The increasingly stringent service environment poses higher requirements for the future application of  high-entropy alloys in the aerospace field. Shot peening technology can refine grain size, improve material surface integrity and fatigue performance. The impact of shot peening on the fatigue performance of CoCrFeMnNi high-entropy alloy was investigated. Ceramic beads were utilized for shot peening treatment, and surface residual stresses were measured using X-ray diffraction. Rotating bending fatigue tests were conducted on the specimens. The results revealed that shot peening induced residual compressive stresses on the surface of the CoCrFeMnNi high-entropy alloy, with a maximum value of 437 MPa. At a stress level of 450 MPa, the fatigue life of the CoCrFeMnNi high-entropy alloy extended to approximately 12 times that of the untreated specimens, with the fatigue limit increasing from 245 MPa to 400 MPa. The fatigue performance of CoCrFeMnNi high-entropy alloy was significantly improved by shot peening. Additionally, Shot peening treatment changed the crack initiation location of high-entropy alloy specimens. Fatigue cracks in the shot-peened specimens initiated in the subsurface layer beneath the material surface, while in the untreated specimens, fatigue cracks originated at the material surface.

A variable admittance adaptive active fault-tolerant control method based on position control as self disturbance rejection was proposed for industrial robot systems affected by external disturbances, actuator failures, and environmental disturbances. First, an auto-disturbance rejection controller was designed to achieve position tracking while eliminating the impact of external disturbances on the actuator. Second, in order to obtain accurate internal fault information of joints in actual operations except for external disturbances, an adaptive active fault-tolerant mechanism was introduced on the basis of position control to detect and compensate for faults that occur during the robot’s control process. Finally, a variable admittance controller was used to optimize the end flexibility performance of the robot by adjusting admittance parameters online to improve the stability of the robot system. After simulation verification, the proposed method can effectively improve the fault tolerance and flexibility of industrial robots, and has good robustness and reliability in the  robot control process, providing new ideas and methods for the intelligence and automation of industrial robots.

Laser engraving process for chemical milling is an important way of aircraft skin machining, but there is still a lack of measurement method. To solve this problem, an on-machine accuracy measurement method for chemical milling engraving lines based on laser profiler was proposed. Firstly, the kinematics model of the five-axis laser engraving machine and laser profiler was established based on coordinate transformation. The transformation between the laser measuring coordinate system and the workpiece coordinate system was determined, based on which the scanning point cloud was obtained. Then, the profile features of single frame groove section were extracted based on template matching. The width, depth and position of the groove line were solved by Levenberg-Marquardt algorithm. The contour error of laser engraving was obtained by point cloud segmentation, contour matching and contour error calculation. Finally, the effectiveness of the proposed method was verified by laser engraving on-machine accuracy test. The results show that this method can evaluate the uniformity and profile accuracy of the profile, which provides a reference for tracing the machining error, modifying the machining process and improving the contour accuracy of the engraving line.

TC4ELI titanium alloy is widely used in integral load carrying components of aircraft due to its excellent strength, ductility and damage tolerance. However, due to the different primary β grain morphology and microstructure of TC4ELI titanium alloy component manufactured by additive manufacturing, different heat treatment methods are often required from forgings. Therefore, to obtain a suitable heat treatment method for additive manufacturing TC4ELI, the microstructure of as-deposited TC4ELI titanium alloy fabricated by laser additive manufacturing and the effect of hightemperature annealing on the microstructure and mechanical properties of laser additive manufacturing TC4ELI titanium were studied. The results show that with the increase of annealing temperature in the dual-phase zone, the width of primary α phase increases, the content of primary α phase decreases, and the secondary α participates. After the single-phase zone annealing, TC4ELI titanium is still ultrafine basket-weave microstructure. The microhardness and yield strength of TC4ELI titanium alloy after annealing in the dual-phase zone decreases slightly, the tensile strength increases slightly, the ductility dose not change much, and the anisotropy dose not improve significantly. However, the strength increases slightly and the ductility decreases significantly after annealing in the single-phase zone. Different from the annealing of forging TC4ELI in the single-phase zone, the strength and ductility matching of additive manufacturing TC4ELI is better after annealing in the dual-phase zone.

Electrochemical machining (ECM) is suitable for machining parts with complex cavities and made by material that hard to cut. However, allowance distribution of complex cavities during ECM still needs to be researched further. To solve the problems that angles between normal direction and feeding direction are different at points on cathode surface, making forming process changed, differential equations of machining gap at points with specific angles were constructed to simulate different angles between normal direction and feeding direction. Cathodes with regular shapes were used to carry out contrastive experiments of direct current ECM and pulse-vibration ECM to choose suitable differential equations to simulate forming process of complex cavity under the above machining  modes. Achievement of research has been used in efficient machining of integral shrouded blisk channels.

The surface micro-pit array plays a huge role in mechanical sealing, friction and wear, surface lubrication, heat transfer and heat dissipation. To be able to jet electrochemical machining micro-pit array on GH4169 nickel-based superalloy, the polarization curves of the alloy in different electrolytes were tested and the electrolyte was optimized. Then, the influence of processing voltage and jet velocity on the micro-pits by jet electrochemical machining was explored, and the micro-pit array was processed by optimizing the process parameters. Finally, using mass fraction 10% NaNO₃ as the electrolyte, processing voltage of 25 V, and jet velocity of 10 m/s, the micro-pit array with high precision and good consistency is fabricated. The aspect ratio is 0.376 and the standard deviation of the aspect ratio is 0.004372 for the micropit array.

