还原炉挠性夹套的焊接残余应力有限元模拟

摘要

A jacket is a kind of heating or cooling equipment which is widely used in chemical,pharmaceutical and other industries. The welding area of a jacket is the failure part where cracks and leakage are often found. The welding residual stress in the weld area is one of the most important causes for the leakage. A numercial simulation by FEM on temperature field, welding residual thermal stress and plastic strain of a new type of jacket with flexibility of polysilicon reduction furnace has been conducted. By using the ANSYS APDL programming, the element birth and death technology, the direct thermo - structure coupling method, Gaussian heat source and the BKIN material constitutive model with various parameters at different temperature are all employed in the simulation including the transient heat transmission analysis and the steady stress analysis with the coupling effect of thermal deformation and field. As results,the distribution of residual stress in the weld area is obtained. The effective methods are provided for the weld strength evaluation of the similar type of flexible jackets.%夹套是广泛运用在化工、医药等行业设备上的加热冷却装置,夹套焊缝是常常发生开裂泄漏的失效部位,焊接残余应力是导致开裂泄漏的重要因素之一.利用有限元技术对一种新型多晶硅还原炉挠性冷却夹套的焊接过程的温度场、残余应力和塑性应变场进行了数值模拟.借助ANSYS 的APDL编程和单元生死技术,采用热-结构直接耦合法,传热分析采用含高斯热源的瞬态过程、应力分析为稳态,材料本构为随温度变化的双线性随动强化弹塑性模型.通过模拟获得焊缝区域残余应力和塑性应变的分布规律,为同类夹套的焊接强度评定提供了有效方法.