- Volume 45,Issue 6,2015 Table of Contents
>综述
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2015, 45(6).
Abstract:
Microwave absorbing materials play an important role in the radar stealth. Research on microwave ab-sorbing materials is significant for both military and civilian. Graphene has become a hot spot in the study of new ab-sorbing materials due to its unique absorbing properties. In this study, microwave absorbing materials including gra-phene/ ferrite,graphene/ metal powder,graphene/ magnetic metal,graphene/ conductive polymer and graphene/ magnet-ic material/ conducting polymer composite microwave absorbing materials were reviewed in detail and the future devel-opments of the microwave absorbing materials are prospected. -
2015, 45(6).
Abstract:The development status of the stealth materials of spaceaerocraft is introduced, including Radar and
IR stealth materials,respectively. Based on the stealth demand of spaceaerocraft, the development trend of stealth ma-
terials is presented. -
2015, 45(6).
Abstract:The paper reviewed the present development process and current status of polyacrylonitrile carbon fi-
bers. The application progress of carbon fiber in the aerospace is introduced. In the end, some suggestions on develo-
ping domestic PAN-based carbon fibers are discussed. -
2015, 45(6).
Abstract:The development of the shelf life prediction technology of nonmetallic materials/ parts applied in aero-
space industry is briefly summarized from several aspects, i. e. , the aging mechanism of nonmetallic materials, the
models of life prediction for nonmetallic materials, the characterization technique of nonmetallic materials aging, the
environmental tests and the method of life prediction of nonmetallic materials. >计算材料学
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2015, 45(6).
Abstract:A new structural model was built to study the bending properties of three-dimensional curved shallow-
crossing linking woven composites (3D composites) using mapping software Pro/ Engineer. The distribution of stress
& strain on fibers,resin and 3D composites, as well as the failure mode, was discussed and predicted, respectively,
under bending loads of 5 mm displacement using finite element software ANSYS workbench. The results show that un-
der the bending loads the most easily damaging parts of the 3D composites occurred on the point-surface contacts,
where the samples contacted with the up and down pressure heads,the main loads were supported by reinforced fibers
and the minor loads are supported by matrix resin. The main failure mode of the 3D composites is resin fracture under
bending loads of 5 mm displacement. -
2015, 45(6).
Abstract:By using the finite element analysis(FEA) software Patran/ Nastran, the model of composite paraboli-
c antenna was built and the structure properties were also simulated. The effects of reflector laying-up, and stiffening
rib structure and laying-up on the antenna fundamental frequency were further analyzed. The analysis results show that
the fundamental frequency of the antenna reflector using the [0/45/ -45/90] s laying-up is the highest. Fixing the cir-
cumferential and radial ribs on the reflector can obviously improve the fundamental frequency. By using the [0/30/
90/ -30] s laying-up in the stiffening ribs, the antenna fundamental frequency is further increased. The optimal struc-
ture of composite parabolic antenna with stiffening ribs is determined by FEA, which can provide the guidance for the
preparation of this composite parabolic antenna. -
Tool Condition Monitoring Technology for CFRP Drilling Based onHeterogeneous Ensemble Learning Model
2015, 45(6).
Abstract:Tool condition monitoring (TCM) plays an important role in guaranteeing workpiece quality. There-
fore, it is meaningful to monitoring the tool wear condition in time. In this paper, a tool wear monitoring system based
on the heterogeneous ensemble learning model was proposed to overcome the limitation of the single classifier. In this
system, the SVM, RBF and HMM models were selected as base classifiers depend on the base classifier selection cri-
terion. In order to test the performance of the monitoring system, carbon fibre reinforced plastics (CFRP) drilling ex-
periment is carried out. Feature extraction technology in time domain is used for force and vibration signals, and the
LPP algorithm is used to realize the feature selection. By the comparison with ensemble learning and single classifiers,
it’s proved that the ensemble learning has better accuracy and stability. -
2015, 45(6).
