Generative Design Rocket Motor Can

TARC, The American Rocketry Challenge, is a national competition in which teams of students work to build a model rocket with the goal of reaching a target height and flight time while complying with certain limits like weight.

I am Russell, currently in the 10th grade. I developed this project as part of the rocket for my high school's TARC team. The motor can of the rocket connects the motor and fins to the rest of the rocket. This motor can was designed to be removable from the rest of the rocket while also having fins that can be removed and replaced in case they are broken. I used Fusion 360's generative design to create this design and later 3D printed it out of light-weight PLA.

Hardware:

8x - M3 Threaded Insert

8x - M3x6mm Machine Screws

8x - M3x14mm Machine Screws

8x - M3 Nuts

100mm - 29mm Motor Tube

350mm - BT-80 Body Tube

Software:

Fusion 360

Openrocket

3D Printing:

3D Printer

Light-Weight PLA Filament

First, a model is needed to act as the starting geometry that fulfills the design requirements. In Fusion 360 I made a base motor can that was bolted into the body tube of the rocket and had slots to allow fins to be bolted in which fulfilled my requirements for a motor can that allowed for easy replacement. However, this initial motor can was too heavy and therefore threw off the balance of the rocket. This is where Fusion 360's generative design comes into play.

I created a new file in Fusion 360 and Imported all the reference bodies. I then split the reference bodies only keeping a single quadrant of the bodies in order to achieve radial symmetry around the motor. Next, I added a 45 degree construction plane as a symmetry plane. Then, I added preserve geometry where the bolts and threaded inserts would interface with the generated design. I also added Obstacle geometry to represent the bolts and threaded inserts.

The next step in creating a generative design is to set the parameters for the design. First, I added a structural constraint to the top surface of the preserve geometry where the motor mount interfaces with the rest of the mass of the rocket. Next, I added forces where the motor and fins interact with the motor can. Lastly, I set the design objective to minimize mass, manufacturing constraint to additive, and the material

The last step is to take the result from generative design and use a circular pattern to create the full part which is exported as a .stl file to be printed. The design is printed in LW-PLA, attached to the motor tube, and inserted into the rocket.