【作者】 田仲可；

【导师】 马泽恩；

【作者基本信息】 西北工业大学 ， 航空宇航器制造工程， 2002， 博士

【摘要】 内高压胀形工艺与先分片(段)成形再拼焊的传统制造工艺相比，具备整体成形几何形状非常复杂的中空薄壁结构件的能力。几何构形一体化程度的改善既有助于精简工序环节、降低工装成本，又有利于提高零件的比强度、比刚度与疲劳寿命。伴随着计算机数字控制技术、传感器测试技术以及液压密封技术的日益成熟与完善，内高压胀形工艺已进入实用化阶段。目前，这种先进塑性成形工艺正在世界汽车工业轻量化进程中发挥着积极作用。可以预见，内高压胀形工艺也将有力地促进航空、航天、船舶、机车等产业的制造技术水平的进步与提高。 本论文围绕管材内高压胀形工艺，针对塑性成形工艺设计方法和塑性变形稳定性等问题展开了研究。 塑性成形工艺设计所涉及的因素一般较多，而且每个因素的具体水平也比较多。基于偏差的分析表明，均匀试验设计要比正交试验设计更适合于多因素多水平复杂试验方案的优化设计问题。与传统的多元回归分析数据处理方式相比，多层前馈神经网络的隐式统计推理功能，对于建立成形结果与塑性成形工艺参数之间的内在映射关系，则更具有工程实用意义。本论文以管材无模轴压胀形的有限元数值模拟为研究平台，首次采用均匀试验设计与神经网络技术相结合的方法，就基于成形指标约束的塑性成形工艺参数设计方法的技术可行性进行了研究，以期从策略上提高塑性成形工艺参数设计的主动性和针对性，克服传统试错方式的被动性和盲目性。 塑性皱曲是管材内高压胀形工艺的一种典型失效形式。对塑性皱曲的发生和发展进行理论上的分析，不仅具有重要的学术价值，同时也有助于加深对管材内高压胀形工艺变形机理的认识，进而为确定合理的加载方案提供必要的指导。受到轴向载荷作用下的薄壁管轴对称坍塌的机构化模型的启发，在将该机构化模型的适用材料类型由理想塑性材料推广至线性强化材料之后，本论文针对管材无模轴压胀形端部皱曲的局部性特征，首次提出了一种“皱曲区—膨胀区—皱曲区”的管坯区划理论模型。在此基础上，通过将基于塑性失稳系数的薄壳塑性稳定性理论与能量准则相结合，在系统势能极小条件下，建立起管材无模轴压胀形端部 摘 要皱曲临界载荷的理论计算方法。 此外，本论文还对内高压胀形材料的力学性能测试与建模、内高压胀形工艺的有限元数值模拟技术以及加载控制实验系统开发等问题进行了实践与探索。更多还原

【Abstract】 Compared with the conventional stamping plus welding approach,the Internal High Pressure Forming (IHPF) technology has the ability to entirely form hollow thin-walled components with complex configuration. Higher structural integrity will bring about less procedure amount,lower tooling cost,but higher specific strength,bigger specific stiffness and longer fatigue lifetime. Due to the great advancement of the hydraulic seal performance and the transducer control capability,the IHPF technology already reaches the practical level. Currently,this advanced plastic forming technology plays an important role on the lightweight issue in the automotive industry. It can be imagined that this technology is also significant for the manufacturing art improvement of the aircraft,shipping and locomotive.Centering on the tube hydroforming (THF) technology,this paper studies the methodology for the plastic forming process design and the stability of the plastic deformation.Generally,the plastic forming process design involves certain parameters,while each parameter has several cases. The discrepancy analysis demonstrates that,for the multi-factor and multi-level project design,the uniform experimental design is better than the orthogonal one. Unlike the regression analysis method,the implicit statistical inference ability of the multi-layer feedforward neural network provides a more pragmatistic way to establish the mapping relationship between the plastic deformation and the process parameters. In order to enhance the efficiency of the plastic forming process design and to overcome the drawbacks of the trial-and-error approach,on the basis of the Finite Element model of the dieless tube hydroforming under internal pressure and axial compression,this dissertation for the first time combines the uniform experimental design method with the neural network technique to design the plastic forming process parameters,which will lead to the designated deformation.Plastic wrinkling is a typical defective mode during the THF. The theoretical study on the wrinkle’s onset and growth is academically valuable and useful to understand the mechanism of the THF in depth,which will make a positive contribution to the loading design. Inspired by the symmetric collapse model of thin-walled tube under axial compression and expanding its applicable material type from the ideal plastic case to the linear hardening one,this dissertation for the first time proposes a zoning model to explore the local wrinkling characteristic of the THF. According to the thin shell plastic stability theory,which is based on the plastic instability coefficients,and under the condition of the system potential minimization,this paper formulates a method to calculate the critical wrinkling loads of the THF.Besides,some IHPF-related topics,such as material properties evaluation,Finite Element simulation and loading control experimental system,are also included in this paper.更多还原