Aerospace Fields Research Articles

Data-driven design of novel lightweight refractory high-entropy alloys with superb hardness and corrosion resistance

AbstractLightweight refractory high-entropy alloys (LW-RHEAs) hold significant potential in the fields of aviation, aerospace, and nuclear energy due to their low density, high strength, high hardness, and corrosion resistance. However, the enormous composition space has severely hindered the development of novel LW-RHEAs with excellent comprehensive performance. In this paper, an machine learning (ML)-based alloy design strategy combined with a multi-objective optimization method was proposed and applied for a rational design of Al-Nb-Ti-V-Zr-Cr-Mo-Hf LW-RHEAs. The quantitative relation of “composition-structure-property” was first established by ML modeling. Then, feature analysis reveals that Cr content greater than 12 at.% is a key criterion for alloys with high corrosion resistance. The phase structure, density, melting point, hardness and corrosion resistance of the alloys were screened layer by layer, and finally, three LW-RHEAs with superb hard and corrosion resistance were successfully designed. Key experimental validation indicates that three target alloys have densities around 6.5 g/cm3, and all alloys are disordered bcc_A2 single-phase with the highest hardness of 593 HV and the largest pitting potential of 2.5 VSCE, which far exceeds all the literature reports. The successful demonstration in this paper clearly demonstrates that the present design strategy driven by the ML technique should be generally applicable to other RHEA systems.

Design and experimental evaluation of a compact inchworm piezoelectric actuator with bridge-type displacement amplification mechanism

Abstract Miniaturization is an important direction in piezoelectric actuator research, with related efforts focusing on reducing structural complexity and simplifying guiding mechanisms. However, some actuators experience backward movement after miniaturization design. There remains significant room for improvement in mechanism configuration and the design of flexible amplification mechanisms to further reduce actuator size. In this paper, a compact inchworm actuator with bridge-type displacement amplification mechanism (BTDAM) is proposed, which does not require an additional guiding mechanism and adopts a three-dimensional packaging approach with high space utilization and a compact amplification mechanism. Because the output capacity of the BTDAM significantly impacts the operating performance of the actuator, mathematical modeling and simulation analysis are conducted. Compared with the experimental results of the amplification ratio of the BTDAM, the error of the theoretical model was 5.05%, and that of the FEM analysis was 9.1%. The dimensions of the prototype are 23 × 23 × 19 mm, and it weighs 23 g. The test results indicate that the proposed actuator can achieve stable stepping motion without backward movement. Under a voltage of 75 V, the proposed actuator achieves a maximum motion speed of 384 μm/s and a maximum output force of 1.7 N. With its compact structure and light weight, the proposed actuator shows promising application prospects in the aerospace and bioengineering fields.

Raising the Oxidation Resistance of Low-Alloyed Mg-Ca Alloys Through a Preheating Treatment in an Argon Atmosphere

With the rise and development of aerospace, communications, electronics, medical, transportation and other fields, magnesium (Mg) and its alloys have attracted much attention for their high specific strength and stiffness, good electromagnetic shielding properties, excellent damping properties and other advantages. However, magnesium has a high affinity for oxygen, producing magnesium oxide (MgO), and MgO’s Pilling–Bedworth ratio (PBR) of 0.81 is not protective. The occurrence of catastrophic oxidation is unavoidable with the increase of oxidation time and temperature. A promising approach is to perform an appropriate pretreatment in conjunction with alloying to obtain a dense and compact composite protective film. In this work, the effect of a preheating treatment on the oxidation resistance (OR) of Mg-xCa (x = 1, 3 and 5 wt. %) was investigated. The preheating was carried out in an Ar atmosphere at 400 °C for 8 h. Upon it, a dense and compact MgO/CaO composite protective film was formed on the surface, which is CaO-rich especially in the vicinity to the surface. The alloys’ oxidation resistance was strongly increased due to the composite protective film formed during the preheating treatment, in particular for Mg-3Ca. Relative to the Mg-hcp phase, the OR of the Mg2Ca phase was significantly raised.

Flexible Inverse Opal Structural Color Films with High Strength and Harsh Environment Stability.

