Tension–compression fatigue behavior of a H-VARTM manufactured unnotched and notched carbon/epoxy composite

The tension–compression fatigue behavior of a four-harness satin weave carbon fiber/epoxy (IM7/EPON 862) composite manufactured from the H-VARTM (Heated Vacuum Assisted Resin Transfer Molding) process was investigated. Unnotched and notched specimens were both tested in this study. The notch was a circular hole located at the center of specimen. The fatigue lives of the unnotched IM7/EPON 862 composites in the fully reversed tension–compression fatigue testing condition were significantly shorter than in the tension–tension fatigue testing condition. However, there was no effect of the notch on the fatigue life/strength. Damage mechanisms involved initial matrix cracking followed by delamination, microbuckling, fiber kinking and finally fiber breakage. The final failure occurred under compression in the shear mode. In the notched specimen, the damage was initially concentrated at the maximum stress concentration location (edge of hole).