密封材料空间环境失效分析

对空间环境造成载人航天器密封材料的各种失效机理进行了分析。材料低温脆化,高温时表面脆化;真空时材料内挥发成份的溢出,使材料渗透性增大;辐照使密封件失去弹性：这些是空间环境中温度、真空和辐照使密封失效的主要原因。真空条件下,密封件挥发成份中的可凝物在光学元件表面的凝聚从而破坏表面光学特性,是密封设计中一个值得重视的现象。     

Light weight optimization of stratospheric airship envelope based on reliability analysis

A stratospheric airship is an essential flight vehicle in the aviation field. In this paper, optimal design approach of stratospheric airships is developed to optimize envelope shape considering three failure modes and multidisciplinary analysis models, and could also reduce the mass of a stratospheric airship to be deployed at a specific location. Based on a theoretical analysis, three failure modes of airships including bending wrinkling failure, hoop tearing failure and bending kink failure, are given to describe and illustrate the failure mechanism of stratospheric airships. The results show that the location, length and size of the local uniform load and the large fineness ratio are easier to lead to bending wrinkling failure and bending kink failure. The small fineness ratio and the increasing differential pressure are more prone to cause hoop tearing failure for an airship hull. The failure probability is sensitive to the wind field. From an optimization design, the reliability analysis is essential to be carried out based on the safety of the airship. The solution in this study can provide economical design recommendations.     

Failure behavior analysis of phased-mission systems considering functional and physical isolation effects

Phased-Mission Systems(PMS) are widely applied in aerospace, telecommunication and intelligent systems for multiple, consecutive and non-overlapping phases of missions. The phasedependent stresses and system structure cause some difficulties to the reliability analysis of PMSs.In this paper, we analyze the physical isolation effects on the degradation speeds and across-phase damage accumulations of failure mechanisms. And, some corresponding reliability and unreliability formulas are derived. Be...     

各向异性屈服准则对铝合金板深冲起皱预测的影响

基于板料成形深冲过程的数值模拟,研究了不同的各向异性屈服准则(Hill1948,Barlat YLD91和CMTP)对铝合金板深冲成形过程起皱预测的影响,并对模拟结果进行了比较,结果表明:采用不同屈服准则模拟的应力和应变分布有所不同,采用CMTP和Balart YLD91屈服准则比Hill1948屈服准则预测的要高。     

面向需求的通用弹药质量评价

为更好地发挥军事需求的牵引作用,将武器装备符合性质量观念提升到适用性质量观念,提高通用弹药质量水平,科学地评价通用弹药质量非常重要.分析了外军武器装备需求实现和现代质量观念,提出了面向需求的武器装备质量评价理念,论述了面向需求的武器装备质量评价的作用,研究并建立了面向需求的武器装备质量评价模型,评价模型贯彻了需求牵引的思想.通过对通用弹药的特点和基本需求分析,建立了科学的、系统的通用弹药质量评价指标体系.     

Stress analysis and damage evolution in individual plies of notched composite laminates subjected to in-plane loads

This work aims to investigate local stress distribution, damage evolution and failure of notched composite laminates under in-plane loads. An analytic method containing uniformed boundary equations using a complex variable approach is developed to present layer-by-layer stresses around the notch. The uniformed boundary equations established in series together with conformal mapping functions are capable of dealing with irregular boundary issues around the notch and at infinity. Stress results are employed to evaluate the damage initiation and propagation of notched composites by progressive damage analysis(PDA). A user-defined subroutine is developed in the finite element(FE) model based on coupling theories for mixed failure criteria and damage mechanics to efficiently investigate damage evolution as well as failure modes. Carbon/epoxy laminates with a stacking sequence of [45°/0°/ 60°/90°]sare used to investigate surface strains, in-plane load capacity and microstructure of failure zones to provide analytic and FE methods with strong validation. Good agreement is observed between the analytic method, the FE model and experiments in terms of the stress(strain) distributions, damage evaluation and ultimate strength, and the layerby-layer stress components vary according to a combination effect of fiber orientation and loading type, causing diverse failure modes in individuals.     

Evaluation of tensile properties of a compositemetal joint with a novel metal insert design by experimental and numerical methods

Composite-metal joints with a metal insert are one kind of connecting structure.In this paper,tensile experimental tests were carried out to investigate tensile properties of a composite metal joint with a novel metal insert design.Finite element models of the joint were established,and strain distribution and tensile strength were analyzed.The numerical results are in good agree ment with the experimental results.Results show that the joint failure is dominated by shear properties of the resin layer.Increasing the resin layer thickness in a certain range will improve the tensile strength of the joint,while increasing the radius of the fillet on the ending side of the metal insert will decrease the joint strength.Increasing the resin layer plasticity will improve the joint strength.The effect of the embedded depth of the metal insert can be ignored.     

基于灰色模型的故障预测方法研究

随着人们对系统发生故障所带来财产损失、人员伤亡以及危害性的无法承受,故障预测与健康管理（PHM）技术应用越来越广泛。介绍了灰色模型,并利用某型号发控设备压控振荡器电路检测积分器输入信号检测的历史数据作为研究依据,验证了灰色模型在故障预测中的应用是可行的,准确度能够达到要求。     

湿热环境下复合材料孔板压缩性能的研究

采用压缩试验的方法,对含孔机织碳纤维环氧复合材料层板进行了湿热环境下的压缩试验,研究了湿热环境对其压缩性能的影响。分析了复合材料孔板的吸湿特性、压缩强度、破坏模式及动态力学性能。结果表明:机织碳纤维环氧复合材料吸湿率较低,其饱和吸湿率仅为0.88%左右。湿热环境会降低由基体性能主导的压缩强度,130℃下湿态试样的开孔压缩强度保持率约为70%。含孔复合材料层合板的破坏模式均为过孔破坏,破坏均发生在应力集中的区域,并且断裂都是沿着应力集中最大的方向扩展。侧面断口主要为剪切失效,有分层和屈曲的特征。吸湿后复合材料的DMA Tg为125℃,比干态时下降了16℃。     

MSC．Dytran在坠撞仿真中的应用

介绍了MSC．Dytran在坠撞仿真中的应用。从国外和国内的案例可以看出，用MSC．Dytran能较快较好地解决飞机坠撞问题。