Facing the issue of selecting rolling process parameter for high-precision titanium alloy bolts, the finite element simulation model is built for the rolling at root fillet of bolt. The distribution law of residual stress at root fillet of bolt after rolling is studied. The effects of rolling speed, processing time, friction coefficient, coating thickness and rolling force on the distribution of residual stress are analyzed and the optimal choice of rolling parameters is obtained. Moreover, targeting on the goal of minimizing the median integral of residual stress in root fillet rolling, the mathematical model of rolling parameters and residual stress is established in accordance with the simulation results. The optimal process parameters of rolling strengthening for the root fillet of high-precision bolt are obtained through parameter optimization. Moreover, the finite element simulation and experimental verification are carried out to validate the optimal results. The research results can offer theoretical guidance and technical support for the fillet rolling strengthening technology of highprecision bolts.

After carburizing heat treatment, a modified layer forms on the surface of alloy steel, within which the mechanical properties of the material change along the depth direction. In this paper, a delamination test method for measuring Johnson–Cook damage parameters is proposed for the surface modification layer of 18CrNiMo7–6 alloy steel after carburizing heat treatment. Thin plate samples with different metamorphic layer depths were obtained by wireelectrode cutting from the modified layer of the material. In order to obtain tensile results under different stress triaxiality, this work prefabricated tensile shear specimens with different fracture directions, and determined the stress triaxiality considering the cumulative effect of strain through combination of experimental and simulation methods. In addition, the relationship between material failure strain and stress triaxiality was measured and the relationship between failure strain and strain rate of tensile specimens was measured using a wide pulse tensile system. The results show that the failure strain of a material in the same layer decreases with the increase of stress triaxiality, and at the same stress triaxiality level, the failure strain increases with the increase of depth. The samples at different layer depths had significant strain rate weakening effects, and at the same strain rate level, the failure strain increased with the increase of layer depth. Based on the measured parameters, a numerical simulation of the tensile process was conducted and compared with the experiment to verify the accuracy of the parameters measured in this paper.

In this study, laser shock peening (LSP) induced residual stress distributions on the aircraft fuselage used TC21 titanium alloy cylinder components were investigated. The effects of overlapping rate, laser energy, and impact times on the radial, circumferential and axial residual stress distributions were systematically studied. Results show that LSP has negligible influence on the distribution of radial stress, but significant influence on the distribution of circumferential and axial stress. Obvious stress concentration in the core of the cylinder components is observed, which is further eased by increasing the overlapping rate. The depth of residual stress layer induced by LSP in the cylinder components is not sensitive to laser energy or overlapping rate, which only exhibits a slight increase in the case of increasing the impact times. The optimized LSP parameters for TC21 titanium alloy cylinder components are of an overlapping rate of 50% and an impact times of two. The laser energy should be determined according to the actual service stress of the components.

This paper performs high-speed milling experiments on a typical wave-absorption honeycomb with crushed-tooth cutter under varied cutting parameters. The effects of cutting process on such parameters as cutting force, machined surface quality, cutting power, and cutting temperature are investigated. Then the optimized cutting parameters for high-speed milling of wave-absorption honeycomb are determined. The results indicate that the increase in cutting speed can help to decrease the cutting force and promote the machined surface quality. Meanwhile, the increase in feed speed, cutting depth, or cutting width causes the increase in specific material removal volume, which leads to higher cutting force and cutting temperature as well as severer machined surface defects. Taking the burr defects suppression as the main machining target and giving an overall consideration for the above other parameters, the optimized cutting parameters are recommended as the spindle speed of 16000 r·min^–1, feed speed of 4000 mm·min^–1, cutting depth of 10 mm, and cutting width of 15 mm. The research can provide guidances for selection of cutting parameters during high-speed milling of waveabsorption honeycombs.

Aiming at the problem of low machining quality caused by unreasonable selection of robot milling station for large composite components, a single robot multi-station milling station optimization method based on optimal stiffness is proposed. The stiffness of the robot is obtained by the forward and inverse kinematics of the robot, and the stiffness function model related to the robot position is established. The robot milling tasks at different stations are allocated, and the robot milling station optimization research is carried out through the stiffness-based station optimization algorithm to obtain a set of stations with the best robot stiffness. The optimization effect of robot milling position is verified by robot milling experiment. The results show that the station optimization based on the optimal stiffness can significantly improve the stability of the robot milling edge, and reduces the surface roughness of the milling edge by more than 33% compared with before optimization.

In response to the impact of curvature radius on the precision of robot abrasive belt polishing in the polishing process of complex curved parts, an experimental study on robot abrasive belt polishing based on multi curvature radius nickel based high-temperature alloy was carried out. The main focus was on exploring the machining performance of test pieces with different curvature radii, setting corresponding sand belt particle size and polishing process parameters for abrasive belt polishing of nickel based high-temperature alloy test pieces with different curvature radii, collecting the material removal depth of the test piece and analyzing the experimental results. The experimental results show that the variation of curvature radius has a certain impact on the depth of material removal. As the curvature radius changes from large to small, the depth of material removal also increases, indicating a negative correlation between the depth of material removal and the curvature radius. Based on a multiple nonlinear regression model, prediction model for the depth of material removal in robot abrasive grinding and polishing is proposed on the abrasive belt particle size, feed rate, contact force and workpiece curvature radius. The average prediction error of the prediction model is 1.45 μm, an accuracy rate is 91.04%, and a prediction error range is – 5.34–4.57 μm. The significance test of the prediction model indicates that the prediction model can provide important theoretical support for the early process parameter design of actual robot abrasive belt grinding and polishing processing.