曲拐模锻件折叠缺陷优化分析

针对机器设备用曲拐锻件试制中出现质量不稳定、不同程度折叠的现象,通过建立塑性有限元和结构有限元模型,优化分析了原有成形工艺方案,提高了生产率,降低了模具成本;并在此基础上分析了产生折叠缺陷的关键影响因素:坯料规格和凹圆角半径,并提出了具体实施措施,保证了锻件成形质量。     

激光拼焊板冲压成形的数值模拟研究

用 DYNAFORM 软件对拼焊板成形过程进行有限元模拟研究.建立了盒形油箱零件的有限元模型,研究分析不同厚度、不同材料拼焊板的成形及焊缝对零件成形的影响.结果表明,以真实焊缝材料性能建立的焊缝模型能够较准确地描述拼焊板成形过程中的塑性变形及应变分布情况.     

基于AutoForm的超深冲汽车电池盒成形工艺设计与仿真

以拉延深度高达238 mm的新能源汽车电池盒上板为研究对象,通过分析零件图的结构形状特征,利用Auto Form有限元分析软件建模及数值模拟方法对板料的冲压成形过程进行了多种拉延方案的工艺模拟分析,依据有限元软件的成形仿真结果预测板料在拉延过程中出现的开裂、起皱等成形缺陷,研究分析了缺陷产生的原因,确定了零件的最佳成形方案,并优化了成形工艺参数。     

三维曲面柔性卷板成形技术及其数值模拟

介绍三维曲面柔性卷板成形技术,并与传统卷板成形和多点成形进行了对比.对柔性卷板成形装置进行研究并开发出相应的实验装置.建立柔性卷板成形的有限元模型,并对其成形过程进行数值模拟,得到了较好的模拟结果.模拟了两种不同材料板材的成形效果,分析了其产生不同成形效果的原因.     

中厚板轧制过程的数值模拟分析

在中厚板轧制成形过程中采用有限元方法进行数值模拟分析可以为实际生产提供合理的工艺参数，便于延长轧机的寿命。提高产品质量和减少试错过程的消耗等。文中阐述了利用有限元软件对中厚板轧制成形过程的非线性数值模拟分析中的一些广为关心的问题，包括：摩擦力在轧件表面的分布情况以及摩擦力大小对轧制过程的影响；材料的等向强化模型、运动强化模型和混合强化模型对中厚板轧制过程的影响；热一力耦合对厚板轧制成形过程的影响及其数值模拟分析方法。     

双金属复合材料弯曲成形有限元模拟的材料模型研究

由于双金属材料中两层复合组织结构的非均质性,对其零件成形过程进行有限元模拟是一个比较复杂的过程,其中最关键的一点就是材料模型问题.本文在经典的复合材料层合板理论的基础上对双金属复合材料的本构关系进行了推导计算,根据材料具体的加工工艺,在有限元软件MSC Marc中,建立了等效层合板模型,可以较准确地描述双金属材料结构的真实情况.     

冷弯成形实验的有限元分析中的影响因素研究

使用ANSYS/LS-DYNA有限元软件建立了模型,利用ANSYS的显式求解功能对板料冷弯成形测试实验中试件的变形进行有限元弹塑性分析,着重分析了在有限元分析过程中,求解时间、试件厚度、网格密度、模具倒角及试件翼端长度对试件内最大等效应力的影响.     

楔横轧成形25CrMo4厚壁空心轴件的不圆度分析

机械结构轻量化的主要途径是在结构上采用空心轴.近年来, 采用楔横轧带芯棒轧制空心轴类件的工艺得到了较广泛的关注.厚壁空心轴类件在楔横轧轧制过程中易发生“失圆”现象.本文通过热压缩实验研究了25CrMo4合金钢在楔横轧变形条件下热变形行为, 获得其真应力-应变曲线.在此基础上, 基于Deform-3D有限元软件, 建立25CrMo4厚壁空心轴楔横轧有限元仿真模型, 分析厚壁空心轴楔横轧成形机理, 研究得出断面收缩率、成形角、展宽角对轧件不圆度的影响规律: 断面收缩率增大, 不圆度减小; 成形角增大不圆度减小, 轧制温度越高减小趋势越明显; 展宽角增大不圆度增大, 提高轧制温度抑制增大趋势.选取部分工艺参数进行楔横轧验证实验, 对比了有限元仿真结果和实验结果, 表明有限元仿真模型预测精度较高.      

