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- Input the following parameters into the Matlab script per your preferences
- Yield Stress for case material (for aluminum 6061-T6, it's roughly 35000 psi)
- Design chamber pressure
- Case inner diameter
- Case outer diameter
- The number of bolts in a ring
- the bolt's major diameter
- the bolt's head diameter
- Number of bolt rings
- By running the script, the program will output three factors of safety
- relates to the compressive, shear, and tensile stress on the aluminum case as a result of the bolts
- per our rocket team adopted standards, all three values must have a factor of safety of 2 or above (margin of safety above 1)
- if the bolt pattern meets these requirements, it is a valid design
- Important assumptions
- these calculations simplify the process by assuming the case of the motor is always the weakest link in the connection, the other factors being when the forward closure/nozzle carrier will break, or what pressure the bolts will shear. a similar calculation can be run for the forward closure/ nozzle carrier, just update the values to reflect the designed diameters of the connected ring (but as long as the thickness of the nozzle carrier is larger than that of the case, it should be fine). bolt shear can be calculated through a simple shear stress calculation on the cross-section of the boltsThe current version assumes a single bolt ring, but will be updated to include multiple rings in a future version
- minimum edge distance between the bolt center and the edge of the case is standardized at 1.25 times the major diameter of the bolt
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