硬夹层中含有垂直裂纹的焊接接头的断裂参量研究

FRACTURE PARAMETERS FOR A JOINT CONTAINING A TRANSVERSE CRACK IN THE LONGITUDINA(?) OVERMATCHED WELD

本文将焊缝或热影响区中含有横向裂纹的高匹配焊接接头简化为带有硬夹层的中心裂纹板模型,硬夹层中的裂纹垂直于夹层与基体的分界。在平面应变条件下,用弹塑性有限元方法计算了硬夹层宽度不同的模型在不同载荷作用下的J积分、裂纹张开位移及加载点的位移,并将所得结果与用EPRI方法按均质材料计算的结果进行比较来说明力学性能不均匀性的影响.研究结果表明,在非线性阶段,力学性能不均匀性对J积分和COD等的影响规律与裂纹平行于硬夹层与基体的分界的情形相似,EPRI方法只能在修正后才适用。本文给出的用有限元方法对于非均匀模型算得的数值与用EPRI方法按均质材料计算的数值之比可看作修正系数.

A welded joint with a cross crack in a hard weld or HAZ is simplified to be a model of the strip with a longitudinal sandwiched hard layer containing a crack perpendicular to interfaccs,The i-intergral, COD at the centre of the crack and load-point-displacement in models containing a hard layer of different width are calculated by means of the elastoplastic FEM under plane stress condition. The effects of mechanical heterogeneity are described by a comparison of the results obtained by the FEM with those estimated by the EPRI engineering approach for homogeneous material. The results of our study show that in the nonlinear stage, the effects of heterogeneity are similar to those in the models with a transverse sandwiched hard layer containing a crack parallel to the interfaces. The ratios of the values calcuted by the FEM for heterogeneous models to those by the EPRI approach can be regarded as modifying coefficients.