Abstract:Abstract Grinding surface topography is one of the important indexes of surface integrity, which plays a key role in the contact stress, wear resistance, corrosion resistance and fatigue strength of materials. This article summarizes the development of modeling methods, technical routes and research results of grinding surface topography at home and abroad, overviews three methods of surface topography modeling (empirical modeling method, theoretical modeling method, finite element analysis method) , discusses advantages and disadvantages of these modeling methods in detail and pointes out the problems existing in the study of grinding surface topography. Finally, the research puts forward the direction of surface topography modeling for grinding.

Abstract:Carbon fiber reinforced polymer (CFRP) is widely used in the manufacturing industry due to its excellent comprehensive performance. However, due to the anisotropy of mechanical properties and the heterogeneous characteristics of the organization, processing defects such as delamination, burrs, and fiber tearing are prone to occur during the processing. In order to better monitor and control the CFRP processing process in real time to improve the final processing quality, the research results of scholars in recent years are reviewed from the three aspects of CFRP cutting processing prediction, state monitoring and intelligent control during cutting, and the future research trends are analyzed and discussed.

Abstract:In order to improve the stiffness of satellite main load-bearing structure, the variable stiffness sandwich panel skin is designed based on the constant curvature arc curve and translation method. The equivalent modeling, modal analysis and modal fundamental frequency optimization of sandwich panel with different initial / ending angle combinations are carried out by using ABAQUS secondary development method and response surface method. The numerical results show that the modal fundamental frequency of the sandwich panel with variable stiffness design increases first and then decreases with the increase of the initial angle and then decreases, and increases with the increase of the ending angle. The maximum lifting percentage of the fundamental frequency is 12.33%, which can reduce the dynamic coupling effect between the honeycomb basic bearing structure and the equipment.

Abstract:The finite element analysis software ABAQUS was used to analyze the influence of geometric parameters of the boom on its mechanical properties, providing a theoretical basis for the design of the boom of drag sail device. The results show that: 1) increasing the shell thickness and decreasing the radius of cross section with a constant arc length and increasing the angle of the shell section can effectively improve the automatic expansion capacity of the drag sail device and the support stiffness of the boom. 2) the internal bending stress of the boom is only related to material properties, the radius of cross section r, bending radius R and shell thickness t. As the radius of cross section decreases and the shell thickness increases, the internal bending stress of the boom will increase, which may lead to the plastic deformation of the boom when it is convolved. Therefore, the influence of the geometric parameters of the boom on its expansion capacity and winding performance should be considered comprehensively when designing the boom of the drag sail device.

Abstract:In order to study the heat transfer rule and temperature distribution characteristics of carbon fiber reinforced polymer (CFRP) during drilling were studied .the heat transfer rule and temperature field distribution in unidirectional CFRP drilling were studied by homogenizing the material thermal physical properties and establishing the numerical simulation model of unidirectional CFRP drilling temperature field by COMSOL multiphysics.The investigation revealed that the temperature field at the outlet is elliptical, the minimum eccentricity e is 0.771, and the long axis of the ellipse is parallel to the fiber direction.?The experimental results show that the temperature errors of fiber direction and vertical fiber direction are 7.5% and 7.8% ,respectively, and the simulation results were in good agreement with the experimental results, which verifies the correctness of the numerical simulation model.

Abstract:By controlling deposition time (5 h, 15 h, 30 h and 50 h), PyC interface with different thickness were obtained, and then S5, S15, S30 and S50-C/ZrC-SiC composites were prepared by precursor impregnation pyrolysis process. The effects of PyC interface thickness on the flexural and fracture properties of C/ZrC-SiC composites and its mechanism were studied. The results show that with the increasing of deposition time, the PyC interface thickness become bigger, and the flexural mechanical properties and fracture toughness of C/ZrC-SiC composites increase firstly and then decrease. This is mainly due to the release of fiber damage and fiber/matrix thermal mismatch with the increasing of PyC interface thickness, which will improve the strength of C/ZrC-SiC composites at last. But as PyC interface thickness become too larger, the bonding force between fiber and matrix and the content of ZrC SiC matrix will be reduced, which will eventually lead to the decrease of strength of C/ZrC-SiC composites. At the meantime, S30-C/ZrC-SiC composites exhibits more “fiber bridging”, “crack deflection” and “crack branching”, which are beneficial to the consumption of fracture energy, and therefore it shows better fracture properties.

