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[ Mechanics
/ Strength of Materials Menu ] [ Fastener
Thread Analysis Menu ]
The screw should fail before the thread strips. For this, it is necessary
the shear area of the threaded feature be at least 2 times the tensile area.
(Assuming the threaded feature is of the identical material).
Where: Le = Thread Engagement Length
At = Tensile Stress Area
D = Major
Diameter of fastener (screw)
p = 1 / Number of threads per inch
(n)
Threaded Hole / Fastener Ratio
This assumes that the male and female thread materials have the same
strength. If the Female Material strength is lower i.e. J as calculated
below is greater than 1 then the length of engagement must be increased to
prevent the female thread stripping
Where:
J = Thread Engagement Ratio
If the value of J is greater than 1 then the length of engagement
must be increased to at least
Where:
le = Thread Engagement Length
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