Summarized Table of the minimum diameter for bolts:
a=0 (only force of piston) | Max Acceleration | |
Piston Mount | 0.001 m | - |
Mission Package Tube | 0.001 m | 0.0006 m |
Diaphragm Cup | 0.0001 m | - |
...
Calculated min D is 0.0001 m
Thread Stripping Calculations for U-Bolt:
yield stress of 316 stainless steel: Y = 290 MPa
piston force: F = 477 lb-F = 2121.8 N
dimensions of threads in U-bolt:
- height = 0.0301"
- minor diameter = 0.2458" = 0.00624 m
- major diameter = 0.306" = 0.00777 m
number of threads on each end of U-bolt: 0.2675" * 18 threads/1" = 4.7 threads
surface area of threads on each end of U-bolt: 4.7 threads * pi * ((0.00777 m/2)^2 - (0.00624 m/2)^2) = 7.911*10^-5 m
the threads on each end will experience half of the piston force: F = 2121.8 N/2 = 1060.9 N
stress on the threads on each end of the U-bolt: 1060.9 N / 7.911*10^-5 m = 1.341*10^7 Pa = 13.41 MPa
the stress on the threads on each end of the U-bolt is less than the yield stress of stainless steel, so no thread stripping should occur
assumptions and simplifications made during calculations:
- the force is distributed uniformly on the surface of the threads
- the pitch angle is 0 degrees (in reality, it is 30 degrees)