油泵齿轮轴精锻成形工艺研究及缺陷分析

针对油泵齿轮轴特殊形状设计了齿轮轴精锻模具.通过有限元仿真和精锻实验研究了齿轮轴成形过程和金属流动规律.分析了对油泵齿轮轴精锻工艺中产生齿形角隅填充不满缺陷的原因:角隅填充是成形终了时成形载荷陡增的主要原因之一,由于齿轮轴精锻模具结构的特殊性,其强度无法满足齿形角隅填充所需高成形载荷的需要.基于角隅填充状况,提出了齿形端面斜面分流和环形槽分流,并对传统精锻工艺和两种分流锻造工艺进行了有限元仿真.分析结果表明两种分流方法均能有效减小齿形角隅填充时金属流动阻力,保证齿形良好填充,降低成形载荷,并且斜面分流优于环形槽分流.锻造实验验证了有限元仿真的准确性.      

喷雾阀嘴多步成形有限元分析

喷雾阀嘴是喷雾罐的关键部件,其成形过程复杂、难度较大。采用三维光学扫描仪检测喷雾阀嘴各步成形件的三维尺寸,推导模具方案进行逆向建模。同时采用有限元技术分析喷雾阀嘴成形过程特点,探索材料性能对其成形质量的影响。结果表明,模型实现了精确分析喷雾阀嘴复杂的多步成形过程,可分析喷雾阀嘴任一时刻、任一位置的成形状态和成形质量状况。同时得出,MR T3-BA材料或比其屈服强度更高的材料容易出现成形质量问题。     

铝型材挤压成型过程有限元模拟及模具优化设计

应用UGNX建立了平面分流组合模的几何模型,利用有限元软件DEFORM-3D对挤压过程进行有限元模拟,研究了挤压铝合金空心型材时金属的流动情况。模拟结果表明,即便是对称性较好的铝合金窗用光企型材（有一个对称轴）模具,按照常规的设计方法也很难避免金属的流速不均问题,影响型材的成型度。对于绝大多数空心型材来说,其断面往往都是不对称的,仅依靠设计者的经验和判断设计模具是很难避免金属流速不均问题的。而采用有限元模拟的方法,则可以及时发现设计中存在的不足,并通过修改设计方案,达到满意的效果,为设计模具提供科学的依据。     

T型电梯导轨冷拔过程有限元模拟

根据T型电梯导轨冷拔过程的变形特点,通过对冷拔过程的有限元模拟,研究了两种不同模具对冷拔金属流动的影响,得出改进模具形状可减小导轨弯曲度,与生产实践相符.     

铝粉末压制过程有限元模拟研究

根据粉末材料的塑性理论及Shima-Oyane屈服准则,利用体积可压缩有限元法,采用MARC有限元分析软件对铝粉的单向压制和双向压制过程进行了数值模拟。得到了粉末材料在压制过程中的变形特征、相对密度分布及粉末质点的流动规律,得到单向压制和双向压制的密度分布图,并对其差异进行了分析。模拟结果对揭示粉末压制过程机理,制订压制工艺都有显著意义。     

Effect of die shape on the deformation behavior in equal-channel angular pressing

Experimental studies and finite element analysis of equal-channel angular pressing (ECAP) were carried out to clarify the deformation behavior in a sharp corner die and a round corner die under the condition without a frictional effect. It was found in both the experiment and the finite element simulation that the geometry of the die itself has a great influence on the homogeneity in deformation, resulting in more uniform shear deformation in the sharp corner die than in the round corner die under the condition without friction. The shear deformation was concentrated homogeneously on the diagonal plane of the sharp corner, which was in good agreement with the postulation of the conventional theory. In the case of the round corner die, however, plastic deformation was spread over a wide sector of the corner where shear deformation was confined to the inner part, and nonshear deformation was found in the outer part. The inhomogeneous deformation of the round corner die due to geometrical effects exhibited forward-curved flow in the outer part of the corner differently from backward-curved flow caused by frictional effects. The numerical analysis showed that more inhomogeneous distribution of stress was generated on the inlet cross section of the round corner, resulting in a variation of the normal stress from a compressive stress in the inner part to a tensile stress in the outer part. Tension followed by compression was a dominant deformation mode of the material during passing through the outer corner, and a gradual bending of the material occurred instead of shear deformation.     

