【作者】 谢邵辉；

【导师】 柳玉起；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2011， 博士

【摘要】 在航空制造领域中,产品设计理念不断更新,零件功能性由单一型向复合型转变,大量新材料得到应用,零件外形特征日趋复杂,产品质量要求日益提高,使得传统经验型确定方法已经无法满足发展的需要。随着有限元方法应用水平的提高,数值模拟技术已经在飞机钣金件成形中得到应用,有效地减少了产品开发周期和成本。但现有CAE在实际应用中会遇到专业性不强、数据转换损失、软件操作繁琐、计算速度低、设计与分析脱节和分析重复建模等问题。因此,需要开发一套面向飞机钣金件产品设计与工艺分析的CAD/CAE无缝集成系统。论文结合材料成形与模具技术国家重点实验室项目“新一代飞行器钣金件冷成形快速同步模拟技术研究与开发”,对飞机钣金零件成形缺陷评估、成形工艺分析、CAD/CAE无缝集成技术进行了深入研究,并在此基础上建立了飞机钣金件成形的有限元分析模拟算法,提出了飞机钣金件成形质量评估准则,并在CATIA V5平台上开发了飞机钣金件冷成形快速模拟系统。在研究初始坯料尺寸对蒙皮零件表面质量影响的基础上,论文采用有限元逆算法,提出了基于厚向应变、成形极限曲线和起皱极限曲线的蒙皮零件初始坯料优化模型。针对铝合金材料,分别从材料的轧制方向、硬化指数和摩擦系数等方面研究了初始板坯尺寸对蒙皮零件表面质量的影响。在分析飞机钣金件成形特点的基础上,建立了橡皮囊液压成形的简化模型,将橡皮囊腔内液压等效加载于板料上,增加了橡皮囊层对板料摩擦力的处理；建立了蒙皮拉形的分析模型,将夹钳定义为钳口夹紧区域板料约束节点,并将夹钳模具的运动轨迹进行约束处理；建立了型材拉弯成形理论模型,将夹钳钳口和转臂定义为整体运动机构,控制了由动力效应引起的板料发散节点。在此基础上,采用三维弹塑性有限元动力显式算法和BT及BWC壳单元,开发了橡皮囊液压成形模拟算法、蒙皮拉形模拟算法和型材拉弯成形模拟算法。并提出了橡皮囊成形中液压加载以及摩擦的处理方法,蒙皮拉形中夹钳和成形模具运动轨迹加载方法,型材拉弯成形中发散节点动力效应控制方法。在飞机钣金件成形模拟理论和算法研究基础上,采用CATIA CAA二次开发技术,开发了面向飞机钣金件成形快速模拟的CAD/CAE无缝集成系统,包括飞机钣金件初始坯料精确展开系统BES (Blank Eestimation System),橡皮囊液压成形模拟系统EHFS (Elasto Hydro Forming System)、蒙皮拉形模拟系统SSFS (Skin Stretching Forming System)和型材拉弯成形模拟系统ESFS (Extrusion Stretch Forming System)。实现了与CATIA V5平台的无缝集成,克服了CAE技术无法参与飞机钣金件全流程开发的局限性,将该系统应用于飞机产品开发、工艺方案优化、模具设计以及虚拟成形的全流程中,可以有效地降低生产成本、提高产品质量以及生产效率。更多还原

【Abstract】 In the current aviation manufacturing field, design ideas of aircraft parts are updated, functions of aircraft parts are changed from monotony to composite, lots of new materials are applied, shape features of aircraft parts are complex, and quality requirements of aircraft parts are high, so the process plan determined by the traditional experience has been failed to meet the needs of current development. With the improvement of finite element method, numerical simulation technology has been applied in the forming of aircraft sheet metal parts, which reduces the development cycle and cost of products efficiently. However, there are still many problems appeared in the practical CAE application, including un-profession, data losses in the transformation, fussy operation, separation between design and analysis, and repeated modeling. Thus a CAD/CAE seamless integration system for design and analysis of aircraft sheet metal parts should be developed.The work of this paper is supported by Research and Development on Rapid Synchronous Simulation Technology for New Generation Aircraft Sheet Metal Parts Forming from State Key Laboratory of Material Processing and Die & Mould Technology. Finite element algorithms for aircraft sheet metal parts forming are built, quality assessment criteria for aircraft sheet metal parts are present, and rapid simulation systems for aircraft sheet metal parts forming are developed based on CATIA V5 to study forming defects evaluation, forming features analysis and CAD/CAE seamless integration technology for aircraft sheet metal parts.Based on thickness strain, formablity limit curve and winkle limit curve, an optimization model is present to to study the effect of the initial blank size on the surface quality of aircraft sheet metal parts with using the finite element inverse approach. The effect of initial blank size on the skin parts has been studied from rolling direction, hardening exponent and friction coefficient of the aluminum alloy material.Based on forming features of aircraft sheet metal parts, a simplified model for elasto hydro forming is proposed, hydraulic pressure in the elasto hydro cavity should be loaded on the sheet metal part, and friction bewteen the elasto hydro layer and the sheet metal has been treated;an analysis model for skin stretch forming is put forward, the clamp is defined as constraint nodes located in the areas of the clamp mouth, the trajectory of the clamp mould is restricted;a theoretical model for extrusion stretch forming is presented, the clamp and the arm are defined as the whole movement mechanism, divergent nodes caused by dynamic effects have been controlled. The simulation algorithms for elasto hydro forming, skin stretch forming and extrusion stretch forming based on BT and BWC shell elements are developed by using the elastic-plastic three-dimensional finite element dynamic explicit method. And key algorithms are investigated, including the load method of hydraulic pressure and firction treatment in the elasto hydro forming, the trajectory load method of the clamp and the mould in the skin stretch forming, and the control method for divergent nodes in the extrusion stretch forming.Based on the research of the theory and algorithm for aircraft sheet metal parts forming, CAD/CAE seamless integration systems for rapid simulation of aircraft sheet metal parts have been developed firstly with the secondary development technology of CATIA/CAA, including the blank estimation system-BES for aircraft sheet metal parts, the elasto hydro forming system-EHFS, the skin stretching forming system-SSFS and the extrusion stretch forming system-ESFS. The integrated systems can be applied in the whole process of aircraft parts manufacturing, including product development, process optimization, mould designing and virtual forming, to realize the seamless integration with CATIA and overcome the limitations of CAE employed in the whole development of aircraft parts, contributing to low cost, good quality and high productivity.更多还原