Abstract:

Optical metamaterials generally refer to artificial composite structural materials that achieve optical properties not possessed by traditional materials through the artificial design of sub-wavelength structural units.In the ultraviolet，visible or infrared bands，the permittivity and permeability of optical matematerial can break through the limit constraints of traditional materials.And optical materials are expected to show great application potential in aerospace fields such as detection，communication，stealth，power，and thermal control.This paper mainly elaborates on the important subsystems of aerospace equipment and then proposes possible future application scenarios of optical metamaterials.And then，the research progress of optical metamaterials in the face of these application scenarios are summarized.

Abstract:

Aiming to realize the optimal design and automatic forming of the conical composite oblique grid structure，the differential geometry method was applied，and combined with engineering applications，a comparative design was carried out on the conical composite oblique grid structures with equal-pitch spiral ribs，equal-helix-angle spiral ribs and geodesic spiral ribs that were easy for automatic forming，and a skinless conical composite hybrid triangular grid satellite support was designed.The corresponding relationship between two types of geodesics was given，thereby simplifying process and reducing costs.Aiming at the problem that the equal-thickness winding of the skin could not be achieved by the equal-pitch spiral trajectory，equal-helix-angle spiral trajectory and geodesic trajectory，a winding forming scheme combining the dense spiral trajectory on the conical surface as the main part with the geodesic trajectory was proposed to realize the automatic laying of the skin with equal thickness for the conical composite oblique grid structure.The conical composite oblique grid structure has met the design and production conditions，and process forming tests can be carried out in combination with engineering applications.Different forms of composite grid structures can be optimized for different application scenarios to ultimately achieve the optimal application effect.

Abstract:

Combined with engineering applications，a comparative calculation was conducted on the strength of the grid structures with equal-pitch spiral ribs，equal-helix-angle spiral ribs and geodesic spiral ribs on cone section.The results show that under the condition of identical grid structure parameters，the load bearing capacities of three spiral rib grid structures are roughly equivalent.Therefore，the forming process can be selected based on engineering practice from the perspectives of simple process and low manufacturing cost.Taking advantage of the characteristics of non-planar curves of the conical spiral and the ellipsoidal geodesic，the fiber tow winding trajectories of the double-head closure composite grid structure with geodesic spiral ribs are accurately calculated，which realizes the continuous and automated winding forming of fiber tows without overlapping or omission，improves the forming quality and consistency of the structure，and enhances the quality and load-bearing capacity at the nodes.The calculation of the fiber tow winding trajectories for two opposite large-end composite grid structures with geodesic spiral ribs save materials and improve production efficiency.

Abstract:

A comparative design was carried out on the aluminum alloy forming devices for the grid structures with equal-pitch spiral ribs，equal-helix-angle spiral ribs and geodesic spiral ribs on the conical section. The three-dimensional conical surface was developed into a plane， and the development law of the conical spiral was studied simultaneously. The three-dimensional aluminum alloy grid mold was converted into a planar silicone rubber grid mold， which was formed by planar casting and then attached to the conical surface， thereby further reducing the research and development costs. The design problem of the forming device for the conical composite grid structure was solved through the design of aluminum alloy and silicone rubber grid molds. Combined with the engineering application scenarios and the characteristics of the aluminum alloy male molds and silicone rubber grid molds for the three types of conical section grid structures， the selection and application methods for various grid molds were proposed. The problem of variable satellite interface dimensions is addressed by adopting shared technologies， which accelerate the production schedule， reduce costs and enhance the commercial competitiveness of the conical composite oblique grid satellite support. The designed and manufactured forming devices are applied to the forming of the corresponding composite structures， achieving excellent results， and pass the flight test verification and attained a complete success.

