- Volume 46,Issue 2,2016 Table of Contents
>综述
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2016, 46(2).
Abstract:
Spacecraft materials will encounter different space environments in space and there are relevance between damage mechanism of different space environments on spacecraft materials. In this paper, space environmentsand their effects on spacecraft materials are introduced firstly, then damage mechanism and their relevance of spaceenvironments such as vacuum, temperature, microgravity, plasma, particle radiation, solar electromagnetic irradiation, space atmospheres, space debris and micrometeoroid, space contamination, spatial dynamics, erosion, spacebiology, etc, on spacecraft materials are studied. At last, the developing trends and problems of the spacecraft materials are commented. >计算材料学
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2016, 46(2).
Abstract:
Based on the thermal conduct law and curing kinetics theory, a three-dimensional finite elementmodel of thermosetting resin matrix composite was developed during the curing process, the reliability of the developedmodel is verified by comparing with the experimental results in literature. Based on the model, temperature and curingdegree fields of the scarf repaired AS4/3501 composite laminate were calculated during the curing process, effect ofcuring temperature and heating rate on temperature and curing degree fields of the patch is analyzed. The results indicate that the effect is very small during the initial stage of curing reaction; the effect increase with the curing time;however, the effect decrease with curing time during the initial stage of the second heating stage; the temperature andcuring degree of composite patch do not change with heating rate during the final stage of constant temperature period. >综述
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2016, 46(2).
Abstract:
The rigid carbon fiber preform (Fiberform) was prepared by vacuum molding using chopped carbonfibers as the raw material and thermal setting phenolic resin powder as the cross linking agent. The resulting Fiberformwas further impregnated with phenolic resin solution through reaction and drying process, to obtain phenolic impregnated carbon ablator (PICA). Fiberform consists of interconnected chopped carbon fiber oriented preferentially in thehorizontal direction, making it a transverse isotropic material with different material properties. The longitudinal compressive strength and transverse compressive strength were varied from 0. 10 to 0. 39 MPa and 0. 33 to 0. 79 MPa, respectively, depending on the density of Fiberform. PICA had an aerogel like composite structure consisting of phenolicnanoparticles and carbon fiber network. The density of PICA could be controlled from 0. 27 to 0. 43 g/ cm3 by changing the concentration of phenolic resin solution. The longitudinal and transverse compressive strengths of PICA weretherefore adjusted from 0. 45 to 2. 42 MPa and from 1. 36 to 2. 27 MPa, respectively. The PICA had the similar thermal insulation with the Fiberform, 0. 08 W/ ( m·K) in through the thickness and 0. 11 W/ ( m·K) in plane directions. -
2016, 46(2).
Abstract:
The moisture resistance coating was fabricated on the silica fabric composite using perhydropolysilazaneand nano silica as starting materials. The structural revolution of the moisture resistance coating in the solidifying andhigh temperature heating processes was studied by SEM, EDS, IR, DSC TG. It is found that the moisture absorptionpercentage of the silica fabric composite at the temperature of 40 and humidity of 95% for 24 h decreased from 11.71% to 0.31% due to the moisture resistance coating. The radio wave transmissivity of the moisture resistance coatingis close to that of the silica fabric composite due to its similar constituents to the silica fabric composite. -
2016, 46(2).
Abstract:
Curved shallow crossing linking reinforcement was prepared from glass roving of 2400 tex on a 3Dweaving machine modeled SGA598. To improve interfacial properties between reinforcement and resin, the surfacetreatment of the reinforcement was conducted by smearing the silane coupling agent KH-570 onto the surface of thereinforcement and then dipping the reinforcement into the solution of KH-570. The resin matrix was composed of epoxy resin E51 and polyether amine WHR-H023 in a mass ratio of 1 1. The 3D curved shallow crossing linking wovencomposite was then made from surface treatment reinforcement and resin matrix in a mass ratio of 1 by hand lay upmethod. Fourier transform infrared spectrum(FT-IR), atomic force microscope(AFM), universal material testing machine and scanning electron microscope(SEM) were used to characterized the treatment effect of KH-570 on reinforcement and the following composites. The results showed that after the treatment with surface鄄active agent KH-570, thesurface roughness and specific surface area of fibers in the reinforcement increased which in turn led to a tighter integration between reinforcement and resin matrix; the bending properties of the 3D composites was enhanced with theincrease of the amount of KH-570; the main failure mode of the 3D composites performed as fracture of fibers rather than fibers pulling out of the resin matrix >新材料新工艺
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2016, 46(2).
