GH4169合金惯性摩擦焊接头温度场显式有限元数值模拟

借助ABAQUS/Explicit显式有限元模拟软件,采用热力耦合方法,建立了GH4169高温合金管状工件三维弹塑性有限元大变形计算模型.考虑了计算设置中质量放大因子(mass scaling)对飞轮转动惯量的影响,确定了放大因子与转动惯量缩小倍数之间的相互关系.在此基础上对整个焊接过程工件的温度场进行了综合分析.结果...     

Initial temperature field’s simulation and analysis of 2024 aluminum alloy piate's friction stirring welding

搅拌摩擦焊下压过程中温度场的建立对工件的焊接质量有重要的影响.在搅拌摩擦焊接过程中,搅拌工具与焊接工件的摩擦接触关系及焊接工艺参数的选取,决定了焊接过程中工件的温度场分布.基于修正的库仑摩擦定律,建立了火箭燃料贮箱所用3mm厚2024铝合金材料搅拌摩擦焊接下压过程的热量输入模型,通过有限元分析得到了整个过程中的温度场分布.分析结果表明,该模型的下压阶段温度场计算精度较高.模型的计算结果对指导铝合金焊接初始下压过程中转速、下压速度及项锻力的大小等焊接工艺参数的选取具有重要意义.     

2024铝合金搅拌摩擦焊初始温度场数值模拟与分析

搅拌摩擦焊下压过程中温度场的建立对工件的焊接质量有重要的影响。在搅拌摩擦焊接过程中,搅拌工具与焊接工件的摩擦接触关系及焊接工艺参数的选取,决定了焊接过程中工件的温度场分布。基于修正的库仑摩擦定律,建立了火箭燃料贮箱所用3 mm厚2024铝合金材料搅拌摩擦焊接下压过程的热量输入模型,通过有限元分析得到了整个过程中的温度场分布。分析结果表明,该模型的下压阶段温度场计算精度较高。模型的计算结果对指导铝合金焊接初始下压过程中转速、下压速度及顶锻力的大小等焊接工艺参数的选取具有重要意义。     

铝/镁异种金属搭接搅拌摩擦焊接温度场数值模拟研究

利用有限元分析软件ABAQUS对铝/镁异种金属搭接搅拌摩擦焊温度场进行模拟研究,计算了焊接过程中不同焊接参数对温度场的影响.结果表明:数值模拟结果与测量结果能够较好吻合,热源模型的建立基本符合搅拌摩擦焊接过程,验证了已建立的模型的可靠性.     

焊接工艺参数对LF5铝合金搅拌摩擦焊温度场的影响

以LF5铝合金为研究对象,利用有限元软件MSC.Marc建立了平板对接接头搅拌摩擦焊过程的有限元模型,分析了焊接过程的温度场.结果表明:由于热传导区域范围的减少,当焊接热源接近平板端部时焊缝区域的温度峰值上升,不利于接头性能;当焊接速度减少或搅拌头的旋转速度升高时,焊接过程中的温度峰值升高甚至超过母材熔点.综合考虑实际工程效率与温度场影响接头质量的规律,给出了搅拌摩擦焊焊接工艺参数的优选方法.     

2A14-T6铝合金双轴肩搅拌摩擦焊接温度场研究

搅拌摩擦焊接过程的温度场分布对焊接接头质量有非常重要的影响。本文应用ANSYS有限元分析软件对2A14-T6铝合金双轴肩搅拌摩擦焊接过程的温度场进行数值模拟,研究了焊接过程试板表面和厚度方向温度分布特征。运用热电偶测温技术对试板特征点进行温度测量,分析各特征点温度变化规律,同时验证了模拟的正确性。     

搅拌摩擦焊接中参数变化对温度场分布的影响

文章建立了搅拌摩擦焊接过程的三维有限元热分析模型,讨论了旋转速度、搅拌头半径、轴肩半径、搅拌针锥角以及螺纹角等焊接参数对工件温度场的影响。计算结果表明,在焊接过程中,工件的最高温度低于熔点,为固相连接。在焊接工艺参数许可的范围内,旋转速度和搅拌针半径的增加,会使搅拌摩擦焊接过程中的最高温度值增加,而锥角和螺纹角增加,会使最高温度值随之减小,轴肩半径的改变对工件温度场的影响相对较小。     

45钢线性摩擦焊接过程的数值分析

基于Abaqus/Explicit显式有限元分析软件,建立了线性摩擦焊接同质接头的二维计算模型,研究了线性摩擦焊接45钢接头温度场、应力应变场、轴向缩短量和焊接后期接头的降温过程.结果表明,焊接界面中心温度可在不到1s内骤升至800℃,之后界面温度缓慢上升至900℃左右,随着焊接过程的进行,焊接接头主要是温度场的均匀化、不断的轴向缩短和飞边的形成,随后接头经历了较快的降温过程.试验验证了计算模型的可靠性.     

