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      , (6.16)
a  1  m
2  
where    1 0 – coefficient of sensitivity to the


0
asymmetry of the cycle.
Broken lines ACD (fig. 6.5) limits the area of safety design: on
site AC - equation (6.15) on the site CD - the equation (6.16).
Let the set operating mode details, which is characterized by
alternating stress  and constant stress  . Then a series of
a m
standard fittings that are equally strong given the details
determined by the average stress

  
m m
and variable stress at the point N (fig. 6.6)

 k
  a  .
a
 
 
Limit values of constant and variable components of stress at a
point M (fig. 6.6), respectively:

n  k
    n  ,      a  . (6.17)


m гр  m a гр
  

Analytical expressions for the factor of safety get in the joint
solution of the equations of straight sections AC and CD
respectively:
          і          .



a гр  1  m гр a гр m гр т
Taking into account the expressions (6.17) we have
n  k n  k
 a        т  a   n    ,
n  ,


т
1
m
   
   
where
 
n   1 , n  т .
 k  k (6.18)
        
a  m a m
   
   
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