Flexible photonic crystals (PCs) constructed by PCs and special polymers are very promising to achieve a combination of vivid structural colors, mechanical robustness, and environment stability. However, PCs that incorporate polymer binders are still susceptible to destruction and subsequent loss of structural color when subjected to significant external forces or harsh environments. Besides, because most of these polymers are highly flammable, crucial fire safety is difficult to be guaranteed in the application of these materials. In this study, we report a poly(m-phenyleneisophthalamide) inverse opal (PMIA IO) structural color film through a SiO2 PC template sacrificing method. Benefiting from the high rigid PMIA molecular structural configuration, the PMIA IO films are able to maintain their structural colors even in harsh conditions, such as large tensile stress, high and low temperatures, potent acids and bases, and ultraviolet radiation. More attractively, the PMIA IO films demonstrate excellent flame retardancy, with the limiting oxygen index (LOI) and flame retardant rating reaching 28 vol % and V0, respectively. We believe that the flexible structural color films with high strength, harsh environment stability, and flame retardancy, which are difficult for other structural color materials to possess simultaneously, have great potential for special applications in fire protection, national defense, aviation, marine, and aerospace fields.

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.

Analysis and Design of a Recyclable Inductive Power Transfer System for Sustainable Multi-Stage Rocket Microgrid with Multi-Constant Voltage Output Characteristics—Theoretical Considerations

After a traditional one-time rocket is launched, most of its parts will fall into the atmosphere and burn or fall into the ocean. The parts cannot be recycled, so the cost is relatively high. Multi-stage rockets can be recovered after launch, which greatly reduces the cost of space launches. Moreover, recycling rockets can reduce the generation of waste and reduce pollution and damage to the environment. With the reduction in rocket launch costs and technological advances, space exploration and development can be carried out more frequently and economically. It provides technical support for the sustainable use of space resources. It not only promotes the sustainable development of the aerospace field but also has a positive impact on global environmental protection, resource utilization, and economic development. In order to adapt to the stage-by-stage separation structure of the rocket, this paper proposes a new multi-stage rocket inductive power transfer (IPT) system to power the rocket microgrid. The planar coil structure is used to form wireless power transfer between each stage of the rocket, reducing the volume of the magnetic coupling structure. The volume of the circuit topology structure is reduced by introducing an auxiliary coil. An equivalent three-stage S/T topology is proposed, and the constant voltage output characteristics of multiple loads are analyzed. A multi-stage coil structure is proposed to supply power to multiple loads simultaneously. In order to eliminate undesired magnetic coupling between coils, ferrite cores are added between coils for effective electromagnetic shielding. The parameters of the magnetic coupling structure are optimized based on the finite element method (FEM). A prototype of the proposed IPT system is built to simulate a multi-stage rocket. A series of experiments are conducted to verify the advantages of the proposed IPT system, and the three-stage rocket system efficiency reached 88.5%. This project is theoretical. Its verification was performed only in the laboratory conditions.

Study on micro-grinding mechanism and surface quality of hardened 20 vol% SiCp/Al composites

Particle-reinforced aluminum-based silicon carbide composites (SiCp/Al) are widely used in aerospace, rail transit, and other fields due to their excellent comprehensive properties. However, the incorporation of high-brittle SiC particles poses challenges in the high-performance processing of SiCp/Al composites. This study focuses on hardened 20 vol% SiCp/Al composites, establishing two-dimensional finite element cutting models for single SiC particles. Micro-grinding experiments are conducted under various processing parameters. The influence law of surface defects on individual SiC particles relative to tool position and single factor machining parameters was analyzed, revealing the micro-grinding mechanisms affecting surface and subsurface quality. The results show that the interaction among particle damage mechanisms, crack propagation directions, and the restraining effects of the Al matrix leads to diverse types of defects at different cutting positions. Both simulation and experimental observations reveal surface defects such as pits, gullies, and burrs, while subsurface damage primarily results from crack invasion, cavity interstices, and pits due to particle breakage. The experiment achieved a minimum roughness of 0.057 μm. Taking into account the thermal softening of the material and the micro-behavior of the tool-chip interface, optimal conditions for improved surface quality involve a grinding depth of 0.03 mm, a spindle speed of 12,000 rpm, and a relatively low feed rate.

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.

