Efficient progressive damage modeling of hybrid composite/titanium bolted joints

In an attempt to gain better understanding and predictability of the mechanical behavior of titanium-lamella reinforced CFRP bolted joints, an efficient progressive damage model was developed in this work. The model was used to represent bearing effects in a double-lap composite bolted joint subjected to tensile loading. The progressive damage model relies on stress-based failure criteria accounting for three orthogonal fracture planes and a continuous degradation method depending on stress-state and stress history. It is shown that the model, which for material specification uses available elastic moduli and strength values, can be refined to reasonable accuracy with regard to experiments through a parameter identification process. For pure CFRP bolted joints, the model predicts accurately both bolt strength and total displacement at final failure. The predicted strength enhancement, achieved by replacing CFRP layers with titanium sheets, is in good agreement with experimental data obtained from the literature.