焊接残余应力及几何缺陷对桁架臂稳定性影响分析

Analysis of influence of welding residual stress and geometric defects on stability of lattice boom

针对履带起重机桁架臂生产制造过程中产生的初始几何缺陷和焊接残余应力,建立了桁架臂多尺度有限元力学模型,采用MPC技术实现梁单元和实体单元之间的连接.利用生死单元技术模拟焊缝金属的填充过程和温度场向应力场的转换.基于缺陷模态法模拟桁架臂的初始几何缺陷,并定义了适合桁架臂结构的缺陷幅值,分析了前六阶缺陷模态对桁架臂承载能力的影响.同时对理想臂架,及仅考虑几何缺陷、仅考虑残余应力和同时考虑几何缺陷和残余应力的臂架进行了非线性稳定性分析.结果表明,几何缺陷和残余应力会对桁架臂稳定性产生不同程度的影响,使承载能力降低.整体失稳缺陷模态对臂架承载力的影响要弱于局部失稳模态的,残余应力对臂架承载力的影响与几何缺陷的影响相当.

Aiming at the initial geometric defects and welding residual stress in the manufacturing process of the lattice boom of crawler cranes,a multi-scale finite element mechanical model of the lattice boom was established,and MPC technology was used to realize the connection between beam elements and solid elements.The life and death unit technology was used to simulate the filling process of weld metal and the conversion of temperature field to stress field.The initial geometric defects of the lattice boom were simulated based on the defect mode method,the defect amplitude suitable for the lattice boom structure was defined,and the influence of the first six defect modes on the bearing capacity of the lattice boom was analyzed.At the same time,the nonlinear stability research and analysis of the ideal boom,considering geometric defects,considering residual stress,and considering both geometric defects and residual stress were carried out.The results show that geometric defects and residual stress will affect the stability of the lattice boom to varying degrees and reduce the bearing capacity.The influence of the overall instability defect mode on the bearing capacity of the boom is weaker than that of the local instability mode,and the influence of residual stress on the bearing capacity of the boom is equivalent to the influence of geometric defects.