28 April 2016, Volume 34 Issue 8
    

  • Select all
    |
    Spescial Issues
  • ZHAO Fagang, FENG Yanjun, FAN Fan, ZHOU Xubin, ZHOU Chunhua
    Science & Technology Review. 2016, 34(8): 15-17.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Accurate and timely locating of cracks, delamination and other damages in spacecraft structures is necessary for high reliability and long lifespan of the spacecraft. Composite structural health monitoring (SHM) is a revolutionary technology to ensure the completeness of composite structures. SHM plays an important role in the processes of designing, processing and maintaining spacecraft structures. Meanwhile, SHM contributes to the improvement of safety and reduction of cost. This paper first briefly introduces domestic and overseas advances in the spacecraft SHM, and then describes the problems encountered in the application of SHM for spacecraft.
  • TAO Jiongming, SU Ruobin, KONG Xiangsen, ZHAO Chuan, ZHOU Jing
    Science & Technology Review. 2016, 34(8): 18-20.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The continuous progress and innovation of new materials and new techniques have provided a solid basis for the development of satellite structure technology. On the other hand, the developing trend and requirements of structure technology are the source power of new materials and new techniques. The development of new techniques and new materials will promote the development of satellite structure technology, and vice versa. From the view of designing, this paper summarizes the key development orientation of specific structure technology according to the subsequent development trend of satellites. Meanwhile, the application requirements of new composite materials are proposed.
  • LIU Minjing, WU Zhanjun
    Science & Technology Review. 2016, 34(8): 21-25.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Honeycomb sandwich panel structure is one of the most efficient structures in aircraft. Several types of honeycomb sandwich panels, honeycomb core material and the typical cellular geometry are introduced, as well as corresponding performances. The application situations of honeycomb sandwich structures in both major foreign and domestic aircraft are described. Finally, some design ideas and concepts are discussed.
  • ZHANG Jing, YU Jin, XIONG Lei, SUN Wei
    Science & Technology Review. 2016, 34(8): 26-30.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Carbon fiber reinforced plastics (CFRP) have been recognized as the most ideal light-weight material in automotive industry due to their superior mechanical and chemical properties, including high strength, high stiffness, high fracture toughness, corrosion resistance, high damping capacity, and so on. The application of CFRP can significantly improve the service life, fuel efficiency, safety and comfort of a vehicle. The conventional molding technology of CFRP originated from the high variety, low volume and high cost production of aviation industry; so the mainstream vehicle manufacturers have developed several new rapid molding processes in order to meet the requirements of high productivity, low cost and mass production of vehicle components. In this paper, the properties and advantages of CFRP are introduced by comparing with traditional light-weight materials such as high strength steel, aluminum and magnesium alloys. Several promising rapid molding technologies of CFRP with typical application examples are described and analyzed.
  • ZHANG Si, ZHANG Yang, ZHANG Baoyan
    Science & Technology Review. 2016, 34(8): 31-34.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The basic performance of bismaleimide resin and the importance of toughening modification are reported in the paper. The methods of modification are reviewed, including allyl compounds modification, binary amine modification, combination of epoxy resin, high performance thermoplastic resin modification, cyanate ester resin modification, synthesis of new type bismaleimide resin, rubber modification, inorganic filler modification, liquid crystal modification, nanometer material modification, fexible material modification, etc. The mechanism of modification is depicted, such as addition reaction, Diels-Alde reaction, oligomerization reaction, Michael addition reaction, copolymerization reaction, crack mechanism of screw anchor, and half interpenetrating network mechanism. Besides, new advancement of the research is discussed.
  • YUAN Yuguo, WANG Jingyun, FU Nihong, ZANG Shuliang,
    Science & Technology Review. 2016, 34(8): 35-39.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Microcrystalline cellulose is degraded in 1-allyl-3-methylimidazolium chloride ([Amim]Cl) ionic liquid using heteropoly acid H3PW12O40 as catalyst under the mild environment. The effects of reaction temperature and time, the amount of catalysts and water on the degradation of cellulose have been investigated in details. When using 0.09eq of H3PW12O40, 0.07 mL of water, ca. 0.6 mmol of microcrystalline cellulose and 2.0 g of [Amim]Cl under microwave irradiation for 30 min at 160℃, 66.8% of total reducing sugar (TRS) yield, 32.8% of glucose yield and 17.6% of the cellobiose yield can be obtained.
