基于ST14材料冲压工艺有限元分析应用

以ST14材料的左右后门窗框前支架工件为载体,以AutoForm冲压工艺有限元分析软件为平台,针对ST14材料的经验结构工艺模拟材料的成形过程,分析了工件冲压成形工艺过程中的缺陷问题,通过工件工艺结构的反复修正,实现了解决冲压工艺缺陷问题的目的.     

Multi-field coupling finite element analysis for determining the influence of temperature field on die service life during precision-forming process of steel synchronizer ring

Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.     

基于热力耦合的减振轴套挤压成形有限元模拟研究

利用基于有限变形理论的热力耦合基本方程,对减振轴套挤压成形模进行了三维热力耦合计算.分析发现应力集中明显,且其部位与模具实际裂纹位置相吻合.为改善模具体内应力分布,对该模具的主要结构参数进行了优化设计.获得优化的结构尺寸,使最大应力下降153%,从而延长了模具的使用寿命.     

Investigation of the influence of various process parameters on the radial forging processes by the finite element method (FEM)

In this study, the finite deformation theory was used to develop a large rigid-plastic deformation finite element program which could simulate the radial forging process of work-hardening materials. First, experiments were carried out to confirm the accuracy of the program. Then we investigated the influence of each parameter on the forging process. The parameters adopted in this study are die corner radius (R), ring gap height (H), friction factor (m), and work-hardening coefficient (n). The effects of parameters on the flange thickness ratio (h/H) and the outer protruding shape ratio (D/D ₀) are also obtained. The relationship between the process parameters and the deformation behaviours under radial forging is obtained through simulation. When the radius of die corner and the ring gap height are larger, the flange thickness ratio (h/H) becomes larger, but the outer protruding shape ratio (D/D ₀) decreases. The value of friction factor (m) doesn’t seem to affect the flange thickness ratio (h/H) much, but the outer protruding shape ratio (D/D ₀) decreases upon increasing the friction factor . When the work-hardening coefficient (n) is larger, the flange thickness ratio (h/H) is also larger, but the outer protruding shape ratio (D/D ₀) decreases. The results of this study offer some advanced knowledge about finding the best designs of process and die in radial forging process.     

Gear hot forging process robust design based on finite element method

During the hot forging process, the shaping property and forging quality will fluctuate because of die wear, manufacturing tolerance, dimensional variation caused by temperature and the different friction conditions, etc. In order to control this variation in performance and to optimize the process parameters, a robust design method is proposed in this paper, based on the finite element method for the hot forging process. During the robust design process, the Taguchi method is the basic robust theory. The finite element analysis is incorporated in order to simulate the hot forging process. In addition, in order to calculate the objective function value, an orthogonal design method is selected to arrange experiments and collect sample points. The ANOVA method is employed to analyze the relationships of the design parameters and design objectives and to find the best parameters. Finally, a case study for the gear hot forging process is conducted. With the objective to reduce the forging force and its variation, the robust design mathematical model is established. The optimal design parameters obtained from this study indicate that the forging force has been reduced and its variation has been controlled.     

热流道板的热平衡及温度场的有限元分析

热平衡是热流道系统的核心问题之一,热流道板的主要任务是恒温地将熔体从主流道送入各个单独喷嘴.热流道板必须处于热平衡状态,热损失必须通过加热来补偿.通过分析热流道板的热损失,进行加热器功率的计算,并利用ANSYS软件分析热流道板的温度场.     

基于有限元的橡胶-金属联轴器功率流研究

基于橡胶粘弹性理论讨论了橡胶-金属联轴器在高速旋转时橡胶组件产生的拉压应力对橡胶材料减振性能的影响,并通过基于有限元计算的功率流减振效果评估方法进行定量分析。结果表明橡胶-金属联轴器在结构材料确定的情况下,通过改变输入转速和扭矩可使联轴器在确保某一功率传递时达到该工况下的最佳减振效果,对这一类联轴器的工程应用有一定的指导意义。     

箱体结构的声固耦合有限元分析

基于声学有限元法和声固耦合理论,建立了箱体结构的有限元模型,采用有限元AN-SYS软件,针对不同厚度的壁板以及不同位置的加筋处理两种情况,对箱体结构振动与内部噪声进行了分析研究,确定部分结构参数的改变对箱体内部噪声的影响规律.     

铝热精轧轧制区温度场三维有限元模拟

根据某铝热连轧厂生产线实际结构参数和工艺参数,应用弹塑性有限元法,考虑轧件金属塑性变形热、摩擦热、界面接触热导等对轧件和轧辊传热的影响,运用大型通用有限元分析软件MSC.Marc建立了铝热连轧精轧机组F2机架的热力耦合三维有限元仿真模型.通过分析轧件温度场的分布规律,为更好地控制轧件的温度分布、提高产品的质量提供依据.     

Application of hot press forming process to manufacture an automotive part and its finite element analysis considering phase transformation plasticity

An automotive flex plate that is installed in the automotive engine and delivers a torque to a transmission is manufactured by hot press forming technique. By this technique, significant increase of strength through quenching of heated high carbon SK5 steel sheet and higher dimensional stability after forming through the press operation at high temperature can be attainable. The indirect method with a pre-forming step and direct oil quenching to attain uniform and fast cooling rate are employed considering cooling characteristics of the SK5 steel and large thickness of the flex plate. A new tool design is proposed for the hot press forming process, and an optimized heat treatment condition is determined by studying two frequently utilized heat treatments: austempering and quenching with tempering heat treatments. By introducing designed tools and selected heat treatment condition, the target product can be successfully manufactured, which satisfies two main manufacturer's specifications: high hardness and good dimensional accuracy. Moreover, finite element analysis, which considers transformation induced plasticity (TRIP) during phase transformations, is performed to understand the thermo-mechanical behavior of hot press formed sheet. The analysis verifies that phase transformations play significant roles in strengthening by transforming hard martensitic phase and in reducing dimensional change by additional plastic deformation during phase transformations.     

