The large aviation die forging hydraulic cylinder is the core component of the aviation die forging hydraulic press, providing a power source for the production of important die forging components in aircraft and aeroengines. Based on the constraints of quality inspection on the processing and the coupling relationship between two processes in the high-quality production process of such hydraulic cylinders, a production scheduling model for large aviation die forging hydraulic cylinders considering quality inspection was proposed to optimize the scheduling of both processing and quality inspection processes simultaneously. A dual-process hybrid double-layer coding method was designed, along with a decoding method based on the parity judgment of the total process numbers to determine the type of process. A scheduling system with functions such as parameter adjustment, task allocation, progress monitoring, and data feedback was developed based on the theories of NSGA–II and MOSA algorithm, and the effectiveness of the model and algorithm was verified through examples. Finally, the scheduling system was applied to a hydraulic production enterprise, ensuring that the quality of large aviation die forging hydraulic cylinders was excellent while significantly improving production efficiency.
Resonant sound absorption metamaterials have excellent noise control capability and great potential for application as a lightweight aerostructure, but challenges remain in low-frequency broadband noise control. In order to promote the synergistic design of low-frequency and broadband sound absorption of metamaterials, a design method for resonant sound absorption metamaterials with a triangular back cavity in a perforated plate is proposed and the acoustic properties are investigated. The metamaterial divides the honeycomb cavity into six independent triangular units, and microperforations are arranged in the center of each triangular unit to achieve broadband sound absorption by using the coupling effect between the units. The effects of hole diameter, depth and height on the absorption coefficient and peak frequency are investigated, and the multi-unit coupling mechanism of the acoustic metamaterial’s broadband sound absorption is analyzed in terms of the zero-pole distribution of the complex frequency plane and the energy dissipation of the metamaterial. The low-frequency broadband sound absorption metamaterials designed according to the units and their coupling characteristics achieve more than 80% absorption in the low-frequency range of 309–464 Hz, with a thickness of 50 mm, which is only 1/22 of the longest working wavelength, and an equivalent density of about 0.31 g/cm3, which realizes materials’ lightweighting. The structure was prepared by light-curing molding technology and its acoustic performance was experimentally verified in an impedance tube. This lightweight sound absorption metamaterial design provides support for low-frequency noise control of equipment.
One of the methods to solve the lightweight problem of some components in aerospace field is to design the three-dimensional ordered porous micro-truss lattice structure to meet the specific needs. Firstly, based on the solid isotropic microstructure with penalization (SIMP) topology optimization algorithm, the lattice cells are optimized under different load boundary conditions with the goal of minimum flexibility, after which the topology optimized lattice cells are geometrically reconstructed. Then, the elastic matrix and elastic modulus surface of the cells under different relative densities are analyzed by using the three-position numerical homogenization algorithm and the mechanical properties of the four cells are compared as well. Physical experiments are conducted on the specimens manufactured by selective laser sintering (SLS) additive manufacturing technology and the experimental results are compared to obtain the mechanical properties of the lattice structure cells with different configurations. Finally, a three-point curved beam is taken as an example to analyze the stress distribution, and the variable density design for lattice structure of Octet cell of the beam is carried out according to the stress distribution. A uniform lattice structure is designed as the control to be compared with the variable density lattice structure in terms of mechanical properties through the three-point bending experiment. The results show that the homogenization simulation results of the four types of cells after optimization and reconstruction are in good agreement with the compression test results. S Star Tet cell has the largest elastic modulus, while Octet cell has the highest shear modulus and good isotropy. Compared with the uniform lattice structure, the bending stiffness and bending strength of the variable density lattice structure is increased by 162.6% and 250.5%, respectively.
Voronoi tessellation is popular in porous structure design, known for its excellent impact resistance and energy absorption. However, the mechanical properties of Voronoi porous structures are apt to be affected by the gradient of pore size. In this study, the influence of gradient parameters on the mechanical properties of Voronoi porous structures is investigated to achieve the mechanical property enhancement. Three types of gradient Voronoi porous structures with varying gradient spans (G–2, G–3, G–4) were designed by controlling the distribution of seeds in the Voronoi pattern. The gradient Voronoi porous samples with 70% porosity were fabricated using selective laser melting (SLM) technology. The influence of gradient parameters on the mechanical properties of gradient Voronoi porous structures was investigated by experiments and finite element simulation, and the deformation mechanisms within their intrinsic structures were analyzed. The results demonstrate that the yield strength of the gradient Voronoi porous structures improves with increasing gradient span. Moreover, among these structure, G–3 exhibits superior energy-absorption ability as a result of possessing higher flow stresses during both strain platform and densification stage due to its moderate gradient span. Smaller gradient spans lead to localized densification region formation within the structure; small pores and high pore densities cause more drastic deformation in internal support structure, thereby enhancing densification behavior.
