It is difficult to realize automatic molding due to the complex structural characteristics of the composite heat protection structure for the symmetric lifting body, such as the alternation of positive and negative curvatures and the existence of large curvature mutation areas. This paper innovatively presents the automatic profiling paving technology of the composite heat protection structure, adopts the self-developed automatic profiling paving head to carry out the molding test, and analyzes the positions of the nodes that need to be pressurized during the molding process by combining with the developability of the profiling surfaces. The finite element model of automatic profiling paving molding was established to analyze the contact area and contact stress between the vacuum suction cup and the mold at the curvature change position. The paving and molding experiments were carried out, the quality of paving and molding was analyzed, and the vacuum suction cup array scheme was optimized to improve the quality of paving and molding. The results show that by using the self-developed automatic profiling paving device and the optimized vacuum suction cup combination scheme, defects such as indentations on both sides of the suction cups, vacuum pores, and bridging in the paving molding samples are significantly reduced, approaching the ideal paving state.

The increasingly serious electromagnetic radiation environment poses a threat to human health, interferes with the normal operation of precision instruments, and threatens national defense and information security. Lightweight, corrosion-resistant, easy to process, and low-cost carbon-based electromagnetic shielding composites restrict electromagnetic waves through the shielding body. The electromagnetic shielding performance of carbon-based composites is closely related to the design of three-dimensional conductive structures. Carbon-based composites can be designed as homogeneous structures, network structures, oriented structures, and multilayer structures. Based on the microstructure of carbon based electromagnetic shielding composites, the specific shielding mechanism of carbon-based composites was analyzed, and the control of carbon's conductive structure and specific application forms were summarized. The research direction and development trend of carbon based electromagnetic shielding composites in the future were also discussed.

Equal channel angular pressing (ECAP) is one of the important methods for achieving severe plastic deformation in magnesium alloys. In order to further reveal the recrystallization mechanism of ECAP samples under different conditions, through the finite element simulation and experiment on AZ80 magnesium alloy, the deformation characteristics and microstructure evolution of the samples in different deformation regions, under different deformation temperatures and extrusion passes were studied. The results indicate that the proportion of high-angle grain boundaries in the microstructure is significantly higher during severe plastic deformation, indicating that discontinuous dynamic recrystallization is the main recrystallization mechanism in the ECAP process. Magnesium alloys subjected to singlepass ECAP exhibit significant differences in microstructure at similar temperatures (360 ℃ and 380 ℃), showing strong temperature sensitivity. The difference of the average equivalent strain and its variation are significant among different deformation paths for multi-pass ECAP. The interaction between the heating process and multi-pass extrusion jointly promotes the optimization of the microstructure of magnesium alloys and the improvement of grain properties.

Selective laser melting (SLM) technology is widely used in the manufacture of complex lattice structures, but the thermal-mechanical behavior of lattice structures affects the forming quality of the workpiece during printing. In order to study the effect of pillar size on the temperature changes, residual stress and deformation of titanium alloy lattice thin-walled parts, three groups of Ti6Al4V lattice thin-walled parts models with different pillar sizes were designed. The temperature change distribution during the forming process was observed, and the Von-Mises stress and deformation of the formed parts after cooling to room temperature were analyzed. The results show that for lattice structures with different pillar sizes, with the increase of pillar size, the maximum instantaneous temperature increases from 1271.35 ℃ to 1396.28 ℃, and the maximum residual stress also increases from 1207.8 MPa to 1369.2 MPa. The larger residual stress is mainly distributed in the node area of each structure, and the stress in the Z-direction is the largest, followed by the X-direction and the Y-direction. Due to the increase of the pillar size, the residual stress and the weight of a single pillar increases, and the deformation of the lattice structure also increases from 0.0919 mm to 0.1730 mm, and the deformation of the pillars on both sides is observed to be the largest. Therefore, in the actual printing process, it is necessary to add support at the position with the maximum deformation according to the simulation results to prevent serious deformation of the thin-walled parts during the printing process, so as to control the forming quality.

As one of the most practical metal laser additive manufacturing technologies, selective laser melting (SLM) has been widely adopted in aviation, aerospace, and energy sectors due to its advantages in rapid forming of complex thin-walled components. However, the consistency issue during the forming process still limits further improvements in component quality, which is closely related to defects arising from the constant variations in melt pool size and shape. Therefore, to more effectively monitor the dynamic changes of the melt pool, a method for predicting melt pool melting state categories based on extraction of high-dimensional melt pool motion features and a long short-term memory (LSTM) model is proposed. Firstly, the U-net model is utilized to extract melt pool morphology features from melt pool images, and the distances from the melt pool centroid to its boundary are calculated and unfolded along the contour into highdimensional vectors to represent the motion features of the melt pool. Subsequently, the k-means clustering algorithm is applied to perform clustering analysis on the melt pool motion features under different process parameters, leading to the construction of four categories of melt pool melting states. Time series prediction of the melting state categories is then conducted using the LSTM model. Taking the SLM process of Inconel 625, a typical high-temperature alloy material for aviation, as an example, verification of melt pool state category prediction was conducted. The results demonstrate a prediction accuracy of 85.92%, providing a novel approach and insight for real-time monitoring and quality control in the SLM process.

The spinning technology, with its advantages of high precision, good process flexibility, ease of automation, and material savings, has been widely applied in industrial fields such as aerospace, aviation, and automotive. As the demand for processes continues to expand, spinning technology for non-circular cross-sections and nonaxisymmetric rotational bodies has emerged. To adapt to the metal flow trends for forming target shapes, corresponding shapes such as non-circular cross-sections and eccentric clamping are used for pre-processing traditional circular blanks in spinning technology. Additionally, research on spinning technology for welded composite blanks, either for blank size or material-saving purposes, has also gained attention. Compared with traditional circular blanks, non-circular blank spinning can, to a certain extent, make the spinning process more stable. It can effectively eliminate flanges and reduce the uneven distribution of wall thickness, greatly improving the forming accuracy and achieving betterforming results. Offset blank spinning can be used when the product does not have high requirements for wall thickness uniformity and shape accuracy. It effectively saves materials and improves production efficiency. This paper reviews the current research status of two types of prefabricated blank spinning technologies and provides prospects for the spinning technology of prefabricated hole blanks.