Abstract:

To further reduce costs and lighten the structural mass of forming equipment for facilitating process forming， the aluminum alloy grid mold was combined with the flat-cast silicone rubber grid mold and upgraded to a three-dimensional cast silicone rubber grid mold for the conical composite oblique grid structure， which enables low-cost automated winding forming while meeting winding precision requirements. The fiber tow winding trajectories for double-head closure of the geodesic spiral rib composite grid structure with two pieces opposite to the large end via elliptical geodesic transition were calculated with high precision， thereby making the automated continuous winding smoother and more stable， as well as saving materials and improving production efficiency. High-efficiency automatic continuous cyclic winding was realized， and a braided effect was achieved at the nodes. Flat silicone rubber grid strips for resin absorption and compaction were prepared to further improve the structural quality of the ribs and nodes. The formed structural components have passed various tests and can be applied in practical engineering.

Abstract:

To address the problems of large curing deformation and residual stress in the rotating shell structures of carbon fiber composites applied in the aerospace field，this paper established a three-dimensional finite element model for analyzing the curing process of composite rotating shell structures，and predicted the curing deformation and residual stress of the structures.A method for the optimal control of curing process and post-curing process parameters was proposed，and the curing process curve of the structures was optimized and designed.Under the standard curing system，the predicted results of the maximum residual stress and curing deformation of the composite shell structure are 409.12 MPa and 335.9 μm，respectively.Based on the established finite element model，the influences of various process parameters on the maximum residual stress and curing deformation of the structure are analyzed.Furthermore，combined with the analysis results of each process parameter， the combined optimization of curing process parameters is completed.Under the conditions of the obtained optimal curing process scheme，the maximum residual stress and deformation of the structure are 325.11 MPa and 295.1 μm，respectively，which are reduced by 20.53% and 13.21% compared with the standard curing system.

Abstract:

In order to reveal the structural evolution process of hollow glass microsphere（HGM） at high temperature，and further grasp the thermal ablation mechanism of HGM in composites at high temperature，SEM，TG and EDS were used to characterize the micromorphology，thermal weight loss and distribution of elements of HGM heated at 500~1 400 ℃.And HGM reinforced EPDM composites were prepared，and the ablation rate and microstructure of carbonated layer were characterized by oxyacetylene ablation test and SEM.The results show that the chemical properties of HGM are stable within 1 400 ℃，and the weight loss rate，element composition and distribution are basically the same as the initial properties.After heating at 500~700 ℃，HGM appears broken，and with the increase of temperature and time，the broken rate increases.The high temperature breakage resistance of HS46 and HS38 is better than that of HS22.With the further increase of temperature，the melt first transforms into porous structure and then into non-porous dense melt.In EPDM composites，HGM is broken under the action of oxyacetylene flame and a large number of small diameter microspheres appeares.Under the effect of efficient heat insulation of the carbonized layer，the HGM on the back of the carbonized layer is basically a complete sphere structure，but part of it shrinks and wrinkles at high temperature；HGM effectively reduces the linear ablation rate of EPDM composites by about 20%~30%，and the smaller the particle size，the more obvious the effect.

Abstract:

The effects of high-temperature treatment （HTT） processes with different parameters on the corrosion resistance of high-alloyed AlZnMgCu alloys were investigated by means of hardness testing， conductivity testing， exfoliation corrosion testing， and bright-field observation via transmission electron microscopy （TEM）.The results show that the optimal HTT temperature for high-alloyed AlZnMgCu alloys is 445 ℃. For the Al-Zn8.33-Mg2.08-Cu2.45 alloy， the optimal HTT process is as follows： solution treatment at 470 ℃ for 1 h → holding at 445 ℃ for 45 min → quenching → aging at 120 ℃ for 18 h → quenching.Compared with the conventional single-stage aging process， this process only adds an HTT step after the solution treatment， but it can significantly improve the corrosion resistance of high-alloyed AlZnMgCu alloys. This research can provide a theoretical basis for the industrial production of high-performance， corrosion-resistant high-alloyed AlZnMgCu alloys.

