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a prime
consideration in bolted joint assembly. Tension produced by torque control
alone may show significant variation due to (e.g) the influence of
friction. 
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result
from the tensile stress in a bolt and determine the strength and endurance
of the joint. Cannot economically be measured during assembly.  |
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is
the measurement of bolt head rotation, in degrees, starting at the
threshold and measured up to the specified torque. Used in conjunction
with the torque for more accurate tension control.
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is the
point at which elastic deformation of the fastener ends and permanent
deformation (elongation) begins. 
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is
the point at which the tested fastener is ruptured to determine its
ultimate strength.  |
is
the increase in torque per revolution of the fastener. When plotted as a
graph, the steepness of the resulting curve determines the hardness of the
joint. 
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is
the loss of tension in threaded joints when components such as shims,
washers, seals or gaskets initially resist clamping pressure, but over a
period of time, yield plastically into permanent deformation. 
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is the
point at which the torque curve begins to rise steeply due to friction
between the fastener and the base material. 
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