5A06铝合金搅拌摩擦焊温度场数值模拟

采用热量自适应热源模型,利用ANSYS有限元软件对5 mm厚5A06铝合金搅拌摩擦焊接过程温度场进行模拟,研究不同转速、焊接速度对搅拌摩擦焊温度场的影响。结果表明:当焊接速度提高或搅拌头旋转速度降低时,焊接过程中的峰值温度降低;焊接过程进入稳态后,峰值温度稳定在420°C左右;沿焊缝两侧温度场分布不完全对称,前进侧温度略高于返回侧温度。     

搅拌摩擦焊接过程温度场数值模拟

在深入考虑搅拌摩擦焊的具体焊接过程后,提出了简化的热输入模型。利用ANSYS有限元分析程序建立了随热源一起移动的坐标系,采用分步加载的方法对搅拌摩擦焊过程的温度场进行了模拟。得到了3mmLY12硬铝合金薄板在整个焊接过程中焊缝区每一时刻的瞬态温度场以及焊缝区各点的焊接热循环曲线,确立了温度场空间分布和时间变化的规律,并且通过测量特征点的实际温度验证了计算结果的准确性。     

基于ABAQUS药芯铝焊丝铝带成型过程的仿真研究

在对显式动力学有限元方法的概念、基本理论和应用范围进行了阐述的基础上,通过ABAQUS有限元仿真软件,在Explict显式动力学模块中,对4047铝药芯焊丝轧制过程中4047铝带成型过程进行了模拟仿真.比较不同铝带速度下铝带成型质量.比较不同质量缩放因子下仿真结果稳定的4047铝合金的成型质量,择优选出成型质量最好、运算速度最快的质量缩放因子.比较不同上下轧辊轴线距离时4047铝合金成型质量,得出了当上下轧辊的距离为4047铝带厚度时其成型质量最佳.     

环件轧制三维有限元模拟中质量缩放方法的运用

阐述了环件轧制三维有限元模拟中运用质量缩放方法的意义及其理论依据,并对显式动力学有限元模拟中各种质量缩放方法进行了分类,给出了环件轧制模拟中质量缩放方法的选取原则。最后基于ABAQUS/EXPLIC-IT操作平台,建立了铅环件的环件轧制三维有限元模型,通过具体模拟及分析比较计算结果对选取原则进行了验证,从而总结出了适合于环件轧制模拟的有效的质量缩放方法。     

Study of dynamic explicit analysis in sheet metal forming processes using faster punch velocity and mass scaling scheme

A finite element formulation using dynamic explicit time integration scheme is developed for numerical analysis of autobody panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and direct trial and error method. To investigate the effects of punch velocity, various values of punch velocity are used for numerical analysis. The mass scaling scheme is introduced for economic analysis. To investigate the effects of mass scaling, various mass scalings are used. Computations are performed for analysis of complicated autobody panel stamping processes including the formation of an oilpan and a fuel tank.     

高速列车铝合金车身双热源搅拌摩擦焊仿真

高速列车采用超长铝合金型材作为车身新材料。搅拌摩擦焊以固相连接原理成为高铁车身制造新工艺。针对单热源模型不足,考虑搅拌轴肩转动摩擦生热和搅拌头塑变剪切生热,建立搅拌摩擦焊双热源有限元模型。基于传统熔焊方式,实现满足搅拌焊特征的双面挤压型材接头变形设计。通过ANSYS二次开发,完成该工艺移动瞬态热交换数值仿真,获得焊接全程三维温度场分布,仿真结果与试验数据吻合良好。结果表明,该仿真模型可行．仿真结果合理,为高铁车身国产化制造工艺吸收和工艺优化提供参考。     

Elastic-plastic finite element analysis of automotive body panel stamping processes using dynamic explicit time integration scheme

In this article, the elastic-plastic finite element formulations using dynamic explicit time-integration schemes are proposed for numerical analysis of automotive body panel stamping processes. A general formulation of finite element simulation for complex sheet forming processes with arbitrarily shaped tools is briefly introduced. In finite element simulation of automotive body panel stamping processes, the robustness and stability of computation are important requirements since the computation time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry and boundary conditions. For analyses of more complex cases with larger and more refined meshes, the explicit method is more time effective than the implicit method, and it has no convergency problem and has the robust nature of contact and friction algorithms, although the implicit method is widely used because of excellent accuracy and reliability. The elastic-plastic scheme is more reliable and rigorous, while the rigid-plastic scheme requires short computation time. The performance of the dynamic explicit algorithms is investigated by comparing the simulation results of forming of complex-shaped automotive body parts, such as a fuel tank and a rear hinge, with the experimental results. It has been shown that dynamic explicit schemes provide quite similar results to the experimental results. It is thus shown that the proposed dynamic explicit elastic-plastic finite element method enables an effective computation for complicated automotive body panel stamping processes.     

