双平板封头结构的焊接残余应力有限元模拟

摘要

The key problem of double -layer flat head structure is the leakage induced by the crack in the welding position between the panel and the nozzle .Welding residual stress is one of the main influential factors.In this work,numerical simulation on welding temperature field and thermal stress of double -lay-er flat head structure was carried out based on APDL of ANSYS software ,element birth and death technol-ogy and thermal -mechanical coupling method , and the distribution law of welding residual stress was found out .The simulation results indicate that the hoop stress is much larger at the welding zone , which easily induces the cracking and leakage sometimes .The compressive stress is very high near the welding zone ,and it is mainly caused by the expansion of heating welding material .The analysis from calculation results provides some theory references for evaluating and controlling the welding residual stress .It is of great significance for increasing the reliability and safety of double -layer flat head structure .%双平板封头结构最常见的问题是面板与工艺接管焊接部位开裂引起泄漏，而焊接残余应力是重要的影响因素之一。基于ANSYS软件中的APDL语言、单元生死技术以及热-结构间接耦合法对双平板封头结构焊接温度场、应力场进行了数值模拟，获得了焊接残余应力的大小与分布规律。计算结果表明：在焊缝区环向应力水平较高，易诱使焊缝开裂失效；在焊缝附近区域产生了较大压应力，主要是由于焊缝区材料受热向外膨胀而产生。模拟结果为焊接残余应力评定、控制焊接残余应力提供了理论依据，并对提高双平板封头结构的可靠性和安全性具有重要意义。