In order to reveal the relationship between the process and structural properties & failure mechanism, the influence of typical process parameters on the mechanical properties and failure mechanism of fused deposition modeling (FDM) composites was studied based on the experimental method, and the optimized printing process parameters were proposed. Meanwhile, based on the hierarchical multi-scale theory, a high-fidelity finite element model containing typical defects such as voids and resin-rich regions was established, and a method for predicting the macroscopic tensile properties of composite component was presented, the results of which were thereafter compared with its experimental counterparts. The results show that the filling rate of printing resin has a significant effect on the properties of the component. When the filling rate increases from 50% to 100%, the tensile strength of the specimen increases by 47.6%; when the layer thickness increases from 0.2 mm to 0.4 mm, the tensile strength decreases by 51% and tensile modulus decreases by 21%, while the influence of printing temperature and printing speed on tensile strength is relatively slight. The relative error of tensile modulus calculated based on the multi-scale finite element model is 2.73%, demonstrating its ability to accurately predict the mechanical properties of the composite structure by additive manufacturing.
Honeycomb structure is one of the most widely used energy-absorbing structures. In this study, a bionic arclike hierarchical honeycomb structure is designed using motherwort rhizome, quadrangular bamboo, and spider web as bionic prototypes. The simplified super-folded unit theory is used to derive the analytical value of the average collision force of the bionic arc-like hierarchical honeycomb structure under axial impact load, and the accuracy of theoretical value is verified by numerical simulation to analyze the influence of layer number and dimensional parameter on the structural crashworthiness. The results show that the increase in layer number can effectively reduce the peak collision force of the arc-like honeycomb structure and greatly improve the mean collision force of the structure, and the mean collision force of the primary and secondary structures can be improved significantly by 25.46% and 29.98%, respectively, compared with that of the zero-level structure. The increase of the wall thickness and wall length can significantly improve the mean collision force of the structure, in which the wall thickness has more significant influence on the mean collision force and the specific energy absorption of the structure.
In recent years, robotic additive manufacturing technology demonstrated significant potential in fabricating aerospace lightweight structures, characterized by its high efficiency, expansive scale, and mobility. This paper systematically reviews the research progress in aerospace lightweight structures, starting from the demands of manufacturing and repair, and discusses the research background and importance of lightweight technology. In terms of the additive manufacturing technology, a detailed introduction to the design and fabrication of lightweight structures, materials, and functional integration is provided. The key technologies of robotic additive manufacturing are analyzed in depth, including technical characteristics, typical process principles, robot mechanism, equipment, and process planning; the critical challenges of robotic additive manufacturing technology for lightweight structures are also discussed. Finally, future research directions are outlined based on the current technological development status, including multi-process hybrid manufacturing, intelligent monitoring & control, and digital twin technologies, as well as the potential of human–machine collaborative additive manufacturing. This paper aims to provide a comprehensive and cutting-edge scientific view of the research and development of aerospace lightweight structures from the perspective of robotic additive manufacturing, and provides references for promoting the development of this area.
In this study, the phenolic coating material suitable for powder bed 3D printing was prepared by highspeed stirring. The silicon carbide and carbon fiber green parts were then produced through powder bed fusion. Two types of silicon carbide composite materials containing silicon carbide powder and carbon fiber were obtained through subsequent impregnation and densification or reaction sintering processes. The microstructures, phase characteristics, mechanical properties, and permittivities of the two materials were compared in order to analyze their wave-absorbing properties via calculation. The results indicate that carbon fiber/silicon carbide composite has better mechanical properties and wave-absorbing properties with a bending strength reaching (289±22.4) MPa, bulk density of (2.69±0.05) g/cm3, porosity reaching 0.472%. When the composite thickness is 2.77 mm, the minimum reflection loss (RLmin) of CF–S composite reaches –40.7 dB at 11.14 GHz; when the thickness increased to 6 mm, the RLmin value reaches –35.1 dB at 5.77 GHz. The composite maintains good wave-absorbing performance under high temperature oxidation condition. These research findings provide technology and theory supports for the integrated wave-absorption–structure silicon carbide composites.
