应力水平下的激光冲击小孔构件疲劳扩展研究

发布时间：2018-11-03 09:59

【摘要】：激光冲击强化可以降低小孔构件裂纹扩展速率,提高疲劳寿命。疲劳扩展是疲劳寿命的主要组成部分,不同的应力水平会影响疲劳扩展,其对未强化试样和强化试样的影响是不同的。为此通过激光冲击强化TC4-DT钛合金双联小孔试样,然后进行疲劳试验,研究应力水平下的激光冲击小孔构件疲劳扩展。研究结果表明:应力水平提高会导致疲劳条带宽度增大,同时强化端同比增大尺寸大于未强化端,未强化端(I_0)和强化端疲劳条带宽度(I_1)差值(I_0-I_1)与未冲击端疲劳条带宽度(I_0)的比值也有降低的趋势。因此,增大应力水平会增大疲劳条带宽度,应力水平的变化对激光冲击强化后试样的疲劳扩展影响更大,应力水平增大降低激光冲击强化疲劳寿命增益;在激光冲击强化参数一定时,应该规定适用的应力水平范围。
[Abstract]:Laser shock hardening can reduce the crack growth rate and increase the fatigue life. Fatigue propagation is the main component of fatigue life. Different stress level will affect fatigue propagation, and its effect on unstrengthened specimen and strengthened specimen is different. In order to improve the fatigue propagation of TC4-DT titanium alloy by laser shock, the fatigue test was carried out to study the fatigue propagation of the small hole member under laser shock. The results show that the increase of stress level will lead to the increase of the width of the fatigue strip, and the size of the strengthened end is larger than that of the unstrengthened end. The ratio of the difference (I_0-I_1) of the fatigue strip width (I _ s _ 1) and the fatigue band width (I _ 0) at the unstrengthened end (I _ S _ 0) and the fatigue strip width (I _ s _ 0) at the non-impact end also tended to decrease. Therefore, increasing the stress level will increase the width of the fatigue strip, and the change of the stress level will have a greater effect on the fatigue growth of the specimen after laser impact strengthening, and the increase of the stress level will reduce the fatigue life gain of the laser impact hardening. When the laser shock hardening parameters are fixed, the applicable stress level should be defined.
【作者单位】：江苏大学机械工程学院;
【基金】：国家自然科学基金项目(No.51075193) 国防科工局项目(No.GKGJ2060)资助
【分类号】：TN249

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