Abstract:Spacecraft in orbit will encounter space radiation environments such as electron,proton,heavy ions, photon,etc.,which results in the space radiation effects such as single event effects,total ionizing dose effects, displacement damage effects, surface charging and discharging or electrostatic discharging and internal charging effects. So it is necessary to protect the spacecraft from space radiation.In this paper,the protection principle and validity from space environments on spacecraft are introduced firstly,and the protection materials and structures such as mass shielding material,ESD protection material,radiation hardening functional material,local protection structure,whole-spacecraft protection structure,are discussed in light of three dimensions including material,subsystem,spacecraft.Finally some development directions on protection material and structure from space radiation environments are proposed.

Abstract:Organometallic polymers are widely used and easy to process,and their unique properties make them a complement to advanced metal-free organic polymers.This review systematically summarizes the research progress of organometallic polymers in the fields of luminescence,photovoltaics,conduction,information storage, liquid crystal materials,functional ceramic materials,nanolithography and nanoscience,and stimulus-response materials. The applications and perspective of these materials are also discussed.

Abstract:Due to lack of researches on the structural performance of adhesively repaired foam core sandwich composite,both a finite element model and a stability analytical model were built after repairing the sandwich composite and compressive experiment.The two models were validated by comparing them with the experiment.The adhesive was simplified in the finite element model.The results show that the critical compressive load can be obtained efficiently by using the stability analytical model for sandwich structures.The main failure modes of the adhesively repaired foam sandwich composite under compressive load are the first-order and second-order buckling.The finite element analysis model and the stability analytical model of adhesively repaired sandwich composite are accurate enough and have good potentials in engineering fields.

Abstract:TiAl alloys were widely used in aviation,aerospace and other manufacturing fields because of their excellent properties.However,due to the physical and chemical characteristics of TiAl alloys,their cutting performance was poor,and surface cracks,burns and so on issues were easy to occur in processing.In order to study the effect of cutting parameters on surface cracks in the milling of TiAl alloy,the orthogonal experiment of TiAl alloy cutting parameters and machined surface cracks was designed.The results show that the cutting speed has the greatest influence on the surface crack of TiAl alloy milling,followed by the cutting depth and cutting width, and the feed per tooth has the least effect on the surface crack.According to genetic algorithm,taking the surface crack length as the objective function,the optimal combination of parameters are:a_e=0.2 mm,a_p=0.2003 mm/z,f_z=0.02001 mm/z,v_c=20.0004 m/min.It is found that the error between the actual machining crack length and the optimized crack length is very small,which used the milling parameters optimized by GA.The optimal method is feasible and has low error.

Abstract:In view of the higher requirements of thermal environment,a novel light-weight high-temperature insulation material was proposed and fabricated.The system used high temperature resistant phenolic resin as matrix and added fibers and functional fillers as reinforcement.Then by performing low-pressure curing molding through pre-mixed sheet to obtain the final material.The density,thermal properties and mechanical properties of the material were tested.The results indicate that the density of the material is 0.6 to 0.9 g/cm³,the initial decomposition temperature is higher than 450 ℃,the tensile strength under room temperature and 200 ℃ are higher than 12 MPa and 10 MPa respectively,and the thermal conductivity is lower than 0.25 W/(m·K).All the properties can be designed and regulated according to application environment.The prepared heat insulation material test piece passed the ablation examination of model wind tunnel,the large-sized special-shaped structural cabin prepared by the material system passed the combined force-heat test at the same time, and the results can meet the overall design requirements.

Abstract:The automation forming technology of composite materials had become the most effective method and simplest approach due to the high efficiency and low cost.For the purpose of improving traditional low production efficiency and poor quality stability,by using self-designed mechanical forming equipment of composite stingers,the effects of process parameters such as the forming rate and forming temperature on the quality of forming parts are studied.The optimum forming parameters for[90°/45°/0°/-45°]_2s L-type parts are obtained through characterizing the thickness of the corner,the fiber volume,the porosity and fiber deformation by size measurement and metallographic analysis,i.e forming rate of 1 to 3 mm/min,forming temperature of 97 ℃ when the forming space is 2.99 mm.Under this condition,the parts obtain good quality as uniform thickness,small pore defects and fiber defection.A Teflon cloth protective layer on the surface of the layup can effectively improve the deflection and deformation of the fiber in the 45° direction of the surface layer.

