Design optimization of aircraft canopy and structures against the threat of bird strike

The threat of bird strike in aviation has become a significant problem. Bird strikes can cause serious costs and loss of life. In order for aircraft structures to survive bird strike accidents without any damage, tests and finite element analyzes are carried out in accordance with the relevant regulations. In addition to being durable, aircraft structures are also lightweight, which is important in terms of flight performance and cost. In this study, design optimization of national combat aircraft structures against bird strike was carried out. First of all, the bird finite element model was compared with the tests in the literature. The bird was modeled using the SPH method and its behavior during impact was validated with the tests. Then, a literature review was conducted to analyze bird strikes on aircraft structures. Bird strike tests are planned for national combat aircraft structures. The tests were carried out on Roketsan's gas gun test system. Artificial gelatin bird models were produced for use in tests. In order to determine the national combat aircraft structures to be tested, finite element models suitable for the test conditions were first created. For the national combat aircraft canopy, polycarbonate (PC) and stretched polymethyl methacrylate (SPMMA) materials are layered with a thermoplastic polyurethane (TPU) adhesive. In order to model PC and SPMMA materials, the Johnson Cook material model, which can give strength and damage output depending on the strain rate and temperature, was chosen. Firstly, a mesh convergence study was carried out in the finite element model created for canopy bird strike test conditions. Then, the lightest structure that provides good crash performance was investigated. For this purpose, a data set was created with the latin hypercube sampling (LHS) method and a support vector machine (SVM) model that could predict the collision outcome was created. With this mathematical model, optimization was made using a genetic algorithm and the lightest design was determined. Similarly, for composite structures, a finite element model was first created and a mesh convergence study was conducted and it was validated by bird strike tests on a composite leading edge found in the literature. Then, the lightest composite plate resistant to bird strike under test conditions was determined by analysis. Bird strike tests on the canopy and composite plates supplied by TAI were carried out at Roketsan. As a result of the tests, the plates showed good collision performance and the finite element model was consistent with the test results.