铝合金交叉筋壁板激光诱导热成形扫描策略研究

发布时间：2018-03-30 10:03

本文选题：激光诱导热成形　切入点：交叉筋壁板　出处：《哈尔滨工业大学》2017年硕士论文

【摘要】：整体壁板式舱体结构具有结构效率高、密封性能好等优点,是航天器密封舱体的最佳选择。带筋壁板的弯曲成形是舱体制造过程中的关键步骤,目前常用的成形方法如压弯成形、时效蠕变成形等都需要通过外力和工具的配合来完成,存在成形周期长、回弹严重等问题。激光诱导热成形技术是一种无模、高柔性的快速成形方法,板材的变形由热应力诱导,不需施加外力。因此,使用激光诱导热成形技术成形整体壁板可以大大缩短成形周期,同时减小回弹。本文主要研究5A06铝合金交叉筋壁板的激光诱导热成形技术。以实现交叉筋壁板的圆柱面成形为目标,对壁板的单道扫描成形和多道扫描成形进行了研究,提出了相应的扫描策略,并通过仿真和试验进行了验证。首先,建立了激光诱导热成形的有限元模型。采用顺序耦合的方法,基于有限元分析软件ABAQUS建立了激光诱导热成形的有限元模型,通过温度场和位移场对模型的有效性进行了验证,为定量研究交叉筋壁板的变形过程奠定了基础。其次,对交叉筋壁板网格区的单道扫描成形行为进行了研究。分析了扫描过程中温度场和应力应变场的变化规律,揭示了壁板非期望变形产生的原因;仿真分析了激光功率、扫描速度、光斑直径、扫描次数和扫描线距自由端的距离对壁板成形的影响,为合理选择扫描参数提供了依据;为提高网格区扫描成形的形状精度,提出了变功率扫描、局部多次扫描、外力辅助扫描和综合扫描等扫描策略,通过仿真比较了各种策略对非期望变形的抑制效果,并通过试验验证了最优策略。最后,对交叉筋壁板多道扫描成形圆柱面的相关问题进行了研究。通过仿真分析了边缘区扫描和筋部扫描时壁板的成形特点,讨论了扫描方式对壁板成形的影响;针对多道扫描过程中非期望变形的累积效应,提出一种筋部扫描策略来减小自由端的纵向弯曲程度;规划了交叉筋壁板多道扫描成形圆柱面的扫描流程和扫描策略,并进行了成形试验,较好地实现圆柱面弯曲成形。
[Abstract]:The integral wall plate bulkhead structure has the advantages of high structural efficiency and good sealing performance, so it is the best choice for the spacecrafts to seal the cabin. The bending and forming of the stiffened panel is the key step in the manufacturing process of the bulkhead. The commonly used forming methods, such as bending forming and aging creep forming, need to be completed by the cooperation of external forces and tools, and there are many problems such as long forming period and severe springback. Laser induced hot forming is a kind of die less forming technology. In high flexible rapid prototyping, the deformation of sheet metal is induced by thermal stress without external force. Therefore, the forming period of the whole wall plate can be greatly shortened by laser induced hot forming technology. At the same time, the springback is reduced. In this paper, the laser induced hot forming technology of 5A06 aluminum alloy cross-bar wall plate is studied. The single-pass scanning forming and multi-channel scanning forming of the cross-stiffened plate are studied in order to realize the cylindrical forming of the cross-stiffened plate. The corresponding scanning strategy is proposed and verified by simulation and experiment. Firstly, the finite element model of laser-induced thermal forming is established, and the sequential coupling method is used. Based on the finite element analysis software ABAQUS, the finite element model of laser-induced thermal forming is established. The validity of the model is verified by the temperature field and displacement field, which lays a foundation for the quantitative study of the deformation process of cross-stiffened panels. In this paper, the behavior of single channel scanning forming in the grid region of cross-stiffened slabs is studied. The variation law of temperature field and stress-strain field during the scanning process is analyzed, and the causes of the undesired deformation of the panel are revealed, and the laser power is simulated and analyzed. The influence of scanning speed, spot diameter, scanning times and distance from the free end of scanning line to the forming of the wall plate provides the basis for the reasonable selection of scanning parameters, and in order to improve the shape accuracy of the mesh area scanning, the variable power scanning is proposed. Some scanning strategies, such as local multiple scanning, external force assisted scanning and comprehensive scanning, are used to simulate and compare the effects of various strategies on the suppression of unexpected deformation, and the optimal strategy is verified by experiments. Finally, In this paper, the problems related to the multi-channel scanning forming of cross-stiffened panels are studied. The forming characteristics of the plates during the edge scanning and the reinforcement scanning are analyzed by simulation, and the influence of the scanning mode on the forming of the plates is discussed. In view of the cumulative effect of non-expected deformation during multi-channel scanning, a reinforcement scanning strategy is proposed to reduce the longitudinal bending degree of free end, and the scanning process and scanning strategy for multi-channel scanning cylindrical surface of cross-stiffened slabs are planned. The forming test is carried out, and the bending forming of cylindrical surface is realized well.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

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