PSI - Issue 37

6

Oleg Staroverov et al. / Procedia Structural Integrity 37 (2022) 804–810 Oleg Staroverov, Dmitrii Lobanov/ Structural Integrity Procedia 00 (2019) 000 – 000

809

fatigue destruction

from e ’ = 0,33 to e ’ = 0,66

e ’ = 0,75

e ’ = 0,8

e ’ = 0,9

Fig. 6. Photographs of CFRP specimens after preliminary impact and subsequent cyclic impact tests

In case of fatigue failure without preliminary impact action, carbon fiber specimens laminated along the entire working zone, and fractures showed broken threads and multiple laminations. The same failure pattern was observed in the case of fatigue after impact with the intensity within e’ = 0.33 to e’ = 0.66. Impacts with energies of e’ = 0.75 to e’ = 0.9 caused a mixed type of fatigue failure. The images of failed specimens showed zones of fiber breaking with longitudinal fractures. This type of failure is similar to interlaminar shear (by short-beam method) by Lobanov D.S. et all (2021). 4. Conclusions A complex experimental study was done for the effects of preliminary impact action of various intensity on fatigue life of structural carbon fiber composite using testing and diagnostic systems for recording acoustic emission and temperature field signals. The threshold of impact sensitivity was found for the carbon fiber under study. Failure patterns of specimens after impacts and further cyclic loading were analyzed. A link was demonstrated between structural damages resulted from preliminary impacting and mechanical behavior during cyclic loading.