旋转速度对高强铝厚板搅拌摩擦焊温度场的影响

基于ANSYS，通过对高强铝厚板搅拌摩擦焊的三维温度场有限元数值模拟，定量分析了厚板搅拌摩擦焊中最重要的工艺参数——旋转速度对搅拌区焊接温度场的影响。结果表明，在厚板焊接时，随着旋转速度增加，搅拌区温度总体升高，且高温区的贯穿深度增加。分析表明焊缝金属流变区最低温度在靠焊件底面搅棒表面处，该温度是限制厚板搅拌摩擦焊接性和焊接速度的主要因素。     

搅拌摩擦焊温度场最新研究进展

早期的搅拌摩擦焊温度场模型只考虑了摩擦产热,而忽略了塑性变形产热。在刚结束的第五届搅拌摩擦焊国际会议上,有许多学者就塑性变形产热对其温度场的影响进行了研究,本文对此作了概括地介绍分析。     

搅拌摩擦焊温度场最新研究进展

早期的搅拌摩擦焊温度场模型只考虑了摩擦产热，而忽略了塑性变形产热。在刚结束的第五届搅拌摩擦焊国际会议上，有许多学者就塑性变形产热对其温度场的影响进行了研究，本文对此作了概括地介绍分析。     

搅拌摩擦焊过程中搅拌头温度场分布特征

试验测定了搅拌头温度分布曲线,分析了搅拌头温度场的分布特征,对比研究了不同材质搅拌头温度分布的特点.结果表明,摩擦焊初始阶段,搅拌区域金属的软化致使摩擦针与试板之间的摩擦产热量降低,在搅拌头轴肩与试板接触之前,搅拌头温度出现滞涨,并出现一定程度的回落;稳定焊接阶段,摩擦热传递至搅拌头的热量与通过其散失的热量处于动平衡状态,其温度波动较小;高速旋转搅拌头的表面与周围空气进行强烈的热交换,搅拌头轴线上的温度高于外缘的温度;采用比热容小、热导率高材质制作的搅拌头,焊接过程中其温度变化快,整体温度高.     

2219铝合金搅拌摩擦焊温度场的三维实体耦合数值模拟

为更贴近实际的模拟搅拌摩擦焊焊接过程中复杂的热力行为,试验通过建立三维搅拌摩擦焊过程数学模型,采用三维实体耦合的有限元方法来分析2219铝合金搅拌摩擦焊热过程和温度场分布.结果表明,搅拌摩擦焊焊缝的温度场梯度呈现上密下疏,前密后疏的分布状态,最高温度位于后退侧的搅拌针与轴肩的过渡区,焊缝后退边的温度高于前进边,搅拌针底部温度超过2219铝合金的再结晶温度,可确保对接接头根部形成紧密焊缝,模拟结果为研究搅拌摩擦焊的机理和优化搅拌摩擦焊焊接工艺提供了支持.     

铝合金搅拌摩擦焊温度场检测

通过对铝合金搅拌摩擦焊过程中各特征点温度的系统检测,得出了铝合金搅拌摩擦焊过程中温度场变化的基本规律.焊接过程中材料旋入侧温度高于材料旋出侧温度,上层温度高于下层温度,焊缝中心的温度最高,焊接结束时被焊材料末端的温度较焊接稳定区有所升高.     

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.     

2024-T4铝合金薄板超声辅助搅拌摩擦焊温度场数值模拟

以2024-T4铝合金为研究对象,利用有限元软件MSC.Marc建立了UAFSW和FSW模型,对比分析其温度场,研究超声对FSW温度分布的影响,探索合适的UAFSW工艺参数范围。结果表明:在同等条件下,UAFSW模型峰值温度高于FSW,说明超声的加入有温度补偿作用;超声的加入增大了焊接工艺窗口,提高了焊接效率。     

热量自适应搅拌摩擦焊热源模型

当前采用的温度场热源数值模型在准确表征焊接过程材料性能和产热机制与温度变化关系上存在困难.依据摩擦学原理,以材料屈服强度ReL为产热基本参数建立新型热源模型,产热量随温度、材料性能改变,实现搅拌摩擦焊产热自适应过程,更准确地描述了搅拌摩擦焊过程物理现象的本质.温度场试验与模拟结果的比较表明,该热量自适应热源模型具有较高的计算精度.     

汽车轮毂搅拌摩擦焊的数值模拟

利用ANSYS软件对其搅拌摩擦焊过程的温度场进行了分析,结果表明,搅拌摩擦焊过程的最高温度为570℃,位于轴肩与工件的接触面上,热源中心温度场分布形状为圆环形,高温由圆环面向周围逐渐扩散降低。数值模拟与试验得到的熔池轮廓较为相似,焊缝熔池形状为杯锥状,说明车轮毂搅拌摩擦焊的有限元模拟过程较为合理。     

Artificial-neural-network-based storage method for three-dimensional temperature field data during friction stir welding

In this paper, a new storage method for the three-dimensional temperature field data based on artificial neural network(ANN)was proposed. A multilayer perceptron that takes the coordinate(x, y, z)al welding temperature field. Effect of number of ANN layers and number of neurons on the fitting errors is investigated. It is found that the errors decrease with the number of hidden layers and neural numbers per layers generally. When the number of hidden layers increases from1 to 6, the maximum temp...     