Preface

In order to promote academic exchanges and cooperation in aerospace and mechanics and share the latest research results and cutting-edge technologies, we gathered in Shenyang, China during 12th to 14th July 2024, to usher in the 2024 International Conference on Aerospace and Mechanics (ICAM 2024). This Proceedings of ICAM 2024 gathers the wisdom of top scholars, experts and business elites from all over the world, aiming to provide a high-level and internationalized communication platform for the participants. The conference aimed to stimulate innovative thinking and promote the development of the discipline through an in-depth discussion of the latest advances and challenges in the field of aerospace and mechanics, and to contribute to the prosperity of the global aerospace industry. It was organized with keynote speeches, oral presentations, poster presentations, and academic investigation, attracting more than 150 delegates around the world. The technical program hosted by Hui Li (Chairman of this year’s conference, Professor of Northeastern University) actually started on the morning of July 13th with an opening speech by Aiping Zhang (Dean of the School of Mechanical Engineering, Northeast Electric Power University). And then, 16 experts and scholars from home and abroad, including Bangchun Wen (Academician of Chinese Academy of Sciences, Professor of Northeastern University), Ramesh K. Agarwal (IEEE Fellow, Professor of Washington University in St. Louis, USA), Hui Ma (Professor of Northeastern University), Jin Zhou (Professor of Xi’an Jiaotong University), Zhongwei Guan (Professor from Advanced Materials Research Center, Technology Innovation Institute, UAE), among others, gave presentations to share the achievements of scientific research and innovation in different fields. They provided in-depth analysis and sharing on cutting-edge hotspots such as aerospace technology, aerospace mechanics, new materials and structures, aerodynamics, fluid mechanics, vibration and noise control. In addition, the conference also set up special seminars to discuss the current hot issues in the field, providing participants with opportunities for in-depth exchanges and collision of ideas. ICAM 2024 came to an end on the afternoon of July 14th and was indeed very successful! National and international leading scientists and researchers have gathered at the conference and created a stimulating scientific atmosphere for themselves and for the young scholars. And the conference has promoted the development and application in the fields of and related to aerospace and mechanics, as well as fostered the industrial cooperation of academic achievements. List of Committee Member is available in this Pdf.

Droplet trampoline surface for regulating contact time of a bouncing droplet across a wide spectrum of Weber numbers verified by in-situ observation

The dynamic superhydrophobicity of metallic surfaces is crucial for anti-icing and anti-adhesion in the fields of aerospace and transportation. Generally, fabricating micro/nanostructures on metallic surfaces is an effective method for facilitating rapid detachment of droplets, and the micro/nanoscale composite structure can significantly reduce the solid–liquid contact area. Meanwhile, the exploration of the correlation between solid–liquid contact time and the spacing of microstructures across a wide range of Weber numbers is of great significance. In this study, it is observed that the contact time of a bouncing droplet on microstructures with small spacing exhibits a notable correlation with the Weber number. This observation challenges the prevailing understanding that the contact time of a bouncing droplet is commonly perceived as independent of the Weber number, equated to the impact velocity. Increasing the structure spacing appropriately proves advantageous in preventing pinning effect, consequently reducing the duration of solid–liquid contact. Subsequently, a regulatory diagram is generated to demonstrate the correlation between contact time and the dual dimensions of the structure spacing and Weber number. Specifically, a novel theory for predicting the contact time based on the Weber number has been established, which reveals the unconventional correlation and enriches the knowledge of droplet dynamics.

A new type of arc-plate flexible driving foot stick-slip piezoelectric actuator

Abstract Because of its high precision and high speed, stick-slip actuators in piezoelectric actuators have important research significance in aerospace and other fields. To make the performance of the actuator superior, a high-performance stick-slip actuator suitable for the aerospace field is developed. In this paper, based on the in-depth study of the related theories, a kind of arc-plate flexible driving foot is proposed. On this basis, a kind of arc-plate flexible driving foot stick-slip piezoelectric actuator is designed to further improve the performance of the actuator. After the test, its maximum speed can reach 4.12 mm/s, and the maximum load is 330 g.

