Research On The Fracture Behavior Of Carbon Fiber T-joints

In this paper, the fracture behavior of carbon fiber composite T-joints under static stretching loadwas studied combined with numerical simulation and experiment.Consisted with laminated layers and filling areas, the composite T-joint is one of the typicalintegrated structure of composite material. The finite element model was built to work out the stressand strain distribution based on the classic laminated layer theory of composite material andcementation features. It was showed by the finite element results, stress concentration occurred in thefilling area and lead to the initial damage. According to this, the parameters of the T-joint’s fillingarea was optimized and numerical results proved that increasing the circular arc radius within therange that the structure weight gain permitted would enhance the performance of the T-joint.Further investigation was taken to study the fracture behavior of the composite T-joint understretching load. Numerical model of the T-joint was built to emulate its damage appearance, spread aswell as the failure process under tensile load. Then the static stretching experiment took place. It isdemonstrated that the initial damage load was about9.8KN to12.0KN and the bearing load of theT-joints decreased in a sudden of about27%to38%. However, the joint still possessed its bearingcapacity. The joint became completely unglued under the load of8.0KN to8.6KN which is slightlylower than the initial damage load. Corresponding with the numerical results, the experiment showedthat the filling area was the most dangerous part of the T-joint which was the most vulnerable.Crackles swiftly spread to the glue layers surrounded after the filling area was damaged and lead tothe peeling off of the glue layer which was account for the failure of the T-joint.This result provides positive reference to the study of the damage and failure behavior if carbonfiber composite material structure under tensile load. Sponsored by beforehand funds, the researchwas undertaken in the State Key Laboratory of Mechanics and Control of Mechanical Structures.