Characterization of fatigue damage in long fiber epoxy composite laminates

A study of damage characterization of a GFRC laminate is presented here. Forty fatigue tests were executed and S–N curves traced. Two parameters were chosen to monitor damage evolution during each test: stiffness and dissipated energy per cycle. Moreover, the presence of three zones in graphs of processed data can be observed and it is evident that the most important structural transformations take place only in the very final part of life. Adopting a continuum mechanics approach, the degradation through the whole life in composite is evaluated and it is shown that the two parameters are strictly related to damage state of composite material. A method for predicting the remaining life in a GFRC is here proposed.