Abstract:In this paper, an NDT method based on modal flexibility curvature matrix was discussed to detect de-
lamination of composite cylinders. The natural frequency and shift values of the composite cylinder are simulated by
modal analysis. The damage of composite cylinder is detected by the calculated axial and circumferential flexibility
curvature matrix. Analysis shows that both axial and circumferential flexibility curvature matrix methods can accurately
identify the location and size of delamination. From the inner wall of the cylinder to the outer wall, the closer the de-
lamination to the outer wall, the more obviously of flexibility curvature mutations, and more easily the delamination to
be detected. And relatively speaking, the mutation of the axial flexibility curvature F c at delaminated location is far
greater than circumferential flexibility curvature F c , so F c is easier to identify delaminations. But due to itself small
mutation at the fixed end boundary, when damage occurs near the fixed end along axis direction, the axial flexibility
curvature F c may cause misjudgment, in this case, the circumferential flexibility curvature F d can be used to identify
damages. >新材料新工艺
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2015, 45(6).
Abstract:
Hydrogenated WC/ C multilayer coating was deposited by unbalanced sputtering technology. It wasproduced by isolating the acetylene gas, sputtering the graphite target and tungsten carbide target at the same time. ACr translation layer and a WC translation layer were arranged for the coating on 304 stainless steel or silicon wafers.The microstructure and mechanical properties of coatings were analyzed by scanning electron microscope(SEM), Ra-man spectrometer, X-ray diffractometer (XRD) and nanoidenter. Rtec friction tester was used to investigate the tribo-logical properties of coating under PAO base oil, engine oil and corrosive engine oil. The results indicate that plentifulgraphite-like sp 2 bonds were formed in the coating. It has the multiphase composite structure in which WC 1-x phase isembedded in the amorphous carbon. Compared with 304 stainless steel, WC/ C coating has higher hardness, elasticmodulus and the value of H/ E significantly. Besides, the coating exhibits lower friction coefficients and wear ratesthan base materials under three kinds of lubricating oil conditions. -
2015, 45(6).
Abstract:
In this paper, diallyl bisphenol A and N,N’-(4,4’-diphenylmethane)bismaleimide were used tomodify bisphenol A discyanate ester to improve process capability and heat resistance. Cure behavior and heat resist-ance of the modified resin was investigated by differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and dynamic mechanical analyzer (DMA). In addition, mechanical properties and dielectric properties inhigh frenquency of the resin were also investigated. The result indicated that DSC result showed that the temperatureof the curing reaction of modified resin was lowedca 60℃. TGA results showed 5% weight loss temperature were about400℃. DMA results showed the inflection point of tanδare about 270℃. In 7 to 15 GHz, the dielectric constant <3,dielectric loss 0. 008 to 0. 01, showing a good dielectric properties. -
2015, 45(6).
Abstract:
The suspensions were prepared with different carbon nanomaterials. The UV spectrum proved that thehybrid materials were prepared successful. The dispersion of suspensions was characterized by the UV spectrum, opti-cal microscopy and sedimentation tests. The results showed that hybrid materials both have the excellent dispersion aswell. However, due to the difference of synthesis mechanism, the dispersion of hybrid materials (one step) were bet-ter than the hybrid materials (multi-step) owing to the PACl which had the same opportunity to react with GnPs-OHand MWCNTs- OH to hinder the aggregation of MWCNTs-OH. So the aiming of optimization of dispersion for carbonnanomaterials was achieved. -
2015, 45(6).
Abstract:
The double cone drill and twist drill were used to drill T700 carbon fiber reinforced plastics(CFRP). The drilling axial force, hole exit quality and surface roughness were used to analysis the double cone drillhole making features under different processing parameters. Compared with carbide twist drill, the double cone drillperformed excellent cutting performance because of its drilling axial force reduced by about 20%, the hole exit qualityis better, and the hole surface roughness is smaller. So, the double cone drill is more suitable for drilling CFRP. -
2015, 45(6).
Abstract:
The manufacturing process of PCE(positive continuous engagement) type sprag clutch in China now-days was summarized. In order to manufacture high-quality sprag clutch, a processing technology of sprags based onthe WEDM-LS(low speed wire cut electrical discharge machining)was proposed. Adopting orthogonal method to exper-iment on wire cutting electrical parameters and analysizing surfaces of wire cutting sample with scanning electron mi-croscope. The result shows that the sequence of factors effecting the surface roughness is pulse width, stop time, theservo ratio and the initial voltage, and there is a loose structure on the metamorphic layer, which contains Cu and Znand with the thickness of about 15 to 20 μm. >测试分析
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2015, 45(6).
