Abstract:As competition in the aerospace field intensifies，both domestic and international entities have increased their efforts to develop the “crown jewel” of pressure vessels—made of liner-less fiber-wrapped composite materials （Ⅴ-type COPV）.The liner-less structure necessitates an integrated design that combines the sealing/shielding function of the composite material layers with structural load-bearing capabilities，presenting significant challenges in terms of material performance and structural design.This paper systematically reviews the structural design of Ⅴ-type COPVs，summerizes the latest research progress in their structural design.It focuses on functional barrier layers，morphology，interface design，and various analysis and optimization methods.The paper introduces a novel Ⅴ-type COPV configuration based on a modular design philosophy and provides insights into the future development of structural design for V-type COPVs in the aerospace industry.

Abstract:Space shuttle vehicles employ different thermal protection materials under varying conditions.This paper reviews five commonly used thermal protection materials：thermal protection coatings，thermal protection/structural integrated materials，thermal insulation tiles，flexible thermal protection materials，and honeycomb-reinforced ablation materials，summarizes their recent research progress，and offers recommendations for future development.Thermal protective coatings require further enhancement of resin high-temperature resistance；thermal protection/structure-integrated materials still face challenges in structural design，manufacturing，and failure mechanisms；insulating tiles need improved high-temperature mechanical performance and refined fabrication processes；flexible thermal protection materials，being foldable and adhesive，hold diverse application prospects；and honeycomb-reinforced ablative materials are lightweight and commonly used for large-area thermal protection on spacecraft.With the continual advancement of aerospace equipment，thermal protection materials are entering a major period of development.

Abstract:Carbon aerogel （CA） shows great promise for use in ultra-high-temperature thermal insulation materials due to its low thermal conductivity and thermal stability up to 3 000 ℃. However， it is prone to oxidation in oxygen-rich environments above 400 ℃， leading to a significant decline in performance. Therefore， improving its thermal insulation capabilities in oxygen-rich environments is essential. This paper addresses the challenge of applying carbon aerogel in high-temperature oxygen-rich environments. It conducts a comprehensive review of current research on carbon aerogel oxidation resistance both domestically and internationally. Through two aspects—matrix modification and coating modification—the paper thoroughly discusses existing research， existing shortcomings， and future trends in the field of carbon aerogel oxidation resistance， providing new insights and perspectives for carbon aerogel oxidation resistance research.

Abstract:In the future， high-precision loads impose stringent requirements on the dimensional stability of spacecraft structures.The sandwich structure of carbon fiber-reinforced polymer （CFRP） honeycomb is a new lightweight structural design with excellent thermal dimensional stability，capable of meeting the design requirements for load-bearing structures under such conditions.This paper reviews the current development status of CFRP honeycomb manufacturing methods.Based on the manufacturing processes and corresponding technology methods that influence the dimensional stability of CFRP honeycomb structures，the manufacturing methods are categorized into two main types：multi-step forming methods and integral forming methods.The technical advantages and disadvantages of various manufacturing methods are analyzed，and the technical challenges of new manufacturing methods are discussed.Finally，the future development direction of manufacturing technology for dimensionally stable CFRP honeycombs is explored.

Abstract:Thin-walled cylindrical structures were prone to buckling under axial compression. In this paper， the thin-walled cylinders made of glass/carbon fiber hybrid composites （G/CFHC） were taken as the object of study， six lay-up sequences were designed， and with the help of ABAQUS finite element analysis software， the effects of the position of the single-layer carbon fiber composite boards， the thickness of lay-ups， and the mixing ratio of the glass/carbon fibers on the buckling loads of the thin-walled cylinders made of G/CFHC were designed. The results show that under the same layup angle， the change of the position of the single-layer carbon fiber plate will lead to the change of the structural buckling load， and for the unidirectional layup of G/CFHC thin-walled cylinders， the influence on the buckling load is consistent， the maximum buckling load occurs in the single-layer carbon fiber plate located in the outermost layer， and the increase of the single-layer carbon fiber plate in the multi-directional layup even makes the structural buckling load decrease. For the different layup sequences of the thin-walled cylinders， the corresponding buckling load increases gradually with the increase of the layup thickness. When the thickness and the number of layers of the structure are certain， the increase of the single-layer carbon fiber composite and the reasonable change of the mixing method of the glass/carbon fibers will increase the buckling critical load of the structure and improve the stability of the structure.

