【摘要】 焊接接头疲劳评定的“局部法”(localapproach)是近年来疲劳评定研究的重要方向。这种方法的基本原理是采用与疲劳断裂直接相关的应力集中区域应力场的“局部参量”作为疲劳断裂的控制参量 ,建立具有普遍适用性的“局部参量”与循环次数N表示的S—N曲线 ,据此进行疲劳强度和疲劳寿命预测与评定。由于局部法包括焊接接头局部焊缝几何细节等因素 ,因而更能反映焊接结构疲劳断裂的实际情况 ,受到国际焊接学会和工程界的普遍重视。目前已发展多种疲劳评定的局部方法 ,如缺口应力强度因子法 (N SIF)、等效应力强度因子法 (E SIF)、临界距离法 (CDM) :包括点 (PM )、线 (LM)、面 (AM)和体积法 (VM )、临界面法和包括应力梯度的体积法等。本文对这些局部法的基本原理、分析步骤及影响因素进行简要探讨。更多还原

【Abstract】 The local approach is one of the most important method developed in recent years for fatigue assessment of welded joints. The basic principle of local approach is taking the “local parameter" of the stress concentration region as a characteristic parameter to describe the fatigue behavior and to establish the general S—N curves expressed by the correlate local parameters and the loading cycles N which lead to the prediction of fatigue life and strength of welded components possible. The local approaches could effectively represent the practical fatigue performances of welded structures due to the inclusion of the local geometrical details of the welded joints. This method is recommended by the International Institute of Welding (IIW) and widely employed by various societies in Europe. Various local fatigue criteria for fatigue assessment are developed in recent years, such as notch stress intensity factor (N-SIF), equivalent stress intensity factor (E-SIF), critical distance method (CMD) which includes point method (PM), line method (LM), area method (AM) and volumetric method (VM). The principles, procedures and effect factors about the local approaches are discussed in this paper.更多还原