Abstract:The main lightweight structure materials including lightweight alloy and composite materials for aerospace applications were introduced in the article. The development direction of the lightweight structure materials are analysed briefly combining the application requirements of aerospace.

Abstract:The topologies of the periodic lattices are analyzed together with their manufacturing methods. Simultaneously, the design and performance testing for composite grid structures are introduced. And, the overview of the applications to the structures in the aerospace engineering are presented.

Abstract:The status of applications such as HIP technology in the fields of metals, metal matrix composites, inorganic non-metallic materials and polymer materials is discussed, and the simulation technology of the isostatic pressing is reviewed. At the same time, the development trend of composite molding process of the isostatic pressing technology and 3D printing technology is analyzed, and the future of isostatic pressing techniques is prospected.

Abstract:The ageing of non-metallic materials was one of the most important factors which affected the storage reliability of missile. This article introduced the current research and application of storage life evaluation technology for missile used non-metallic materials at home and abroad, summarized the typical ageing models and lifetime evaluation methods for non-metallic materials, and predicted the future development of storage life evaluation technology for non-metallic materials.

Abstract:Based on the theory of experimental modal analysis, the modal theory and testing system of composite laminates is established. Firstly, composite laminates of 150 mm×80 mm×3.75 mm (length×width×thickness) were built-up. By using DH5922N dynamic data acquisition instrument, the frequency response function and the excitation signal sensed by acceleration sensor and force hammer are obtained. And frequency response function is analysised in the dynamic signal analysis system DHDAS. The first and second natural frequencies were 323.103 Hz and 656.180 Hz respectively, and the shift values of each measurement point corresponding to the frequency were obtained. The experimental results show that the experimental theory and the equipment used in this paper can be used to accurately extract the modal information of composite laminates.

Abstract:Considering the defect into fiber bundle and outer matrix,a multiscale unit-cell model is establiashed.At first,according to the scanning electron microscope(SEM) photograph and the density into the material,the geometric dimensioning of the unit-cell of fiber bundle and composite is confirmed.Then,introducing into the periodic boundary condition,the initial modulus and strength are calculated by using the fiber bundle unit-cell containing defects.At last,using the composite unit-cell model which confirming geometric dimensioning by SEM photograph,the stiffness is predicted by the material parameters from previous scale.The stiffness matrix of the damaged unit-cell for fiber bundle was established.The damage evolvement method by introducing damage variables of different damage modes were considered as the progressive damage of the material integral points.It was analyzed and discussed by comparing numerical predictions with experimental data.And the damaged material properties under uniaxial load are given at last.The results indicate that numerical simulation of the nonlinear stress-strain behavior based on Hashin failure criteria with various damage modes gives good agreement compared to experimental results.

Abstract:The external and internal hydro-proof test investigation of the cylinder structures are developed in the present paper. The needling C/C composite cylinder sample preparation and the fixture are designed according to the testing condition. The stress distribution information of the structures is obtained during the test process. The 3D hydro-proof FEM simulation model is established to compare with the experiment results. The simulation results are in good agreement with the test results,which indicates the validity and accuracy of the FEM simulation model. The test and simulation conclusions can provide some important guidance for the nozzle carbon/carbon composite with cone structure design, material constitutive model parameter modification and structure safety tolerance prediction.

Abstract:Micro-holes were ablated on the brazing sureface of C_f/SiC CMCs by laser roughing technology. And the C_f/SiC-TC4 brazing joint was achieved by Ag-based filler. Then mechanical properites were tested, the microstructure of the joints and the shear fracture were observed. The results show that, the filler can filled the micro-holes, and the shearing strength of the joints were enhanced.

Abstract:First, the silver coated aluminum powder was selected as the optimal conductive filler by testing the mechanical strength, elongation ratio, compression set, electronic conductive properties and shielding effectiveness of three silicone rubber with different fillers parallel. Then the volume fraction of silver coated aluminum powder was fixed as 55% through investigating the effect of silver coated aluminum powder content on the mechanical strength, elongation ratio, compression set, micro-morphology and conductive properties of rubbers. Based on the demand of rubber products for long service life, the conductive properties of these rubbers were investigated thoroughly after ageing at environmental temperature and humidity and elevated temperature accelerated testing separately. The result showed that with the ageing time increased, the volume resistivity increased implying electronic conductivity weakened. The volume resistivity was almost not affected after initial 60 days ageing at environmental temperature and humidity, then increased from 4.6×10^-3 Ω·cm to 7.5×10^-2 Ω·cm after 900 days ageing. The volume resistivity increased to 9.5×10^-2 Ω·cm after ageing at 150℃ for 30 days. The result also indicated that the silver coated aluminum powder/silicone rubber can retain the electronic conductive properties after ageing at two conditions. The ageing effect of elevated temperature accelerated testing was more significant than natural storage ageing.

Abstract:Accelerated ageing tests have been carried out for polysilazane adhesive in high-temperature and high-humidity environments. After 90 days' accelerated ageing tests the lap shear strengths of adhesive specimen increased by more than 50%. In high-temperature and high-humidity environments adhesive postcure strengthening and humid interface weakening occured simultaneously, but the former is much larger than the latter. The accelerated ageing results after 90 days combine the ageing mechanism showed that polysilazane adhesive had good high-temperature and humidity resistant properties, which indicated the relatively long storage lifetime of this adhesive.