Continuous fiber reinforced composite via additive manufacturing (AM) is an emerging in-situ forming technology that, combined with the digital fabrication approach, offers the advantages of efficient design and rapid manufacturing. In order to give full play to its design freedom and further realize the lightweight performance of composite, a stress-driven continuous fiber path infill method was proposed based on the wave projection function. The fiber infill morphology was optimized according to the stress field distribution of load-bearing structure, and different filling densities were set to adjust the structural load-bearing performance. At the same time, the simulated annealing algorithm was employed to generate continuous fiber paths with minimal interruptions and shortest total length. The application cases of 2D satellite silo plate and 3D UAV wing segment further verify the applicability of this method. This generative design for composite structure is a typical AM-driven approach, which is expected to provide a theoretical and technical basis for the integration of functional design and manufacturing of composite structures in the future.
The present study investigated the metallographic characteristics and distribution of precipitated phases within the weld nugget of 10 mm thick 2219–C10S aluminum alloy medium-thickness plate under different welding speeds using Bobbin tool friction stir welding (BT–FSW), providing significant reference value for improving the quality and performance of BT–FSW joints of 2219–C10S aluminum alloy. The results indicate that the inhomogeneity of heat input in the thickness direction of the plate leads to the formation of a clustered structure in center region of the weld nugget. There is a notable disparity in the content, size, and distribution of the Al2Cu precipitates across various regions of the weld. In the center of weld nugget zone, the area proportion and average size of the precipitates are the smallest, with a particle-like dispersion and the highest number of particles. The shoulder-affected zone has the highest area proportion of precipitates, while the sizes of precipitates in the shoulder- and heat-affected zones are comparable. Periodic immersion corrosion tests revealed that the base material exhibits the poorest corrosion resistance, followed by the heat- and shoulder-affected zones, with the center of weld nugget zone demonstrating the optimal corrosion resistance.
The critical problem that Ti/Al dissimilar single-sided high speed FA–MIG welding faced to is the great difference in Ti/Al interfacial structural properties. Laser remelting on the back weld was used to deal with the Ti/Al interfacial heterogeneity and improve the joint mechanical properties. Contrastive analysis was conducted to study the influence of laser offset to the Al side d, laser power q, and welding speed v on the joint structural properties. The results showed that the joint structural properties were greatly influenced by d, q, and v. With optimal parameters of d=2 mm，q=1.3 kW，v=5 mm·s–1, the Ti/Al interfacial reaction layers thickness of the remelted joint root increased and difference in microstructure in the thickness-direction decreased; the tensile strength of the joint reached >280 MPa, which is approximately 20% higher than that of untreated joints; the tensile fractured surface exhibited fracture mechanism of plastic+ductile mixed.
The thermal structural components of aerospace vehicles using carbon fiber reinforced carbon matrix (C/C) composites as raw materials, are facing harsh service conditions and require oxidation resistant ceramic coatings on their surfaces to resist the erosion in thermo–mechanical–oxygenic coupling environments. However, the brittleness of ceramic coatings make them highly susceptible to damage under external forces, posing a serious threat to the service safety of thermal structural components. Driven by the repair needs of oxidation resistant ceramic coatings and based on the damage size of coatings, the self-healing technology for micro damage and the remanufacturing technology for macro damage are introduced. The implementation methods, research status, repair effects, advantages & disadvantages and application scenarios of the two technologies are elaborated. Finally, the future development directions of the self-healing and remanufacturing of oxidation resistant ceramic coatings are discussed.
The 17–4PH stainless steel is widely used in critical components such as turbine blades in the aerospace industry. To realize the repair and remanufacturing of damaged aerospace components made of 17–4PH, 15–5PH coating was prepared on the surface of 17–4PH using laser cladding technology. The phases, microstructure, microhardness, wear resistance, and corrosion resistance of the coating were analyzed. The results show that the coating is mainly composed of Fe–Cr, martensite, and α–Fe phases. The bonding area between the coating and substrate is a planar crystal structure, with columnar grains predominating at the bottom and middle, and a mixture of columnar and a small amount of equiaxed grains at the top. The average microhardness of the coating and substrate is 408.7HV0.5 and 347.5HV0.5, respectively, with an increase in coating hardness of 17.6%. The average friction coefficients of the coating and substrate are 0.3051 and 0.3754, and the wear cross-sectional areas are 813.74 μm2 and 2058.12 μm2, respectively, indicating a significantly improved wear resistance of coating compared to the substrate. The corrosion potentials (Ecorr) of the coating and substrate are –1.0780 V and –1.0975 V, and the corrosion current densities (Icorr) are 1.229×10–3 mA/cm2 and 0.907×10–3 mA/cm2, respectively, demonstrating comparable corrosion resistance. The microstructure and surface properties of the coating suggest that laser cladding with 15–5PH coating can be applied to the repair and remanufacturing of aerospace components made of 17–4PH.
