Ultem(R)ate Bracket C1 (0.018 lbs, 0.376 cu in)

grabcad

This set of ultralightweight brackets weighs only 0.018 lbs with a volume of 0.376 cubic inches. The total mass can be reduced to 0.016 lbs, but this may lead to an unstable part for 3D printing and violate edge distance requirements. Common 3D printing features are used to reduce the mass of unstressed but thick parts (bosses). The bracket is designed as two mirrored parts that only require two bolts to connect it to a launch vehicle. All stresses in the bracket are less than 4500 psi, and a singularity/stress riser due to contact between the bolt and bracket has been analytically calculated for correct contact pressure and Hertzian stresses. No optimization is needed as preliminary sizing was done using basic mechanical theory and verified using FEM. The bracket can be printed without supporting structures, with an elastic hinge allowing alignment during mounting on the launch vehicle. There's ample space for tools to reach the bolts. Infill density in unstressed areas is reduced by 15% to further reduce mass. An extra load case of 14.7 psi differential pressure inside the infill volume has been considered to prevent bracket breakup during ascent. The pdf file attached provides all details on calculations and design considerations, with a comparison picture showing stress distributions caused by real contact between the bracket and bolt versus fixed bore hole contact. Kind regards, Wilbert Engels