Optimal design of multi-component structures of agricultural engineering

Реальные задачи проектирования агротехники отличаются необходимостью применения комплексных моделей функционирования, сложной пространственной геометрией, большим количеством критериев и ограничений. Рассмотрены стадии оптимизации многокомпонентных конструкций агротехники: выбор комплексных многодисциплинарных математических моделей анализа функционирования; определение параметров проектирования в пространстве поиска; выбор функционалов качества (критериев цели) и ограничений оптимизируемого агрегата; определение метода оптимизации. Проанализирован многоуровневый иерархический подход. Разработаны две базовые методики анализа чувствительности и оптимизации при проведении исследования жизненного цикла многокомпонентных конструкций агротехники - от проектирования до эксплуатации и утилизации. Приведены примеры реализованных прикладных инжиниринговых разработок и проектирования изделий агротехники.The works in optimal design of agricultural engineering have been described in this article. Short information is resulted about the basic creative stages and fundamental scientific achievements of National Technical University "Kharkiv Polytechnic Institute". The real problem of modeling agricultural machines is the need to use complex models of functioning, complex spatial geometry, a large number of criteria and functional limitations. The stages of optimization of multi-component structures of agricultural machines have been considered: the choice of mathematical analysis models; selection of design parameters of the search space; functional definition of quality (objective criteria) and restrictions optimized unit; optimization methods. Multi-level hierarchical approach is analyzed. Two basic analysis techniques of sensitivity and optimization when carrying out a research of life cycle of multicomponent constructions of an agrotechnology – from design before operation and utilization have been developed. The use of technology of "Simulation based design" is based on the application of multiple modeling by finite elements of arbitrary characteristics of loaded structures of agriculture in different production environments. Examples of the realized applicationoriented engineering development and design of products of an agrotechnology are given

Performance-based optimization of structures: theory and applications

Performance-based Optimization of Structures introduces a method to bridge the gap between optimization theory and its practical applications to structural engineering. The performance-based optimization (PBO) method combines modern structural optimization theory with performance-based design concepts to produce a powerful technique for use in structural design. This book provides the latest PBO techniques for achieving optimal topologies and shapes of continuum structures with stress, displacement and mean compliance constraints. The emphasis is strongly placed on practical applications of automated PBO techniques to the strut-and-tie modeling of structural concrete, which includes reinforced and prestressed concrete structures. Basic concepts underlying the development of strut-and-tie models, design optimization procedure, and detailing of structural concrete are described in detail. The design optimization of lateral load resisting systems for multi-story steel and steel-concrete composite buildings is also presented. Numerous practical design examples are given which illustrate the nature of the load transfer mechanisms of structures

ВИЗНАЧЕННЯ ОПТИМАЛЬНОЇ ДОРОЖНЬОЇ КОНСТРУКЦІЇ З ПОПЕРЕЧНИМИ ДРЕНАЖАМИ МІЛКОГО ЗАКЛАДАННЯ

Optimal engineering solutions are not always available in the design of road pavement, resulting in large losses in road construction. The justification of the optimal design should be based on an analysis of the range of natural conditions. An assessment of the range of technical and technological parameters determining the work of shallow drainage structures is carried out by means of a collective expert assessment carried out by means of questionnaires from leading experts in the sector. A target function has been defined for finding the most optimal design of shallow drainage under two groups of criteria: estimated cost and a set of technical and technological indicators, which are characterized by the efficiency of its operation. Of the eight proposed shallow drainage structures, the best engineering design was validated and recommended at the lowest estimated cost.Optimal engineering solutions are not always available in the design of road pavement, resulting in large losses in road construction. The justification of the optimal design should be based on an analysis of the range of natural conditions. An assessment of the range of technical and technological parameters determining the work of shallow drainage structures is carried out by means of a collective expert assessment carried out by means of questionnaires from leading experts in the sector. A target function has been defined for finding the most optimal design of shallow drainage under two groups of criteria: estimated cost and a set of technical and technological indicators, which are characterized by the efficiency of its operation. Of the eight proposed shallow drainage structures, the best engineering design was validated and recommended at the lowest estimated cost

Earthquake Engineering

The book Earthquake Engineering - From Engineering Seismology to Optimal Seismic Design of Engineering Structures contains fifteen chapters written by researchers and experts in the fields of earthquake and structural engineering. This book provides the state-of-the-art on recent progress in the field of seimology, earthquake engineering and structural engineering. The book should be useful to graduate students, researchers and practicing structural engineers. It deals with seismicity, seismic hazard assessment and system oriented emergency response for abrupt earthquake disaster, the nature and the components of strong ground motions and several other interesting topics, such as dam-induced earthquakes, seismic stability of slopes and landslides. The book also tackles the dynamic response of underground pipes to blast loads, the optimal seismic design of RC multi-storey buildings, the finite-element analysis of cable-stayed bridges under strong ground motions and the acute psychiatric trauma intervention due to earthquakes

Supporting brace sizing in structures with added linear viscous fluid dampers: A filter design solution

Viscous fluid dampers have proved to be effective in suppressing unwanted vibrations in a range of engineering structures. When dampers are fitted in a structure, a brace is typically used to attach them to the main structure. The stiffness of this brace can significantly alter the effectiveness of the damper, and in structures with multiple dampers, this can be a complex scenario to model. In this paper, we demonstrate that the effects of the brace compliance on the damper performance can be modelled by way of a first-order filter. We use this result to formulate a procedure that calculates the stiffness required by the supporting brace to provide a specified effectiveness of the damping action. The proposed procedure assumes that viscous dampers have been sized in a previous design step based on any optimal methodology in which, as is usually the case, the presence of supporting braces and their dynamic effects were neglected. Firstly considering a one degree-of-freedom system, we show that the proposed method ensures a desired level of damper efficiency for all frequencies within a selected bandwidth. Then the analysis is extended to the case of multi-degree-of-freedom systems to show that the design criteria can be applied in a straightforward and successful manner to more complex structures

Size and Shape Optimization of Space Trusses Considering Geometrical Imperfection-Sensitivity in Buckling Constraints

Optimal design considering buckling of compressive members is an important subject in structural engineering. The strength of compressive members can be compensated by initial geometrical imperfection due to the manufacturing process; therefore, geometrical imperfection can affect the optimal design of structures. In this study, the metaheuristic teaching-learning-based-optimization (TLBO) algorithm is applied to study the geometrical imperfection-sensitivity of members’ buckling in the optimal design of space trusses. Three benchmark trusses and a real-life bridge with continuous and discrete design variables are considered, and the results of optimization are compared for different degrees of imperfection, namely 0.001, 0.002, and 0.003. The design variables are the cross-sectional areas, and the objective is to minimize the total weight of the structures under the following constraints: tensile and compressive yielding stress, Euler buckling stress considering imperfection, nodal displacement, and available cross-sectional areas. The results reveal that higher geometrical imperfection degrees significantly change the critical buckling load of compressive members, and consequently, increase the weight of the optimal design. This increase varies from 0.4 to 119% for different degrees of imperfection in the studied trusses