Free vibration analysis of rectangular plates resting on an elastic foundation

Abstract Rectangular plate on elastic foundations is a common structural form in aerospace fields, while there still lacks a general analytical method for free vibration analysis of this kind of structure. Thus, the extended separation-of-variable method is used to obtain the analytical free vibration solutions for plates with all kinds of homogeneous boundary conditions. The mode functions are assumed to be in separation-of-variable form, and the natural frequencies of two-direction mode functions are mathematically independent. Then, the free vibration solutions are obtained according to the two-direction boundary conditions. The correctness of the present results is verified via numerical comparisons. Parameter study shows that the elastic foundation significantly affects the flexural vibration behaviors of rectangular plates, and the influence is dependent on boundary conditions and mode orders of rectangular plates.

Experimental study on the thermal insulation performance of semi-transparent materials based on convection heating method

Radiation heat transfer inside the aerogel materials belongs to medium radiation, so different heating methods have different measurement results of thermal conductivity. For aerogel materials applied in high temperature air flow environment (aerospace field), since the real boundary conditions of aerogel materials during operation can be simulated by convection heating method (CHM), the combustion-gas wind tunnel device based on two-stages atomization, two-stages combustion/mixing mode is constructed, and the performance test is conducted. The operation safety and combustion performance of the device meet the test requirements, so the thermal conductivity test of aerogel materials can be carried out. When the average temperatures are 469 K, 622 K and 763 K respectively, the effective thermal conductivity (ETC) measured by the CHM is smaller than that measured by the thermal conduction heating method (TCHM), which decreases by 2.7 %, 7.84 % and 9.23 % respectively. The CHM solves the limitations of the TCHM, so the ETC of aerogel materials measured by CHM is more valuable for the design of thermal protection system.

The properties of axion with three different sets of parameters in two flavor Nambu-Jona-Lasinio model

Abstract While the properties of axions have been studied primarily through high-energy physics and cosmology, there are some potential connections between the research results and the aerospace field. We study the properties of axions in hot and dense matter with three different sets of parameters in the Nambu-Jona-Lasinio model, including axion mass and self-coupling. We discussed axion mass and self-coupling, noting that axion properties are very sensitive to chiral phase transitions for three sets of parameters. The axion mass and self-coupling rapidly decrease in the chiral crossover region. The value of self-coupling becomes very sharp, appearing as a kinklike feature in the chiral phase transition.

High cycle fatigue properties of Ti-48Al-2Cr-2Nb alloy additively manufactured via twin-wire directed energy deposition-arc

Recently, additive manufacturing for titanium aluminide has received sustained attention. Considering the extensive applications on low pressure turbine blades in aerospace field, dynamic mechanical properties of titanium aluminide, especially the fatigue properties, are of great importance. In present work, fatigue test at ambient temperature was conducted for the first time on twin-wire directed energy deposition-arc (TW-DED-arc) fabricated Ti-48Al-2Cr-2Nb alloy with equiaxed lamellar colonies. More detailed researches on fatigue fracture characteristics and deformation modes are also investigated. The experiment results indicate that TW-DED-arc fabricated Ti-48Al-2Cr-2Nb alloy exhibits flat S–N behavior with a good resistance to fatigue. Fatigue life fluctuates widely at same stress level, but such fluctuations gradually weaken as stress decreases. Furthermore, γ/α2 interface and lamellar colony boundary as well as special microstructures of as-fabricated Ti-48Al-2Cr-2Nb alloy are weak areas during fatigue process, which easily become crack nucleation sites. As stress level decreases, deformation mode of as-fabricated Ti-48Al-2Cr-2Nb alloy translates from twinning and dislocation slip to predominantly dislocation slip. In general, these findings provide an important reference for engineering applications of titanium aluminide.

Microstructure and crack propagation behavior of 2195 aluminum lithium alloy with different orientations in the friction stir welding nugget zone

The 2195 aluminum-lithium alloy is widely used in the aerospace field, where using friction stir welding technology can achieve lightweight and reduced wear designs for components. Fatigue failure, as one of the main modes of damage affecting the life and reliability of structural components, is particularly significant. This paper thoroughly explores the differences in microstructure and fatigue crack propagation behavior between the advancing side and retreating side of the friction stir welded joint in different sampling directions, providing a theoretical basis for enhancing the fatigue performance of friction stir welds. Characterization of the microstructure of the samples was performed using Electron Backscatter Diffraction (EBSD) and X-Ray Diffraction (XRD), and the fatigue properties were investigated using fatigue crack propagation rate curves and crack growth rate curves. The results indicate that the longitudinal base material grains tend to a fibrous structure, while the axial base material grains are distributed in a lamellar fashion. Compared to the advancing side of weld nugget zone, the retreating side of weld nugget zone has significantly reduced grain size and texture types. The fatigue performance of the retreating side of the weld nugget zone is superior to that of the advancing side, and the circumferential welds outperform the longitudinal welds in terms of fatigue performance.

