text: Of course, the time necessary to produce 
  fatigue failure is related to the magnitude of 
  the cyclic stress. This relationship is typified 
  by 
  fatigue 
  strength of a material can be demonstrated by 
  a plot of cyclic stress versus cycles of stress 
  required to produce fatigue failure. As might 
  be expected, a very high stress level requires 
  relatively few cycles to produce fatigue failure. 
  Moderate stress levels require a fairly 
  large 
  number of cycles to produce failure and a very 
  low stress may require nearly an infinite num- 
  ber of cycles to produce failure. The very 
  the aircraft must 
  certain implication 
  is that 
  be capable of withstanding 
  the gamut of 
  service loads without producing fatigue failure 
  of the primary structure. 
  
  the graph of  figure 5.1. The 
  
  The various components of the aircraft and 
  powerplant structure must be capable of oper- 
  failure or excessive deformation 
  ating without 
  throughout 
  intended service life. The 
  repetition of various service loads can produce 
  fatigue damage in the structure and special 
  attention must be given to prevent fatigue 
  failure within 
  the service life, Also, the sus- 
  taining of various service loads can produce 
  creep damage and special attention must ‘be 
  to prevent excessive deformation or 
  given 
  creep failure within 
  the service life, This is 
  a particular feature of components which are 
  temperatures. 
  subjected to operation at high 
  
  For each mission type of aircraft 