Abstract:
The study on the influencing factors of its mechanical properties is important for the improvement ofits mechanical properties. Three types of nomex honeycomb with different resin distribution were made through twodifferent gumming processes. Then mechanical properties testing on the honeycomb and micro observation on phenolicresin distribution at honeycomb hole wall were performed to study the effect of resin distribution and wall thickness ofhoneycomb holes on their mechanical properties. The results show that sufficient flow of the resin may increase thecompressive strength of the honeycomb by 8% to 40%, decrease the shear strength by 9% to 21%. The resin formsgum pillars at the end of the honeycomb nodes, which is the main cause for the increase of the compressive strength.The forming of gum pillars results in the decrease of the average thickness of honeycomb hole walls and thus leads tothe decline of the shear strength. -
2016, 46(2).
Abstract:
To improve the friction coefficient stability of resin-based friction material, and improve the propertyof inhibit thermal degradation. Carbon fibers as reinforcing fibers, carbon fibers reinforced resin based friction materials were prepared by thermoforming process. Friction and wear properties were measured through XD-MSM type constantspeed friction tester, the effects of different carbon fiber content on friction and wear properties of resin -basedfriction material were studied. Worn surface morphology was observed by using VK-X200 three-dimensional laser scanning microscope, and wear mechanism was discussed. The results show that the hardness, compressive strength andshear strength of carbon fibers reinforced resin-based friction materials were improved, and increased gradually withthe increase of carbon fiber content. Carbon fiber improved the friction coefficient stability of resin-based friction material, enhanced the wear resistance and changed the form of friction and wear. The properties of friction coefficient stability and inhibit thermal degradation was great, and the wear mechanism was fatigue wear when the mass percentageof carbon fiber was 4wt% in the resin-based friction material. -
2016, 46(2).
Abstract:
Using the hexagon instead of the actual honeycomb core, the flat compression strength of sandwichstructure and its relationship with the width to thickness ratio was deduced. Eight kinds of specifications of core flatcompressive strength were evaluated. Statistical results revealed that although there are deviations from the deducedresults, the law is consistent, namely honeycomb sandwich structure of flat compression strength decreases exponen鄄tially with the increase of core width to thickness ratio d / ts. -
2016, 46(2).
Abstract:
this paper, the SPR-adhesive bonded joints of 8090 aluminum-lithium Alloys and 5052 aluminum alloyswere made by SPR and adhesive techniques. 3MDP100PLUS and 3MDP100 were used. The strength of joints weretested under tension-shear loading. The results show that the forming quality and strength of joints have a strong relationship with the viscosity of adhesive. But the using of adhesive does not improve the energy absorption of joints.Therefore, the using of suitable adhesive can promote combination of these two. -
2016, 46(2).
Abstract:
The drilling on titanium alloy (TC4) performance of TiAlN coated carbide twist drill was investigatedfocusing on the influence of cutting parameterson drilling axial force, surface roughness of hole wall and chip shape.The results showed that drilling axial force increases with the increase of feed rate. Drilling axial force increase withthe decrease of speed. The exponential formula models of drilling force were obtained through regression analysis meth鄄od and the regulation of the drilling force about TC4 influenced by the feed and cutting speedwas obtained. The error ofthe equation has been tested less than 7%. With the increase of feed rate,chip breakability increase and chip lengthget shorter gradually. When feed rate is 50mm/ min and speed is low,chip morphology is short spiral chips, and chipremoval and hole side roughness are the best -
2016, 46(2).
Abstract:
摇In order to study the influence of the number and distance of rivets on the performance of self鄄piercingriveted joints, the numerical simulation and experiments were conducted to optimize the parameters of self鄄piercingriveting (SPR), and three different types of joints were made. The static performance and failure modes of differentjoints were studied based on the tensile鄄shear tests. And the energy absorption value was calculated accurately thoughthe user defined development which is based on MATLAB R2014b platform. The results show that the numerical sim鄄ulation result was highly identical to the experimental result. The single鄄riveted joints failed by the rivet being pulledout from the lower sheet, and the double鄄riveted joints failed due to the sheet fracture. The performance of double鄄riv鄄eted joints was obviously superior to that of single鄄riveted joints. However, the distance of rivets had little influence onthe static failure strength and energy absorption performance. >测试分析
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2016, 46(2).
Abstract:
In order to realize the accuracy of the thermal property of thin sheet materials. Based on the basicprinciple of parallel hot wire technique, temperature measuring points are arranged at direction of thickness of thespecimen instead of the original direction which is arranged parallel to hotline, and consider the impact of heat pene鄄tration effect. The directly measured coefficient of thermal conductivity and thermal diffusivity using numerical methodcombined with computer programming material. The intelligent test system about thermal properties is developed. Theobjects of the thermal property test experiment are glass, asbestos, diatomite refractory brick, and so on. The resultsagree well with national standard test method for test values and literature values. Considering the impact of heat pene鄄tration effect, it can also accurately achieve thermo鄄physical properties of thin solid plate by controlling the effectivetesting time, need not melt sample, through which the application range of the hot wire method is effectively expand鄄ed. -
2016, 46(2).
