Study on main failure modes of multiple-holes structures based on branch-bound method

Aiming at the typical five-hole structure on the aircraft skin, combined with the failure criterion of multi crack structure and considering the random factors affecting the residual life distribution of multiple crack structure, this paper applies the branch and bound algorithm to the screening of the main failure modes of typical five-hole structure, and gives the specific screening steps. The residual life of the structure is predicted by Franc3D crack propagation software, and the life interference model is established. Finally, the residual life distribution curve of the five-hole structure is formed to complete the screening of its main failure modes. The results show that the efficiency of using the algorithm to screen the main failure modes of the structure has been improved by 77.2%, and the error between the corresponding median life and that before screening is about 12%, indicating that the result of screening the main failure modes of the structure by the algorithm is more accurate. Compared with the existing test results, the median life predicted by the life distribution is more conservative and has certain reliability and accuracy. This method has certain reference significance for the evaluation of the safe life of this multi-holes structure.