Abstract:First， the recent research progress in kinematics，tool wear，chip morphology，cutting force and surface integrity in the process of turn-milling compound cutting is reviews.Then，the application of turn-milling compound in the machining of aerospace parts and shaft parts is described.Finally， the develepment direction of turn-milling compound cutting is prospected.

Abstract:The research status of grinding process acoustic emission monitoring technology is systematically described from four aspects： grinding process acoustic emission monitoring principle， feature extraction and selection， monitoring model and monitoring system development. Firstly， a review of the sources and characteristics of acoustic emission signals in grinding is presented， focusing on the principles of acoustic emission monitoring in different grinding conditions. Then the common feature extraction and selection methods and monitoring models for acoustic emission monitoring of grinding processes are compared， and the advantages and disadvantages of each method are compared. The development of existing monitoring systems is summarized. Finally， the problems in the current research on acoustic emission monitoring of grinding processes are summarized and the future development direction is prospected.

Abstract:To further improve the accuracy and convenience of prediction on the surface roughness （R_a） of milled 7475 aluminum alloy， the least squares vector machine （LSSVM） was optimized based on the Aquila Optimizer algorithm （AO）. The R_a prediction model of milled aluminum alloy was constructed with four milling parameters as the input values and R_a as the output value. This model was compared with two other algorithms， PSO-LSSVM and LSSVM. The correlation between the milling parameters and surface roughness was analyzed using gray correlation . The R_a prediction system was built through the GUI interface. The results show that the prediction error of the R_a prediction model based on AO-LSSVM is 4.2876%， and the goodness-of-fit reaches 0.93864， which is better than other algorithms. The correlation between feed per tooth and R_a is the largest， with a gray correlation value of 0.764. The GUI prediction application system can realize efficient， convenient， and accurate prediction of R_a values.

Abstract:Taking the scarf repair of AS4/3501-6 materials as the research background，based on the time-dependent properties of the thermodynamic parameters of materials， the finite element model of thermal-mechanical-chemical multi physical field was established for the patch and the adhesive layer. The effects of different scarf angles and adhesive layer thickness on the residual shear stress of the adhesive layer were studied and the residual shear stress distribution of the adhesive layer under different program was explored. The results show that the residual shear stress concentration of the adhesive layer will be aggravated by increasing the scarf angle and the thickness of the adhesive layer.The residual shear stress and the radial average shear stress gradient along the adhesive layer can be effectively reduced by reducing the scarf angle； The residual shear stress at the radial midpoint of the adhesive layer is 17% lower and the radial average shear stress gradient is 92% lower for 3° scarf angle than that at 15° scarf angle； When the thickness of the adhesive layer is reduced， the residual shear stress of the adhesive layer decreases，while the average shear stress gradient increases. For 0.3 mm adhesive thickness， the residual shear stress at the radial midpoint of the layer is 15% lower and the average radial shear stress gradient is 30% higher than that for 1.5 mm adhesive thickness. It is verified that the 3D finite element model and calculation method are correct， which provides a basis for improving the repair process and improving the repair quality.

Abstract:In order to examine the failure of uniaxial tension of mechanical perforated 3D woven composite lug joint， a multi-scale analysis way was used to investigate the pore edge yarn failure process. The results showes that there were a lot of longitudinal damage in the continuous warp yarn near the hole of orthogonal three-way（ORT） woven composite joint， a large number of transverse damage appeared in the weft element， and the damage gradually expanded along the 45° direction of the hole edge， there was shear damage in the weft yarn， finally， the joint failed shear failure. The error between the numerical simulation and experimental results is 1.14%， which verifies the correctness of the multi-scale finite element simulation method. The yarn damage in the meso-area of the hole edge extends from the hole edge to the edge of the side joint. The distribution position of hole edge yarns is different， and the destruction form of yarns is different， but it does not affect the expansion trend of destruction.