Abstract:Large sand casting magnesium alloys were prone to coarse grains,resulting in poor elongation at room temperature.In order to solve the above problems， the slow cooling conditions of large castings was simulated and the optimum process parameters of room temperature strengthening and toughening of large Mg-Gd-Y magnesium alloy castings were studied by composition optimization,microstructure analysis and heat treatment optimization.It is found that Mg-6Gd-3Y-0.5Zr (GW63K) has good comprehensive performance，the optimum solution treatment parameters for GW63K are 475 ℃/7 h+495 ℃/3 h,and the optimum aging treatment parameters are 200 ℃/80 h，and the average tensile,yield strength and elongation at room temperature are 334.5 MPa,201.0 MPa和6.2%,respectively.This study provides a reference for the application of Mg-Gd-Y alloys on large castings.

Abstract:In order to study the effects of different pre-deformation on creep behavior and mechanical properties of aluminum alloy, the 2219 aluminum alloy was taken as example.Under condition of 175 ℃ and 180 MPa,creep behavior and mechanical properties of 2219 aluminum alloys with 0 to 8% pre-deformation after creep aging were investigated.The results show that the creep deformation and mechanical properties of materials increase greatly with the introduction of pre-deformation treatment.When the pre-deformation treatment is 1%,the creep deformation of the sample increases by 118% compared with that of the untreated sample.However,as the amount of pre-deformation continues to increase,the mechanical properties of the sample decline rapidly.With comprehensive consideration of creep deformation and the mechanical property,the most favorable pre-stretching for creep aging forming of components is 3%.

Abstract:The present paper is concerned with the thermal insulation property and evaluation of ablative performance of phenolic resin based carbon foam,which is prepared from phenolic resin,cyclopentane,tween-80 and P-toluenesulfonic via processes of foaming, solidifying and carbonization.The thermal insulation properties of carbon foam are investigated at 25 ℃，200 ℃，400 ℃ and 600 ℃ by LFA457 laser flash apparatus , while ablation resistance behaviors of carbon foam are studied using a custom built oxyacetylene torch test facility and the results are compared with that of C/C composites. The results show that thermal conductivity of carbon foam whose density and compressive strength of carbon foam are 0.3 g/cm³ and 11.7 MPa,respectively is 0.141 W（/ m·K）and 0.344 W（/m·K） at 25 ℃ and 600 ℃.The liner ablation rate of carbon foam is 0.03 1mm/s, and the back-face peak temperature of carbon foam is about 150 ℃ lower than C/C composites.On the contrary,the front-face peak temperature of carbon foam is about 400 ℃ higher than C/C composites.The conclusion is drew that carbon foam with low density has excellent thermal insulation property and ablation resistance behavior.

Abstract:In order to study the influence of fiber hybridization on the low-velocity impact performance of 3D woven composites,two kinds of composites of T700 carbon fiber reinforced and E-glass/T700 fiber hybrid were fabricated based on the same interlock 3D woven structure.Low-velocity impact experiments were carried out, and the impact energies were set as 10 J,23 J and 40 J,respectively.The results show that under the impact energy of no more than 40 J,the two composites are not broken.Under the three kinds of impact energies, the peak forces of hybrid materials are smaller than that of all-carbon materials,but hybrid materials have better impact energy absorption capability and larger maximum displacement.Under the impact energy of 10 J and 23 J,the damage degree of hybrid materials is smaller than that of all-carbon materials. However,when the impact energy reaches 40 J,the damage degree of hybrid materials is greater than that of all-carbon materials.

