their quasi-static load, the superimposed double amplitude cyclic load, 

 and the cumulative number of load cycles at or greater than the given 

 cyclic load. 



90 



80 



£■ 60 



double amplitude cyclic 

 load component - 



Figure 6-4. Examples of cyclic loading. 



The design procedures that follow were developed by Herrmann 

 (1980). The procedures incorporate a number of conservative assump- 

 tions and "worst case" values in obtaining the limiting conditions . 

 Because of this, lower factors of safety are allowable. Whereas values 

 of 2 to 3 were recommended for static cases, for similar conditions, 

 values of 1.25 to 1.75 are recommended for cyclic load conditions. 

 These factors are to be applied to the loads, not to the number of 

 cycles . 



53 



