钢桥十字形焊接细节应力强度因子的参数敏感性研究

Parameter Sensitivity Study on Stress Intensity Factors of Cruciform Weld Details in Steel Bridges

焊接细节断裂参数与其疲劳裂纹扩展和疲劳性能直接相关,为探讨几何参数和裂纹参数对应力强度因子的影响规律,选取十字形焊接细节为研究对象。借助ANSYS软件建立了含半椭圆形裂纹的三维断裂力学模型,基于位移法分析了应力强度因子,讨论了几何参数(焊缝尺寸、板厚、对接焊缝参数)和裂纹参数(裂纹尺寸和裂纹形状比)对其的影响规律,拟合了裂纹形状修正系数函数。研究结果表明:(1)应力强度因子随对接焊缝余高和腹板板厚的增大而逐渐减小,而基本不受焊脚尺寸、翼缘板板厚和对接焊缝宽度的影响;(2)应力强度因子随裂纹形状比的增大而先增大后逐渐减小,但是随裂纹尺寸的增长而逐渐增大;(3)裂纹形状比和裂纹尺寸对应力强度因子影响最为显著,其影响幅度达18.0%。

The fracture parameters of the welded details are directly related to the fatigue crack propa⁃gation and fatigue performance.In order to investigate the influence of geometric parameters and crack parameters on the stress intensity factor,the cruciform weld detail was selected as the research object.A three-dimensional fracture mechanical model with a semi-elliptical crack was established by using ANSYS software.The stress intensity factor of each joint on the front edge of the crack was analyzed based on the displacement method.The influence of geometric parameters(including weld size,plate thickness,butt weld parameters)and crack parameters(including crack size and crack shape ratio)on the stress intensity factors was discussed,and the crack shape correction coefficient function was fit⁃ted.The results show that the stress intensity factor decreases with the increase of the butt weld rein⁃forcement and web thickness,but has little relationship with the weld size,flange plate thickness and butt weld width.The stress intensity factor increases firstly and then decreases with the increase of the crack shape ratio,but rises with the increase of the crack length.The crack shape ratio and crack length have the greatest influence on the stress intensity factor,and the influence amplitude is as high as 18.0%.