研究了6101铝合金单股导线的表面粗糙度对其疲劳性能的影响。结果表明,随着表面粗糙度参数(轮廓最大高度R_z)的增加,铝合金导线的疲劳强度逐渐降低,当R_z从57.9 μm增加到161.7 μm时,疲劳极限下降了约36.4%。分析认为,R_z的增加引起理论应力集中系数 K_{\mathrm{t}}的增加,导致疲劳裂纹更易于萌生,致使样品的疲劳强度较低。结合有限元分析研究了R_z对 K_{\mathrm{t}}的影响,将表面粗糙度等效成尺寸为 a_{\mathrm{0}} = \frac{\sqrt[]{\mathrm{\pi }L{R}_{\mathrm{z}}}}{\mathrm{2}} (L为平均缺口宽度)的初始裂纹,基于能量理论和Pairs公式提出了不同表面粗糙度铝合金导线疲劳寿命预测模型,有效地预测了铝合金导线疲劳服役可靠性。

The power industry is changing from rapid growth to high-quality development, and there are urgent demands for the high-quality and high-service reliability of overhead lines. Al-Mg-Si alloys are widely used in the production of long-distance overhead lines owing to their high strength-to-density ratio, good conductivity, and corrosion resistance. In the overhead line service, surface defects reduce their mechanical properties, and surface roughness greatly affects its fatigue properties. A single-strand conductor of 6101 aluminum alloy was employed to investigate the fatigue properties of the conductors with different roughness. The fatigue strength of the alloy wires decreased gradually with an increase in the surface roughness (maximum height of profile, R_z). As R_zincreased from 57.9 to 161.7 μm, the fatigue limit decreased by ~36.4%. The result indicates that an increase of R_z increases the theoretical stress concentration factor K_{\mathrm{t}}, which facilitates the initiation of fatigue cracks, and the fatigue strength decreases accordingly. Furthermore, the surface roughness is equivalent to the size of the initial crack a_{\mathrm{0}} = \frac{\sqrt[]{\mathrm{\pi }L{R}_{\mathrm{z}}}}{\mathrm{2}} (L is the average value of the arerage width of profile element). A model suitable for predicting the fatigue life of conductors with different surface roughness was obtained.