基于固有应变理论的机械结构件焊接变形控制方法

机械结构件是工业制造生产中十分重要的承载部件,同时也是影响架构生产质量的重要因素。为此,本研究提出一种基于固有应变理论的机械结构件焊接变形控制方法。首先通过热-弹塑性耦合法分析机械结构件焊接变形的产生机制,然后利用固有应变法构建机械结构件三维分析模型,根据实际焊接参数和顺序对该模型进行加载计算,得到焊接过程中的瞬态温度场变化情况,以此为依据获取最优机械结构件焊接变形控制参数。经实验测试证明:该方法可以有效完成机械结构件焊接变形控制。

面向精度控制的船体焊接工艺规划技术研究

船舶建造过程的精度控制是现代精益造船的重要环节,分段装焊工艺制定是船舶建造的核心内容。针对我国船舶焊接工艺规划缺乏有效的精度控制手段,提出以典型船舶分段建造为对象,结合计算机辅助工艺设计手段,建立面向精度控制的船体焊接工艺计算机辅助规划技术体系。首先,通过规则推理技术实现焊接工艺的合理规划;进而结合仿真和实验手段实现典型焊接工艺的仿真和精度分析;最后,建立船体焊接工艺精度规划系统,并以典型船体分段建造的焊接工艺制定过程为例,验证了面向精度控制的船体焊接工艺计算机辅助规划技术过程的有效性和可行性。

Prediction of Welding Deformation of Underframe

An inherent strain method was applied to the welding deformation analysis of left girder of GM’s Buick’s chassis underframe assembly. Three models are used in the calculation. Model 1 takes into account the longitudinal and transverse inherent strains; model 2 considers only longitudinal inherent strain; model 3 also takes into account the longitudinal and transverse inherent strains, but inherent strains are taken according to the function instead of the constant, for simulating the variation of the girder’s stiffness during welding process. The result shows the deformation of model 2 is less than that of the model 1, the error is less than 10% of the absolute displacement. So the longitudinal inherent strain is the main factor determining boxes-girder’s welding deformation. The deformation of model 3 is also less than that of the model 1, because the inherent strains of the model 3 are less than that of the model 1. At last, the welding deformation of the whole underframe was analyzed. The analysis results can be taken as references not only for the choices of welding sequence, welding parameters and fixture’s location, but also for welding deformation prediction of other car chassis.

焊接变形预测中基于假定热应变法的弹性有限元建模

传统的固有应变法在固有应变载荷的施加中,因难以准确反映实际固有应变分布规律而影响焊接变形预测精度。通过传统等效载荷法与应变直接边界法的融合优化,所提出假定热应变法能够有效弥补传统载荷法逐层输入固有应变载荷的失真,以及应变直接边界法无法预测凸型角变形及纵向弯曲的不足。同时,该方法通过等效力学模型综合考虑多样的固有应变分布,使由凸型角变形和凹型纵向弯曲组成的马鞍形屈曲变形实现准确的分析计算。通过试验、热-弹塑性有限元模型,应变直接边界法弹性模型和假定热应变弹性模型综合比较,研究5052铝合金平板堆焊下所形成的屈曲变形。结果表明,假定热应变弹性模型对屈曲变形实现准确和快速的预测,可以应用于大型焊接结构及激光增材制造中的变形预测,并能够为固有应变理论中实现实际固有应变分布的转换提供新的思路。