Aeroelastic Optimization Design of the Global Stiffness for a Joined Wing Aircraft

Due to the complexity and particularity of the joined wing layout, traditional design methods for the global stiffness of a high-aspect wing are not applicable for a joined wing. Herein, a beam-frame model and a three-dimensional wing-box model are built to solve the global stiffness aeroelastic optimization design problem for a joined wing. The goal is to minimize the weight, and the constraints are the overall aeroelastic requirements. Based on a genetic algorithm, two methods for the beam-frame model and one method for the three-dimensional model are used for comparative analysis. The results show that the optimization method for a diagonal beam section and the optimization method for an exponential/linear combination function fit are adequate for optimizing and designating the joined wing global stiffness. The distributions obtained using the two methods have good consistency and are similar to the distribution of the three-dimensional model. The stiffness distribution data and the beam section parameters can be converted from each other, which is convenient for redesigning the structure parameters using the stiffness distribution data, and is valuable for engineering applications.

INVESTIGATION OF BEHAVIOR OF INTERIOR STEEL CONNECTIONS WITH OPENINGS IN BEAM WEB AND FLANGE UNDER MONOTONIC LOADING

Connections are considered to be one of the most prominent components of steel moment frames and have received studious attention in recent years. The core problem of welded connections is premature brittle fracture of weld in the critical beam-to-column connection region. Within the framework of this issue, various approaches have been proposed to solve the mentioned problem. Intentional weakening of the beam web or flange is in line with the purpose of leading the plastic hinge away from the column face, hence, increasing the ductility. The aim of this research is to investigate the behavior of interior connections subjected to monotonic lateral loading in case of presence of openings in beam web or flange. To do so, an ordinary fully welded rigid connection, reduced beam section, reduced web section, and drilled flange connection models are simulated numerically, utilizing finite element software, ANSYS. The results indicate that scrupulous selection of opening sizes are of great importance to fulfill the desired outcome which is avoiding the brittle failure of connections. Furthermore, the use of drilled flange, reduced beam section, or reduced web section connections satisfy the expected performance and it is proposed to use them according to practicability, architectural and economic considerations as well as site conditions. Shear deformation and local buckling is observed in reduced web section connections while in drilled flange connections, stress concentration around the opening is critical.

Behavior of under and over-reinforced concrete slender beams at failure

The focus of this paper is to examine the behavior of under and over-reinforced concrete slender beams at failure. The total number of the beams were five, with the provision of the following percentage of tension reinforcements: 1.01% for beam 1 (B1), 1.51% for beam 2 (B2), 2.01% for beam 3 (B3), 2.62% for beam 4 (B4) and 3.01% for beam 5 (B5). The beams were loaded with point loads at the center, with shear span/depth ratio of 3.8. The actual ultimate load of the experimental beam B1 was 141% of the estimated ultimate, while for beams B2, B3, B4 and B5, the actual ultimate loads were between 68% and 87% of the estimated ultimate loads for the beams respectively. The reinforced concrete beams B1, B2 and B3 had the capacity to sustain large deformation under constant loads before their ultimate failure, hence will give warning about the impending failure. For beams B4 and B5, although failed at higher loads had limited rotation capacity, hence will not give warnings about the impending failure. Therefore, 2.01% tension reinforcement is recommended as the maximum to be provided, so that the beam section can behave as a ductile section.

By the problem of the possibility of technological movement of large assembly units along ice transportation routes

В настоящей работе авторами приводится теоретический анализ практической возможности транспортирования тяжеловесного судового оборудования или сборочно-монтажных единиц (СМЕ) судового оборудования по специально созданным технологическим ледяным путям. Для обоснования выбранной темы научного исследования авторы ссылаются на ряд литературных источников, посвященных вопросам практического использования льда в качестве материала для транспортирования различных грузов. Приводятся примеры использования льда для создания: взлетно-посадочных полос аэродромов; переправ через водные преграды; зимних трасс в северных широтах в Росси и ряде других стран для транспортирования тяжеловесных сооружений и т.п. Авторами рассматриваются физико-механические свойства пресноводного льда с целью определения параметров транспортировочных балок, включающих в свой состав опорный ледяной массив. В статье приведена схема расположения и назначение элементов транспортировочной оснастки, расположенной под полкой агрегата СМЕ. Выполненное теоретическое исследование совместной работы транспортировочной балки с ледяным массивом, упругой компенсирующей прокладкой и жесткой полкой СМЕ позволило установить взаимосвязь толщины ледового бруса и толщины прокладки с упругой деформацией транспортировочного пути и его жесткостью, используя которую можно обоснованно назначать: - толщину сечения ледового бруса и грузонесущей балки; - параметры сечения и материал компенсирующей прокладки; - размеры транспортировочной балки и в целом конструкцию транспортировочных путей. In this article, the authors investigate the theoretical analysis of the practical possibilities of transporting heavyweight ship equipment or assembly units of ship equipment on the specially created technological ice paths. For substantiate the chosen theme of scientific research, the authors refer to a number of scientific sources devoted to the practical use of ice as a material for the transportation of various cargoes. Examples of using ice to create: airfield runways; crossings over water obstacles; winter routes in the northern territories of Russia and other countries for the transportation of heavy constructions, etc. The authors investigate the physical and mechanical properties of freshwater ice in order to determine the parameters of the transport beams, which include the supporting ice block. The article shows the layout and purpose of the elements of the transportation equipment located under the shelf of the assembly unit. The results theoretical research of the operation of a transport beam with the ice block, the elastic compensating gasket and the bearing construction assembly unit made possible to determine the correlation between the thickness of the ice block and the thickness of the gasket with the elastic deformation of the transportation path and its rigidity, using which one we can reasonably assign: - the thickness of the section of the ice block and the load-carrying beam; - section parameters and material of the compensating gasket; - the parameters of the transport beam and the construction of the transport routes in general.