Dynamic and static failure behavior of notched CFRP laminate investigated by digital image correlation

Static and dynamic fracture behavior of notched CFRP laminates are investigated experimentally. The dynamic tensile loading apparatus is developed based on a split Hopkinson bar. Impact tensile tests for notched (open-hole) CFRP specimens are performed. The full-field strain around the hole in the specimen is evaluated employing digital image correlation method using photographs obtained using a high-speed camera at a frame rate of 1,000,000 frames/s. Far-field strain at the failure is obtained from the specimen-mounted strain gauge. Increased strain around the hole is observed over time. A static tensile test for the notched CFRP specimen is then conducted as well. The strain distribution and far-field strain at failure are obtained similarly. The results show that the far-field strain at failure varies with the strain rate. The strain distributions obtained from two tests are compared and a mechanism causing the difference is discussed. The results show that high strain is distributed along the transverse direction to the loading direction from the hole for the impact (high-strain-rate) tests, although high strain exists on the side hole in loading direction for the static tests. The difference is possibly attributable to the difference of internal damage, which depends on the strain rate.