Optimized Boattail Support Bracket

Mass = 0.084 lb Volume = 2.43 in^3 Max Stress = 4098 PSI 1st Mode Natural Freq = 2912 Hz Design Features = Optimized for 3D printing without support material My submission for the ULA Rocket Hardware challenge is a bracket that has been optimized to have the minimum mass while still being able to be printed using a traditional FDM style printer, without any support material. To prove the bracket's design, it was printed using a MakerBot 3D printer, using ABS as the material with an 80% infill. It printed extremely well without support material. This model was also weighed to provide the final mass. Since ABS and Ultem 9085 have different densities (ABS 1.05 g/cm^3 and Ultem 9085 1.34 g/cm^3), the weight of the 3D printed model was scaled up by 1.28 (1.34/1.05) to provide the final mass of 0.084lb. Analysis on the bracket was performed in ANSYS to determine the maximum stresses. With the 4 bolt holes rigidly connected to a simulated rocket body, a 600lb load was applied to the load face. With this load, a maximum stress of 4098PSI was found, well below the design requirement of 4500PSI. A modal analysis was also performed to determine the natural frequencies of the support bracket. The first mode natural frequency was found to be at 2912Hz, well above any frequencies that would affect the launch vehicle dynamics. The maximum stress in the bracket due to the vibration of the launch vehicle (14.1Grms according to NASA GEVS Levels) was only 15PSI. The bracket would survive launch with no ill affects. This bracket demonstrates sound engineering design that meets all of the design requirements and also is optimized for easy manufacturing using an FDM 3D Printer.