Analysis of mechanical properties of single crystal copper under low-temperature indentation test

Abstract As a common superconducting material in the aerospace field, the mechanical properties of single-crystal copper at low temperatures have attracted much attention. Combined with the current low-temperature nanoindentation test technology and the research status of micromechanical properties of crystal copper at home and abroad, this paper puts forward the low-temperature nanoindentation test on single-crystal copper. It analyzes the changes in mechanical properties of the low-temperature environment by indentation curve. Before the formal test, we first analyzed the Oliver-Pharr micro and nanoindentation test theory and described briefly the advantages of using nanoindentation to test the mechanical properties. The final test results show that in the temperature range of 300K~150K, the hardness and elastic modulus of the single-crystal copper increase with the decrease in temperature. The lower the temperature is, the faster the increase of hardness and elastic modulus is. At the same temperature, the hardness and elastic modulus of single-crystal copper with three crystal faces are (111) > (110) > (100). The mechanical properties at low temperatures are effectively reflected by means of low-temperature nanoindentation, which can be used to guide the production of materials in real life.

Optimization of Composite Wheel Fender for Manned Lunar Vehicle

Abstract Weight reduction is the eternal theme of aerospace optimization. In the process of weight reduction, the main ways are material change, structural change, and processing method change. In the process of aerospace structure design, the boundary and load conditions are more complicated, which restricts the development of optimization technology in the aerospace field to some extent. At present, the research object of optimization technology in the aerospace field is mainly the large parts of the aerospace craft, and the structural optimization of small aerospace parts is rarely involved. Therefore, the research of structural optimization design method has important theoretical and engineering significance. A complete optimization design process is proposed, the structural performance of aviation products is simulated by finite element software, and the feasibility of the optimization theory is verified. This article mainly compares several schemes for weight reduction design of composite material wheel fenders in the process of design.

Design and application of inertia switch with the zero-time trigger sensor for projectile overload impulse

The paper introduces a novel inertial trigger sensor featuring a multi-layer stacked single-arm brass beam pendulum, aimed at applications in automotive and aerospace fields, etc. It employs the Lagrangian equation for dynamic modeling and finite element analysis to achieve precise inertia force measurements. The design incorporates advanced fabrication techniques and a high-precision latching mechanism that combines circuit self-locking with mechanical triggering. Validated through simulations and testing, The results of the live ammunition tests indicate that, apart from failures of the Inertia Switch due to errors in the manufacturing process, all other inertial switches functioned normally. This demonstrates that the inertial sensor provides an adjustable trigger time of 0–5 ms and reliably withstands extreme overloads of up to 15000 g. This work significantly enhances the performance of inertial sensors in high-stress environments.

Multi-scale structure and reinforcement mechanisms of multi-element composite ceramic coatings

Ceramic coating is of significant importance for improving metallic materials in terms of mechanical properties or durability, which is commonly encountered in the field of machinery, civil engineering, and aerospace, etc. However, ceramic materials optimization is a great challenge due to the complex multi-scale design from atomic to macro level. This paper investigates the multiscale characteristics of multi-element composite ceramic coating, including electronic properties, 3D pore structure, and engineering performances and gives their bottom-up connections, via first-principles calculations and multiscale experiments. The doping of Ti, Zr, and Ce in the alumina-based ceramic crystal improves the overlap of electronic clouds between oxygen and metal atoms, which modifies the atomic charges and enhances the ionic bonding. In terms of microstructure, it reveals the mechanisms of phase transformation toughening effect of ZrO2 and the grain refinement and grain boundary purification effects of CeO2, which facilitates the amelioration of pore structure and macro mechanical properties. It provides multiscale information on the phase stability of multi-element alumina-based ceramics, shedding light on the fundamental atomic level mechanisms that play a crucial role in customizable functional designs