Micro–macro simulation of sintering process by coupling Monte Carlo and finite element methods

A micro–macro method for simulating a sintering process of ceramic powder compacts based on the Monte Carlo and finite element methods is proposed. Macroscopic non-uniform shrinkage during the sintering is calculated by the viscoplastic finite element method. In the microscopic approach using the Monte Carlo method, powder particles and pores among the particles are divided into many cells, and the growth of grains in the particles and the disappearance of pores are simulated by means of the Potts model.The shrinkage strain rate required as a materials constant in the macroscopic method is calculated by the microscopic approach. The microscopic and macroscopic approaches are coupled by exchanging microscopic and macroscopic results in each finite element step. In the Monte Carlo method, the effect of macroscopic viscoplastic deformation on the microstructural change is taken into consideration by including viscoplastic strain rate calculated by the finite element method in the disappearance frequency of pore cells. The shrinkage behaviour in the sintering of circular two-layer compacts is simulated by the proposed micro–macro method.     

Analysis and design of flat-die hot extrusion process 1. Three-dimensional finite element analysis

Non-steady-state-coupled three-dimensional analysis is required for investigating complex material flow in practical flat-die hot extrusion processes of aluminum alloys in various channel sections. It is important since the material flow behavior actually determines the amount of distortion of the extruded product. Thus, a non-steady thermo-rigid-viscoplastic finite element program was developed for numerical simulations of the process. Since severely deforming elements of the workpiece can easily interfere with the sharp edges of the flat-die, an automatic remeshing module based on a simple section-sweeping scheme and new contact algorithm were incorporated to allow continuous simulation without manual intervention with less volume loss and computation time. With developed finite element program, non-steady finite element analyses of extrusion processes were carried out for two types of channel-section with constant bearing length of 5 mm. From simulation results, it was found that the exit velocity of the workpiece varied depending on the cross-sectional thickness of the exit and the amount of deflection of the workpiece was not greatly affected by variations of either the workpiece temperature or punch velocity under the present simulation conditions.     

基于ANSYS的二维结构声场混合有限元模型研究

为了求解复杂结构体下的声场分布,采用ANSYS软件建立了声场-结构二维混合有限元模型,给出了ANSYS软件中混合模型的建模方法,通过在结构体四周设置结构体与空气耦合单元,将结构模型因受力发生形变而产生的噪声声压耦合到空气中,实现了混合声场模型的求解。模型求解结果表明,该模型能很好地解决声场与结构场的耦合问题。     

Analysis of drawbead process by static-explicit finite element method

The problem analyzed here is a sheet metal forming process which requires a drawbead. The drawbead provides the sheet metal enough tension to be deformed plastically along the punch face and consequently, ensures a proper shape of final products by fixing the sheet to the die. Therefore, the optimum design of drawbead is indispensable in obtaining the desired formability. A static-explicit Finite element analysis is carried out to provide a perspective tool for designing the drawbead. The finite element formulation is constructed from static equilibrium equation and takes into account the boundary condition that involves a proper contact condition. The deformation behavior of sheet material is formulated by the elastic-plastic constitutive equation. The finite element formulation has been solved based on an existing method that is called the static-explicit method. The main features of the static-explicit method are first that there is no convergence problem. Second, the problem of contact and friction is easily solved by application of very small time interval. During the analysis of drawbead processes, the strain distribution and the drawing force on drawbead can be analyzed. And the effects of bead shape and number of beads on sheet forming processes were investigated. The results of the static explicit analysis of drawbead processes show no convergence problem and comparatively accurate results even though severe high geometric and contact-friction nonlinearity. Moreover, the computational results of a static-explicit finite element analysis can supply very valuable information for designing the drawbead process in which the defects of final sheet product can be removed.     

喷丸残余应力场有限元模拟研究进展

喷丸强化处理工艺可以显著提高金属材料的抗疲劳和抗应力腐蚀等性能,这与喷丸后在金属表面层形成的残余应力场紧密相关,因此对喷丸残余应力的大小及分布进行预测具有重要意义.对近年国内外喷丸残余应力场的有限元模拟进行评述,总结出6种典型的残余应力分析模型,分别是二维轴对称模型、四对称面模型、三对称面模型、双对称面模型、单对称面模...     

Characterization of interfacial friction in coated sheet steels: influence of stamping process parameters and wear mechanisms

By means of a tensile strip testing system, the nature of interfacial friction in stamping operations were investigated for three different coated sheet steels. Friction coefficient measurements were taken at seventeen distinct operating conditions by varying the sheet strip coating material (lead and zinc), applied lubricant (oil-base lubricants and greases) and pin radii (10 and 20 mm). In addition to determining the friction coefficient, the surface roughnesses of the sheet strips were measured before and after the completion of each test. From the experimental results, several relationships were ascertained for the role of the microscopic wear in determining the character of interfacial friction during stamping processes.     

基于自由度耦合的携行式外骨骼机械结构有限元分析

以携行式外骨骼为研究对象,使用ANSYS 10.0软件,建立机械结构的有限元模型,采用自由度耦合方法,处理构件与液压缸之间的连接问题,并对其进行强度分析,根据计算结果,对机械结构设计提出了修改意见,为后续研究奠定了基础.