2020 Vol. 40, No. 1

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2020, 40(1)
[Abstract](2755) [FullText HTML] (1405) [PDF 612KB](41)
Abstract:
Research progress and development trend of aluminum-lithium alloys
Zhaohui FENG, Juan YU, Min HAO, Weiyi ZHAO, Guoai LI, Junzhou CHEN
2020, 40(1): 1-11.
[Abstract](5910) [FullText HTML] (3294) [PDF 996KB](230)
Abstract:
Aluminum-lithium alloys have formed a perfect material system with high specific strength, high toughness and high damage tolerance resistance after the development of three generations. It is attractive to replace the traditional aluminum alloys owing to their excellent weight reduction ability. It is considered as the ideal structural materials for the aircraft and warship in the 21st century. This paper briefly reviews the development of Al-Li alloys, and introduces the idea of composition design, manufacturing and advanced application technology of the Al-Li alloys. It is pointed out that the high cost is the main problem restricting the further large-scale application of Al-Li alloys. The research directions, like to improve the product types of Al-Li alloys, develop anti-fatigue, anti-damage and low density Al-Li alloys, study the overall manufacturing technology of Al-Li alloy large parts, develop the Al-Li alloy aging forming technology, laser welding, friction stir welding and other advanced joining technologies, and other applications are also proposed in this paper.
Research progress of alumina-based absorbing materials
Zhihong WU, Qian WANG, Luping ZHANG, Haikang ZHENG, Kai SHANG
2020, 40(1): 12-20.
[Abstract](3067) [FullText HTML] (1531) [PDF 948KB](103)
Abstract:
Radar absorbing materials (RAM) play an important role in the defense field. Thin, light mass, broad bandwidth, and strong absorption are required for the RAM in current research filed. Weapons and equipment flying at high Mach make the local temperature of the body very high due to air resistance, and the absorbing materials at room temperature can not be applied. It is urgent to study the absorbing materials which can resist high temperature and absorb electromagnetic wave efficiently. High temperature resistant and high temperature absorbing materials prepared by composite of different types of absorbents with alumina as the matrix have been widely concerned and studied. The metal (alloy)/alumina, non-metal/aluminum, and other alumina-containing composite absorbing material systems are deeply discussed, and the current research status of alumina-based composites are systematically summarized in this paper. The structure, properties and absorption mechanism of composite absorbers prepared by different structures (nanowires, microspheres and nanoparticles) and alumina matrix of various forms (porous membranes, fibers or nanoparticles) are analyzed. It was also prospected about the future development of the metal (alloy)/alumina and non-metal/aluminum composite absorbing material. In the metal (alloy)/alumina composite absorbing material system, it should be: (1) to develop the nanoscale spherical ultrafine metal absorbing agent and the wave absorption performance using the special effect of nanoparticles; (2) to achieve good absorbent and matrix matching by further exploring the reasonable preparation technology. In nonmetallic/alumina composite absorbing material system, it should be: (1) further to strengthen the research on the composite of alumina fiber cloth and alumina mesh matrix with nano absorbent; (2) to strengthen the study of polymer special core-shell structure and impedance matching layer; (3) to strengthen the study of the modification of wide band absorbing materials and absorbing agents; (4) to study the inorganic matrix composed of metal oxide powder and inorganic binder.
Research progress of nitride based ceramic high temperature wave transparent materials
Xuefeng CUI, Jianping LI, Mingxing LI, Jie ZHOU, Xin LI, Laifei CHENG, Yongsheng LIU, Fang YE
2020, 40(1): 21-34.
[Abstract](3302) [FullText HTML] (1650) [PDF 896KB](127)
Abstract:
Nitride-based ceramic materials have excellent comprehensive properties such as high strength, high modulus, high temperature resistance, thermal shock resistance and wave-transparent performance. They are the main candidates for high-temperature wave-transparent components. The reports about their application are few, and the preparation technologies and properties need to be improved. In this paper, the research progress of nitride ceramics, nitride composite ceramics and nitride ceramic matrix composites was summarized. It is found that the comprehensive properties of porous Si3N4 ceramics, BN-Si3N4 composite ceramics and BNw/Si3N4 composites are excellent, with the dielectric constant less than 5, the dielectric loss less than 0.01, and the room-temperature flexural strength higher than 200 MPa, respectively. In this paper, the existing problems of the studies on the nitride-based ceramic as high-temperature wave-transparent materials were analyzed, which is mainly that the mechanical properties and dielectric properties are difficult to improve in coordination, and the future development direction of the selection of high-temperature wave-transparent material systems and preparation technologies are prospected.
Thermal coupling analysis of lightning strike laminates
Xiang LU, Mingjun LUO, Miao ZHAO, Zezhong SHAN
2020, 40(1): 35-45.
