【摘要】 利用扫描电镜对多轴比例和非比例加载下的疲劳试样的断口面和外表面进行扫描观测分析。根据薄壁管拉—扭复合加载试件断口附近表面观测结果 ,统计其裂纹扩展的位向 ,研究多轴疲劳裂纹萌生及扩展机理。研究表明 ,多轴疲劳裂纹主要是沿最大剪切平面或垂直于管形试样的轴线方向扩展。在多轴比例加载条件下 ,裂纹分布的分散性较小。在非比例加载条件下 ,随着相位差的增大 ,分散性增大。更多还原

【Abstract】 The fracture surfaces of multiaxial fatigue specimens under proportional and non-proportional multiaxial loadings were observed and analyzed by using a scan electron microscope. According to the observed results near the fracture surfaces, the orientations of the fatigue crack initiation and propagation were investigated to study the mechanism of multiaxial fatigue crack propagation. The results showed that most multiaxial fatigue cracks were initiated and propagated along the direction of maximum shear plane or on the direction perpendicular to the tubular specimen’s axis. For the multiaxial proportional loading, the dispersion degree of fatigue cracks was low. For the nonproportional loading the dispersion become larger with the phase difference increasing.更多还原