A novel approximate method for determining mixed mode I/II bridging law of laminated composites

This paper has been presented according to the importance of crack bridging in mixed mode I/II delamination of laminated composites and it is aimed to understand the physics of crack bridging. Firstly, the most important micro-mechanisms involved during fiber bridging are introduced. To do this, interlaminar fracture tests have been performed on composite specimens. Also, the fracture surfaces and the damage zone on the edge of the specimens have been observed using a scanning electron microscope (SEM). In the following, due to the complexity of the existing bridging models and the difficulty of determining their various parameters, a novel approximate method has been presented. In this method, which is based on a more complex physics-based model, the bridging laws are extracted by preserving the physics of the problem and considering simple approximations. The main advantage of the proposed method is the achievement of bridging laws using simpler relationships with fewer required parameters. Finally, the validity of the method has been evaluated through a comparison of the traction-separation behavior predicted by the proposed approximate bridging laws with the experimental traction-separation curves in different mode mixities.