TY - GEN
T1 - Characterization of the fibre bridging contribution in mode I fatigue delamination in composite laminates
AU - Yao, Liaojun
AU - AlderliestenAssociate Professor, R. C.
AU - ZhaoProfessor, Meiying
AU - BenedictusProfessor, Rinze
PY - 2014
Y1 - 2014
N2 - Characterizing fatigue delamination in composite laminates is important for the application of these materials in aerospace, as it provides the necessary information as input for the damage tolerance design philosophy. Fibre bridging is a significant phenomenon that will increase the fracture toughness by restraining the crack opening during interlaminar crack extension. This paper presents a study, in which a series of mode I fatigue delamination tests with different quasi-static or fatigue pre-crack lengths were conducted on unidirectional and multidirectional DCB specimens of M30SC/DT120 carbon/epoxy to investigate the bridging effect on fatigue delamination growth. With the increase of pre-crack length, the obtained fatigue resistance curves shift from left to right in the delamination resistance graph, because more bridging is generated by a longer pre-crack. As a result, the delamination growth rate decreased significantly at a given strain energy release rate (SERR) range with increased bridging. It therefore seems insufficient to use only one resistance curve to determine the delamination property in composite laminates. Similar to the R-curve concept in quasi-static delamination, a fatigue R-curve method will be presented here, by plotting the SERR range and corresponding crack extension at a given delamination growth rate. Comparing the obtained resistance curves for the same quasi-static and fatigue pre-crack length, a significant difference is observed. This implies different damage and fibre bridging states are generated under quasi-static and fatigue loading. So this paper will conclude that it is incorrect to employ quasi-static test results to normalize fatigue test results, as currently proposed in literature and considered for standardization.
AB - Characterizing fatigue delamination in composite laminates is important for the application of these materials in aerospace, as it provides the necessary information as input for the damage tolerance design philosophy. Fibre bridging is a significant phenomenon that will increase the fracture toughness by restraining the crack opening during interlaminar crack extension. This paper presents a study, in which a series of mode I fatigue delamination tests with different quasi-static or fatigue pre-crack lengths were conducted on unidirectional and multidirectional DCB specimens of M30SC/DT120 carbon/epoxy to investigate the bridging effect on fatigue delamination growth. With the increase of pre-crack length, the obtained fatigue resistance curves shift from left to right in the delamination resistance graph, because more bridging is generated by a longer pre-crack. As a result, the delamination growth rate decreased significantly at a given strain energy release rate (SERR) range with increased bridging. It therefore seems insufficient to use only one resistance curve to determine the delamination property in composite laminates. Similar to the R-curve concept in quasi-static delamination, a fatigue R-curve method will be presented here, by plotting the SERR range and corresponding crack extension at a given delamination growth rate. Comparing the obtained resistance curves for the same quasi-static and fatigue pre-crack length, a significant difference is observed. This implies different damage and fibre bridging states are generated under quasi-static and fatigue loading. So this paper will conclude that it is incorrect to employ quasi-static test results to normalize fatigue test results, as currently proposed in literature and considered for standardization.
UR - https://www.scopus.com/pages/publications/84922106298
M3 - 会议稿件
AN - SCOPUS:84922106298
T3 - Proceedings of the American Society for Composites - 29th Technical Conference, ASC 2014; 16th US-Japan Conference on Composite Materials; ASTM-D30 Meeting
BT - Proceedings of the American Society for Composites - 29th Technical Conference, ASC 2014; 16th US-Japan Conference on Composite Materials; ASTM-D30 Meeting
PB - DEStech Publications
T2 - 29th Annual Technical Conference of the American Society for Composites, ASC 2014; 16th US-Japan Conference on Composite Materials; ASTM-D30 Meeting
Y2 - 8 September 2014 through 10 September 2014
ER -