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Part | Component Status | Responsible Engineers |
|---|---|---|
| Sustainer Forward Retention Ring | Manufacturing Prep | Chad Meier 2023 |
Purpose
The forward retention ring serves 2 main purposes:
It retains the forward closure from sliding past the end of the motor casing.
It couples the motor casing to the airframe.
Requirements
Must withstand the force applied by the forward closure (4,330 lb)
Must be able to interface with motor casing (2.75”)
Must be able to interface with airframe (3”)
Design
In order to accomplish thisthe requirements, certain design considerations were made. The forward closure presses upward on the aft end of the FRR. The force it applies is equal to the chamber pressure times the inner cross-sectional area of the motor casing. The FRR must be able to withstand the load of the peak pressure (given by the Propulsion Sub-team) with a safety factor of 2. Working with Propulsion, we decided that the FRR will have 1 row of 12 ¼-20 holes that interface with the motor casing. This was based on calculations that Prop did for the motor casing.
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Using Solidworks FEA, I decided that this cross-section worked under the following conditions:
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In this design, the wall thickness is only large where the bolt tension is acting, saving quite a lot of mass. This also gives the bolts lots of thread length to engage with.
The FEA was set up with the face that contacts the forward closure fixed. The 4330 lb force is acting upward on the top surface of the bolt holes and 960 lb shear force acts radial outward on each hole to simulate the bolt tension. The safety factor is 2.27.
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