Abstract:
The influence of hygrothermal environment on compressive property of woven carbon fiber epoxy resincomposite was investigated via compress test under different hygrothermal environment. Moisture absorption, compres-sive property, failure modes and dynamic mechanical property were analyzed. The results show that the moisture ab-sorption of woven carbon fiber epoxy resin composite is not high, which is just about 0. 88%. The compressive strengthof the laminates, dominated by the matrix, are reduced by the hygrothermal conditions. The retention rate of compres-sive strength are about 70% on the condition of 130℃ after moisture absorption. The failure modes of composite lami-nate with hole were hole failure, the damage occurred in the area of stress concentration, and the fracture was extendin the direction of the stress concentration of the largest. The side of fracture morphology was mainly shear failure,and the characteristic of buckling and delaminating. The glass transition temperature(DMA T g ) of composite aftermoisture absorption is 125℃, which is 16℃ lower than dry contitions. -
2015, 45(6).
Abstract:
Structural health monitoring (SHM) technology was widely introduced to the aircraft design and ma-intenance, based on the current development of SHM technology, this paper integrates the SHM and MSG-3 analysis,and presents a formulation process of the aircraft structural scheduled maintenance task with the application of SHMtechnology. -
2015, 45(6).
Abstract:
The ingot including impurity of YG8 cutter hard alloy was made by the measure of VAR. Φ40 mmbars were made from ingot by forging and the position of impurity was located by ultrasonic detection. The appearanceof impurity was observed through optical microscope and SEM. The results show that hard alloy melts partially and theboundary has transition area. The transition area includes elements of titanium and elements of cutter hard alloy,where diffusion happens. The existence of impurity leads to stress focus which produces fatigue flaw easily, then influ-ences the quality of product. -
Nondestructive Testing of Spot Welded Joints of Stainless Steel Based onScanning Acoustic Microscope
2015, 45(6).
Abstract:
Non-destructive testing of spot weld joints on 1 mm thick SUS304 stainless steel sheet is carried outby the scanning acoustic microscope(SAM). The C-scan images under different welding process are analyzed, and A-scan signals in the specific parts of the C-scan images are collected and processed. Then the relationship betweenthem is analyzed. The diameter of the spot weld is measured through ultrasonic C-scan imagery method. The resultshow that SAM can be used to inspect the flaws of spot welded joints. The C-scan images can be used to distinguishthe type of inner defects. When the electrode force is 0. 15 MPa and the welding current is 8 kA or above C-scan ima-ges can clearly reflect the splash and burnt and so on. The A-scan signals of the specific parts of the ultrasonic C-scanimages are different. The diameter of the spot weld are in the range of 4. 39 to 5. 25 mm based on ultrasonic C-scanimagery method. -
2015, 45(6).
Abstract:
Two kinds of heat treatment process was studied on the influence of the microstructure and mechanicalproperties of K465 casting superalloy, the comparison with the same level superalloy used in the generic blade wasperformed. The microstructures of K465 alloy were observed using optical microscopy (OM) and scan electron mi-croscopy (SEM). The tensile and stress rupture properties of K465 alloy were measured. The results show that thecharacteristics of blade made in china are smaller grain size,bigger dendritic structure, bigger size of γ′ phase bycomparison with the same level superalloy used in the generic blade. The hot isostatic pressing (HIP) process may bepartially or completely eliminated the loose in K465 alloy, however, the loose distribution is dense for the ordinaryprocess. HIP process can effectively reduce the size of γ′ phase, make dendritic densification and improve the tensileand stress rupture properties. A small amount of loose, dense dendritic structure, regular dendritic arrangement andthe smaller size of γ′ phase may be the key factor of vibration fatigue property for the blade. -
2015, 45(6).
Abstract:
The sound impedance of C/ SiC composite is measured by the method of ultrasonic immersing pulseecho,and which is between 4. 0×10 6 kg/ m 2 s and 4. 7×10 6 kg/ m 2 s. The relationship of reflection is about 1 when thereis crack in brazing interface and it is between 0. 71 and 0. 74 when there is no crack. For the differential value of theamplitude of reflection wave is at least 6 dB between two status, the amplitude of more than second reflection wavewill be monitored when C-scan. The result of C-scan is certified by metallographic analysis, and the uniformity of bothis good.
