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91.
The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local load ing process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element (FE) simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increas ing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology (RSM).The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the pro cess forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great impor tance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components. 相似文献
92.
93.
A blank panel design algorithm based on feature mapping methods for integral wing skin panels with supercritical airfoil surface is presented.The model of a wing panel is decomposed into features,and features of the panel are decomposed into information of location,direction,dimension and Boolean types.Features are mapped into the plane through optimal surface development algorithm.The plane panel is modeled by rebuilding the mapped features.Blanks of shot-peen forming panels are designed to identify the effectiveness of the methods. 相似文献
94.
以2195-T8态铝锂合金为研究对象,探究工艺参数对其应力松弛时效行为的影响规律。试样经过固溶、淬火,进行不同预变形、时效温度及时效时间条件下的应力松弛时效实验。通过室温拉伸,测得应力松弛时效后试样的力学性能。基于正交试验的极差分析和方差分析,探究了预变形、时效温度和时效时间3个工艺参数对应力松弛量、屈服强度和延伸率的影响权重占比;进一步研究发现预变形不仅可以提高2195铝锂合金时效后的强度,还降低了应力梯度对材料力学性能不均匀性的影响;查明了实现2195铝锂合金应力松弛时效形性协同制造的合理工艺制度:180℃+4%预变形+时效时间12~16 h。研究工作为大型铝锂合金构件应力松弛时效形性协同制造工艺窗口的确定提供了重要支撑。 相似文献
95.
《中国航空学报》2016,(5):1445-1454
The initial temper of the material may directly affect the whole creep age forming(CAF)process. In terms of creep deformation and stress relaxation, using the constant-stress creep aging and constant-strain stress relaxation aging tests, the relationship between initial temper and CAF formability is investigated for an Al-Zn-Mg-Cu alloy at 165 °C for 18 h. Three tempers are selected as the initial tempers in CAF, viz., solution, retrogression and re-solution. The CAF formability of this alloy with initial temper of retrogression is the best, and the creep strain of the retrogression tempered specimen after creep aging of 18 h is about 1.21 and 1.34 times than that of the solution and the re-solution tempered specimens, respectively. The calculated stress exponents of this alloy with three initial tempers range from 7.3 to 9.5, indicating that the CAF of this alloy is mainly controlled by the dislocation creep. The various formability for three initial tempers are attributed to different inhibitions of the transgranular precipitates on the dislocation movement. For the retrogression temper, the initial fine and uniformly distributed precipitates are seriously coarsened after6 h of CAF, which minimally inhibit the dislocation movement. While, for the re-solution temper,the fine precipitates are re-precipitated in the matrix of the alloy, which observably hinder the dislocation movement and lead to the worst formability. 相似文献
96.
在DD3单晶上进行FGH95粉末激光多层涂覆:单晶涂层组织形式规律研究 总被引:3,自引:0,他引:3
利用高温合金 FGH95粉末在 DD3单晶的不同晶面上进行激光多层涂覆实验 ,深入研究了涂覆层中凝固显微组织的生长规律。研究表明基材的晶体取向和局部凝固条件对涂层中的凝固显微组织有很大的影响。当单晶基材择优晶向与热流方向夹角小于 30°时 ,可以得到从基材上外延生长的单晶 ,涂层内二次臂退化 ,枝晶一次间距为 10~ 2 0 μm;当实验所在的单晶基材的择优晶向与热流的方向夹角大于 30°时 ,涂层中晶体取向偏离基材的取向 ,并出现多晶。即便当实验在同一个择优晶面上进行时 ,局部凝固条件不同 ,涂层内的凝固显微组织也有很大的差别。二次臂退化 ,一次臂间距大约为 10~ 2 0 μm。进一步的研究表明 ,涂层中主要组成相为枝晶干上分布的基体相 γ和沉淀硬化相 γ′以及枝晶间的 γ+γ′花状共晶和少量碳化物 ,γ′相主要为具有良好强化效果的细小立方体 ,尺度约为 0 .1μm 相似文献
97.
98.
以3Cr13高熔点合金进行电弧熔射实验,总结了电弧熔射成形的工艺过程,解决了存在的技术难题;分析了熔射成形件的微观组织以及熔射层表面粗糙度的影响因素,提出了改善熔射层质量的途径和措施。 相似文献
99.
100.
窄条喷丸成形的数值模拟 总被引:4,自引:0,他引:4
在分析窄条喷丸成形的变形特点基础上,提出了通过等效变形实现数值模拟的方法。由喷丸成形基本工艺参数试验,建立了壁板等效变形力与喷丸成形基本工艺参数之间的定量关系。利用上述定量关系,采用弹性薄壳有限元法模拟给定喷丸参数下的壁板外形。给出的算例验证了算法的正确性和有效性。 相似文献