7075铝合金高筋壁板时效成形研究及有限元模拟

发布时间：2018-05-16 22:33

本文选题：7075铝合金 + 蠕变时效成形　；参考：《南昌航空大学》2017年硕士论文

【摘要】：在航空航天制造领域中,整体高筋壁板因其优异的轻量化结构特点取代传统的铆接方式具备良好的应用前景。而经过加工而成的整体高筋壁板因其复杂的结构,运用传统成形工艺对成形效果比较难以控制,蠕变时效成形技术(CAF)作为一种全新的成形工艺,对大型整体高筋壁板成形具有明显的优势。但是,运用蠕变时效工艺对高筋壁板进行成形,它的成形将会受到时效工艺参数与高筋壁板结构参数的共同影响。所以研究高筋壁板结构件在蠕变时效下的成形过程,总结出高筋壁板在蠕变时效下的成形规律就显得很有必要,继而能为高筋类零件的低成本生产制造提供一定的理论基础和实际指导。本文以7075铝合金高筋壁板典型结构件为研究对象,首先,针对高筋壁板的结构特点设计了导柱式工装模具,利用DK7650慢走丝线切割机床制备了7075铝合金高筋壁板典型结构件;通过正交试验研究时效时间、时效温度、筋条高度以及筋条厚度对工件成形质量的影响,利用数学分析方法得出了时效与结构参数对7075高筋壁板时效成形回弹的影响程度;并通过试验研究得出主要影响因素时效时间、筋条高度、筋条厚度对工件成形回弹的规律,针对试验中工件出现的筋条失稳现象,研究得出了筋条高厚比H/t(筋条高度/筋条厚度)对工件失稳的规律。其次,对7075铝合金板材进行单轴拉伸试验,根据得出的试验数据,推导出基于时效强化模型的材料本构方程,把本构方程的拟合曲线与试验曲线对比分析,发现两者误差在试验允许范围之内,证明了本构模型的准确性;之后运用有限元软件ABAQUS平台,建立了7075铝合金高筋壁板蠕变时效成形有限元模型,并通过与试验数据对比验证了有限元模型的准确性。最后,利用已建立的7075铝合金高筋壁板蠕变时效成形有限元分析模型,对成形过程中影响工件回弹和失稳的其它因素进行进一步研究,通过模拟时效时间、加载压力、预加载模具半径、板材厚度以及板材宽度对工件成形回弹影响,得出了回弹率随各因素变化的影响规律,同时针对筋条在试验中出现的失稳现象,以最大侧向位移为筋条失稳的宏观表现,模拟了筋条高厚比H/t(筋条高度/筋条厚度)、工件宽厚比B/t(筋板宽度/筋条厚度)以及工件的相对厚度t/l(筋条厚度/弯曲支撑点间距)对工件失稳的影响,得出了筋条最大侧向位移随各比值变化的影响规律。
[Abstract]:In the field of aerospace manufacturing, the integral high-stiffened wall plate has a good application prospect because of its excellent lightweight structure to replace the traditional riveting method. Because of its complex structure, it is difficult to control the forming effect by the traditional forming technology. The creep aging forming technology is a new forming process. It has obvious advantages to the forming of large whole high-stiffened wall plate. However, the creep aging process is used to form the high stiffened wall plate, and its forming will be affected by both the aging process parameters and the structural parameters of the high stiffened wall plate. Therefore, it is necessary to study the forming process of high stiffened wall structure under creep aging, and summarize the forming law of high stiffened wall under creep aging. Then it can provide some theoretical basis and practical guidance for low-cost manufacturing of high-stiffened parts. In this paper, the typical structural parts of 7075 aluminum alloy panel with high reinforcement are studied. Firstly, according to the structural characteristics of the high stiffened panel, the guide column tooling is designed, and the typical structural part of 7075 aluminum alloy high stiffened wall plate is fabricated by DK7650 slow wire cutting machine. The effects of aging time, aging temperature, bar height and thickness on the forming quality of workpiece were studied by orthogonal test. The influence of aging and structural parameters on the springback of 7075 high stiffened wall sheet was obtained by mathematical analysis. The main influencing factors, such as aging time, bar height and thickness of steel bar, are found to be the main factors influencing the springback of workpiece forming. The effect of H / T ratio on the instability of workpiece is studied. Secondly, the uniaxial tensile test of 7075 aluminum alloy sheet is carried out. According to the experimental data, the material constitutive equation based on aging strengthening model is derived, and the fitting curve of the constitutive equation is compared with the test curve. It is found that the errors are within the allowable range of the test, which proves the accuracy of the constitutive model, and then establishes the creep aging forming finite element model of 7075 aluminum alloy plate with high reinforcement by using the finite element software ABAQUS. The accuracy of the finite element model is verified by comparing with the experimental data. Finally, using the established finite element analysis model for creep aging forming of 7075 aluminum alloy plate with high reinforcement, the other factors affecting the springback and instability of the workpiece during the forming process are further studied, and the aging time and loading pressure are simulated. The influence of preloading die radius, plate thickness and plate width on the springback of workpiece forming is obtained. Taking the maximum lateral displacement as the macroscopic performance of the buckling of the bar, The effects of H / T ratio of stiffener height / strip thickness, B / T ratio of workpiece width to thickness and relative thickness of workpiece t / L on the instability of workpiece are simulated. The influence of the maximum lateral displacement of the bar on the ratio is obtained.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TG166.3

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