Damage mechanism of composite sleeve-type bolt interference fit structure during the installation process

Composite interference fit joints have become an advanced joint form because they can significantly reduce the stress concentration around the holes and thus improve the bearing capacity and fatigue life of the structure. However, due to the low interlaminar strength of composite materials, unreasonable interference bolt structure style, dimension and installation method can easily cause hole wall delamination and reduce the structure bearing capacity. To solve this problem, an interference joint structure based on sleeve-type bolts was proposed, and the experiment and finite element analysis of the structure during installation were carried out. The changes of installation force and damage around hole were measured. A damage prediction model based on progressive damage and cohesive element of composite was established by taking into full account the factors of intralaminar damage and interlaminar delamination. Through the comparative analysis of the insertion force and damage of sleeving bolts with 2.2% interference, it is found that the finite element model fits well with the test results, which proves the accuracy of the model. The reason why sleeve-type bolt can improve the quality of hole wall is explained and the range of reliable interference is put forward through comparative analysis under different interference and critical interference percentage calculation.