Case Study on Improving Vibration Failure of an Aircraft Heat Exchanger Brackets

Aircraft heat exchangers are devices used to cool the lubricating oil supplied to the gearbox and drive unit by utilizing low-temperature fuel/air. The bracket failure of heat exchanger was occurred while operating in a vibration environment. In this study, the cause of bracket crack was analyzed and an improvement method was proposed. From the results of scanning electron microscope(SEM) observation of the fracture surface, it was confirmed that the crack was initiated and propagated by resonance due to excessive vibration. Finite element analysis including modal and stress analysis of the heat exchanger structure was performed, and a vibration test was performed to compare the analysis and experimental results. Based on these results, an improved bracket thickness was obtained, and the safety factor was 9 or higher as the standard for the shear fatigue strength. The safety and durability of the improved bracket were verified through a vibration test.