Abstract:The research progress of the mechanical properties of the coating is introduced, and the test methods and the application of crosslink density are summarized. The existing constitutive model is analyzed and suggestions for improvement are put forward. The mechanical properties of the coating in complex environment is the key point for the next research. Investigating macro mechanical properties of the coating through micro-mechanism analysis is the trend for mechanice analysis. Application of modern instruments like NMR can overcome the shortages of the conventional methods, which prospects a positive future.

Abstract:Pull type lockbolts is widely applied in aerospace composite case.The assembling efficiency and quality of aerospace composite case can be improved by the realization of automatic drilling-riveting technology.In this papers the riveting principle of pull type lockbolts is introduced.Some automatic drilling-riveting technology in China and abroad and the recent developments are reviewed in the paper.Working characteristics and effect of common automatic drilling-riveting system are analyzed.Further more a new kind of automatic drilling-riveting scheme for composite case assembling are presented,which lays a foundation for the automatic drilling-riveting of the composite case.

Abstract:Uniaxial tensile test and shear test were operated on wide temperature butyl isoprene rubber under -55,-40,20 and 65℃ to study the applicability of constitutive models.The ability of the constitutive model to predict other deformations was verified.On this basis,the finite element method was used to analyze errors of constitutive models and the applicability of models to butyl isoprene rubber at different temperatures and strains were determined.The results show that the higher order of constitutive model corresponds the worse prediction ability and low-order Neo-Hookean model has best prediction ability. At the same time,Yeoh model and third-order-five-term model are adopted when working temperature is between -55℃ and 20℃,and Yeoh model is chosen when the temperature is between 20℃ and 65℃ in finite element calculation of butyl isoprene rubber in flexible joint.

Abstract:The hydrothermal behavior of low curing temperature HS40 carbon fiber/cyanate ester resin composites under different hydrothermal environments as well as under three cycles of moisture absorption and desorption processes and continuous moisture for 60 d were investigated. The results show that the saturated moisture absorption of composites exposed to the environment of 70℃ water bath and 70℃/95% RH for 31d are 0.71% and 0.11%, respectively, which shows a good humidity resistance.The moisture absorption of composites at 70℃ water bath for the first 10d is 0.69%, and the moisture absorption of the second and the third immersion are 0.72% and 0.74%, respectively. Additionally, after three cycles of moisture absorption and desorption,the interlaminar shear strength of all the specimens reduces and the extent of decrease is more obvious as the increase of cyclic times. For the specimens after three cycles of moisture absorption and desorption, the interlaminar shear strength decreases by 50.77% compared with the dry specimens. For the specimens with continuous water absorption for 60d, the interlaminar shear strength decreases by 58.98% compared with the dry specimens.

Abstract:High silica glass fiber (hSGF) reinforced phenolic(PF)and phenolic foam (PFa) composites were prepared, and the structure and properties of the composites were characterized by Infrared spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results show that the hSGF/PFa composites have similar chemical structure and curing reaction temperature in comparison to hSGF/phenolic resin (PF) composites, and both have good heat resistance. The properties of the composites were investigated. The density and the thermal conductivity decrease from 1.65 g/cm³ and 0.5 W/(m·K) to 0.5 g/cm³ and 0.09 W/(m·K), respectively, with decrease of the mechanical strength, when the matrix was changed from PF to PFa.

Abstract:The quartz fiber was hollowed and the hollow fiber/phenolic resin composites were prepared by compression molding. The results show that the cavity diameter of hollow fiber is 4~7 μm. With increase of the fiber hollowness from 0 to 0.5, the mechanical strength of the fiber increases. Under the same fiber volume content, when the fiber hollowness increases from 0 to 0.5, the density and thermal conductivity of the composites decrease from 1.63 g/cm³ and 0.49 W/(m·K) to 1.46 g/cm³ and 0.41 W/(m·K), respectively, and the ablation resistance remains unchanged. The hollow fiber/phenolic composites prepared by this method behave good thermal insulation performance and ablative properties.

