【作者】 刘斌；

【导师】 崔海涛；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2012， 硕士

【摘要】 微动损伤是工程中非常普通的一种损伤形式。研究表明，微动疲劳会使构件的寿命降低30%以上。随着钛合金在航空结构中的应用不断扩大，微动损伤问题变得日益尖锐，己成为其应用的主要障碍之一。因此，研究钛合金的微动疲劳特性，采用相应的措施对微动疲劳进行防护，比如改进结构设计，寻找有效的表面改性方法等对提高钛合金微动疲劳寿命具有重要的航空应用意义。本文首先研究了基于临界面法的SWT寿命预测模型，并进一步对该模型提出修正，将有限元分析与试验数据综合处理，得到两个修正参数，并确立了微动疲劳寿命预测模型。与相关的试验对比表明，修正后的寿命预测模型具有较高的准确性和可靠度。提出基于圆弧接触面结构的抗微动疲劳设计方法。本文通过有限元分析，研究了构件微动区域的应力场随着圆弧面半径的变化规律，并确定了适合的圆弧面半径；设计、加工了6套圆弧接触面微动疲劳试验件，并完成了圆弧面接触结构的微动疲劳试验。试验结果表明，圆弧接触面的微动疲劳寿命明显高于平面-平面接触的寿命值，在两种工况下分别提高了108.45%和44.09%，验证了圆弧接触面设计的可行性。另一方面，利用所提出的寿命预测模型对圆弧接触面结构进行了寿命预测。理论分析与试验研究对比表明，寿命预测误差较小，说明了寿命预测模型的适用性。提出基于表面强化工艺的结构抗微动疲劳设计方法。选用激光淬火工艺对6套平面—平面接触试验件进行表面处理，并对处理后的试验件进行了微动疲劳试验。结果表明：激光淬火后，平面-平面接触结构在两种工况下的微动疲劳寿命值分别提高了110.78%和17.56%。同时，对工艺处理后的试验件采用所提出的寿命预测模型进行了微动疲劳寿命预测。为提高寿命预测精度，引入硬度与弹性模量的关系，研究了表面硬度变化对构件微动疲劳寿命的影响。预测结果表明：寿命预测的误差较小，证明了寿命预测模型的有效性。更多还原

【Abstract】 Fretting damage is a very common construction in the forms of damage. Studies have shown thatfretting fatigue would reduce the life of components by30%or more. With the development of theuse of titanium alloy in aeronautics structure, the problem of fretting damage has become more acuteand actually one of the main obstacles to its application. Therefore, the study of fretting fatiguebehavior, and using the appropriate measures for protection, such as improve the structural design,and to find effective methods of surface modification to improve the fretting fatigue life of titaniumalloy for aerospace applications has important significance.This paper first studied the SWT life prediction model based on critical plane method, andproposed further amendments to this model. Finite element analysis and experimental data wereintegrated to get two modified parameters. Then the life prediction model was established. Comparedwith related experiments, the modified model was verified to be more accurate and reliable.Anti fretting fatigue design method based on the structure of arc contact was put forward. In thispaper, finite element method was used to research the stress field in the micro region with the changeof arc contact radius. Then the appropriate radius was determined. Six sets of test pieces weredesigned and processed to completed the arc contact experiments. The results showed that the frettingfatigue life of the arc contact structure was significantly higher than the plane to plane contact. In twoconditions, the experimental life value were increased by108.45%and44.09%. This verified thefeasibility of arc contact structure design. On the other hand, the proposed life prediction model wasused to predict the fretting fatigue life of arc contact structure. The theory analysis and experimentalresearch comparison showed that the life prediction error is small, indicated the applicability of lifeprediction model.Anti fretting fatigue design method based on surface hardening process was advanced. Six sets ofplane-plane contact structure specimens were processed by laser hardening. Then the fretting fatiguetests were completed. The results showed that the fretting fatigue life of plane-plane contact structurewas increased by110.78%and17.56%in two conditions after laser hardening process. And themodified life prediction model was used to the specimens after laser hardening process. To improvethe accuracy of life prediction, the relationship between hardness and elastic modulus was introduced,and the influence of surface hardness to the fretting fatigue life was studied. The results showed thatthe error of life prediction model was small, and the life prediction model was proved to be valid.更多还原