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排序方式: 共有416条查询结果,搜索用时 62 毫秒
411.
《中国航空学报》2023,36(5):582-594
The Large-size Conical Cylinders with Inner Transverse High Ribs (LCCWITHR) can reduce the weight of the parts while maintaining high rigidity and strength. Radially Loading Rotary Extrusion (RLRE) forming technology can achieve integral forming of LCCWITHR through the synergy of radial and rotary movements of dies. The flow law of the material during the forming process is the key to forming large-size inner ribs. At present, there is no unified understanding of the metal flow law of RLRE forming technology. An analytical expression was derived to predict the Radial Direction (RD) deformation loads. The FE simulation and process experiment were carried out to investigate the effects of the inclination angle, thickness factor and transition arc radius of the split top dies on the spacing of the metal diversion plane, the metal flow velocity of the rib area and the final radius of the inner rib. The influence of the split top dies loading distance and the bottom die rotation angle of each pass on the inner radius of the inner rib was verified. And the optimal combination of dies shape parameters and loading paths which can make the metal flow orderly was obtained: the inclination angle is 140°, the thickness factor is 3.64, the transition arc radius is 16 mm; the top dies loading distance is 15 mm, the bottom die rotation angle is 45°. The FE simulation results have been found to be in close agreement with physics experiment. The research results reveal the metal flow law of rib growth in the RLRE of LCCWITHR, which lays a theoretical foundation for subsequent thorough research and process optimization. 相似文献
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413.
对成败型航空发动机部件可靠性增长试验抽样数的确定问题进行了研究。推导出了初始故障数服从典型离散分布时的最小化最大准则(Max-Min准则),提出了一种逐次抽样样本估计值反馈修正方法。最后给出了一个应用实例,验证了该方法的有效性。 相似文献
414.
《中国航空学报》2023,36(8):395-407
The wear condition of the piston/cylinder pair is crucial to the performance and reliability of the axial piston pump. The hard piston surface, the soft cylinder bore surface, and the interface oil film affects each other during the wear process. Specifically, in the mixed lubrication region, the geometry of the hard piston surface asperity directly affects the wear of soft cylinder bore surface, while the asperities may deform or even degrade when penetrating and sliding against the cylinder bore. So far, there is no suitable method to simulate their coupled evolution. This paper proposed a wear process simulation model considering the real-time interaction between the elasto-plastic deformation of the piston surface asperity, the wear contour of the cylinder bore, and the lubrication condition of the interface. An offline library of the elasto-plastic constitutive behavior of the asperity based on the finite element method (FEM) is established as a part of the simulation model to precisely analyze the deformation and degradation of the asperity and quickly invoke them in the numerical wear process simulation. The simulation and experimental results show that the piston asperity and the cylinder bore contour converge to a steady state after running-in for about 0.5 h. The distribution of the simulated asperity degradation and wear depth is also verified by the experiment. 相似文献
415.
阵列碳纤维复合材料管是由碳纤维增强复合材料(CFRP)薄壁圆筒壳阵列排布后粘接制备而成,兼具碳纤维复合材料和蜂窝结构的优异性能,是一种新型的可应用于深空探测反射面板的理想材料结构。由于材料和制备方面的特殊性,在阵列碳纤维复合材料管加工过程中会由于磨削力过大导致多种加工损伤,为其高效低损伤加工带来了挑战。本文开展CFRP薄壁圆筒壳磨削加工正交试验,系统研究磨削深度、切出角度、主轴转速、进给率对磨削力的影响规律和影响程度。研究结果表明:工艺参数对水平面合力的影响程度依次为进给率、磨削深度、切出角度、主轴转速,对轴向力的影响程度依次为切出角度、主轴转速、进给率、磨削深度。研究对阵列碳纤维复合材料管高效低损伤加工工艺的制订具有参考意义。 相似文献
416.