tension de conexion en tornillos
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Tension ConnectionTension Connection A threaded fastener
connection has clearance gaps
that are used to assemble theconnection.
A connection can be loaded in
either tension/compression or
shear.
Because of the clearance gaps,dowel pins are often used for
accurately positioning of
mating parts.
Shigley, Fig. 8-12
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Proof Load & Proof StressProof Load & Proof Stress
Proof LoadProof Load : Maximum force that a fastener can withstand
without acquiring a permanent set.
Proof StressProof Stress: Proof Load divided by the tensile-stress-area
of the fastener.
The proof stress is slightly less than the yield stress
of the material due to stress concentrations in thethreads.
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Bolt PreloadBolt Preload Purpose of bolt is to clamp
two parts together.
Turning the nut on the
threads will stretch the bolt
to create a clamping force.
The clamping force will
impart a compressive force
on the mating parts.
The clamping force is called
preload or initial tension.
grip
Shigley, Fig. 8-12
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Clamped Part StiffnessClamped Part Stiffness
L1
L2
L3
333
222
111
321m
mi
LEAkLEAk
LEAk
k
1
k
1
k
1
k
1
kF
=
=
=
++=
=
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PressurePressure--Cone EquationsCone Equations
Shigley, Fig. 8-14
( )( )
( )( )
++
++
=
dDdD1.15t
dDdD1.15tln
Ed0.577k
Reference Shigley, page
339-340 for derivation
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External Load InteractionExternal Load Interaction
Preloaded ConnectionPreloaded Connection
Shigley, Fig. 8-12
mb
bb
mb
m
bmb
m
m
b
b
kk
PkP
PPP
k
kPP
k
P
k
P
+
=
+=
=
==
i
mb
mm
i
mb
bb
ibb
Fkk
PkF
Fkk
PkF
FPF
+
=
+
+
=
+=
0Fm
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