基于ANSYS Workbench断裂分析模块,根据某小型水电站压力钢管部分管段纵焊缝未焊透的情况,建立含未焊透缺陷钢管段有限元模型,求解管壁的环向应力,并确定16Mn钢的临界应力强度因子。按照焊缝缺陷特征在管壁建立裂纹的有限元网格,再次计算并提取正常发电工况及水锤工况下钢管缺陷尖点的Ⅰ型应力强度因子。根据临界应力强度因子判断准则,其未焊透缺陷不影响钢管的安全性,在后续检测中未发现缺陷有扩展趋势。

To assess the safety of penstock in a small power station where some segments of penstock are defective with incomplete longitudinal weld, we built the finite element model of the penstock segment which contains such defects using ANSYS Workbench to solve the circumferential stress of penstock wall, and to determine the critical stress intensity factor of 16Mn steel. Furthermore, we built the finite element meshes of fractures in accordance with the weld’s defect characteristics and calculated the type I stress intensity factor at the tip of defect. Finally, according to the criterion of critical stress intensity factor, we concluded that the weld defects had no impact on the penstock safety, and did not expand in subsequent inspections.