Abstract:
The effect of thermal behavior on tensile properties of 30% carbon fiber reinforced polyether鄄ether鄄ke鄄tone (CF/ PEEK) and the damage mechanism at high temperature was investigated. The fracture morphology of ten鄄sile sample was observed with SEM. Test results show that with the increase of the temperature, the elastic modulusand the tensile strength decrease dramatically while the elongation at break rises continuously. Fiber鄄matrix debond鄄ing, even the failure at the fiber鄄matrix interphase and glass transition of the matrix is the main reason of the decreasein the tensile properties. Finite element method (FEM) was used to analyze the fatigue life of the rudder pedal madeof this material in different environment temperatures. The fatigue life decreases with the increase of temperature.Based on the equation of Coffin鄄Manson and Manson爷s slopes equation, the relationship between fatigue life and tem鄄perature was built. -
2016, 46(2).
Abstract:
Several runs of thermal expansion measurements was presented for Pyros specimen, the precision andbias of the result show that the instrument is in a good condition. A large number of thermal expansion measurementswas presented for the glass fiber/ phenolic resin composites as a function of holding time, heating rate and curing treat鄄ment. The specimen was further cured by the increase of temperature, and the shrinkage of the specimen by the lossof volatiles and the thermal deformation of curing reaction can counteract the expansion by the heating, which causedplateau on the heating curves. Repeated expansion measurements for the specimen shows that the curves of heatingand cooling progress were almost identical. Heating treatment is necessary before thermal expansion measurements,and the heating temperature should be higher than the measurement temperature, but lower than curing temperaturewhich keeps the microstructure of composites unchanged. The appropriate heating rate should be applied, for higherheating rate will infect precision of the measured result, while lower heating rate will increase time cost -
2016, 46(2).
Abstract:
Abstract摇The quality of spot welds in 1mm SUS304 austenitic stainless steel sheet metal was evaluated by usingultrasonic water immersion focusing method. The specifics of nugget diameters and the ultrasonic C鄄scan image wereanalyzed under different welding process parameters. Furthermore, the tensile鄄shear tests were carried out to examinethe mechanical behavior of sport welds. Results show that the C鄄scan image can get nugget diameter and effective in鄄formation from the inner pattern of the spot weld based on ultrasonic water immersion focusing method. When thewelding current is 4 kA and the supply pressure is 0. 15 MPa, it can get the information which included splash, solderto wear and other weld defects from the ultrasonic C鄄scan image. When the supply pressure is 0. 45 MPa, the nuggetdiameter is increasing. But the excessive supply pressure leads to the joint thickness decreasing and the joint quality isfailing. When the supply pressure is 0. 4 MPa and the welding current is 9 kA, the failure strength and energy absorp鄄tion value decrease rapidly, it can get the information which includes splash, solder to wear and other weld defectsfrom the ultrasonic C鄄scan image -
2016, 46(2).
Abstract:
1420 aluminum鄄lithium alloy sheets (AL1420) with itself, H62 copper alloy sheets (H62), Q215 gal鄄vanized steel sheets (Q215) and TA1 industrial pure titanium sheets (TA1) were applied to fabricated different types ofsingle鄄lap self鄄piercing riveted joints. The static failure loads and energy absorption properties of the joints were ana鄄lyzed using the static tests, and the macroscopic failure mechanisms were discussed and inferred based on the failuremodes of the joints. The results show that: TA1鄄AL1420 joints have the highest static failure loads, and Q215鄄AL1420joints possess the optimum energy absorption properties; except for TA1鄄AL1420 joints, the laws of the failure displace鄄ments are consistent to those of the energy absorption values for the other type joints. When the gap of the yieldstrengths between the upper and lower sheets was small, the failure modes of the joints were the lower sheets separatedwith the rivet; when it was large, the joints mainly failed due to the sheets with lower yield strength fractured. >工程实践
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2016, 46(2).
Abstract:
Composite pipes are always used together with joints and the bonding strength between them is a de鄄termining factor for the pipes properties. The tensile strength of the composite pipes affected by memory alloy ringhave been analyzed with finite element analysis. And then tensile test were conducted for comparison. The experimental results indicate that the tensile strength of composite pipes could be enhanced by 10. 1% which meet the finite element analysis results. The present results provide a reference for the designing and optimization of composite pipes. -
2016, 46(2).
Abstract:
This article aimed to analyze the features of the cylinder and the mould of cylinder. An idea was pres鄄ented that the mould of cylinder and the cylinder could be separated by the demoulding fixture. Through the analysisof technical difficulties about the demoulding fixture and the possible emergence during demoulding, the process of thedesign and the demoulding was introduced. It had been found that the structure of demoulding fixture was feasible. Itcould meet the demoulding requirement of the mould .
