模块式小型堆反应堆压力容器内支承环和筒体焊接残余应力数值计算

Numerical simulation on welding residual stress of supporting ring and cylinder in reactor pressure vessel of small modular reactor

通过有限元数值模拟研究300mm厚模块式小型堆反应堆压力容器(RPV)内支承环和筒体焊接模拟件的残余应力分布,并采用小孔法测试验证计算结果。结果表明,模拟件焊缝区域径向应力沿厚度呈自平衡分布,上下表面区域径向应力为拉伸应力,内部为压缩应力;焊缝区域环向应力为基本拉伸应力,上下表面区域应力大于内部环向应力,峰值拉伸环向应力出现在距表面一定深度位置;最小环向及径向应力在焊缝中心线上的位置由模拟件第二步焊接工序完成后的焊缝金属高度决定;由于第一步和第二步焊接后模拟件刚度足够大,第一步焊接的焊缝金属表面位置处应力变化较大。

The welding residual stress of reactor pressure vessel's(RPV) supporting ring and cylinder welded mockup with a thickness of 300 mm was investigated with the finite element method,and the stress was measured with the hole-drilling method to validate the simulated result. The investigated results shows that the through-thickness radial stress distribution within the weld zone presents a self-equilibrating distribution,and the through-thickness hoop stress within the weld zone is almost tensile stress with the peak tensile stress occurring at a certain depth beneath the surfaces and a minimum stress appears near the mid-thickness. The location where the minimum hoop and radial stress appears at the weld centerline is decided by the weld metal height of the second welding step for the welding procedure used in the present study. In addition,a large stress change occurs near the top surface of the weld metal after the first welding step due to the strong stiffness of the mockups.