  • PENG Xuefeng, HOU Jieping, YU Haibin, ZHANG Jingcheng, XU Haibing
    Science & Technology Review. 2016, 34(8): 40-44.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    4, 5-bis(5-chloro-2-methylthiophen-3-yl)-1, 2-diphenyl-1H-imidazole (L) is synthesized and characterized by 1H NMR, 13C NMR and elemental analysis. The effects of acid on the absorption spectra, fluorescence spectra and thermal stability of L are investigated. The results show that the acid effect on the absorption spectra of L is very little, but the fluorescence spectra and thermal stability of L can be effectively regulated by the acid. In addition, L shows good photochromism before and after the protonation, as well as the distinctive "on to on" fluorescence characteristic.
  • CUI Meili, GUO Fangjie, ZHOU Mingdong
    Science & Technology Review. 2016, 34(8): 45-53.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In recent years, water-soluble N-heterocyclic carbene metal complex have been widely used in organic synthesis due to its high catalytic efficiency, good selectivity and stability. It is playing an increasingly important role in the selective catalytic organic reactions and has aroused great concern. This paper reviews the types, the synthesis and the application of research results of water-soluble Nheterocyclic carbene metal compound in the field of organometallic catalytic chemistry, and its prospect is also depicted.
  • DANG Chengyi, WU Zhenyu, JIA Hongyu, LIU Ningning
    Science & Technology Review. 2016, 34(8): 54-59.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Polyvinylidene fluoride (PVDF) ultrafiltration membranes modified by nano-ZnO are prepared by phase inversion method to improve their hydrophilicity and enhance application in water treatment. The effects of nano-ZnO amount on the structure and performances of the membranes are investigated. The porosity, hydrophilicity, microstructure, mechanical strength, pure water flux, protein rejection and flux recovery efficiency are characterized by porosity measurement, contact angle measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), mechanical property test and ultrafiltration experiments, respectively. The results show the following. When the mass fraction of nano-ZnO is 0.2%, the contact angle of the membrane is decreased from 76.3° to 63.4°, indicating a significant hydrophilic improvement. The porosity increases from 53.4% to 54.1% and the tensile strength increases from 2.09 MPa to 2.82 MPa. Pure water flux, protein rejection and flux recovery efficiency are improved to a certain degree. The cross-section structure of the membrane is regular, the size of finger-like hole is large and the surface of the membrane is smooth.
  • XIA Chengsen, WEN Cuilian, ZHAN Xiaozhang, HUANG Xiaogui, LUO Lijin
    Science & Technology Review. 2016, 34(8): 60-66.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    MAO/HA/CNTs composite coating is synthesized on magnesium alloy by micro arc oxidation (MAO) with Hydroxyapatite/CNTs (HA/CNTs) nano composite powders as additives, which is obtained by chemical precipitation method. SEM, XRD, FTIR and electrochemical workstation are adopted to investigate morphology and phase composition of as-prepared composite coating, corrosion resistance and bioactivities of samples in SBF solutions. The results show that the prepared HA/CNTs composite powders are well crystallized and without any impurities. The HA/CNTs can be deposited on the surface of samples successfully during MAO process, sealing the holes of MAO coating. Moreover, the corrosion potential of MAO/HA/CNTs modified samples is -1.50 V; the surface is deposited by a large number of submicron scale particles after soaking in SBF for 30 days, which shows better biological activity and higher corrosion resistance compared with Mg substrate and MAO modified samples.
  • XIE Mingliang, PENG Chaoyi, DING Haibin
    Science & Technology Review. 2016, 34(8): 67-70.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    This paper investigates the properties of carbon fabric in ohmic heating and mechanical loads. The results show that the resistance of carbon fabric decreases basically linearly with the increase of temperature; but the variation range is small. For deformations caused by either tensile load or compressive load, the resistance of carbon fabric will increase with the increase of deformation, but the effects of these two loads are different. That is, the resistance increases linearly with the increase of tensile load, but there is great volatility in the initial loading and before tensile failure. For the bending load, the resistance has no significant change in the initial loading; but when the load reaches a critical value, the resistance increases linearly with the increase of the bending load.
  • LIANG Pinghui, SU Hao, DU Houwu
    Science & Technology Review. 2016, 34(8): 71-76.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    With the self-developed multi-functional glycidyl amine-ether epoxy resin, a liquid acid anhydride, and a modified aromatic amine curing agent as the basic raw materials, a high-temperature resistant epoxy pultrusion composite matrix resin for overhead wires composite mandrel has been produced. This resin has good pultrusion process performance such as lower viscosity, longer pot life in room temperature, and fast curing at high temperature. The above advantages ensure the resin and fibers infiltrate well in the high speed pultrusion process. By introducing complex accelerator and the situ split-phase toughening technique, the internal stress generated by the fast curing process is effectively decreased; therefore, the pultrusion composites have high strength, high-temperature resistance.