Thermoelectric method for temperature measurement in friction stir welding

Abstract

Previous research within friction stir welding (FSW) has demonstrated that online control of welding parameters can improve the mechanical properties and is necessary for certain applications to guarantee a consistent weld quality. One approach to control the process is by adapting the heat input to maintain a stable welding temperature, within the specified operating boundaries. This requires accurate in-process temperature measurements. This paper presents a novel method to measure the temperature at the interface of the FSW tool and workpiece. The method is based on the thermoelectric effect between dissimilar materials. The measurements are compared to thermocouple measurements and to a physical model and show good correspondence to each other. Experiments demonstrate that the method can quickly detect temperature variations, due to geometrical variations of the workpiece or due to parameter changes. This allows use of the method for online control of robotic FSW.     

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。     

搅拌摩擦焊接过程流体数值模拟概述

为了对搅拌摩擦焊接机理有进一步的理解，需要对FSW过程中塑性材料的流体流动进行深入研究。搅拌摩擦焊接过程的数值模拟是研究FSW过程中塑性材料流体流动的一种重要手段。介绍了FSW过程数值模拟的一些研究进展，对资料中建立的模型和模拟结果进行了简要的描述。     

搅拌摩擦焊接三维流动模型

建立了搅拌摩擦焊焊接过程中塑性软化层的流动行为物理模型,该模型根据不同部位的流动特点将软化层的流动分成三部分,轴肩端面附近的软化层流动、搅拌针上部的软化层流动和搅拌针端部附近的软化层流动行为。轴肩端面附近的软化材料首先流入搅拌针行进过程中于搅拌针后部形成的空腔内,剩余软化材料围绕着轴肩侧面缓缓地由前进侧流动到搅拌针的后部,并于轴肩后部侧表面上形成了焊缝表面弧形纹的弧峰;搅拌针上部附近的软化层以剪切的方式从搅拌针前部流动到搅拌针后部;搅拌针端部附近的软化层以挤压的方式从搅拌针的前部流动到搅拌针的后部。     

超声辅助搅拌摩擦焊温度场及残余应力场分析

超声辅助搅拌摩擦焊是一项在搅拌摩擦焊的搅拌头上添加轴向高频振动的新技术. 以6 mm厚7075铝合金材料为研究对象,建立了超声辅助搅拌摩擦焊与普通搅拌摩擦焊接的热源模型,通过ANSYS软件研究了轴向振动对焊接过程温度场以及焊后残余应力的影响规律. 结果表明,轴向振动的添加能够增大热输入量,提高焊接峰值温度且降低焊缝残余应力;在相同转速及焊接速度下,当振动频率一定时,焊接峰值温度和焊后残余应力随着振动幅值的增加而增大;当振动幅值一定时,随着振动频率的增大,焊接峰值温度及焊后残余应力也相应增加.     

Digital simulation of the friction stir welding process

A recently developed welding process has proven to be well suited to making high strength aluminium alloy joints. This friction stir welding (FSW) process was invented and patented by The Welding Institute (TWI). The objective was to develop a means of simulating the process that could subsequently be used as a means of enhancing the design of these welded structures. Furthermore, these methods will enable easier development of the process, and for improved knowledge of the quality of the workpieces, in particular in terms of residual stresses. It will also make for better forecasting of the lifetime of these structures. These three-dimensional thermomechanical transient calculations were made using two finite element codes (SYSWELD (ESI Group) and MARC (MSc Group)). The heat input of the process was modelled by two different digital heat sources: a surface source with SYSWELD, and a volume source with MARC. The temperature results obtained are then compared with the experimental thermal measurements taken using thermocouples and an infrared camera. Neither the material flow nor the tool itself were modelled in the mechanical calculation. However, the mechanical characteristics of all the microstructure zones (Fig. 1) were factored into the calculations.     

不锈钢搅拌摩擦焊搅拌头温度场模拟

搅拌头技术是搅拌摩擦焊工艺的关键技术,不绣钢搅拌摩擦焊一个重要的难点是确定不锈钢搅拌摩擦焊搅拌头的材料.此材料要求在1000℃或更高的温度下具有良好的耐磨性和韧性.采用搅拌摩擦焊工艺对3 mm厚0Cr18Ni9不锈钢板进行了对接焊接.利用有限元软件DEFORM-3D初步模拟了在旋转速度600 r/min,焊接速度70 mm/min下焊接不锈钢时搅拌头的温度场分布.结果表明,模拟结果与实测结果基本吻合.     

A simple Eulerian thermomechanical modeling of friction stir welding

A simple three-dimensional thermomechanical model for friction stir welding (FSW) is presented. It is developed from the model proposed by Heurtier et al. (2006) based on a combination of fluid mechanics numerical and analytical velocity fields. Those velocity fields are introduced in a steady state thermal calculation to compute the temperature field during welding. They allow partial sliding between the shoulder and the workpiece, the amount of which is provided as an additional result of the model. The thermal calculation accounts for conduction and convection effects by means of the particular derivative. The complete thermomechanical history of the material during the process can then be accessed by temperature and strain rate contours.The numerical results are compared with a set of experimental test cases carried out on an instrumented laboratory device. The choices for modeling assumptions, especially tribological aspects, are discussed according to agreements or deviations observed between experimental and numerical results. The amount of sliding appears to be significantly influenced by the welding conditions (welding and tool rotational velocities), and physical interpretations are proposed for its evolution.     

搅拌摩擦焊角接焊接外侧焊方法

在分析现有搅拌摩擦焊角接焊接的基础上,提出了一种新的搅拌摩擦焊(FSW)角接焊接外侧焊接方法(FSOCW).采用在角接头外侧镶拼辅助工艺垫块,在角接头外侧顶部构成搅拌头台肩摩擦所需平面的方法,将任意角度的角接焊转化为类似平板对接焊,利用垫板与搅拌头台肩产生的摩擦热加热角接焊缝,并在搅拌头搅棒的联合热机作用下形成搅拌摩擦角接焊缝.