【作者】 王树宏；

【导师】 王珉； 左敦稳；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2005， 博士

【摘要】 在我国新一代飞机研制中,大量采用整体结构件。整体结构件具有尺寸大、壁薄、加工精度要求高等特点,加工变形是其制造中存在的突出问题之一,它直接制约重点型号工程研制生产的进度和质量。因此,开展航空整体结构件加工变形研究具有重大的现实意义。本文作为总装备部“十五”预研项目“复杂结构件加工变形控制技术研究”的主要组成部分,以航空铝合金厚板为对象,研究重点定位在其初始残余应力分布规律及其对数控铣削加工变形的影响。本文所完成的主要工作如下:1、铝合金预拉伸厚板内部残余应力的测试方法研究针对厚板内部残余应力测试这一技术难题,在现有测试技术研究的基础上,结合铝合金厚板的特点,提出了一种新的测试方法——改进剥层法。运用弹性力学理论对该方法进行了详细推导,为厚板内部残余应力测试提供了一条新途径。2、铝合金预拉伸板内部残余应力分布规律的研究通过试验研究对改进剥层法测试理论的测试精度及工程实用性进行了分析和评估。在此基础上,首次对国产LY12、美产7050T7451和俄产B95п.ч三种典型的铝合金预拉伸板内部初始残余应力分布进行了测试和对比分析。测试数据为定量预测初始残余应力引起的加工变形奠定了基础。3、工件初始残余应力引起铣削变形的机理分析应用弹性力学理论推导出了二维连续铣削过程中工件内应力再分布及其引起变形的计算递推公式,并编制了计算软件。解决了初始应力加载、材料去除模拟、约束转换等仿真关键技术,建立了残余应力引起铣削变形的二维有限元仿真模型。用解析法对模型的有效性进行了验证。对实例进行了仿真计算,分析了残余应力引起的加工变形规律,为三维铣削变形分析奠定了基础。4、工件初始残余应力引起框类结构件铣削变形的预测分析在归纳了三维有限元分析中六面体单元内应力应变关系和实际框类零件加工变形特点的基础上,对框类零件铣削加工变形的三维有限元分析技术进行了深入研究,解决了三维有限元建模、变形值提取、变形特征分析、变形可视化显示等多项关键技术,并进行了试验验证。采用所建立的模型,分析了单框件铣削加工时由于初始残余应力引起的加工变形规律,对不同走刀路径条件下不同侧壁不同位置的变形以及框底的翘曲变形等进行了详细分析,并结合工程实际完成了实例模拟分析。5、多因素对框类结构件铣削变形的影响研究更多还原

【Abstract】 The machining distortion is one of the neck problems during the manufacture of the aero integrated-structure parts. The study work in the dissertation is an important part of the Tenth Five-Year Defence Advanced Research Project of“study on control technology of the machining distortion for complex structure parts”supported by PLA General Armament Department of China. Theoretical analysis and experimental study are carried out on the initial residual stresses and their effects on milling distortion for thick aero-aluminum-alloy plate. The main work completed in the dissertation is as follows.1. The measurement method of residual stress distribution in thick aluminum alloy plate is studied.Aiming at the difficult problem to measure residual stress distribution in thick plate, a new method is proposed -- modified layer removal method, based on existed measurement theories and according to the characteristics of thick pre-stretched aluminum alloy plate. The new measurement theory is deduced in detail by using elasticity theory. A new approach is provided to measure the residual stress in the thick plate.2. The residual stresses in pre-stretched aluminum alloy plates are successfully measured and analyzed.The measurement precision and applicability of the modified layer removal method are analyzed and evaluated by experiments. The residual stresses in the thick aluminum alloy plates of LY12, B95п.чand 7050T7451 are measured, and the results are analyzed and compared. The data obtained lay a basis for prediction of the machining distortion caused by the residual stresses.3. Mechanism of the milling distortion caused by initial residual stress of workpiece is analyzed.Formulae of stress re-distribution and distortion by stress releasing during milling process are deduced by elasticity theory. The calculation software is developed for the formulae. The key problems in 2D FEM simulation such as the initial stress loading, simulation of material removal, constraint transformation, etc. are solved, and 2D FEM simulation model is built to analyze the milling distortion caused by the residual stress. The FEM model is verified by the elasticity theory. Some machining cases are simulated by using of the FEM model. The machining distortion caused by residual stress are analyzed and summarized using the simulation results.4. The milling distortion of frame shaped part is predicted and analyzed.Based on its characteristic analyzed, the 3D FEM simulation technique for the更多还原