Abstract:

Through tensile shear test of the aerospace adhesive J-47， the effects of factors such as base adhesive air-drying time， curing pressure， adhesive film moisture absorption， heating rate， and bagging method on bond strength were systematically studied. Results indicate that the air-drying time of primer with 35%~45% solids content has negligible impact on the tensile shear strength of medium-temperature cured adhesive film specimens， rendering it unsuitable for characterizing the bonding performance of large-area honeycomb sandwich structural components. With the increase of curing pressure， the tensile shear strength of specimens first rises， then stabilizes， and finally decreases. The maximum tensile shear strength is achieved at curing pressures between 0.15 and 0.3 MPa. The tensile shear strength of the specimens decreases with increasing moisture ingress time into the adhesive layer before stabilizing. At a moisture content of 1.47%， the tensile shear strength reaches its lowest value， decreasing by 20.78% compared to the initial state. Selecting appropriate additives and controlling the heating rate within the range of 0.5~3 °C/min can yield high tensile shear strength.

Abstract:

Using different continuous rolling speeds， small-diameter TC4 titanium alloy bars were heated and rolled in the α+β two-phase region. The effects of continuous rolling speed on the microstructure and properties of TC4 titanium alloy bars were analyzed under identical rolling temperatures and deformation rates. Results indicate that the selection of continuous rolling speed directly influences the microstructure and mechanical properties of TC4 bars. As rolling speed increases， primary α grains exhibit a pronounced tendency toward equiaxed refinement. However， when rolling speed exceeds a critical threshold， phase transformation occurs in the bar core， forming Widmanstätten structure， which subsequently degrades the mechanical properties of the bars. TC4 bars are rolled below this critical speed exhibit a uniform， fine-grained primary α+β two-phase work-hardened microstructure， delivering excellent overall properties.

Abstract:

A novel Ni-based high-temperature brazing filler was developed by adding 5% atomic percent of Si to the ternary eutectic composition of Ni79Nb10B11. This new filler was used to successfully braze C_f/SiC composites to 304 stainless steel at 1 100 °C for 30 minutes. The wettability of the Ni-Nb-B-Si filler on C_f/SiC composites was evaluated using the sessile drop method， and its melting point was determined by DTA. The microstructure of the brazed joints was analyzed by SEM and EDS， while the mechanical properties were assessed through shear tests. The results show that the Ni-Nb-B-Si filler consists mainly of NbNi₈ and Ni-B-Si compounds， with an actual melting temperature range of 1 036~1 060 ℃， which is higher than that of traditional Ag-Cu-Ti and Ti-Zr-Cu-Ni fillers. The filler exhibited good wettability on C_f/SiC composites， with a contact angle of 17.5°. During the brazing process， B and Si atoms diffuse into the 304 stainless steel substrate， and Ni react with SiC to form Ni₂Si and C. The joining layer is primarily composed of Nb₆Ni₁₆Si₇， a Ni-based solid solution， and Cr compounds. The shear strengths of the joint at room temperature and at 900 °C are 32.0 and 21.2 MPa， respectively， with fracture occurring at the interface between the C_f/SiC composite and the joining layer. These results indicate that the novel Ni-Nb-B-Si filler has promising application prospects for joining high-temperature ceramic matrix composites to stainless steel.

Abstract:

Aiming at the problems of poor formability and low mechanical properties of laser additive manufacturing aluminum alloy satellite mounts and the needs of complex configuration and lightweight， taking the satellite flywheel mount as an example， the structural design method of nano-ceramic particles modified aluminum alloy （tau-aluminum） and topology optimization combined with parametric design was proposed. Firstly， through the micro-material scale modification design， the high formability and fine and uniform microstructure of tau-aluminum material is obtained， and the modulus of elasticity， strength and plasticity are significantly improved； secondly， through the topology optimization and parametric design， the flywheel bracket achieves a weight reduction of 55%， and at the same time， through the mechanical simulation analysis， it is proved that the bracket''s stiffness， strength， and enlargement meets the design requirements；finally， the laser additive manufacturing process parameters are adjusted to reduce the defects of ceramic aluminum material and realize the high-quality forming of the designed flywheel bracket. The research results can be popularized and applied to the design and manufacture of more satellite structural components to realize weight reduction and high performance of structural components and improve the development efficiency.

