Abstract:
Bolt connections are extensively employed in the assembly of composite structures, and their connection strength has a significant impact on the reliability of the overall structure. In the light of this issue, the aim of this study is to analyze the characteristics and laws of damage accumulation of bolted joints using the progressive damage method, and to discuss the effects of different failure criteria on the failure behavior. First, the Hashin failure criterion and the Puck failure criterion, along with the exponential stiffness degradation model and the instantaneous stiffness degradation model, are analyzed separately. Subsequntly, a finite element model of a double-lap three-bolt composite plate is developed based on the failure criteria and the stiffness degradation model. Finally, the displacement-load curve is analyzed with different failure criteria and stiffness degradation model taken into account. The impacts of different combination on the prediction error are discussed. The damage evolution process of laminate is studied by using finite element method. The results demonstrate that the Puck criterion based on exponential degradation has the lowest prediction error of 8.3% for the failure load. Tensile failure is the primary reason for the laminate breakage. The tensile failure of the matrix precedes that of the fiber, which occurs first in the ±45° plys and then expands to the 90° plys, while fiber failure initially takes place in the 0° plys and then extends to the ±45° plys. When the fiber tension damage extends from the periphery of the hole to the edge of the laminate, the laminate eventually fails.