Thermal history in UNS S32205 duplex stainless steel friction stir welds

Consolidated UNS S32205 duplex stainless steel joints welds were performed using a friction stir welding (FSW) process. An experimental set-up was used to record the thermal history of duplex stainless steel FSW joint. For points at equal distance from the weld centreline, temperature measured near the beginning of the weld was lower than that measured in the middle of the welded joint. This was attributed to a non-stationary transfer condition. FSW thermal cycle showed shorter time spent at elevated temperature compared that presented by fusion welding, indicating less propensity to detrimental second phase precipitation. To support temperature measurements with thermocouples, a three-dimensional finite element thermal model of FSW was implemented, which provided a good agreement with experimental data.     

搅拌摩擦焊接的传热和力学计算模型

搅拌摩擦焊接（Ｆｒｉｃｔｉｏｎ Ｓｔｉｒ Ｗｅｌｄｉｎｇ）是最近发展起来的一种新的固态连接技术。它主要用于铝合金,可以得到小变形、低成本和高质量的焊接接头。本文提出一个基于三维热弹塑性有限元分析的传热和力学计算模型。利用该模型可以了解搅拌摩擦焊接过程中的温度分布和循环,并预测焊后的残余应力和变形。对６０６１－Ｔ６铝合金搅拌摩擦焊接进行了实例分析。传热分析表明,铝合金搅拌摩擦焊接时的最高温度不超过材料熔点的８０％,因而属固态连接,同时为预测焊接接头的组织性能提供依据。力学计算结果表明,搅拌摩擦焊接的残余应力与变形要比传统的熔化焊接方法小得多。工件中最大的残余应力大约只有母材屈服极限的２５％～３０％。计算结果与试验数据相近,可作为进一步研究搅拌摩擦焊接过程和优化焊接参数的有效工具。     

2219铝合金厚板搅拌摩擦焊搅拌头结构参数优化

为探究搅拌头几何形貌对2219铝合金厚板搅拌摩擦焊核心区温度场的影响，基于ABAQUS/CEL建立了18 mm厚2219铝合金FSW三维过程仿真模型，应用有限元分析法对焊接过程进行仿真研究，得到了焊接核心区测温点实时温度循环曲线。利用自主研发的热电偶测温系统对焊接温度场相应测温点温度进行检测，经过对比可知,不同转速试验和仿真数据曲线变化趋势基本相同，验证了所建立的FSW过程仿真模型的有效性。探究了搅拌头结构参数对FSW过程核心温度场的影响规律，针对搅拌头的轴肩尺寸、搅拌针锥角、轴肩凹角、螺纹升角等结构尺寸设计了4因素3水平正交试验。结果表明，轴肩直径对核心区温差的影响最为显著，当搅拌头的轴肩尺寸为36 mm、搅拌针锥角为6°、轴肩凹角为2.5°、螺纹升角为11°时，搅拌头结构尺寸较为合理，核心区温差值较小。 创新点： 探究了搅拌头几何形貌对搅拌摩擦焊核心区温度场的影响,实现了搅拌头的结构参数优化。     

Modeling friction stir welding process of aluminum alloys

The friction stir welding (FSW) process of aluminum alloys has been modeled using a two-dimensional Eulerian formulation. Velocity field and temperature distribution are strongly coupled and solved together using a standard finite element scheme. A scalar state variable for hardening is also integrated using a streamline integration method along streamlines. A viscoplastic constitutive equation to consider plastic flow and strength variations was implemented for the process modeling. Precipitates inside AA6061 alloys are sensitive to elevated temperatures and affect strength evolution with temperature. The overall effects of the precipitate variations with temperature on strength were reflected using temperature-dependent material parameters. The material parameters of constitutive equations were obtained from isothermal compression tests of various temperatures and strain rates. The effects of FSW process conditions on heating and hardening were investigated mainly near the tool pin. The microhardness distribution of the weld zone was compared with the prediction of strength. In addition, crystallographic texture evolutions were also predicted and compared with the experimental results.