Abstract:Based on modern filament winding technology, processing property and puzzles are analyzed for the microwave absorbing composites cylinders. For winding layer including absorbers, a technique is adopted, which prepreg is prepared using double rolls for the same slot and double lines sandwich core, and absorbing composites cylinders are manufactured through wet filament winding. The results show the winding rules and the processing parameters can meet cylinders manufacture. The content of absorbers dispersed in the different prepreg well-proportioned can be controlled,and the microwave absorbing performance is excellent.

Abstract:In order to obtain the tightening characteristics of C/C composite material bolt, the tightening torque characteristics of C/C composite material bolt with different structures were studied in this paper. The research can include the variation trend of the torque coefficient K of the bolts in different combinations of gasket material, single nuts and double nuts, scribbling with adhesives and non-scribbling with adhesives. The ultimate torsional resistance of C/C composite material bolt was studied. The results show that the torque coefficient K of the bolts is different from that of the metal bolts. The scribbling with adhesives can obviously improve the clamping force.

Abstract:Inclusion of foreign bodies is a typical kind of defect in friction stir welding. The included foreign bodies must be eliminated before performing the joint repairing. By using some fused material, or that one in solid-state, some additional material with the same volume as the removed one must be compensated into the eliminated area in the joint. This process is cumbersome, and would bring in some elements which is not existing in the base material. Furthermore, the thermal treatment induced by the fusion in the joint which need to repair would affect the microstructure in the joint. And, it would weaken the strength of the repaired joint. All above are the shortages in existing repairing methods. In this paper, we proposed a dual-pass friction stir welding method, which can repair the joint after removing inclusion of foreign bodies.Without additional material addition, this method can produce the repaired joint that has the same strength as the original one. And it is convenient in application. Especially, the repaired joint has improved elongation.It can be conclude that the proposed repairing method is practical, and has a great application prospect. It has been proved by experiments that the proposed method can make a repairing joint with the same strength as the original one.

Abstract:The blade in the installation of test failed in the operating process,fault location is located in the root of blade.Through observation,testing and analysis of fault component,the reason blade produced by low cycle fatigue fracture is identified due to improper control of production process.The blade root curing is incomplete in local area,which causes the strength and stiffness of very low. Fiber beam between curing not completely of resin cannot will load effective of passed to near of fiber beam, so dang by fatigue load role in structure stress concentrated regional first occurred layered cracking, and extended until eventually lost stability fracture.The direction for improvement is pointed out.

Abstract:Based on the electron bean circular weld on 2219 T852 transition ring and T87 shell section used for tank, the normal and low mechanical properties of the electron beam welded joints in the segment level were tested, and the staggered amount,fracture types and microstructure of the welded joints were analyzed. The following conclusions can be drawn.The normal and low strength effect coefficient of the segment level electron beam welded joints on 2219 T852 transition ring and T87 shell section are 0.63, and relative to the normal temperature, the low temperature mechanical properties of welded joints have been improved. The staggered amount is inversely proportional to the mechanical properties of welded joints,and it has the most significant effect to elongation, and low temperature should help to ease the weakening effect of staggered to the mechanical properties of welded joints. Because of the uneven tissue and the discontinuous structure of the electron beam welded joints,especially T852 side heat affected zone with coarse grains,the T852 side heat affected zone and the roots of welded joints are the weak area of the electron beam weld, and welded joint is easy to fracture in the area.

Abstract:The quality of spot welded joints was evaluated by the scanning acoustic microscope (SAM). The change characteristics of gray level of C-scan image were analyzed. The feasibility of evaluating the quality of spot welded joints and measuring the nugget diameter by using the change of the gray level was provided. And we analyzed the spot welded joints of 1.0 mm stainless steel under different welding parameters. The calculated values of nugget diameter are compared with the measured values by macrophotograph of samples. The results show that this method is available for measuring nugget diameter of the spot welded joints, and can avoid the influence of artificial factors and reduce production costs. The accuracy of testing result was verified by contrasting the metallographs of actual spot welded joints cross section.

Abstract:The 300M steel bars with diameter of 450 mm were inspected by ultrasonic method. 2.5 MHz soft probe was used to ensure ultrasonic sensitivity and reduce the noise level. Macro- and micro-observations as well as electrical diffraction spectrum analysis were carried out to inspect interior defects of a material. The results showed that inclusions found by ultrasonic detection were consisted of Al₂O₃,MgO and CaO. The largest size of the inclusions was over 100 μm. These inclusions were imported by melting process, and they were detrimental to properties of the material.

Abstract:There is a large superiority in digitalize manufacturing of large subassembly of frame kind. In this paper the method of application of MBD technology to subassembly of frame kind digital manufacturing is discussed. Digital coordination line of subassembly of frame kind and designing method of digital master tooling and its applying method on MBD environment is provided. It has important practical meaning in improving our subassembly of frame kind manufacturing technology and shorting its manufacturing cycle.