吕毅宁, 吕振华. 焊点连接模型对结构刚度的有限元模拟精度的影响分析[J]. 工程力学, 2009, 26(10): 171-176.
引用本文: 吕毅宁, 吕振华. 焊点连接模型对结构刚度的有限元模拟精度的影响分析[J]. 工程力学, 2009, 26(10): 171-176.
LU Yi-ning, LU Zhen-hua. EFFECTS OF SPOT WELD CONNECTING MODELS ON THE PREDICTION ACCURACY OF STRUCTURAL STIFFNESS BY FINITE ELEMENT ANALYSIS[J]. Engineering Mechanics, 2009, 26(10): 171-176.
Citation: LU Yi-ning, LU Zhen-hua. EFFECTS OF SPOT WELD CONNECTING MODELS ON THE PREDICTION ACCURACY OF STRUCTURAL STIFFNESS BY FINITE ELEMENT ANALYSIS[J]. Engineering Mechanics, 2009, 26(10): 171-176.

焊点连接模型对结构刚度的有限元模拟精度的影响分析

EFFECTS OF SPOT WELD CONNECTING MODELS ON THE PREDICTION ACCURACY OF STRUCTURAL STIFFNESS BY FINITE ELEMENT ANALYSIS

  • 摘要: 车身等复杂焊接结构中大量焊点的建模方法对其刚度和固有振动频率(亦即动刚度)的有限元分析精度具有较大影响。基于两个解析分析模型,对不同焊点连接模型及其网格相关性对焊接结构刚度和动态特性有限元模拟精度的影响及其原因进行了分析。分析表明,采用不同焊点连接模型得到的焊点附近局部结构的模拟刚度差异,主要是由于焊点所传递的载荷的分布区域大小不同引起的。焊点附近网格单元尺寸变大时,采用直接连接模型得到的焊点附近局部结构的模拟刚度会相应增加;但是采用RBE3单元连接模型时,也可能会由于受到焊点中心与网格之间的相对位置等因素的影响而出现相反的情况。焊点直径变大时,采用RBE3单元连接模型得到的焊点附近局部结构的模拟刚度也会相应增加,但是通过适当调整被焊接结构的有限元网格划分,可以使得该模拟刚度随焊点直径变化的灵敏度最小。通过对一个双帽形焊接薄壁梁结构的几种不同有限元建模方式及相应的刚度和固有振动频率分析结果讨论,验证了给出的解析分析方法的有效性及结论的正确性。

     

    Abstract: For complex structures such as automotive bodies, the finite element analysis and prediction accuracy of their stiffness and eigen-frequencies (representing dynamic stiffness) are usually greatly influenced by the selected modeling methods for large amount of spot welds. Based on two analytical models, this paper investigates effects of spot weld connecting models (SWCMs), together with their respective meshing-scheme- dependent properties, on the FE analysis and prediction accuracy of local structural stiffness. It is found that SWCMs affect stiffness prediction mainly through the spreading area of the force transmitted by a spot weld. Enlarging local mesh size of a spot weld will result in increased local stiffness prediction for direct SWCM. But for RBE3 SWCM, the effects is more complicated and opposite results may be observed due to extra influencing factors such as the relative positioning of spot weld center point and local meshes. Enlarging spot weld diameter also results in increased local stiffness prediction for RBE3 SWCM, while the variation sensitivity may reach a minimum by properly adjusting local meshing scheme. Several finite element modeling schemes and corresponding stiffness and vibration mode analysis results of a double-hat welded thin-walled beam structure are discussed, which demonstrates the effectiveness of the proposed analytical analysis methods and the correctness of related conclusions.

     

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