Pull-off tests of CFRP T-joints with conventional and 3D reinforced fillets

Published on Sep 1, 2019in Composite Structures5.407
· DOI :10.1016/J.COMPSTRUCT.2019.110893
Tomas Ekermann2
Estimated H-index: 2
(KTH: Royal Institute of Technology),
Stefan Hallström17
Estimated H-index: 17
(KTH: Royal Institute of Technology)
Source
Abstract
Abstract A study of T-joints made of CFRP prepreg is presented where the joints contain either conventional uni-directional (UD) fillets or fillets with three-dimensional (3D) woven reinforcement in the joint cavity. Both pristine and impacted specimens are tested experimentally in a pull-off load case. The T-joints with UD fillets are stronger but also show greater spread in strength than T-joints with 3D fillets. The higher strength is attributed to the UD fillets’ ability to deform transversely to their length direction and efficiently adapt to the T-joint cavity before curing. The 3D fillets do not admit the same level of transverse shape adaptability and if their cross sections do not fit the geometry of the T-joint cavity sufficiently well, local stress concentrations could emerge that reduce the strength of the T-joint. The UD fillets on the other hand are believed to be sensitive to manufacturing flaws causing the greater spread in strength. That in turn is attributed to a lack of crack-arresting capability in the UD fillet. The 3D fillets however have excellent crack-arresting properties due to their multi-directional fibre architecture. With a few exceptions the impact damages did not significantly affect the strength of the T-joints tested in this study.
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