Abstract:This paper takes Al-50wt%Si high-silicon aluminum alloy as the research object， and adopts single factor test method to carry out dry milling test of uncoated carbide tools to analyze the influence of cutting parameters on tool wear and surface roughness. The results show that the surface roughness is most significantly affected by the feed per tooth， and increases with the increase in the feed per tooth. When the feed per tooth increases from 0.07 mm/z to 0.16 mm/z， the surface roughness increased by 2 times； tool wear is most significantly affected by cutting speed， and increases with the increase of cutting speed. When the cutting speed increases from 140 m/min to 260 m/min， the total cutting length decreases by 3 times， but the wear on the flank of the tool is only 0.8 times that at a speed of 260 m/min； the surface roughness increases first and then decreases with the increase of tool wear. The cutting length increases from 350 mm to 1750 mm， the tool wear increases by 4.5 times on average，while the surface roughness decreases by 2 times； the main wear forms of cemented carbide tools are： abrasive wear and chipping.

Abstract:In order to reduce the depth of subsurface damage during processing of carbon fiber reinforced plastic （CFRP）， a macro continuous dynamic cutting CFRP finite element model was established based on the Hashin failure criterion. The variation law of cutting force and subsurface damage depth with the fiber direction angle was analyzed. The cutting force and subsurface damage were reduced by introducing a textural tool.The effects of grooved textured tool， circular textured tool and triangular textured tool on CFRP cutting simulation were compared. The results showed that consistent fiber orientation with the change in the cutting force and damage depth at a different surface texture tool trend，with the minimum value at 0° and the maximum value at 90°. Compared with the conventional non-textured tool，both the cutting force and the subsurface damage depth are reduced when the textured tool is cutting CFRP， and the reduction degree of the circular textured tool is the largest.The simulation models are experimentally proven to be accurate and efficient.

Abstract:In order to achieve the optimum combination of the energy cost for shape recovery and the mechanical performance of composite materials. In this paper， the content of toughening agent Neopentyl Glycol Diglycidyl Ether （NGDE） is increased in the thermotropic epoxy shape memory polymer matrix to reduce its glass transition temperature， and Short Carbon Fiber （SCF） is added to compensate the stiffness reduction caused by toughening agents. The effects of different contents of NGDE and SCF on the shape memory transition temperature， shape memory properties and mechanical performance of the composites were investigated. The results show that increasing the NGDE content can reduce the shape memory transition temperature of the epoxy polymer matrix from 90 ℃ to 43 ℃， and the storage modulus and flexural modulus are synchronously decreased. By adding SCF in the 11%wt NGDE containing sample， the glassy storage modulus， rubbery storage modulus， and flexural modulus of the composites can be increased to 1.9 times， 7 times， and 2.4 times of the original ones.

Abstract:The traditional carbon fiber reinforced material （ CFRP ） resin matrix has poor conductivity and is prone to lightning damage. In this paper， grapheno-nickel plated carbon fiber powder is used as a conductive filler to modify the conductivity of the resin matrix， and a copper mesh is laid on the surface to conduct simulated lightning current impact tests to test the lightning protection of the matrix modification/copper mesh combination.The conductivity of CFRP laminates with modified resin matrix in the 0°， 90° fiber direction， and thickness direction is 1.1571×10⁴ S/m，1.0871×10⁴ S/m，204.2 S/m，which increased by 1.54 times， 1.16 times， and 433.47 times respectively. Under the impact of simulated lightning current A wave of 200 kA， the unprotected specimen is ignited by an flame after being struck by lightning， and the secondary effect persists， while both single copper mesh and combined protection can suppress the secondary effect. The maximum damage diameter of the unprotected surface is 14.62 cm， and the copper mesh is broken down under this energy.The maximum damage diameter of a single copper mesh protective surface is 19.05 cm， while the maximum damage diameter of a combined protection surface is 8.93 cm， a decrease of 53.12%.Compared with no protection， the internal damage area of single copper mesh and combined protection can be reduced by 66.2% and 96.7% respectively.After the breakdown of a single copper mesh， the resin undergoes vaporization and recoil after ablation， increasing the detachment area of the damaged copper mesh. After the combined protective copper mesh is broken down，the modified resin quickly conducts the current， reducing the detachment of the copper mesh and the internal ablation area.

