Evaluation of preventative solutions for fretting fatigue damage of titanium-6242 in aircraft engines.

摘要

Fretting is a wear phenomenon that occurs between two contacted surfaces having oscillatory relative motion of small amplitude. Although the actual fretting wear damage can be slight when combined with cyclic fatigue, it can cause a considerable reduction of fatigue life. This reduction is particularly problematic in the dovetail region of blade and disc combinations within an aircraft engine.; The objective of this thesis is to design a fretting fatigue test rig and associated test specification to aid in the evaluation of potential processes used to increase Titanium 6242 resistance to fretting fatigue. These processes include coatings, anodizing and mechanical hardening techniques. In addition to the fretting fatigue tests, low cycle fatigue and notch sensitivity tests will also be conducted to evaluate the processes effect on other material characteristics.; After testing, it is found that a combination of both shot peening and anodizing provides an improvement of 1.9 times over the current OEM solution of CuNiIn and molybdenum-disulphide without detrimentally altering any other material characteristic.