[Abstract](2270) [FullText HTML] (1322) [PDF 1013KB](32)
Abstract:
In order to study the ablation damage mechanical properties of composite laminated plate under the action of lightning current, a thermal-mechanical coupling finite element analysis model of composite lightning strike was established. The validity of the model was verified by comparison with the experimental results. According to the three-dimensional Hashin failure criterion, the user material subroutines was programmed, and the mechanical damage around the lightning ablation area of the laminate, the mechanical damage distribution of each layer and the stress distributions of the first layer in different directions were obtained respectively. The analysis shows that the ablation damage of the laminates varies with the duration of the lightning current. The results show that due to the existence of a high temperature gradient, the laminated plate has have large thermal expansion stress, which leads to various mechanical damages inside the laminated plate, namely matrix cracking, delamination and fiber breakage. The lightning strike current application time, peak current and temperature field all have a great influence on the ablation area of the laminated plate.
Supercritical carbon dioxide for surface treatment of hollow/solid hybrid quartz fiber
Tian LAN, Qingjie MENG, Yuchen PEI
2020, 40(1): 46-52.
[Abstract](2005) [FullText HTML] (990) [PDF 1522KB](27)
Abstract:
The penetration and carrying ability of supercritical carbon dioxide were used to eliminate fibers’ agent and carry coupling agent (KH-560) into fiber to modify the hollow/solid hybrid quartz fibrics. The surface energy and interfacial tension of modified fiber and the adsorption with resin were measured. The surface morphology of fibers was observed. The results showed that most of the fibers’ agent was removed in the Heat treatment+Solvent bathing+Supercritical carbon dioxide treatment process. The surface energy of fibers was increased, and this indicates that the hybrid quartz fibrics could be impregnated much better by modified cyanate resin. All indicated that the treatment process can improve the mechanical and dielectric properties of composite materials.
Compressive bucking and post-bucking mechanical properties of aeronautic composite stiffened panel
Zhigang GAO, Yu FENG, Binlin MA, Xu DU, Yujian SONG
2020, 40(1): 53-61.
[Abstract](2994) [FullText HTML] (1465) [PDF 973KB](58)
Abstract:
Aeronautical composite stiffened panels are widely used in aeronautical structure design because of their good mechanical properties. In this paper, the compressive buckling and post-buckling mechanical properties of aeronautical composite stiffened panels were studied. Firstly, the compressive stability of composite stiffened panels was calculated by engineering method, and the predictions of the buckling and failure loads of stiffened panels were obtained; Secondly, the compression stability experiment of the composite stiffened plate is carried out, and the buckling and failure modes, the load-strain and load displacement relationship of the experimental piece, and the buckling and failure loads of the experimental piece are obtained. The results show that the calculated results by engineering method are in good agreement with the test results, and the error of buckling load and failure load are 6.12% and 9.31% respectively. The reasonable application of engineering method can provide better guidance for the experiment; The failure modes of stiffened panels are the delamination of the panels, the bulging and tearing of the skin, the fracture of the stiffeners and the debonding of the stiffeners-panels. The buckling ratio of composite stiffened plates is 1.65, the composite stiffened plates have strong post-buckling bearing capacity; The post-buckling bearing capacity of stiffened plates can be fully applied in engineering to improve the utilization efficiency of structures.
Vibration characteristics of adhesive bonding repaired carbon fiber/epoxy laminate under hygrothermal condition
Baohui JIA, Tongxing HAO, Gang ZHANG, Xiang LU
2020, 40(1): 62-70.
[Abstract](2438) [FullText HTML] (1431) [PDF 837KB](27)
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Through theoretical derivation and finite element simulation, the vibration characteristics of composite laminate with four-edge clamped support under hygrothermal condition were studied. Based on the Mindlin first-order shear deformation theory and the Hamilton principle, taking the effect of hygrothermal stress into account and using the equivalence of temperature and humidity, the constitutive equation of composite laminate affected by the hygrothermal environment was derived. The finite element method was used to solve the vibration characteristic equation of the laminate. Bonding repaired laminate model was established by using the finite element software ABAQUS, and the model was compared with literature results. The effects of different hygrothermal environments and the number of additional patches on the vibration characteristic of the bonding repaired laminate were discussed. The results of the example show that in the hygrothermal environment, the introduction of additional patch reduces the natural frequencies of the various orders of the bonding repaired laminate. When the number of additional patches changes from one to two, the first-order natural frequency decreases further. The effect of increased humidity on natural frequency reduction is greater than that of temperature increase on natural frequency. In the environment where the temperature and humidity are simultaneously increased, the introduction of the additional patch will cause the bonding repaired laminate to reach the state of hygrothermal buckling earlier.
Effect of space travel velocity of spray gun on temperature field of Mo/8YSZ composite coating prepared by plasma spraying process
Ming PANG, Xiaohan ZHANG, Guang LIU
2020, 40(1): 71-80.
