- Volume 43,Issue 5,2013 Table of Contents
>综述
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2013, 43(5).
Abstract:
Recent development of thermal protection materials has been reviewed emphasizing on the ablativematerials for deep space exploration. The technical request of ablators for future planet probes has been analyzed vialooking back TPS of several successful missions. -
2013, 43(5).
Abstract:
Recent progress in shape memory polymer composite ( SMPC) in China and abroad has been re鄄viewed. The emphases are put on thermo鄄active SMPC ( TSMPC) and electro鄄active SMPC ( ESMPC). Two鄄wayshape memory composites have arisen in TSMPC. In the aspect of application, SMPC has been known to be used forself鄄repairing of composites structure. Research trends in China and abroad have been summarized. Bottleneck prob鄄lems in application have been pointed out. Meanwhile, suggestions for future development have been given. >计算材料学
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2013, 43(5).
Abstract:
According to the position equation of variable stiffness curved鄄fiber placed in plane, the trajectory ofvariable stiffness composite cylinders were designed. The mathematical model of the fiber鄄placed robot configuration issolved by the Denauit 鄄Hartenbery method. The virtual prototype model of the fiber鄄placed robot is established, whilekinematics simulation is implemented using Solidworks software. The kinematics simulation is analyzed, while the mo鄄tion parameters of each joint are drawn and studied. It is proved the rationality of the designed trajectory. The simula鄄tion results and the results of the mathematical model are compared using Matalb software. The results confirm that themathematical model is accurate and reliable. -
2013, 43(5).
Abstract:
This paper presents the variable鄄stiffness composite laminates with curvilinear fiber placement finiteelement modeling method. According to the curvilinear placement rule definition of every unit of the real constant, thevariable鄄stiffness composite laminates with curvilinear fiber placement modeling was established. Bending and compres鄄sion failure of two kinds of different boundary conditions was discussed, through the Tsai鄄Wu failure criterion, themaximum inverse strength radio index 1/ R was calculated. Taking 1/ R =1 as the critical load of failure,bending con鄄dition of critical failure load is increased by 16% and 21%, compression condition of failure load is increased by51% and 19%. The results show that variable stiffness composite can improve failure properties. >新材料新工艺
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2013, 43(5).
Abstract:
Two鄄layer core sheets of TC4 titanium alloy four鄄sheet strengthened structure were researched. Thesheets were welded by laser penetration welding instead of traditional superplastic forming/ diffusion bonding ( SPF/DB) process coated with check flux. The superplastic forming of the core sheets were simulated by ABAQUS finite el鄄ement analysis(FEM). Optimized pressure鄄time (p鄄t) curve was obtained. The p鄄t curve was used as the pneumaticloading curve of this process,then use superplastic forming test to verify it. It reveals that the FEM results consist withthe experimental results, the thickness distribution is homogeneous,no weld tear phenomenon occurred. So the pro鄄posed process is feasible. -
2013, 43(5).
Abstract:
Nanocrystalline Ni-Zn ferrites powder were prepared by spraying鄄coprecipitation method. Permeabili鄄ty of nanocrystalline Ni-Zn ferrite/ epoxy resin composite were measured with Agilent impedance analyzer in the rangeof 10 to 110 MHz. The results show that the grain size of Ni-Zn ferrite by spraying鄄coprecipitation method is about 30nm calcined at 600益for 1. 5 h. With the decrease of epoxy resin and the increase of forming pressure, the real partof permeability 滋忆of the composition increases and its imaginary permeability 滋义decreases gradually. Under the sameprocess conditions, the real part of permeability 滋忆of the composition increases and its imaginary permeability 滋义de鄄creases with the increas of the grain size of nanocrystalline Ni-Zn ferrite. The maximum permeability for nanocrystal鄄line Ni0. 4Zn0. 6Fe2O4 ferrite can be obtained. -
2013, 43(5).