Abstract:To improve the surface properties of 304 stainless steel， including superhydrophobicity， the material was subjected to femtosecond laser surface microstructuring and silane chemical modification. Scanning electron microscopy （SEM） was used to observe the structural morphology and overall condition after chemical modification， to determine the effect of different morphologies on hydrophobicity， and to analyze the correlation between the roughness of the femtosecond laser-processed microstructure and the contact angle. Simultaneously， performance tests were conducted on the superhydrophobic stainless steel to evaluate its superhydrophobic durability， corrosion resistance， self-cleaning ability， and wear resistance. Analysis and testing reveal that as the surface micro- and nano-structure roughness increases due to laser processing， the contact angle also increases. When the surface roughness reaches 1.75 μm， the hydrophobic angle achieves an optimal value of 154.9°. By calculating the corrosion rates of the two materials， it is found that the corrosion rate of the original stainless steel is 15 times that of the superhydrophobic stainless steel， and the corrosion resistance of the material has been significantly improved. The conclusions indicate that 304 stainless steel modified through surface treatment exhibits excellent superhydrophobic properties， superior corrosion resistance compared to the original stainless steel， and a good self-cleaning effect on the surface.

Abstract:The assembly process of aerospace components involved the machining of a large number of countersunk holes， with the depth of the countersunk holes being a critical technical parameter that required precise control， significantly impacting the quality of component assembly. Helical milling was a new method for drilling assembly holes that had emerged in recent years， and when combined with specialized tools， it could also be used for the machining of countersunk holes. Based on existing portable helical milling equipment， this paper proposed an automatic control method for the depth of countersunk hole machining. First， a spiral milling test platform was established to analyze the sources of error during the machining process. Then， through theoretical analysis and tool contact force measurement experiments， a functional relationship between the contact force and the feed motor torque value was established， and the optimal tooling parameters for machining with a milling and countersinking integrated tool were further determined. Finally， automatic tooling and countersinking machining experiments were conducted on titanium alloy test pieces， and the countersink depth was measured. The results show that the depth error of the countersunk holes after machining is controlled within 0.05 mm， meeting the design accuracy requirements of the components.

Abstract:A hybrid sizing agent containing polyamide-imide （PAI）-functionalized carbon nanotubes was prepared， and its effect on the interface aging resistance of carbon fiber/polyamide-imide （CF/PAI） composite materials was investigated. The results show that before thermal aging treatment， the interfacial shear strength （IFSS） and interlaminar shear strength （ILSS） of the hybrid sizing agent-modified CF/PAI composite are increased by 42.5% and 74.0%， respectively， compared to the unmodified CF/PAI composite. After thermal aging treatment， the IFSS and ILSS of the hybrid sizing agent-modified CF/PAI composite are further increased by 15.8% and 20.8%， respectively. Mechanistic studies reveal that the hybrid sizing agent effectively enhance the micro-interface thermal aging resistance of CF/PAI composites through factors such as chemical bonding， mechanical interlocking， and interfacial compatibility. The introduction of carbon nanotubes and the increase in the modulus of the matrix resin during thermal aging further improves the modulus and hardness of the interface region， thereby enhancing stress transfer efficiency and reducing stress concentration， which in turn improves the macro-interface thermal aging resistance of CF/PAI composites.

Abstract:To reduce the loss of materials due to material flying during the compounding process of insulating materials and the pollution of materials to the environment， combined with the feature that low-melting-point feeding bags of EVA and POE could be compounded together with raw materials and have no significant impact on the performance of insulating layer compounding rubber and vulcanized rubber within a certain usage range， the influence of low-melting-point feeding bags on the mechanical， ablation and vulcanization properties of EPDM insulating layer was studied. The test results show that as the amount of EVA or POE material increases， the torque difference and vulcanization rate index V_c of the insulation layer gradually decreases， and the process vulcanization time t₉₀ is prolonged.EVA or POE materials do not participate in the peroxide vulcanization reaction. With the increase in the amount of POE， the tensile strength and elongation rate at break of the insulation layer significantly increases， but the amount of EVA had no significant effect on the mechanical properties of the insulation layer. With the increase in the amount of POE or EVA materials， the ablation performance of the insulation layer do not change significantly.