Abstract:According to the requirements of winding technology and special use environment of low temperature liquid oxygen tank, the technological characteristics of three kinds of self-made epoxy resin and the property of low temperature crack resistance were studied. Then, the mechanical properties of T700 carbon fiber reinforced composites were investigated under ultra-low temperature and high-low temperature cycling treatments. Finally, a small carbon fiber reinforced composite cylinder was used for the comprehensive performance test. The results showed that SFC-3 epoxy resin had better winding technology and excellent crack resistance property under ultra-low temperature and high-low temperature cycling treatments. After the aforementioned treatments, the tensile performance retention rates of T700/SFC-3 epoxy composites were above 92% respectively, and the composite material had good liquid oxygen compatibility. T700/SFC-3 epoxy resin composite cylinder had excellent high and low temperature stabilities and gas tightness.

Abstract:A kind of MT300/902 polyimide composite was prepared by autoclave molding process, and the effect of three different process parameters (pressing temperature, pressure, curing temperature) on mechanical properties were examined. The influence of process parameters on properties of polyimide composite was studied. According to the results, the best pressing temperature of MT300/902 polyimide composite was 240~260℃, pressure range was not lower than 1.2MPa, and the best curing temperature was 310~330℃. Using the best process parameters, MT300/902 polyimide composite with better mechanical properties and high quality (defect area is less than 2%) than the original and polyimide composite structures were prepared.

Abstract:Composites will have curing spring back deformation resulting in dimensional changes due to unavoidable physical and chemical mechanisms which take place during the autoclave curing process. V-shaped composites are widely used in the outer surface of the aircrafe, therefore it is essential to study the deformation mechanisms of the curing process for improving composites molding precision and effectively reducing the difficulty of assembly. This paper establishes the finite element analysis model and design the typical structure sample in order to analyse the influence of mold forming method on the curing deformation of V-shaped composites.The results show that the deformation between the predicition and the sample is in the range of 5%, and the deformation of the male mold forming is 10%~15% larger than that of the female mold forming.The deformation springback is inversely proportional to the corner angle and the thickness of the workpiece, when the male mold forming and its spring back angle is proportional to the radius of the coener.

Abstract:The mechanical, electrical and heat resistant properties of 5229D/T700 conductive epoxy composites were systematically characterized. At the same time, the space environmental suitability of 5229D/T700 conductive epoxy composites was investigated by thermal vacuum outgassing test, thermal cycling test and total dose radiation test. The results show that the 5229D/T700 conductive epoxy composites has excellent heat resistance (T_g is 236℃, flexural strength retention is 85% at 150℃) and very low pollution (TML is 0.44%, CVCM is 0.05% at 150℃). It is also observed that the mechanical properties of conductive epoxy composites are hardly affected by thermal cycling and total dose radiation, while the electrical properties are slightly increased after total dose radiation, showing excellent space environmental suitability.

Abstract:C/SiC composite is a typical material difficult to machine. It is hard and brittle.In machining, the cutting force is large, the material removal rate is low, the edge is easy to collapse, and the tool wear is serious. In this paper, the grinding of C/SiC composites material along the direction of fiber distribution AUAG is studied respectively.The surface microstructure and mechanical properties of C/SiC composites processed by ultrasonic machining were evaluated. The change of surface quality with the change of processing parameters was studied. The experimental results demonstrate that the optimal surface quality can be obtained through the optimization design of AUAG ultrasonic grinding parameters.

Abstract:In order to assemble and connect the dissimilar aluminum alloy ring parts accurately, a horizontal friction stir welding tool which can change axial movement into radial expansion was designed. The results show that the Al-Cu/Al-Mg dissimilar aluminum alloy ring parts can be assembled and connected with high precision and high quality. The internal quality of the joint meets the requirement of grade I. The tensile strength and elongation of the joint are higher than 245 MPa and 16%, respectively. Besides, all the joints are broken on the side of Al-Mg based aluminum alloy. It can be concluded that the overall performance of the joint is better than that of Al-Mg based aluminum alloy. Finally, the engineering problem of welding cracks during the Al-Cu/Al-Mg dissimilar aluminum alloy welding is solved.