Abstract:

To obtain an electrothermal component configuration with high efficiency， energy conservation， and excellent electrical and thermal conductivity，two materials-graphene （Gr） and carbon nanotubes （CNTs）-that exhibited a synergistic effect were selected.A standard spraying method was adopted to prepare patterned electrothermal coatings， and an electrothermal deicing device was designed based on these coatings.Carbonized conductive oil-based CNT-GO（Carbon nanotube-graphene oxide） was used for coating preparation.Scanning electron microscopy （SEM） was employed to analyze the microscopic morphology of the coating，revealing the internal mechanism underlying the changes in its electrothermal properties at the microscale.Meanwhile，tests on the electrothermal heating performance and deicing performance of the deicing device prototype were conducted on a self-built deicing experimental bench.The results show that the grid-shaped heating coating has a faster temperature rise rate and better surface temperature uniformity.The electrothermal deicing device based on this new type of coating features a simple structure and can be easily integrated with aircraft surfaces.The average temperature generated during its electrothermal process can effectively accelerate ice melting，which verifies the feasibility of this configuration design in reducing the energy consumption of electrothermal deicing.

Abstract:

The microstructure of Al-50Si alloy was complex with a large amount of blocky primary crystalline silicon distributed in the aluminum matrix.Due to two-phase anisotropy during drilling，the chips adhesion at the cutting edge were produced，led to acceleratin tool wear.As cutting parameters varied，axial force and drilling temperature changed accordingly， thereby affecting hole quality.To address this challenging material，drilling experiments on Al-50Si alloy using TiAlN， TiCN， and TiN coated carbide drills were conducted.By revealing the variation patterns of axial force under different cutting parameters，identifying wear types on coated tools，and comparing damage levels at hole entry/exit points and wall surfaces，the research evaluated the drilling performance of coated tools and investigated the drilling quality of Al-50Si alloy.The experimental results indicate coated tool surfaces exhibit aluminum matrix adhesion and chipping，with wear mechanisms primarily involving adhesive wear and abrasive wear；drilling axial force F_z is most significantly influenced by feed rate f；the higher tool shear forces correlate with improved hole entry quality；the hole wall quality correlates with tool cutting performance.The defects such as pitting，scratches，chip adhesion，and substrate tearing appear on the machined surface.The hole exit quality is most affected by drilling axial force F_z，with higher axial force F_z resulting in poorer exit quality.TiAlN-coated tools achieve optimal drilling quality at a cutting speed v of 70 m/min and a feed rate f of 0.05 mm/r.

Abstract:

To address the need for rapid measurement of elastic modulus in aerospace materials，a line-focused sensor was used to perform defocusing measurements on the material surface，simultaneously capturing ultrasonic longitudinal waves and leaky surface waves.Based on the linear relationship between defocusing distance and the time difference of leaky surface waves and reflected longitudinal waves，the elastic modulus of the material was characterized.A scanning mechanism was designed using a three-degree-of-freedom precision motion platform，integrating a high-frequency ultrasonic excitation/receiving module and a high-speed data acquisition module.Ultrasonic measurement software for elastic modulus was developed，resulting in a fully automated ultrasonic elastic modulus measurement system.Measurement experiments on aluminum-lithium alloy and nickel-based alloy were conducted to determine their mechanical properties.The results indicate that the proposed method and developed system not only achieve measurements of elastic modulus and Poisson''s ratio for the two typical materials，but also obtain their shear modulus and bulk modulus parameters.The deviations of the elastic modulus measurements from reference data are 0.45% and 1.51% for the two materials，respectively.This research demonstrates that the developed technology offers advantages of rapid and non-destructive measurement of material mechanical properties，providing support for new material development and structural performance evaluation.