Abstract:Based on the design requirements of solid engine thermal protection system and external heat protection materials，the thermal stability and ablation properties of the two external heat protection materials were tested and analyzed by taking the self-made epoxy-based and silicone rubber-based external heat protection materials in use as the research object，and the specific heat capacity，thermal conductivity，thermal diffusion coefficient，average linear expansion coefficient and other thermophysical properties，so as to obtain the thermal stability and ablation properties of the two external heat protection materials.The results showed that the matrix structure of the epoxy-based external heat protection material after ablation was relatively loose，and the carbon layer formed by the silicone rubber base external heat protection material was more dense.The thermal conductivity of epoxy-based and silicone rubber-based external thermal protection materials within 250 ℃ changed little with the increase of temperature， and they were at a low level.The thermal conductivity of the external heat-resistant material after ablation gradually increases with the increase of temperature， and the average linear expansion coefficient gradually decreases.Compared with the two external heat protection materials， the introduction of high-temperature resistant fibers and flame retardants in silicone rubber-based external heat protection materials requires higher thermal decomposition activation energy，improves the ablation resistance and erosion resistance of external heat protection materials，and can meet the higher heat flow environment. The study of thermal and physical parameters and ablation mechanism before and after ablation of external heat-resistant materials can guide the development of external heat-proof materials.

Abstract:With the development of launch vehicle heavy-duty，the weight of servo actuator increases due to the significant increase of its power level，and the traditional material and structural design methods have been difficult to further improve the power-to-weight ratio of the product.Carbon fiber composites have the advantages of low density， strong designability，high strength，high modulus，corrosion resistance，fatigue resistance，etc.，and have been widely used in aerospace field as large structural parts.Servo actuator as the key single machine of engine thrust vector control，its weight reduction is of great significance，domestic and foreign for carbon fiber composite actuator have carried out relevant research，but the domestic has not yet seen mature engineering applications.This paper focuses on the application characteristics of aerospace servo actuator，takes engineering application as the goal，and carries out relevant research in several aspects，such as structural design of carbon fiber composite actuator，pavement design and simulation，friction sub-surface enhancement and molding process method.The carbon fiber composite servo actuator prototype has been designed and manufactured，with a weight reduction of 49.2% compared with metal actuators of the same specification.The prototype has completed the relevant hydraulic tests，and its functional performance is comparable with that of the existing actuators，so it has a preliminary technical basis for engineering application.This research work has played a positive role in promoting the launch vehicle to enhance its capacity and reduce energy consumption.

Abstract:CQFP packaged devices were extensively applied in various aerospace electronic units， and their soldering quality directly impacted the reliability of the entire electronic system. This paper experimentally investigated the influence of different reinforcement methods for CQFP packaged devices on solder joint reliability. The results indicate that reinforcing the four corners of CQFP devices with EC-2216 epoxy adhesive satisfies the high-reliability soldering requirements of aerospace electronic products， making this the optimal adhesive method. Reinforcement of CQFP devices solely with GD414 silicone adhesive at the four corners exhibits inferior vibration resistance； therefore， silicone adhesive must be used to fill the gap between the printed circuit board and the ceramic body bottom or edges to enhance vibration resistance. However， when silicone rubber D04 completely encapsulates and fills the gull-wing leads of CQFP devices， lead stress cannot be relieved during temperature cycling tests， resulting in solder joint micro-void aggregation and cracking， thus significantly degrading thermal fatigue resistance. Therefore， when silicone reinforcement is applied to such devices， stress-relief regions must be provided around the leads. This study offers a valuable reference for the reinforcement techniques used in aerospace electronic products utilizing CQFP packaged devices.

Abstract:To address issues such as low detection accuracy，significant influence of human factors on detection results，and lack of intuitiveness in detection outcomes in manual inspection，this study employs ultrasonic pulse reflection technology to develop a manual ultrasonic visualization inspection technique based on high-speed camera recognition and localization.The research focuses on achieving high-speed image transmission， recognition and localization，and the development of C-scan display software，thereby establishing a manual ultrasonic visualization inspection system platform.The system is validated using carbon fiber-reinforced polymer （CFRP） specimens.The results indicate that the system has a fast image processing speed，with a detection speed of up to 200 mm/s；the system has high detection accuracy，capable of detecting defects larger than Φ2 mm in CFRP specimens，with a lateral position resolution of approximately 1 mm；the system is highly operable，widely applicable，and provides accurate，reliable，and intuitive results.