Abstract:
The poly (lactic acid) / hollow glass beads (PLA/ HGB) composites toughened by maleic anhydridegrafted ethylene鄄1鄄octene copolymer (EOC鄄g鄄MAH) were fabricated via molten and compression molding. The effectsof mass fraction of EOC鄄g鄄MAH on the microstructures, mechanical properties and thermal stabilities of the compositeswere investigated. The results indicate that the superficial wettabilities of PLA to HGB are facilitated with the presenceof EOC鄄g鄄MAH and the interfacial adhesion between the matrix and HGB is enhanced remarkably. The tensilestrength of PLA/ HGB composites is increased firstly and then decreased. With 3% EOC鄄g鄄MAH, the peak value oftensile strength is obtained which is 14. 23% higher than the controlled sample, whereas the elastic modulus is de鄄clined continuously. In this investigative range, the impact toughness exhibits the trend of rapid increasing and thenmoderating with the increase of PP鄄g鄄MAH. However, only 7% mass fraction of EOC鄄g鄄MAH could lead to a nearly40% improvement in impact toughness which indicates that the EOC鄄g鄄MAH is preferred to improve the impact resist鄄ance of PLA/ HGB composites. The existence of EOC鄄g鄄MAH varies the procedures of thermal decomposition of PLA/HGB composites from one step weight鄄loss to two step weight鄄loss, whereas hardly influence is shown on the thermaldecomposition temperature. -
2013, 43(5).
Abstract:
Carbon cloth was a key material for preparing the 3D woven performs. The property of needled performwas decided by the tensile stress of carbon cloth after needling. The tensile stress of needled carbon cloth could providea reference for optimizing technical parameters and improving properties of performs. The tensile stress and the factorsthat affect the stress of carbon cloth were studied. Among the 3 K plain carbon cloth, the 3K twill carbon cloth and the3K satin carbon cloth, the 3K twill carbon cloth has a high tensile stress and stress retention and shows the best techno鄄logical properties. Under a certain process, the tensile stress of the needled carbon cloth can be simulated by a functionofy = A1 伊e-x / t1 + y0, in which A1, t1 and y0 are constants. The needle punching density was the most important factorthat affected the tensile stress ant the stress retention percent, and the final needle punching density decided the tensilestress. When the needle punching density was 26 n/ cm2, the stress of warp and weft direction of 3K twill carbon clothdecreased 42. 0% and 49. 1% respectively, and when the needle punching density was 32 n/ cm2, the number was71郾4% and 78.8%. -
2013, 43(5).
Abstract:
Kevlar fibers were modified by mechanical method and ultrasonic treated with different time, respec鄄tively. The effects of the two methods on the surface morphology of fibers, the dispersion of fibers within EPDM, andthe mechanical and anti鄄ablative properties of EPDM composites were investigated. Results showed that the roughnesswas remarkably increased for the fibers treated by the two methods basing on different mechanism. The mechanicaland anti鄄ablative properties of EPDM composites (11. 3 MPa and 1. 2 mm, respectively) are superior to that of EPDMcomposites filled with ultrasonic鄄treated Kevlar fibers, which is because of the homogeneous dispersion of fibers withinEPDM phase. -
2013, 43(5).
Abstract:
In present study, the evolution of sp2 hybridization for CCF300 carbon fiber during the heat treatmentprocess was studied by Raman spectroscopy. The transition from sp3 to sp2 hybridization was traced by the method ofdeconvolution for Raman scattering curves. The parameter which can be used to trace the graphitization was defined as琢,namely IGIG +IC. The results indicated that with the increasing of the heat treatment temperature, the amount of amor鄄phous carbon decreased gradually. Before 1 700益, the rate of transition to sp2 hybridization structure is more rapid.After 1 700益, however, this rate had slowed down dramatically and the pseudo鄄graphitic structure is formed graduallyafter the transition to sp2 hybridization structure. >测试分析
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2013, 43(5).
Abstract:
Three flexible insulations made from different ceramic fibers were treated at 300益, 600益and 900益for 30 min in atmosphere, respectively. Tensile strength was studied with a different variation of the heat treatmenttemperature and fiber surface was observed by SEM. By analyzing the fracture mechanism of the fiber, the main rea鄄son leading to the decrease of tensile strength at high temperature was suggested, which was the ablation of agent onfiber surface and the crystal transition of amorphous fiber. -
2013, 43(5).
Abstract:
Different from the method of Oval imaging method on ray detection of narrow鄄bore tube weld, the Ul鄄tra narrow鄄bore tube weld detection normally use the vertical transillumination method. The essay discusses the choiceof oval imaging and the vertical transillumination method through the transillumination thickness ratio and the imagingdisplacement analysis, base on the specific circumstances of the Ultra narrow鄄bore tube. According to the feature ofray image overlay of vertical double鄄wall single shadow transillumination, the essay do key analysis on the image fea鄄ture of the Ultra narrow鄄bore tube opposite reinforcement, propose two practical way of measuring the figure of oppo鄄site reinforcement. The essay concludes that the simplified transillumination satisfy the actual needs of the project. -
2013, 43(5).
