Experimental Methodology for Limit Strain Determination in a Carbon/Epoxy Composite under Tensile Fatigue Loading

Abstract

This work proposes a methodology to obtain the carbon fiber/epoxy composite limit strain for structures surviving 120000 cycles. The damage progression was also evaluated using stiffness reduction and hysteresis loop analysis in order to obtain dynamic and secant modulus. The results provide information about composite fatigue behavior. This approach determined a limit strain range from 0.83 to 0.87%, a fatigue stress limit of 0.8% of the static strength, stiffness degradation (damage index) of about 5% (within the limit strain). The methodology presented herein may be used for determining of material design allowable when fatigue is key consideration.