加载方式对黏性介质外压缩径成形的影响

采用有限元方法分析了加载方式(即注入加载通道的直径和数量)对黏性介质外压缩径过程黏性介质压力场及坯料的失稳起皱过程中压应力变化的影响,并对有限元分析结果进行了验证。研究结果表明,注入黏性介质的加载通道直径较大、数量较多,有利于改善黏性介质压力场的分布,延缓坯料失稳的产生,提高褶皱可消除程度。     

侧围尾灯翻边问题的解决方法

汽车侧围尾灯位置的翻边结构由于点焊焊钳空间的需求容易导致成形起皱和外观圆角不顺的质量问题,在冲压工艺上通过减小过拉伸量或夹料翻边,在制件设计上通过减少翻边角度和增加吸皱特征可以有效解决此类问题.     

S梁的拉深成形数值模拟

采用数值模拟技术可以在模具设计初期预测产品的成形质量,优化工艺参数,从而缩短模具设计周期,降低成本。基于Dynaform有限元分析软件,对S梁的拉深成形过程进行了数值模拟。针对起皱和未充分拉深等缺陷,提出了压边力和拉深筋工艺参数的改进方案并加以比较,得到了较好的成形模拟结果。试验结果表明：压边力为400kN（不加拉深筋）或300kN（加拉深筋）时成形质量较好。     

Numerical study of vented hydrogen explosions in a small scale obstructed chamber

There is a growing need to understand and estimate the explosion hazards associated with hydrogen storage and utilisation. This paper presents a comprehensive numerical study on the explosion characteristics of a lean hydrogen-air mixture in a small-scale obstructed vented chamber. The large eddy simulation (LES) technique is employed to study the highly unsteady turbulence-driven explosion when the flame propagates past successive obstructions. A dynamic flame surface density (DFSD) model is applied to the filtered chemical source term in the LES to account for the progressive wrinkling of the deflagrating flame. The driving mechanism of pressure rise and the underlying physics of flame-obstacle interactions are illustrated using the detailed LES results. The paper considers 11 individual flow experimental configurations of various obstacle number, size and location. They are further classified into six groups to investigate the influence of the level of blockage and the separation distance between adjacent obstructions. Critical safety-related parameters including the maximum overpressure and its incidence time are analysed. A comparison with propane is also made to highlight the substantial overpressure and flame acceleration of hydrogen deflagrations. Satisfactory agreements have been obtained between the LES and the experimental data, and this confirms the capability of the developed computational models in capturing essential explosion features and information for the study of vented hydrogen explosions.     

125摩托车油底壳拉深起皱现象分析与解决

拉深起皱是125摩托车油箱底壳在试模期间经常遇到的问题。以ETA/DynaForm软件为平台,模拟125摩托车油箱底壳拉深起皱现象,并从应力、应变状态着手,分析起皱原因,提出解决方案。经分析结果得到起皱的主要原因为板料在成形过程中应力分量不均衡,采用一模两件的方案有效平衡了制件开口处的应力分布,同时通过加大压边力、改变摩擦系数、增设拉深筋和改变坯料尺寸,基本上消除了制件拉深试模过程中的起皱等缺陷。     

钛/铁复合板平底球形薄壁件充液拉深工艺研究

目的 选用充液拉深先进成形技术制备钛/铁复合板平底球形薄壁件,并研究其充液拉深变形行为,以解决传统拉深工艺制备平底球形薄壁件极易产生褶皱的问题。方法 对钛/铁复合板平底球形薄壁件在不同液压力、压边间隙及凸模与板料间摩擦因数等工艺参数下的充液拉深过程进行数值模拟。对数值模拟结果进行分析,讨论工艺参数对零件成形性能的影响以及抑制起皱的机理。最后在不同拉深工艺下进行成形试验,制备钛/铁复合板平底球形薄壁件并与数值模拟结果进行对比。结果 数值模拟和成形试验结果表明,传统拉深工艺制备的钛/铁复合板平底球形薄壁件出现了明显的褶皱,采用充液拉深工艺可以有效解决零件侧壁起皱的问题。增大液压力、减小压边间隙或增大凸模与板料间摩擦因数会导致零件减薄率的提高并降低零件侧壁起皱的风险。在压边间隙1.5 mm、液压力25 MPa的条件下,采用充液拉深工艺可以制备出侧壁无褶皱的平底球形薄壁件。结论 通过充液拉深工艺可以有效解决钛/铁复合板平底球形薄壁件成形过程中起皱的问题。     

食物搅碎器筛网的冲压工艺及模具设计

分析了筛网冲孔时工艺方案的确定及旋转冲孔模的结构,提出了锥形件在拉伸时出现起皱或断裂问题的解决方法。     

Innovative approach to mass production of fiber metal laminate sheets

Although, lightweight composite structures like sandwich panels and fiber metal laminates (FMLs) are greatly used as a superior material to produce modern structures to provide a substitutive item for monolithic metallic parts, but still there are some challenges in their forming process. There are some inherent limitations for forming FML parts. Also, because the strain of the fibers is limited, conventional approaches are not appropriate for forming complex-shaped laminate parts. Understanding the material behavior during the forming process is critical to find a new technique for relatively intricate and smaller FML parts. To understand the material behavior to present a new forming method, the finite element software and experiments are utilized and the thinning of layer thickness, stress distributions in different layers, and the fiber orientation are studied. Blanks made of intermittent glass fabric/fibers and Al 2024-O alloy sheets. The behavior of the material was appraised utilizing ABAQUS according to Hill yield criteria and then evaluated with the empirical outcomes. Results exhibited that FML parts manufactured by utilizing multilayer hydroforming can enhance the FML applications.