Abstract:In order to study the quantitative relationship between the surface characteristics of carbon fiber and the interfacial shear strength of carbon/epoxy composite. The surface morphology, specific surface area and surface chemical characteristics of T800-grade carbon fibers were characterized by scanning electron microscopy, specific surface area analyzer and X-ray photoelectron spectroscopy. The interfacial shear strength (IFSS) of the composites was characterized by the micro-debond test. Based on the test results of specific surface area of carbon fibers, the real interface area was calculated and taken into account, while the influence of interfacial area and chemical characteristics on the IFSS was analyzed. The results show that there are obvious differences in the specific surface area of T800-grade carbon fibers with different surface conditions, and the difference in specific surface area of the carbon fibers treated by the two desizing methods is 25.4%. It shows a good linear correlation between the real interfacial shear strength (IFSS'), calculated based on the real interfacial area, and the surface oxygen-carbon ratio of carbon fiber, and the coefficient of determination reached 0.94. It is demonstrated that increasing the specific surface area and the surface oxygen-carbon ratio of carbon fiber are effective methods to improve the interfacial shear properties of composites. Moreover, it also provides a new way to quantitatively study the influence of physical and chemical characteristics of the carbon fiber’s surface on the interfacial properties of the composites.

Abstract:The conbined thermal insulation part composed of ceramic tile and phase change composites (PCC) was prepared by ceramic tile, LiCl PCC, LiNO3 PCC, and pentaerythritol PCC. The thermal perotecting performance of the conbined thermal insulation part and its reference sample were characterized in a single-sided heating test equipment at 1200 ℃. The results showed that the back temperature of the conbined thermal insulation part is 222.3 ℃ at the heating time of 7650 s, while the back temperature of the reference sample is 644.0 ℃, which indicates that the conbined thermal insulation part has better thermal insulation performance. The temperature control time for the conbined thermal insulation part is 6780 s at the back temperature of 199.5℃, while that of the reference sample is 3135 s at the back temperature of 199.7℃, which indicates the conbined thermal insulation part has much longer temperature control time at the close back temperature. All the above results suggest that the conbined thermal insulation part has better thermal insulation performance, is a novel thermal protecting structure, and will have broad application perspect in the fields of aerospace and civilan thermal protection.

Abstract:Bisphenol E cyanate ester (BEDCy) was blended with silicone-containing arylacetylene resin (PSA) to prepare a blended resin (BEDCy/PSA) via solution mixing and evaporation process. The curing reaction of the BEDCy/PSA was studied by DSC and in situ infrared monitoring, the heat resistance of the cured blended resins was characterized by TGA and DMA. The dielectric and mechanical properties of the cured blended resins were further evaluated. The results show that PSA can catalyze the curing reaction of BEDCy. With the addition of PSA resin, the temperature of 5% weight loss and residual yield at 800℃ of the cured blended resins under nitrogen and air atmospheres are higher than 450℃, 80% and 19%, respectively. The dielectric constant and dielectric loss of the cured BEDCy resin decreases upon addition of PSA resin.

Abstract:2219 aluminum alloys with dissimilar heat treatment were butt welded respectively by conventional and weaving tungsten inert gas arc welding. The characteristics of mechanical properties , microstructures and hardness distribution of the joints were studied. The analysis results showed that compared with conventional welding process joints, the weaving welding joints’ mechanical properties improved while the micro hardness values decreased in bottom region of PMZ and OAZ, and the width range increased. The joints strain distribution showed that conventional welding process joints’ max strain distribute along diagonal while the weaving joints show like nearly “W” form before fracture occurred. The microstructures observation showed that the quantity and size of the continuous second phase decreased in weaving welding joints’ CYS side PMZ and OAZ meanwhile, the fracture surface were ductile fracture mostly among the mixed fracture mode.

Abstract:Silicon carbide particle reinforced aluminum matrix composites play an important role in aviation, aerospace, electronics, automobile, and other fields due to its excellent mechanical properties. In order to improve its cutting performance, the liquid nitrogen spray experimental device was used to carry out milling experiments. The cutting force, surface integrity, and chip morphology were studied to explore the machining quality of TiAlN coating and TiAlSiN coating milling cutter under normal and low temperature conditions. The results show that when milling at low temperature, the cutting force of the two tools increases, and the surface defects such as aluminum matrix cracking and spalling are significantly improved, and the machined surface damage and roughness are reduced. Low temperature milling can obtain better surface quality. In addition, the cutting force of TiAlSiN coated milling cutters is lower than that of TiAlN coated milling cutters under normal temperature and low temperature. The surface integrity and chip morphology of TiAlSiN coated milling cutters are better than those of TiAlN coated milling cutters under low temperature conditions.

