LAUSR

Strength reduction in structures like aircraft could be resulted in cyclic loads over a period of time and is an important factor for structural life prediction. Service loads are emphasized at the regions of stress concentration, mostly at the connection of components. The initial flaw prompting the service life was expected by using the equivalent initial flaw size (EIFS) which has been recognized as a powerful design tool for life prediction of engineering structures. This method was introduced 30 years ago in an attempt to study the initial quality of structural details. In this paper, the prediction of life based on fracture mechanics in riveted joints has been addressed through the concept of EIFS. For estimation of initial crack length by EIFS, an extrapolation method has been used. The EIFS value is estimated using the coefficient of cyclic intensity (ΔK) and using the cyclic integral (ΔJ), and the results are compared with each other. The simulation results show that if the coefficient of tension has been used in the EIFS estimation, which is based on the Paris law, the EIFS value will be dependent on the loading domain, while the use of the J-cyclic integral in the EIFS decreases its dependence on the load domain dramatically.