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采用等幅轴向低周疲劳试验,通过疲劳寿命、循环应力-应变响应特征及应力-应变滞回曲线等指标研究了Q345钢对接接头的疲劳性能,观察了疲劳断口宏观特征,并在试验研究和有限元分析的基础上,建立了该焊缝材料的疲劳寿命预测公式.结果表明:焊缝材料初始阶段表现为明显循环硬化现象,后期为轻微循环软化,总体上提高了材料的强度及疲劳性能;随着轴向位移的增加,应力幅增大,循环硬化率线性减小;滞回曲线光滑、饱满,材料耗能能力稳定;疲劳断口可明显划分为裂纹源区、裂纹扩展区和裂纹瞬断区,为典型疲劳破坏断口.得到的疲劳寿命预测公式对实际工程中Q345钢结构的疲劳分析和寿命预测具有重要意义.
The fatigue behavior of Q345 steel butt joint was studied by means of constant axial low-cycle fatigue test, fatigue life, cyclic stress-strain response characteristics and stress-strain hysteresis curve. The macroscopic characteristics of fatigue fracture were observed. And the finite element analysis, the prediction formula of the fatigue life of the weld material is established.The results show that: the initial stage of the weld material shows a significant cyclic hardening phenomenon, the latter is a slight cyclic softening, the overall increase of the material strength and fatigue The fatigue fracture can be obviously divided into the source region of crack, crack propagation region and crack. The fatigue crack can be divided into two parts: The instantaneous fracture zone is a typical fatigue failure fracture.The obtained fatigue life prediction formula is of great significance for the fatigue analysis and life prediction of the Q345 steel structure in practical engineering.