Abstract:In this article, three dimensional (3D) micro CT detection technique was employed to test welds with complex structures. The difficulties of testing the complex structure of welds using conventional radiographic testing were analyzed,thus, 3D micro CT, which provided advantages such as micron order focus size, and high resolution, achieved favorable testing results in electron beam weld, edge weld, and solder joint with complex structures. The results showed that 3D micro CT can realize the three-dimensional testing of complex structure welds. Furthermore, 3D micro CT can identify, locate and measure the holes, cracks, and incomplete penetration, providing foundation of weld quality evaluation.

Abstract: _{In order to ensure the image quality, improve the efficiency and reduce the cost of detection, it is necessary to select the appropriate radiograph according to the specific situation in the process of liquid rocket engine product ray detection. In this paper, the characteristics and quality stability of imported Fuji IX100 film and domestic Lekai L7 film were compared, the results show that the background haze of L7 film is slightly higher than that of IX100 film ,the sensitivity is lower than that ofIX100 film, and the tolerance is higher than that of IX100 film; However, both of them belong to T3 category film specified in GB/T19348.1-2003, and their comprehensive properties are relatively close; L7 film is suitable for X-ray inspection of aluminum castings with variable cross-section, steel castings with small machining allowance, titanium castings and most of fusion welds on engines.}

Abstract:The method of nondestructive testing of composite beams is discussed by using the operation mode analysis method of the transmissibility functions, by fitting the least squares of the acceleration transfer function, the frequency and damping are obtained,the mode shape is obtained by decomposing the singular value. Curvature mode shape (CMS) and curvature mode shape change rate (CMSI) are presented as damage indexes, modal analysis of composite beam structures with single, multiple and different damage degrees.The results show: the location and size and multiple damage of the damage can be identified. The transverse coordinates can reflect the location of the damage, and the spacing of the mutated units can reflect the size of the damage; the mutation extreme difference of the CMS and CMSI were found to increase with increasing damage degree, demonstrating that the CMS and CMSI has the ability to quantitatively identify damage degree; Compared with the CMS, the CMSI is more sensitive to the composite beams damage.

Abstract:To overcome the resolution limited of large industrial CT, in this article, Micro-CT was introduced, including its concepts, principles and technological superiority. Furthermore, the advantages of Micro-CT in detection of small size aerospace materials were elaborated through examples measured by Micro-CT techniques. Indicating that Micro-CT can detect micron-level defects in materials and their distribution in space, and the size distribution of defects can be counted by image processing software, a new way for the Nondestructive Testing of Aerospace materials was provided by Micro-CT.

Abstract:Usually, in the process of cured stringer co-bonding with uncured skin for composite stiffened panel, the fiber of the skin at the edge of the stringer flange will be buckling due to the bridging of auxiliary materials. According for these, this article studied that how the angle of chamfering at the edge of the stringer, skin thickness and skin ply angle influence the buckling of fiber in the skin nearing the edge of the stringer flange. The reason and mechanism of fiber buckling also were analyzed. The results show that decreasing the angle of chamfering at the edge of the stringer is beneficial to reduce the buckling degree of skin fiber. At the same time, the fiber buckling degree is positively correlated with the skin thickness, and negatively correlated with the 90 ° ply ratio in the skin ply. In engineering application, proper chamfering of stringer edge is beneficial to improve the forming quality for composite stiffened panel without using the craft soft cover.

Abstract:Abstract In order to manufacture eligible large-scale composite container, this paper formulates a design and manufacturing scheme for the forming mould of a composite container. The composite container is a large long-axis product, the foming mould of which would appear serious deflection and bear large demoulding force. The main mould structure adopts the combination structure of full-length steel pipe, web plates along circle direction, stiffeners along circle direction and skins. For the designed forming mould, the three-dimensional network structure made up by the seamless steel pipe, skeleton and skins effectively guarantees the rigidity; the draft surface and gradual fillet design significantly decreases the demoulding force; thicker steel plates were used in the ejection end to improve its reliability in the demoulding process. The simulation results show that the maximum stress value and deformation value are respectively 42.9MPa and 0.51mm in the simply supported condition, and the maximum stress values and deformation values are respectively 188.6MPa and 0.5mm in demoulding condition. According to the mould structure, the processing route of separately assembly welding and integrated assembling for the forming mould was formulated and the forming mould was manufactured. The simulation and practical use results show that the designed forming mould can meet the production needs of the large-scale composite container.