Effects of Defects on Interlaminar Tensile Behavior in Carbon/Epoxy Composites

Interlaminar tensile behavior of curved-beam specimens under static and constant amplitude fatigue loading exhibits large scatter in strengths and cycles to failure, respectively. Nondestructive analysis by X-ray Computed Micro-Tomography and subsequent finite element analysis identified porosity / voids in the critical area of specimens as the cause of the scatter. The proposed analysis uses high-resolution defect measurements by X-ray Computed Micro-Tomography. The non-destructive measurements are automatically converted into structural models to find interlaminar tensile stress concentrations associated with defect geometry and location. The interlaminar tensile fatigue behavior of a pristine porosity-free carbon/epoxy unidirectional tape composite is presented by applying the proposed analysis to specimens tested under fatigue loading.