A continuum damage model (CDM) based on local hardness in welds is developed to predict fracture of welded tubes. A regression function of hardness distribution in the welds is proposed to establish hardness continuously through hardness mapping method in the finite element model. A constitutive model of the weld zone is determined by the rule of mixture, which estimates the flow stress of the welds from the hardness ratio. Coefficients of the flow stress model in the welds are validated by comparing finite element analysis (FEA) solution and experimental load - displacement data of tensile specimens. Softening after necking is considered by Lemaitre CDM. A damage parameter is newly given as a function of hardness ratio varying with angular position. Coefficients of damage parameter are obtained by the inverse FEA of tensile and flaring tests. The proposed method finely predicts the ductile fracture of welded tubes by considering local plastic properties and damage evolution.

开发了一种基于焊缝局部硬度的连续损伤模型 (CDM) 来预测焊管的断裂。提出了焊缝硬度分布的回归函数，通过有限元模型中的硬度映射方法连续建立硬度。焊接区的本构模型由混合规则确定，该规则根据硬度比估计焊缝的流动应力。通过比较有限元分析 (FEA) 解决方案和拉伸试样的实验载荷 - 位移数据，验证了焊缝中流动应力模型的系数。Lemaitre CDM 考虑了颈缩后的软化。新给出的损伤参数是硬度比随角位置变化的函数。损伤参数系数通过拉伸和扩口试验的逆有限元分析获得。局部塑性特性和损伤演化。