[Abstract](2921) [FullText HTML] (1531) [PDF 1043KB](32)
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In order to break through the technical bottleneck of traditional metal-ceramic double-layer thermal protective coating which is easy to peel in high temperature environment, the influence of the space travel velocity of the spray gun on temperature field in time domain and space domain of the Mo/8YSZ composite coating was studied. Using ANSYS finite element analysis software, a numerical model for preparing Mo/8YSZ functionally graded thermal barrier coatings by plasma spraying was established, and the thermal properties of the material at different temperatures and the latent heat of phase change of the material were also considered in the model. By analyzing the temperature and temperature gradient of the sprayed component under the different space travel velocities of the spray gun, it is found that at the same time of the spraying process, the greater the travel velocity of the spray gun, the less time the spray gun interacts with the component per unit length, the smaller the maximum temperature value of the component, the higher the uniformity of the temperature distribution on the upper surface of the component, and the smaller the maximum temperature gradient value of the component. The first deposited coating has a preheating effect on the post-deposited coating, and the maximum temperature value of the substrate exhibits a "stepped" increase trend. As the thickness of the coating increases, the thermal resistance of the coating increases, and the fluctuation of the substrate temperature gradually decreases. The temperature gradient of the component can be further reduced by adjusting the travel velocity of the spray gun of each coating, and the temperature gradient of the component can be minimized when the spraying is undertaken in accordance with the sequence of maximum bonding layer, transition layer and minimum ceramic layer.
Effect of cold expansion on room-temperature low cycle fatigue life of GH4169 superalloy with hole structure
Chunling XU, Xin WANG, Yinggang SONG, Qiang WANG, Xuekun LUO, Zhihui TANG
2020, 40(1): 81-86.
[Abstract](2128) [FullText HTML] (1370) [PDF 886KB](47)
Abstract:
The fatigue life of GH4169 superalloy plate with central hole was tested at 663 MPa/20 ℃ before and after cold expansion（CE）. The fatigue fractures, the evolution of residual stress fields and surface morphology were respectively analyzed by scanning electron microscope, X-ray diffraction residual stress tester and surface profilometer. The results show that CE increases the fatigue life with the hole structure to 2.6 times compared with as-received. As the result of hole wall surface strengthening by CE, the fatigue source of CE specimens is single originated from chamfering, while the original ones are multi-source and sprouted at the hole wall. The CE surface residual stresses relax during 50000 cycles fatigue process, and however, about 55% and 75% compressive residual stresses are still retained at the inlet and outlet ends respectively. Moreover, CE reduces the surface roughness of the hole wall from Ra 0.354 μm to Ra 0.297 μm.
Prediction method of rotating-bending fatigue life of 40CrNi2Si2MoVA steel specimens after machining and shot peening
Mingbo XU, Hongfei LIU, Yukui GAO
2020, 40(1): 87-92.
[Abstract](2457) [FullText HTML] (1412) [PDF 803KB](52)
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In order to predict the rotating-bending fatigue life of 40CrNi2Si2MoVA steel specimens after machining and shot peening in room temperature, the applicability and accuracy of different numerical calculation methods were compared by combining the commercial finite element software ABAQUS with the fatigue life analysis software FE-SAFE, the empirical formula for predicting the life of 40CrNi2Si2MoVA steel strengthened by shot peening was presented. The results show that using "Brown-Miller" algorithm and surface residual stress in FE-SAFE can obtain a relatively precise prediction result for machined specimens. And for shot peened specimens, this method also can be taken in high stress level. While the "stress-based Brown Miller" algorithm and maximum residual stress are more suitable for shot peened specimens in low stress level. The empirical formula σmax =–64.378•lg N + 1449.268 proposed based on the two methods can enhance the accuracy of fatigue life prediction of 40CrNi2Si2MoVA steel shot peened specimens.
Investigations on correlation between grain size and stress rupture property of GH4169 alloy
Kang WEI, Yong ZHANG, Tao WANG, Zhao LI, Zhipeng WAN
2020, 40(1): 93-99.
[Abstract](2593) [FullText HTML] (1179) [PDF 1025KB](64)
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Taking GH4169 alloy large-size bar as research object, combined with the manufacturing process of the bar, the stress rupture properties of the specimens with different grain sizes were analyzed by means of OM, FE-SEM, EBSD and TEM. The results show that under the high temperature and stress of the long-lasting test, various grain size samples exhibit different stress rupture properties and grain orientation evolution. When the grain size is small, some orientation of〈101〉obviously rotates to 〈001〉or 〈111〉orientation where deformation and fracture occur. Besides, the coordination of macroscopic deformation of fine grain is better. These promote the effective release of stress concentration and then better plasticity. But the diffusion creep caused by more grain boundaries in the fine grain sample is unfavorable to the high temperature strength and cracks are prone to nucleate and expand at the grain boundary adjacent to the hard orientation of 〈111〉, thus the rupture life is reduced. In addition, the deformation of the fine grain sample is larger, mainly concentrated at grain boundaries, and the number fraction of large angle misorientation is more, which is easy to crack and reduce the life.

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