Abstract:

To investigate the fatigue performance of fiber reinforced resin matrix composites under tensile loads， carbon fiber/epoxy resin laminates were fabricated.Tensile fatigue tests were conducted under four different stress levels， and the stress-logarithmic life （S-lgN） curves were plotted.Ultrasonic C-scanning，ultra-depth-of-field 3D microscopy，and scanning electron microscopy （SEM） were employed to observe the internal damage and fracture morphology.The fatigue damage propagation and fracture modes of fiber reinforced composites were discussed.Meanwhile，a model suitable for simulating the fatigue behavior of fiber reinforced composites was established，which could well predict the fatigue life of laminates and efficiently simulate the fatigue damage evolution.Both experimental and simulation results indicate that：in the initial stage of fatigue，damage mostly initiates in the form of cracking；in the middle stage，damage is dominated by delamination and cracking；in the final stage，the damage forms become complex and interact with each other.Delamination，cracking and other types of damage tend to reach saturation，interfacial instability occurs，fibers fracture in clusters，and the material is on the verge of fatigue failure.

Abstract:

To fabricate qualified Ω-shaped composite stringers，this paper formulated the autoclave molding process and mold design scheme for Ω-shaped composite stringers.Adopting the process concept of laying prepregs on the male mold and molding with the female mold，the core problems of Ω-shaped composite stringers was solved， such as the high difficulty in prepreg laying and the inconvenience in demolding.Through using a split metal mold as the outer mold and a flexible non-metallic soft mold as the inner mold， the smooth internal and external surfaces of Ω-shaped composite stringers were obtained while ensuring smooth demolding. Process tests are carried out according to the designed mold and molding process， and products with qualified internal and surface quality are obtained.Meanwhile， it is verified that the autoclave molding process and mold design scheme for Ω-shaped composite stringers are correct and feasible.

Abstract:

In the field of aerospace vehicle manufacturing， embedded nuts served as crucial fasteners，whose performance and quality were directly related to the safety and reliability of aerospace vehicles.This is especially true for composite sandwich structures， where embedded nuts played an even more critical role.Based on composite honeycomb sandwich structures，this paper conducted research on the installation angle of embedded nuts，glue injection methods，glue injection speed，as well as the protective measures after glue injection，and analyzed the influence laws of these factors on the installation quality of embedded nuts.The results show that adopting the direct glue injection method，injecting glue 3 times with 10 min intervals，increasing the glue injection speed， and implementing protection after glue injection are conducive to improving the installation quality of embedded nuts.Moreover，the design scheme with an installation angle of 0° is preferred.This study provides a systematic technical foundation for the application of embedded nuts in composite sandwich structural components of domestically manufactured aircraft.

Abstract:

The bonding of thin-walled rotary components made of 6A02 aluminum alloy and 0Cr18Ni9 stainless steel by means of inertia friction welding technology was achieved.An in-depth investigation was conducted into the effects of process parameters on welding quality，and numerical simulations were performed to analyze the temperature and stress distribution during the welding process.The results demonstrate that effective bonding of the dissimilar metals can be realized when the welding parameters are set as follows：spindle speed of 1 200 r/min，moment of inertia of 35 kg·m²，and upset pressure of 65 MPa.Compared with the joints prepared with nickel-plated or silver-plated steel rings，the joints with uncoated steel rings exhibit superior internal pressure bearing capacity，with the burst pressure reaching 13.8 MPa.Simulation results indicate that the maximum temperature at the steel-aluminum interface occurs in the central region of the bonding surface，and the high-temperature zone on the aluminum alloy side is wider than that on the stainless steel side.Overall， the stress values on the aluminum alloy side are higher than those on the stainless steel side.Under the vibration test conditions of 100 K and an internal pressure of 0.4 MPa，the stress of the friction-welded joint is approximately 33 MPa，which is far below the fracture strength of the base materials.The result of helium mass spectrometry leak detection on the joint is less than 1×10⁻⁸ Pa·m³/s，indicating excellent airtightness that satisfies the functional and performance requirements of the product.