Mechanical behavior of aluminum matrix composite during extrusion in the semisolid state

Semisolid extrusion experiments have been carried out on SiC particle reinforced aluminum composite. Different die diameters and ram velocities have been used in order to obtain a range of extrusion conditions at a constant temperature of 580 °C. The experimental results were fitted to a multiple linear regression to obtain a constitutive equation describing the behavior of the material in these conditions. From the regression equation, it was possible to model the material by finite element analysis. The predicted values fo the extrusion force resulting from the numerical analysis are consistent with the experimental values for the different conditions. The flow of primary phase particles through the die observed on micrographs has been compared with the predicted pattern and shows good agreement. These results also justify the use of a frictional stress factor corresponding to a sticking condition at the interface between the billet and the die components.     

楔横轧梯形螺纹轴成形机理

通过分析螺纹轴齿形成形过程,并结合金属流动特点,获得楔横轧梯形螺纹轴的成形机理.考虑到轧制过程轧件螺旋升角瞬时变化特点和成形段齿形截面变化等因素设计了楔横轧模具,采用有限元分析软件Deform-3D对楔横轧梯形螺纹轴齿形成形过程进行模拟,得到精度较高的梯形螺纹轴轧件.利用有限元点跟踪功能,对轧件多个点进行跟踪,详细分析了轧件螺纹不同位置各点的径向、轴向位移变化情况,从中获得螺纹段各处金属流动规律.采用软件模拟参数进行了相应的楔横轧实验,得到的梯形螺纹轴实验轧件与有限元模拟结果相同.模拟和实验结果表明,模具螺旋升角采用轧件瞬时半径对应螺旋升角时,能够轧制出形状精确的螺纹轴.     

Simulation of electromagnetically induced hyperthermia: a finite element gridding method

A finite element gridding method for simulating electromagnetically (EM) induced hyperthermia is presented. The method uses patient CT data as its primary input, with critical structures manually outlined (on a graphics workstation) for explicit demarcation. The paper outlines the various stages involved in mesh creation, including procedures for conforming the finite element representation of critical structures to their smooth boundaries, modelling of heating equipment, and modelling of the outer boundaries. The procedure for generating the finite element model is illustrated for an example treatment. Additionally, the results of computing the SAR in six patients are compared to measured values. The comparison reveals agreement between the model prediction and actual treatment within the limits of measurement error.     

Computations of Granular Flow and Pressures in a Flat-Bottomed Silo

The most demanding design situations for silo structures usually occur at the onset of discharge, when the silo is still almost full of granular solid. In this condition, the pattern of solids flow affects the wall pressures, and both are currently difficult to predict even using the best numerical models. This paper describes part of an international collaborative study in which finite element and discrete element models were used by many leading research groups around the world to model a single well-defined problem of discharge from a flat-bottomed silo using many different programs. The results show that discrete element models give good qualitative predictions of flow patterns, and the finite-element models give good quantitative predictions of pressure regimes, but there is little agreement on the details either within each modeling paradigm or between them. Further extensive research is needed to reach a scientific consensus on the requirements for a reliable formulation.     

基于剪切修正GTN损伤模型的辊冲工艺数值模拟

在GTN模型基础上,考虑到微孔洞剪切变形对材料劣化的影响,建立适用于压应力状态的剪切修正模型.通过用户子程序接口VUMAT将与损伤耦合的弹塑性本构模型嵌入具有ALE法的有限元软件Abaqus/Explicit中.利用模拟拉伸与纯剪切试验拟合载荷-位移曲线以确定模型参数.将修正模型应用到辊冲工艺有限元模拟中预测断面质量,并进行试验验证.结果表明:前刃口为小间隙冲裁,塌角较小,光亮带较大但带有一定的倾角;后刃口为大间隙冲裁,塌角与断裂带较大,光亮带较小;裂纹会同时在前刃口凸模与凹模侧面萌发,而对于后刃口,会首先在凹模侧面产生.