Abstract:In order to investigate the influence of lay-up area variables on the static aeroelasticity of a high span ratio wing， this paper uses finite element analysis to investigate the influence of the division of the outer wing section lay-up area and the number of 90° lay-up angles on the static aeroelasticity of a high span ratio wing， while accounting for geometrical non-linearity. The results show that the effect of 0°， ±45°， and 90° mixed lay-ups is superior to that of 0° and ±45° lay-ups alone； the wing deformation decreases with the increase of the outer section lay-up area， and the slope of the decrease gradually increases；when the outer section lay-up area is fixed， increasing the number of 90° lay-up angles effectively reduces the wing deformation， and the wing deformation essentially shows a negative correlation with the number of plies， there may exist an optimal value or optimal ratio in the ply design.

Abstract:Based on the urgent demand of aerospace products for super-high strength and toughness rare earth magnesium alloy component， the isothermal forging forming technology was adopted in this paper， the forging process characteristics of VW84M rare earth magnesium alloy were studied. The forging process properties of VW84M high strength and toughness rare earth magnesium alloy were studied， the process structure characteristics of the straight cylinder were analyzed， the forging process of the straight cylinder was established， the forming process of straight cylinder section was studied by three-dimensional modeling， numerical simulation and forming process experiments， the forgings were produced by forming process test. The results showed that VW84M rare earth magnesium alloy has good plastic forming performance at 440 ℃ forging temperature and suitable extrusion speed， and the material has practical engineering application ability.The extrusion load obtained by numerical simulation is 64.72 MN， and the actual extrusion load is 60 MN， with a difference of 7.8%， the shear and axial mechanical properties were better than the requirement with tensile strength not less than 340 MPa， yield strength not less than 210 MPa and elongation not less than 6%.The metal streamline distribution of the straight cylinder is uniform， and the tangential mechanical property is better than the axial one.

Abstract:In order to study the application of Ti doped graphite-like carbon （GLC）films on bearing steel substrate at high temperature，Ti-GLC coatings were prepared on M50 steel substrate by unbalanced magnetron sputtering. Friction and wear tests were performed with Al₂O₃ ceramic balls at different temperatures and different sliding speeds to investigate the high temperature tribological properties and wear mechanism. The results show that the content of sp2 increased with the temperature increase. Meanwhile， the hardness and elastic modulus decreased gradually， the adhesion force displayed a slight downtrend. In the range between RT and 200℃， the prepared Ti-GLC films maintain excellent low friction and wear resistance， therefore is the best service temperature range. At 200 mm/s， the wear mechanism gradually change from slight adhesive wear and abrasive wear to severe abrasive wear and oxidation wear with the increasing temperature.

Abstract:In order to solve the problem that bubbles are easy to occur when the sensor products are filled with silicone gel，and improve the filling efficiency and quality of the sensor on the rocket， this paper adopts the centrifugal defoaming technology to study the defoaming method of silicone gel， and adopts the design method of two-factor optimization test to determine the optimal range of centrifugal defoaming parameters. After repeated tests， the optimal centrifugal defoaming process parameters were obtained， and the defoaming and curing effects were checked. The results show that 740r/min and 12min are the best centrifugal defoaming parameters for defoaming. The minimum diameter of bubbles in the solidified glue section is about 24μm， and the maximum diameter is about 54μm， and bridge is found， the resistance is greater than 200MΩ， no conduction short circuit， in line with NASA standards and no on-off short circuit between two adjacent bubbles. Through the batch production and test verification，the centrifugal defoaming process is ideal，stable， effective and feasible，for batch producion which meet the requirements of sensor products on the rocket.

Abstract:The CFRP/Ti laminate structure is prone to delamination， tearing， burns， hole exit burrs and other hole making defects during the integrated driling process.Based on low-frequency vibration assisted drilling technology， after the second optimization， the optimal processing parameters are obtained in this article. Experimental results show：the hole-making quality is better under these two sets of processing parameters of speed of 400 r/min， feed of 12 mm/min， amplitude of 75 μm and speed of 500 r/min， feed of 21 mm/min， and amplitude 75 μm. Using high speed and large feed can improve processing efficiency.