Abstract:To investigate on the surface generation mechanism and the influence of milling process of the wave-transmitting Si₃N₄ ceramics,experimental study on the surface topography and edge chipping characteristics,as well as the mapping relationship between machining parameters and cutting force,surface roughness and edge chipping had been carried out.Firstly,the surface morphology of the machined surface had been analyzed.Due to the existence of ceramics powder removal and broken particle removal,the surface topography was characterized by gentle change,while the other contains micro-cracks,layered structures,etc.And there were defects such as pits and grooves.Secondly,the edge chipping shape and its mechanism had been studied. When the tool moves to the edge of the exit,micro-cracks would be generated at the stress concentration of the tool tip and spread to the side of the workpiece,thus causing edge chipping on the machined surface and the side.Finally,the influence of process conditions on the processing performance has been analyzed based on the uniform design experiments.The experimental results show that with the cutting depth increases from 0.2 mm to 0.5 mm and the cutting width increases from 1 mm to 4 mm, the cutting force of the x-axis is coupled growth, and that of of the y-axis increases quadratically.The machining surface roughness value is minimum when the cutting depth is 0.2 mm,the cutting width is 1mm and the feed speed is 500 mm/min,respectively.As the rotation speed is 2 000 r/min, the edge chipping amplitude is the smallest when the cutting depth and the cutting width are the smallest.Machining process control can be implemented to improve the milling surface integrity of the wave-transmitting Si₃N₄ ceramics.

Abstract:Aramid fiber-reinforced polymer was easy to occur defects such as ablation and burr in traditional turning process. The method of liquid nitrogen cooling turning process was carried out to reduce the defects of fluff and high temperature ablation of aramid fiber material and improve the cutting performance and machining quality. The experimental results of dry turning and liquid nitrogen cooling turning of materials were analyzed,and the mechanism of liquid nitrogen low temperature turning was discussed.The results show that with the increase of spindle speed, the fiber surface quality is improved.Especially at 1 340 r/min,the optimum surface is obtained.In liquid nitrogen cooling turning process with different speeds,surface qualitis are better.At the same spindle speed,the surface quality of liquid nitrogen cooling turning is better than that of dry turning.Therefore，the decreasing cutting temperature has played a positive role for the improvement of the aramid fiber cutting defects.

Abstract:In order to study the effect of surface structuring on the grinding behavior of the grinding wheel,novel laser structuring method using pulsed laser was proposed and applied to produce certain macro patterns on the surface of resin bonded diamond grinding wheel.The grinding experimental of alumina ceramic was carried out by using six type different patterns of diamond grinding wheel surface.The grinding force model of laser macro-structured diamond grinding wheel was established.The grinding force between six different laser macro-structured diamond grinding wheel and non-structured was compared under different grinding parameters.The grinding wheel surface morphology after manufacturing and the wear behavior were analyzed.The experimental results showes that the type of surface pattern has a strong influence on the grinding results.The grinding force of laser macro-structured grinding wheels can be reduced by 2.5% to 24.5%.The graphitization phenomenon appeares on the surface morphology of the structured grinding wheel.The wear of the groove edge is aggravated. The groove wear doesn't reveal a significant increase in wear of the structured grinding wheel.

Abstract:Aiming at precision measurement in the manufacture process of carbon fiber reinforced composite reflector mold,an in-situ measurement technology based on robot and laser tracking three-dimensional measurement system was studied. Each unit in the in-situ measurement system was correlated by measuring trajectory planning and coordinate frame transformation, the continuous motion of the two systems could be followed to complete the automatic and efficient sampling of point clouds on the mold surface.On this basis,the parabolic surface accuracy evaluation algorithm is studied,and the best fitting between the measurement points and the theoretical model was realized, thus the values of the mold surface accuracy were obtained.The results show that the measurement efficiency is greatly improved by using the in-situ measurement technology,and the numerical and graphic results of the surface accuracy can assist the efficient modification of the mold.

