BS in Materials Engineering
Materials Engineering Department
Samples belonging to four different designs of afterburner flaps, available in the as-cast, solutionized and aged conditions, underwent 4-point bend testing to fracture to investigate straightening. The average maximum load values of the second design samples in the as-cast, solutionized and aged conditions were respectively 33 kN, 29 kN and 27 kN. Regarding the fourth design samples, the average maximum load for the as-cast, solutionized and aged conditions were respectively 23 kN, 28 kN, and 25 kN. The other parameter measured during testing was the maximum extension at fracture. All as-cast samples belonging to the second design fractured at values between 5 and 7 mm, while all aged samples fractured at values between 4 and 6 mm. Independently of the design, most solutionized samples did not fracture at an extension of 9 mm or below; for such samples, 9 mm was the value used as the maximum extension. One-way ANOVA statistical analysis performed on the maximum extension data set revealed that design did not have a significant effect on maximum extension data. This analysis also revealed a significant difference between the solutionized and aged conditions among the two designs, from which it was extrapolated that it is optimal to straighten in the solutionized condition opposed to the aged. The same analysis was performed on the maximum load data set but was inconclusive due to the mean maximum load value of the as-cast condition being the highest value for Design 2 and the lowest value for Design 4. A hardness test was performed to determine the relative positioning of the maximum load data based on heat treatment condition. Due to a positive correlation between hardness and maximum load, it was expected that the ranking of the heat treatment conditions would start with aged as the highest value, then as-cast, followed by solutionized. Neither the maximum load data set for Design 2 nor 4 followed this trend; however, it was observed that while design played a significant role for the as-cast condition, it did not play a significant role for the solutionized and aged conditions. It was therefore concluded that, in general, heat treatment condition was more influential than design on both maximum load and maximum extension data sets, and more samples for testing were required for better accuracy of the results.
Available for download on Tuesday, June 14, 2022