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N
A  x ; (2.30)
 

- determine the allowable longitudinal force (the calculation
of the allowable load)

   A  (2.31)
  .
N
x

2.9 The energy of deformation

Consider a rod that is statically loaded by the tensile strength P
(fig. 2.12 a). Within the elastic deformation the tensile diagram is a
straight line(fig .2.12 b). In the process of loading the rod force P
performs over the rod work, which is converted into potential
energy of deformation. If the force P is slowly removed, the rod
will transfer back to its original state by stored energy. That is, in
terms of energy transformations the rod acts as a spring that can
accumulate and give energy.
The work of some intermediate value P of the load on
1
elongationd
1
dA = P d , (2.32)
1 1 1

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