谱载荷下加载次序效应定量评价的初步研究

通过对40Cr材料光滑试样进行不同加载次序的三级程序载荷疲劳试验，验证并分析了载荷作用次序对疲劳强度累积强化效果的影响。试验结果表明：按照载荷从小到大逐渐增加的次序加载时，锻炼载荷对疲劳强度的累积强化效果最大，并且与三级锻炼载荷分别独立作用时强化效果的叠加值接近;而在其他加载次序下，累积强化效果分别受到不同程度的影响。最后，通过对疲劳试验数据的统计分析，初步研究了谱载荷下加载次序对总体累积强化效果的修正系数，并对之前建立的随机载荷下累积强化效果模型做出了修正，为建立考虑低载强化效应的疲劳累积理论进行了探索。

Preliminary Study of Quantitative Evaluation for Spectrum Load Sequence Effect

According to the three level program load fatigue test on the 40Cr material smooth specimens with different loading sequences, the influences of load sequence on cumulative fatigue strengthening effect were verified and analyzed. The test results show that, in accordance with the sequence from small to large loads, the exercise loads caused the maximum cumulative fatigue strengthening effect, which approached to the added value of three exercise load's strengthening effects independently. Whereas in other load sequences, the cumulative strengthening effect were decreased in different degrees. Finally, based on the statistical analysis of fatigue test data, a correction factor η was proposed, which expressed the influences of spectrum load sequence on overall cumulative strengthening effect. Moreover, the previous fatigue cumulative strengthening effect model under the random load was modified, which made a deep study of fatigue cumulative theory considering load strengthening effect.