  • CHEN Ling, WU Fangfang, MA Heng, WANG Lifeng, WEI Yili, GAO Yibo
    Science & Technology Review. 2016, 34(8): 77-83.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Along with the economic globalization, environmental protection and green energy become the focus of overall construction. Fiber reinforced polymer (FRP) is proved to have excellent properties, such as light weight, high strength, corrosion resistance, insulation and environmental. It has been widely used in electric power networks worldwide. By searching the latest studies and applications, and combining working experiences, the authors overview the applications of FRP in electric power networks from the aspects of composite insulators, FRP towers, FRP electric power fittings, aluminum conductor carbon fiber reinforced core, electrical safety tools and so on. The overview shows that FRP, being of good quality, can satisfy both energy conservation and environment protection requirements. It has great potential in the future.
  • XU Qinglin, ZENG Jingcheng, WU Zhihua, WU Binrui
    Science & Technology Review. 2016, 34(8): 84-88.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The composite adhesive repairing and strengthening technology has many advantages such as fast fix speed, less weight gain, high efficiency and reliability et al., which has become a new technology for repairing and strengthening the concrete structure. In this study, the mechanical properties of the unstrengthened and strengthened RC bridge structures were analyzed and compared by using finite element method (FEM). Besides, the effect of the quantities of the prepreg tape, the fiber orientation, the material type and the lay-up sequence on the mechanical properties of the composites strengthened RC bridge structures were studied. The simulation results show that the internal maximum stress, maximum strain and maximum deformation of the strengthened RC bridge structure decreased clearly, which least can decreased by 60%, 56% and 11%, respectively, in comparison to the unstrengthened RC bridge structure. Furthermore, it is found that the mechanical properties are obviously influenced by the quantities of the prepreg tape and the fiber orientation, but slightly influenced by the material type and the lay-up sequence. The best reinforcement scheme is that lay-up material all adopt CFRP, 5 prepreg tapes, [0]4 lay-up angle. For this strengthened RC bridge structure, the maximum stress, maximum strain and maximum deformation of the bridge is 81.7 MPa, 0.27% and 15.96 mm, respectively.
  • HAN Yong, CHEN Xingyang, ZHOU Chengshuang, ZHENG Jinyang, ZHAO Yongzhi, ZHANG Lin, ZHANG Fenghua
    Science & Technology Review. 2016, 34(8): 89-95.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In hydrogen energy, petroleum and chemical industries the bearing parts in high pressure hydrogen systems are prone to hydrogen-induced damage due to the coupling effect of manufacturing residual effects, high-pressure hydrogen and complicated loadings. In order to ensure long-term, stable, safe and reliable operations of the high-pressure hydrogen system, it is necessary to provide the data of material properties for the development of high-pressure hydrogen system products. Considering the independence and extendibility of data, a database for mechanical properties of metallic materials in high-pressure environment is developed with VB programming language. based on the materials data previously obtained in high-pressure hydrogen environments (slow strain rate tension test, fracture toughness test and fatigue crack propagation test). The analysis of the database, which combines domestic and foreign researches and applications, has shown its versatility and comprehensiveness in terms of metal material hydrogen embrittlement data.
  • Focus
  • Yu Shi
    Science & Technology Review. 2016, 34(8): 107-112.
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In 1915, Einstein predicted gravitational waves, presented the quantum theory of electromagnetic radiation and completed his concept of photon. In one hundred years, gravitational waves were directly detected through the interference of lasers, which are exactly based on Einstein's quantum theory of electromagnetic radiation. The techniques of gravitational wave detection are also related to Einstein 's concept of photons and theory of Brownian motion. The first direct detection of gravitational waves was a commemoration of the centenaries of both contributions of Einstein, one being general relativity and prediction of gravitational waves, the other being quantum theory of radiation. After a review of the “Einsteinian elements” in gravitational detection techniques, that is, the lasers, the photons and the thermal noises, we survey Einstein's research activities in 1916 and look for the historic connections between Einstein's work on gravitational waves and his work on quantum theory of electromagnetic waves, by analyzing the first-hand materials, especially the correspondence of Einstein during that period.