在超声振动载荷下, 对2 mm和5 mm厚5083铝合金薄板进行了超高周弯曲疲劳试验, 研究了铝合金薄板厚度对其超高周弯曲疲劳性能的影响。结果表明: 5083铝合金薄板的S-N曲线呈连续下降特征, 试样在109周次处仍会发生断裂, 与一般铝合金的疲劳特征一致, 即传统的疲劳极限并不存在; 受尺寸效应影响, 2 mm厚薄板的弯曲疲劳强度高于5 mm厚薄板的; 尺寸效应在高周阶段对薄板疲劳性能的影响最大, 超高周阶段的影响逐渐减弱; 试样的疲劳裂纹起源于表面, 表现为多源萌生; 同应力幅值下不同厚度的5083铝合金薄板断口具有相同的解理特征。

Very high cycle bending fatigue test was carried out on 5083 aluminum alloy sheet with thickness of 2 mm and 5 mm at ultrasonic vibratory load, and the effect of thickness of aluminum alloy sheet on very high cycle bending fatigue properties of the sheet was studied. Results show that the S-N curves of the sheet exhibited continuous decline characteristics, the specimens fractured in the life cycle of 109. There was no traditional fatigue limit in the testing as conventional aluminum alloys used to be. Bending fatigue strength of the sheet with thickness of 2 mm was higher than that of the sheet with thickness of 5 mm, this was the result of size effect. In high cycle stage, the effect of size effect on fatigue property was the largest, and the effect gradually weakened in very high cycle stage. It was found that all fatigue cracks emanated from the specimen surface, and the crack was multiple sources. 5083 aluminum alloy sheet with different thicknesses had the same cleavage fracture characteristics at the same stress amplitude.