基于局部应变能密度的厚板T形接头焊趾和焊根疲劳性能分析

以装载机前车架疲劳寿命评估为目的，从前车架焊接结构关键部位中提取三种典型焊接接头，对其进行疲劳试验和分析.以局部应变能密度法为理论基础，对获得的试验数据进行处理，得到了基于局部应变能密度的疲劳寿命曲线，并采用文献中十字接头的疲劳数据验证该理论的准确性和适用性.结果表明，局部应变能密度法既可用于焊根失效疲劳评估，也可以用于焊趾失效疲劳评估；不同位置的疲劳裂纹会影响结构的刚度，进而影响结构的疲劳寿命.此外，研究了焊脚尺寸和熔深对焊接接头疲劳寿命的影响，推导了基于局部应变能密度法的疲劳失效位置转换区间.并通过文献中的疲劳数据验证了文中提出的焊趾失效和焊根失效转换区间的准确性，为合理设计未焊透厚板T形接头抗疲劳性能提供依据.

Fatigue performance analysis of weld toe and root of thick T-joint based on local strain energy density

In this paper, for the purpose of evaluating the fatigue life of the loader’s front frame, three typical welded joints are extracted from the key parts of the welded structure of the front frame, and the fatigue test and analysis are carried out. Based on the local strain energy density method, the fatigue life curve is obtained through the experimental data, the accuracy and applicability of the theory are then verified by the fatigue data of the cross joint in the literature. The results show that the local strain energy density method can be used for the fatigue assessment of weld root and weld toe failure. Fatigue cracks at different positions will affect the rigidity of the structure, and thus the fatigue life of the structure. The influence of the size of the weld foot and the penetration depth of the joint on the fatigue life of the welded joint is studied, then derived the fatigue failure position transition interval from the local strain energy density method. The accuracy of the transition interval between weld toe failure and the root failure was verified by the fatigue data in the literature, which provides a basis for the fatigue design of partial penetration T-joints.