АНАЛІЗ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ ОСОБЛИВОСТЕЙ ЗАБЕЗПЕЧЕННЯ РЕСУРСУ СЕРЕДНЬОЇ ЧАСТИНИ ФЮЗЕЛЯЖУ В ЗОНІ ВИРІЗУ ПІД ДВЕРІ ЛІТАКІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

Abstract

This article is devoted to the analysis of the design and technological features of ensuring the resource of cutouts in the middle part of the pressurized fuselage of transport category aircraft. Aircraft fuselages, due to their functional features, have a large number of different cuts and irregularities. During flight, the fuselage structure perceives loads in the form of transverse and longitudinal forces, bending and torsional moments, which are caused by the general bending of the structure due to the action of aerodynamic, inertial and dynamic loads, as well as overpressure, which is formed in the middle of the pressurized part of the fuselage during operation of the air conditioning system.The main cutouts can be: cutouts for windows, doors, luggage, maintenance and emergency hatches, cutouts for the cargo hatch. Particular attention must be paid to the cutouts that are in the sealed area of the fuselage. The presence of a cutout in the structure of the fuselage shell leads to a weakening of the cross section of the fuselage in the cutout area. As an object of study, a cutout was chosen, which is located in the middle part of the fuselage under the door (1922x1012 mm). The presence of such a cutout in the fuselage shell creates a sufficiently high concentration of stresses, namely in the area of the cutout corner rounding radii. There, in addition to the concentration due to the corners of the cutout, which are rounded, there is also a concentration around the holes for fasteners, which are located near the rounding radii. It is in this zone that there is the highest probability of the formation and development of fatigue cracks.To achieve the desired durability indicators in the zone of significant stress concentration, a number of design and technological solutions are used. The use of constructive and technological solutions provides the requirements of static strength and durability in the areas of cutouts in the pressurized fuselage and puts forward the problem of obtaining a structure with a minimum mass