Abstract:The oxygen content of polysiloxane was characterized using the inert gas fusion infrared method， and the effects of moisture absorption， adsorbed oxygen， particle size， and sample weight on the oxygen content characterization results were analyzed. The results indicate that moisture absorption， particle size， and sample weight are the primary factors influencing the oxygen content characterization results. When the sample is dried， the particle size is <100 μm， and the sample weight is controlled within the range of 30~50 mg， the precision of the oxygen content characterization results for polysiloxane is <3%.

Abstract:C/SiC composites were multi-phase materials consisting of C fibers， SiC matrix， and a thermally decomposed carbon interface layer between the two. This paper analyzed and tested the microstructure and nano-mechanical properties of the fibers， matrix， and interface， thereby complementing the results of macro-mechanical property tests. Optical microscopy （OM）， scanning electron microscopy （SEM）， and energy dispersive spectroscopy （EDS） were employed to characterize the refined microstructure of the C/SiC cross-section. Nanoscratch testing was conducted to measure the hardness and equivalent modulus of representative regions. The results reveal that the C fibers in the C/SiC composite exhibit a “skin-core” structure， with a diameter of approximately 7 μm. The ring-shaped region within a 1.5 μm range of the outer layer has a hardness of （5.45 ± 0.28） GPa and a reduced modulus of （33.1 ± 1.4） GPa； the core region has a hardness of （6.85 ± 0.21） GPa and a reduced modulus of （33.8 ± 0.34） GPa. The SiC matrix comprises three forms： large matrix blocks distributed between fiber layers； small matrix blocks distributed around the large matrix blocks； and fine matrix particles distributed within individual fiber bundles and between different fiber strands. Due to the differing high-temperature pyrolysis environments experienced by these three types of matrix， there are significant differences in hardness and reduced modulus， with hardness values of （34.8 ± 2.64）， （23.6±2.27）， and （21.3±1.81） GPa， respectively， with reduced modulus of （210±19.7）， （165±8.58）， and （124±10.8） GPa， respectively. The interface layer thickness between C fibers and the SiC matrix is approximately 0.3 μm. Its mechanical properties exhibit significant variability， lying between those of the fibers and the matrix， thereby serving as a performance transition layer. Its hardness is （13.6 ± 3.03） GPa， and its reduced modulus is （99.3 ± 13.0） GPa.

Abstract:The corrosion critical relative humidity and corrosion kinetic properties of Mg-Gd-Y-Zn forged magnesium alloy in humid environment were investigated by scanning electron microscope observation， elemental analysis and corrosion weight gain measurement. The results show that （1） the critical relative humidity for corrosion of Mg-Gd-Y-Zn forged magnesium alloy is 40% to 45%， and the corrosion reaction of magnesium alloy starts to occur when the ambient humidity is ≥40%； （2） the activation energy of corrosion reaction of Mg-Gd-Y-Zn forged magnesium alloy is E_a=0.382 eV， and the accelerating constants of the corrosion of magnesium alloy with different relative humidity are m=3.54702.

Abstract:Addressing issues such as inconsistent preload and short-term relaxation in bolted connections，this study focused on composite bolted connection structures.Based on the formation mechanism of preload in conventional bolts，the principles of preload generation in high-lock bolts was analyzed，deriving the torque-preload relationship for high-lock bolts.Through bolt tightening tests，the study determined key parameters such as locking torque，breakaway torque，and fitted the torque-preload relationship curve for high-lock bolts.Single-factor experiments were designed to analyze the effects of tightening speed，lubrication conditions，and tightening steps on the consistency of bolt connection preload.The tests show that tightening speed and lubrication conditions have a significant impact on the consistency of bolt preload force.Higher tightening speeds and the application of lubrication can achieve greater preload force， but the consistency of preload force deteriorates.To address the issue of short-term preload decay after bolt tightening，a 48 h natural relaxation test was designed to investigate the natural relaxation patterns of bolt preload in composite laminated structures under various conditions such as tightening speed， lubrication conditions，and tightening steps.The results indicat that lubrication conditions have the most significant impact on the natural relaxation of bolt preload in composite laminated structures.