The Ph.D. thesis is devoted to the issue of developing a model of external loads acting on a wing of a large elongation (λ≥8) of a transport category aircraft when flying in turbulent air, taking into account aeroelasticity based on calculation and experimental studies. External loads are the initial data for the analysis of the stress-strain state of the structure. They determine the strength of the structure, weight efficiency, and parameters of fatigue strength. The purpose of the research is to obtain a mathematical model of the external loads of the aircraft when flying in turbulent air, which will ensure the correspondence of the results of the numerical solution, taking into account the effects of unsteady aerodynamics, to the results of the experiment. The main part of the thesis consist of four sections. The first chapter considered the methods of determining the loads on the wing of the aircraft during flight in turbulent air. The procedure for calculating loads is formulated. Experimental methods of studying the elastic and aeroelastic characteristics of the structure are described: ground vibration test (GVT), and testing of a dynamically scaled model in a wind tunnel. The method of processing loads measured during flight tests is also considered. The second chapter has formulated an algorithm for determining and constructing the stiffness axis of a complex spatial aggregate. Thus, a spatial beam elastic-mass model of the aircraft has obtained, for which the mathematical algorithms for designing and determining the forms and frequencies of natural oscillations are describe. The methods of determining the aerodynamic loads on the elastic structure of the aircraft are considered. The obtained results made it possible to formulate a method for determining the loads that act on aircraft units, including on the wing during the flight in turbulent air. The third chapter formulates and describes the structure and principle of operation of the integrated model for calculating loads, which act on the aircraft when flying in turbulent air. The list, structure, and order of organization of input and output data, which are necessary to calculate the loads, are also given. The fourth chapter contains the results of mathematical modeling, GVT, and flight tests, which allowed us to analyze the faithfulness of the proposed model of external loads. First of all, we compare DNV and IMAD methods, which used to determine the loads acting on the aircraft during flight in turbulent air. In addition, several methods of mathematical modeling of aircraft flow are considered: DLM, Panel, DLM/CPM, and VFM. Taking into account the effects of non-stationary aerodynamics leads to a change in the values of load increments from air gusts (up to 2% in the root sections of the wing and up to 10% in the end sections). The influence of the number of calculated tones of oscillations of the aircraft structure on the wing loading is considered: when increasing the number of tones from 20 to 40, the values do not differ by more than 0.5% for the vertical overload ny and by no more than 0.1% for the transverse force Qy and moments Mz and Mx. In addition, an analysis of the dynamic response of the aircraft structure was performed by determining the frequencies and forms of natural oscillations of regional transport aircraft (RTL-178). The results of the conducted analysis are compared with the results of the GVT of the An-178 aircraft, and a high (up to 2.5%) convergence of oscillation frequencies was obtained. In addition, the loads that occur in case of sustained wing-mounted engine rotor imbalance conditions of the rotor are determined. That showed the possibility of applying the proposed models of aircraft and loads to solve problems of dynamic loading of aircraft units. The scientific novelty of the results: 1) a mathematical model of external loads during flight in turbulent air for an elastic aircraft is improved, which takes into account the mass, elastic, and aerodynamic characteristics of the aircraft structure and parameters of air gusts and makes it possible to increase the accuracy of calculations up to 2.5%; 2) a new computer-integrated technology for calculating aircraft loads using a comprehensive mathematical model of an elastic transport category aircraft with a high aspect ratio wing based on beam mass-inertial models of aircraft structure and panel aerodynamic methods is synthesized; 3) the parameters of the influence of external factors on the load and dynamic response of the wing structure of a transport category aircraft in accordance with its elastic model and the parameters of external factors, using the proposed loads model, are identified; 4) on the basis of computer technology, the computational methods of DNV and IMAD, as well as the panel aerodynamic methods DLM/CPM, VFM, DLM, and Panel, used to determine the loads acting on the aircraft during flight in turbulent air, are systemically integrated.