Abstract:Aimed at the precision measurement during the manufacture process of antenna reflector, a measurement method based on automatic measurement technique using CAD model and data process technique was proposed. Through the planning of measuring points and aligning of workpiece with CAD model, the complete measuring data of reflector were acquired automatically. The optimum matching between the measuring data and the CAD model was achieved by the optimization algorithm, then the surface accuracy of the reflector was precisely evaluated. The transformation matrix was also obtained. Finally, the surface deviation trend of the antenna reflector was expressed by the deviation vector graph, and the datum was corrected by using the transformation matrix, which ensured the surface accuracy and machining accuracy of reflector. The practical application has indicated that the method could meet the measurement requirements of reflector.

Abstract:Nickel-alloy turbine was corroded after worked for a period of time. The size of turbine blades became smaller. Through observation, testing, the corrosion reason of the tubine was found. The results show that the corrosion was sodium salt hot-corrosion. The oxide was fell off which made the size of turbine blade became samaller. Because the fuel oil was not burned all, some sodium-salt deposited on the turbine's surface, which made the tubine corroded.

Abstract:In order to obtain high-performance bearing bracket for spacecraft, the mechanical properties of short glass fiber reinforced polyether ketone (SGF/PEEK) with different fiberglass content were analyzed.And the injection mold and injection process parameters were optimized by the software of Moldflow. The results show that the mechanical properties of 30wt% SGF/PEEK are optimal. The mold flow simulation can predict the injection process effectively. Improving the sizes of main and secondary runners can effectively enhance the effect of pressure holding. The holding pressure and the mold temperature have remarkable influences on the warpage deformation of bearing brackets. The brackets formed by optimized process parameters have been applied to spacecraft fuel tanks successfully and passed the flight assessment.

Abstract:In order to reveal the anisotropic behavior of the unidirectional carbon fiber reinforced plastics (UD-CFRP) delamination during the drilling, the shape and size of the delamination on the top layer of the hole exit are investigated. The results indicated that the shape of the UD-CFRP delamination was suborbicular rather than smooth elliptical. The size of the delamination decreased with increasing the spindle speed, and the most obvious was in the direction of principal stiffness, but the max decrement was only 0.14 mm. Large area of the fiber bundle tears would easy to occur in the direction of principal stiffness with increasing the feed speed. And the size increased with increasing of the feed speed, the most obvious was also in the direction of principal stiffness, the max decrement was 0.81 mm. The shape of the delamination appeared suddenly change in the direction of principal stiffness due to the large area of the fiber bundle tears.

Abstract:Takes glass fiber reinforced resin matrix composite and its composite stepped hole as the research objects, through performance analysis, tooling and tool design, process parameters optimization, the influence of various factors on the stepped hole is studied. The experimental results show when the pre pressure stress is applied to the material of the drilling area by using the 25 degree (helix angle)/15 degree (rear angle) of the alloy composite bit, the processing quality of the hole is best under the speed of the bit is 250 or 315 r/min, the feed rate of the bit is 0.06 or 0.1 mm/r.

Abstract:Through forming process selection, mould structure design and process parameters optimization, the near net shape forming of the thin-walled profiled resin matrix composite is explored. The results show that the injection molding overcomes the problem that the charging chamber is narrow and difficult to load in the tradional molding process, and then, realize the near-net shape forming of thin-walled profiled resin matrix composites, which greatly improve the material utilization, reduce the difficulty of processing and shorten the molding cycle.

Abstract:Based on the structure feature of high-rubbed and thin-walled titanium alloy blade,the effects of the initial forging temperature,velocity and friction factor were studied with the method of FEM simulation,Selecting the optimized process parameters for physical experiment,the results show that under the conditions of initial forging temperature of 920℃,press speed of 0.5mm/s,friction coefficient of 0.1,the isothermal forging products can meet the quality requirements.