Abstract:
In this paper, the traditional three鄄point short beam shear test and a modified three鄄point shortbeam shear test were used for measurement of interlaminar shear strength of needling C/ C composites nozzle exten鄄sion. The test results showed, the modified method well reduced the stress concentration phenomenon that the tradi鄄tional method caused, and specimems occurred interlaminar shear failure more easily. Moreover, the test values of themodified method were higher than the traditional method,and more approach to the fact. Lastly, the weakness positionof failure test specimems of the modified three鄄point short beam shear test was found by scanning electron microscopy,and made a suggestion on material preparation process. -
2013, 43(5).
Abstract:
The inner flow thermal environment of engine has been simulated by the arc鄄heater double鄄modelsrectangle turbulent duct technique in this paper. And the thermal protection performance of the thermal protection ma鄄terials with high鄄emissivity rear coating has been tested. The improved model installation method, which can provideopen鄄type environment with normal temperature in the material rear, can make sure that the rear coating of materialcan radiated energy to the atmosphere or wall with normal temperature. And the heat transfer environment of the mate鄄rial rear has been simulation by this method. The type鄄K thermocouples and single鄄wavelength infrared thermometerwere used to measure the high鄄emissivity rear coating temperature. According to the rear temperatures measured bythe two kinds of instruments, the spectral emissivity vs. temperature curve can be found. The results show that therear temperature of thermal protection materials with high鄄emissivity rear coating is 81. 1 K lower than that withouthigh鄄emissivity rear coating. The spectral emissivity of high鄄emissivity rear coating 着姿(姿=1. 6 滋m) is 0. 89 to 0. 77for the temperature range from 1 103 to 1 153 K, and 着姿decreases when the temperature increases. -
2013, 43(5).
Abstract:
The compactness of resin was studied by the moisture adsorption method in the paper. The research processwas explained by six kinds of resins, including S-157 phenol resin, Q-913 phenol resion and boron modified phenol resinetc. Six kinds of resins were decomposed to get different residual chars under the protection of nitrogen atmosphere. The re鄄sidual chars were transferred and placed under a laboratory with the controlled humidity and temperature. The weight chan鄄ges of several residual chars were weighed up by a balance with the precision of 0.001 milligram. The compactness of resid鄄ual chars were compared by their increment after adsorption balance of moisture. The relation of the mass change with in鄄crement of six residual chars was gotten after a interval of 200 minute moisture adsorption. The microscope structure of resid鄄ual char was observed by electron scanning microscope, and the compactness in microstructure is in accordance with the a鄄bility of moisture adsorption. >工程实践
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2013, 43(5).
Abstract:
Thermal protection coating is very important for small ultra鄄high speed tactical missile to achieve ad鄄vanced design and excellent performance. Felicitous material & technology is a key to realize it for execution of thecoating. In this paper,surface treatnments, primers,filler decentralization and spraying technology is studied, andthen tests are performed. Test result show that performance of coating,as adhesive force,thermal protective perform鄄ance and environment adaptability,meet the requirements. An effective process scheme is developed. -
2013, 43(5).
Abstract:
For carbon fiber composite vessel with thin鄄wall metal liner, the basis of netting theory and the expe鄄rience value method of developed fiber strength easily induce that practice burst pressure is far higher than designpressure, and developed percentage of fiber strength is higher than design value. The reason is mainly analyzed in thepaper,solving approaches and some methods in design are presented. Firstly,composite technique is designed mainlybased on practical fiber strength;Secondly,load鄄bearing of liner and resin should be calculated;Thirdly,fibers of vari鄄ous tensile strength are classified;Fourthly,iso鄄strength enveloped design method and reinforced dome technology canbe adopted to improve the situation. The above measures are used in order to develop fiber strength of composite vesselsufficiently, to reduce cost and to increase structural efficiency. -
2013, 43(5).
Abstract:
The certain enging was disassembled and inspected because of its turbine blades being invalidated atground starting. In this paper, it records the fault condition, takes computational analysis of clearance between lowpressure first stage turbine working blades and low pressure first stage guide blades of the fault engine, takes metallur鄄gical analysis and workpiece processing analysis and durability testing and mutuality dimension chain computing forengine broken blades. Taking systems analysis for blades broken reason by fault tree, it finds out the reason of engineblades invalidated and advances improving advices. -
2013, 43(5).
Abstract:
In order to improve the drilling quality,diamond abrasive tool is developed. Some experiments on thegrinding tool are carried out. The variations of thrust force and hole quality influenced by process parameters are in鄄vestigated. The results show that better hole quality can be reached when rotate speed is more than 6 000 r/ min andfeed speed is 5 mm/ min.
