低匹配十字接头的“等承载”设计

为提高低匹配接头的静载承载能力和疲劳抗力,根据提出的"等承载"设计思想和实现条件,在确定十字接头应力集中最小化的焊缝形状方案的基础上,通过有限元计算及其结果的回归分析,建立了十字接头几何参数与焊趾、焊根应力集中系数的关系方程,进行了0.571匹配比十字接头等承载目的的接头形状参数设计.结果表明,设计延缓了拉伸及弯曲过程中低强焊缝和焊趾应力的增长速度,低强焊缝不先于母材屈服,应变集中先位于焊趾,随后向母材转移,接头断裂模式转变为安全的全面屈服断裂.该设计对高强度钢低匹配接头的应用具有重要意义.

Design of under-matching cruciform joint based on equal load-carrying ability

To enhance the static load-carrying capacity and fatigue resistance of under-matching joints, according to the features of stress distributions in cruciform joint, the structural design thinking and realization conditions of equal load-carrying capacity(ELCC) were proposed, the weld shape proposals to minimize stress concentration for the K groove cruciform joint were analyzed and determined, the relationship equations between the shape parameters of joints and stress concentration factors at weld toe and weld root were built by the FEA calculating and regression analysis. The shape parameters of ELCC under-matching cruciform joint which yield strength mismatch ratio is 0.571 were designed. FE analysis results show that this design significantly delays the increase speed of stress at weld toe and weld root of the ELCC cruciform joints during tensile and bending loading, the plastic deformation of the weld bead does not occur before plastic deformation of base metal. The peak values of equivalent plastic strain firstly locate at weld toe and then transfer to the base metal outside the weld toe, and the fracture mode can change into a much safer general yield fracture. This design is very important to the application of the under-matching cruciform joint of high strength steel.