厚板焊接温度场和残余应力场的数值模拟

Numerical Simulation of Temperature and Residual Stress Fields in Thick Plate EBM Welding

运用有限元计算软件ABAQUS,对10mm厚钢板电子束焊接温度场和残余应力场进行了数值模拟。有限元模型中选用三维实体单元,采用非耦合方法,并考虑了材料物理性能随温度的变化和周边对流、辐射散热的影响。针对电子束焊接热源的特点采用移动体积生热的高斯锥形分布的模式来模拟匙孔效应。温度场计算结果表明,焊件热影响区狭窄。计算结果分别给出了焊缝部位上、中、下表面的纵向、横向和板厚方向残余应力分布。结果表明,焊缝区大部分区域三个位置的应力无显著差异,但是在起焊点和收焊点三处应力存在显著差异;焊缝区残余纵向拉应力分布在焊缝两侧各20mm区域,最大值达到材料屈服应力。残余应力的分布与厚板焊接理论相一致。

A 3-d finite element model was set up to analyze the temperature field and residual stress field of steel thick plate butt welding using uncoupled thermal-mechanical analysis. During the calculation, enthalpy and temperature dependence of material property were taken into consideration. The moving heat source was modeled using a body conical shape heat source with Gaussian power density distribution in order to reproduce the nail shape of fusion zone. The thermal analysis has revealed temperature contours, which indicate shows the heating affected zone is narrow. The residual stresses results obtained from the thermal analysis show that the values of residual stresses on up, middle and bottom surface of the thick plate have no difference with each others on the main zone of the welding, but on the starting and ending position, the values have sharp difference. The maximum of residual stress is transverse stress, which almost reach yield stress on the welding zone about 20 mm distance form the center line. The distributiou of residual stresses from the simulation agrees with the result from the welding theory.