Optimizing the scheduling of composite materials job-shops is a crucial technology for enhancing the production efficiency of aerospace composite materials, which are characterized by multiple varieties and mixed batches. A multi-constraint planning method is proposed to address the problems of low autoclave utilization rate and long completion time in aerospace composite materials production. Initially, a mathematical model is developed to minimize the maximum completion time based on the mixed-batch characteristics of composite material production. Secondly, interval variables were introduced as decision variables along with logical constraints to establish a multiconstraint programming model for solving the problem. Finally, comparative experiments were carried out using eight sets of examples from a certain aviation enterprise. The results indicate that the proposed method significantly enhances the utilization rate of the autoclave compared with the original job-shop scheduling algorithm. Specifically, the number of autoclave batch configuration uses and the total processing time of the autoclave were reduced by 35.7% and 37.4%, and the job-shop production completion time was shortened by 29.9%, it effectively addresses the job-shop scheduling challenges in composite material production.

Pulsed laser welding of ultra-thin Mg–Li alloy LZ91 with a thickness of 1 mm was conducted to investigate the effects of laser power, duty cycle, and frequency on weld formation, microstructure, and mechanical properties. The results show that fully penetrated welds with good forming consistency can be obtained by pulsed laser welding. The microstructure of the LZ91 welded joint heat-affected zone is coarse α-Mg and β-Li dual phase structure, and numerous short acicular α-Mg phases are distributed in β-Li grains of the weld zone. The increase of laser power has little effect on the phase composition, but leads to an increase in β grain size in both the heat-affected zone and weld zone. The elongation and impact absorbing energy of welded joints decrease with the increase of laser power, whereas the overall changes in tensile strength and hardness are relatively small. The microhardness of the weld zone is the highest, followed by the base metal, while the heat-affected zone has the lowest microhardness.

Laser 3D curve positioning projection is a critical technology for aviation composite material layup processes. This study presents a novel 3D curve positioning and projection system based on a galvanometer scanning mechanism, consisting of a laser source, galvanometer, photosensitive sensor, focusing lens assembly, beam splitter, and auxiliary optics. During high-speed scanning, the photosensitive sensor detects reflected light intensity signals from the retroreflective target surface, while the galvanometer provides real-time control signal feedback. The 3D curve positioning and projection system acquires these two signal data types and utilizes a single hidden layer feedforward neural network (SLFN) to establish the mapping relationship between the input signals and the output laser lines, with calibration completed by solving parameters in the network model. By applying the non-perspective n-point (NPnP) algorithm, the system achieves target positioning and projects pre-designed patterns on the surface without requiring external measurement devices or precision optical component assembly. Experimental validation through retroreflective target positioning and aircraft composite panel contour projection confirms the system’s effectiveness.

Carbon fiber yarn circular braiding is a composite manufacturing process for producing tubular preforms, widely applied in industrial fields such as aerospace. Before circular braiding, it is essential to inversely calculate the takeup speed of the mandrel based on the expected braid angle of the braided composite. However, the traditional inversesolution method relying solely on kinematics has a large error. To address this issue, this paper proposes an inverse-solution algorithm for the mandrel take-up speed in circular braiding that incorporates yarn friction. Firstly, through the mechanical analysis of the interaction between yarns in the convergence zone, the equivalent braid angle under the ideal kinematic model was calculated according to the expected braid angle. Then, by conducting a kinematic analysis of the circular braiding process, the corresponding mandrel take-up speed was obtained based on the equivalent braid angle. To verify the effectiveness of the inverse-solution algorithm, a circular-braiding finite element simulation model and a circular-braiding physical experimental platform were established for simulation and physical experiments. The experimental results indicate that, compared with the traditional inverse-solution method based only on kinematics analysis, the proposed algorithm can effectively reflect the influence of the interaction between yarns during the braiding process. The average error between the obtained braid angle and the expected braid angle is less than 1°, which is significantly reduced compared to traditional kinematic methods.

In order to improve the fatigue performance of Ti–6Al–4V (TC4) titanium alloy, the effects of three surface strengthening methods, namely laser shock (LSP), shot peening (SP) and their composite strengthening (LSP+SP), on the high-cycle fatigue performance of TC4 titanium alloy were investigated; The residual stress distribution of the surface layer of the specimen after the three strengthening processes was analyzed by X-ray diffraction method, and the microhardness was determined by microhardness tester. The fatigue limit of TC4 titanium alloy was tested by X-ray diffraction method, and the microhardness was determined by microhardness tester. Under the condition of high-cycle fatigue loading at 20 ℃, the fatigue limit was tested based on the up and down method, and the Goodman curves and formula for the fatigue life design of TC4 titanium alloy and the P-Goodman curves based on reliability were established. Compared with the unreinforced smooth specimens, the fatigue limits of LSP, SP, and LSP+SP specimens are enhanced by 18.2%, 10.1%, and 26.6%, respectively. Combined with the critical distance theory, the Goodman model considering the effects of residual stress and average stress is obtained, and the error is no more than 5% when compared with the data of composite-reinforced high-cycle fatigue tests; Based on the probability distribution function, the P-Goodman curves under different degrees of reliability for different reinforcement processes are determined. The specimens with composite reinforcement process are less prone to fatigue damage under the same applied load conditions.