Abstract:This paper focuses on the problem that CLF-1 (low-activated ferritic/martensitic steel),a new material to be used as the structural material of the fusion reactor,has no specific standard reference in the process of X-ray detection.The X-ray digital radiography equivalent translucency of CLF-1 steel and Q235 steel with different thickness is studied by using the method of equal effects under the same translucency condition.Based on the same imaging condition,the corresponding X-ray images of the two materials have the same gray value,that is,the transmittance coefficient is the same.By comparing the thickness of the two materials with the same gray value of the image,the equivalent transmittance coefficient of CLF-1 steel corresponding to Q235 steel is obtained. In this paper,test pieces of CLF-1 steel and Q235 steel with thickness from 4 mm to 20 mm,step increased by 0.5 mm,are designed.The translucency test was carried out under the condition of 100 kV to 400 kV (step increased by 50 kV) tube voltage,and the equivalent coefficient of X-ray transmittance of CLF-1 steel relative to Q235 steel under the corresponding voltage was obtained to be 1.10 to 1.13.The results of this paper are instructive to the determination of technical parameters of X-ray detection of CLF-1 steel.

Abstract:In this work, the pulling test condition and test results of post-insert through-hole connector in the honeycomb panel were discussed.The influence of the inserts raw materials and the adhesive amount around the insert on the pulling strength and bonding quality were analyzed.The results show that aluminum alloy inserts and magnesium alloy inserts almost have the same pulling strength under the same condition.Compare to the aluminum and magnesium,the magnesium lithium alloy inserts have less initial failing strength and ultimate breaking strength but the maximum yielding strength is similar to the other two samples.In terms of one specific inserts,increasing the adhesive amount will be benefit to the pulling strength.The conclusions of this work can be used as references for future product test design and processing configuration setup.

Abstract:In order to solve the problem of fused deposition modeling application in space, the forming process test of different materials was carried out on earth.PLA,PC,PEEK and carbon fiber reinforced PLA materials were selected as the research objects in the experiment.The standard samples were successfully printed with the self-developed space microgravity principle prototype, and the mechanical properties, fire resistance, gas concentration after combustion, total mass loss and condensable volatile properties of the samples were tested. The tensile properties of carbon fiber reinforced PLA samples with different fiber directions and the performance difference between FDM and injection samples were studied. The result shows that the material bonding ability is the main factor affecting the performance of FDM parts, and the bonding strength between different materials is the main factor affecting the properties of the composite samples. The higher bonding ability is, the higher the FDM forming quality of the material is. Meanwhile the forming quality of the crystalline material is also affected by the crystallinity. The higher crystallinity is, the better workpiece performances are.

Abstract:In order to investigate the influence of the shape of the mesh electrode on the electrolytic processing of GH4169 high temperature nickel-based alloy,the electrode “lifting and shaking” method was used. The comparison experiment of flat mesh electrodes with 0.5 mm,0.8 mm and 1.0 mm apertures and comparison experiment of flat mesh electrodes and and curved mesh electrodes were carried out.The results show that when the hole diameter is 0.5 mm,maching chips cannot be removed effectively,and the machining can not be continued. With the increase of the electrode hole diameter,the machining stability is improved,and with the machining speed increasing, the machining accuracy is reducing.When the curved mesh electrode is used for processing,the surface of the workpiece is uneven because the shaking plane is not parallel to the required processing surface.Therefore, in actual processing,the shape parameters of the mesh electrode should be reasonably selected according to the specific requirements,such as stability,speed and accuracy.

Abstract:High silica glass fiber/phenolic composites were prepared by thermal expansion molding (SRTEM) with silicone rubber.Morphology of the fracture surface was characterized by scanning electron microscopy.The porosity and performances between SRTEM and traditional molding composites were compared.The variation coefficients of density and tensile strength were analyzed.The results show that the SRTEM composites have higher surface gloss, and its porosity is low and close to 0.The variation coefficient of density is 0.09,and the variation coefficient of tensile strength is 1.95% and lower than that of traditional molding composites.