies on multiple neural network models, which have different activation functions and regression feedback processes based on reasonable selection of sample points. To solve the elongated training time led by comparing these neural networks, genetic algorithm (GA) is used to optimize the iteration speed of one neural network when finding the optimal output value. Thus, better estimation accuracy will be achieved by designing an algorithm to combine these combinatorial neural networks of surrogates (CNNS). Based on the proposed method, the vibration estimation of a rotating flexible plate with enhanced active constrained layer damping (EACLD) treatment, and the vibration suppression capacity of the composite structure under various operating conditions will be investigated.

Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components, the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper. Firstly, the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine, and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing. Secondly, to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores, quasi-static and dynamic mechanical experiments were carried out. The primary evaluations of mechanical properties include secant stiffness, natural frequency, Specific Energy Absorption (SEA), vibration acceleration level, and so on. The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin. The axial gradient material has almost no influence on the vibration frequencies of the shell, whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin. Moreover, compared to the conventional sandwich shells, the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction, stiffness designing, and energy dissipation.

Short-Time Creep Deformation of the Coarse-Grained Nickel-Base Alloy 247 and Its Implications on the High-Cycle Fatigue Behavior

Abstract Cast polycrystalline nickel-base superalloys are typically used for critical high temperature aerospace and automotive components, such as turbine blades or turbocharger wheels. These high temperature components can undergo creep damage caused by, e.g., centrifugal forces on the turbine rotor blades, as well as high-cycle fatigue (HCF) from, for instance, vibrations of the rotor blade. Therefore, both, creep resistance and fatigue strength are important mechanical properties of these materials. The study presented here addresses the introduction of creep damage and its influence on the high-cycle fatigue behavior. For this purpose, fatigue specimens of coarse-grained Alloy 247 LC CC blade root material were prestressed on a pneumatic creep test rig to achieve creep-induced microstructural damage. The isothermal 900 °C short-time creep investigations below 1000 h test duration were performed at different tensile stresses which result in different strain rates. After the creep tests, scanning electron- and optical microscopy investigations of metallographic cross section of selected specimens were performed to determine the creep-induced grain boundary damage such as pore count, pore size, and coarsening of the γ' structure. This was followed by uniaxial, stress-controlled isothermal 850 °C high cycle fatigue tests on undamaged and predamaged specimens at a frequency of 10 Hz and a load ratio of R = −1. Subsequently, fractographic and cross section investigations, which provide information on the fatigue cracking, the failure initiating defects, and the pore morphology, were performed. The results of this study show that the degree of creep induced porosity is a dominant structural parameter for the HCF behavior of the investigated nickel-base superalloy.

Research Progress of Laser Additive Manufacturing Nickel-Based Alloy Metal Matrix Composites

Nickel-based alloy metal matrix composite (NAMMC) is a new type of composite material which is expected to replace traditional Nickel-base superalloy used in the manufacture of important hot-end components in aerospace, naval ships and industrial gas turbine engines due to its excellent high temperature strength, superior thermal fatigue resistance, high oxidation resistance and thermal corrosion resistance. However, these outstanding properties make it hard to process these materials with conventional manufacturing methods such as forging and machining owing to posing problems of high cost and energy consumptions. Laser additive manufacturing (AM) with a high degree of machining freedom and a high-energy-density laser beam as heat source has been used for processing NAMMC hot-end components with superior performance and complicated structure. Nevertheless, some manufacturing defects of poor bonding, high residual stress, cracking, pore etc. still exist in laser AM NAMMC parts. Therefore, this paper reviews research progress of laser AM NAMMC at present. The control method of manufacturing defect and the effect of reinforcements on the microstructure and mechanical properties of NAMMC are summarized. In addition, the challenges and prospects of laser AM NAMMC in the future are also discussed.

Optimization Process Parameters in Testing of Wear properties of Aluminium Alloy 6082

When the two materials are in contact in motion, wear rate of the materials taken an important role. Aluminium alloys used in many applications like automobile components, aerospace components, home appliances, machine tool components. Advanced aluminium alloys are used in aerospace components. In this project wear studies of advanced aluminium alloys are carried using pin-on-disc machine three processing parameters considered are Load, Time and Speed. Twenty seven samples ae been tested to find wear rate of aluminium alloys. A Taguchi method is applied to find optimization process parameters which are having minimum wear rate. Aluminium alloy 6082 has a medium strength and good corrosion resistance. It is the strongest alloy