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4.3 Potential energy of deformation in shear

Believing that the force Q applied statically, find work of this
force on the displacement S and take into account that the work
at full potential energy of deformation element in pure shear. We
obtain:
Q S
A U  . (4.9)
n
2
Substituting formulas (4.1), (4.8) in the expression (4.9), we
obtain:
 2 hF
U  . (4.10)
n
2G
Dividing the value of the volume of material that deforms (), we
obtain the value of the specific potential energy in shear
U  2
u  п  . (4.11)
V 2G

4.4. Condition of strength in shear

The strength condition in shear is written as:
Q
      . (4.12)
F
The value of the allowable stress is determined by the selected
strength theory. For example:
- by the third theory

  0,5   ;
- by the fourth theory
 

     0,6 
 .
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