The use of thin-walled integral structures in aviation on the example of the SAT-AM project

Abstract

Airplanes structures are exposed to various load condition components in flight. Each task in flight consists of a series of maneuvers that generate different loads on the aircraft, both in terms of value and direction of action. A high level of durability and reliability is a basic, strict requirement for modern aircraft structures. This means that many, often conflicting limitations must be taken into account when designing an aircraft. The most important of them is the mass of the structure, which has a decisive impact on both flight and technical properties, as well as the economy of operation. This makes the plane one of the most complex technical products. Modern aircraft structures, or more precisely their load-bearing elements, are almost exclusively thin-walled, which meet the postulate of minimizing the weight of the structure. Systems in which the covering is reinforced with longitudinal and transverse elements are widely used, ensuring the required stiffness and strength of the entire system. While the local loss of stability of the roofing is acceptable under working load conditions, exceeding the critical load levels of structural framing members (frames, stringers, frames) practically amounts to the failure of the structure. The indicated factors force the continuous improvement of both design methods and construction solutions in aviation. The development of materials engineering and the continuous improvement of technological processes are not without significance for the effectiveness of these ideas. These disciplines allow for the construction of geometrically complex integral structures that make it possible not only to use the material properties more rationally, but also, through their appropriate shaping, significantly increase the permissible loads on the load-bearing structure. The main advantage in the design of integral parts is the economic savings achieved by eliminating or reducing assembly operations. Densely ribbed roofing elements made in this technology are elements of the load-bearing structure that reduce the weight and increase the strength parameters of the load-bearing structure. By reducing the thickness of the coating and at the same time introducing densely stiffening longitudinal members, it is possible to obtain a structure with much higher critical loads and, consequently, a more favorable distribution of gradients and stress levels, which directly contributes to increasing the fatigue life. The article attempts to evaluate the introduction of new airframe construction technologies to increase their strength, aerodynamic and mass values.