Structural optimization under equivalent static loads transformed from dynamic loads based on displacement (original) (raw)
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Optimization and Engineering
This paper presents a new computational procedure for optimization of structures subjected to dynamic loads. The optimization problem is formulated with discrete design variables that represent the members from a table of commercially available members. Also, the requirements in the American Institute of Steel Construction (AISC) manual are formulated as constraints. This results in a nondifferentiable optimization problem. In the new procedure, the dynamic load is transformed into equivalent static loads (ESLs). Then the static response optimization problem having discrete design variables is solved using a metaheuristic optimization algorithm. Three methods to calculate the ESLs are investigated. It is found that the ESL cycles cannot converge to the final design. Therefore after a few ESL cycles, the original dynamic loads need to be used in the optimization process. Four example problems are solved to analyze the procedure. Based on this analysis, it is concluded that the new procedure is more efficient compared to a procedure that does not use the ESL cycles because it reduces the total CPU effort to obtain the final design. Also, better final designs are found. The reason is that many more designs are analyzed very efficiently with the ESL procedure.
Optimization of structural dynamic behaviour based on effective modal parameters
International Journal for Numerical Methods in Engineering, 2007
Optimization of complex structures often leads to high calculation costs. Indeed, the structure has to be frequently reanalysed in order to update the optimization criteriums. We propose an optimization method based on effective modal parameters. These parameters are close to the modal matrices used for the modal analysis of a structure. Thus, once the structure has been analysed, it becomes very easy to calculate optimization criteria. First, we will explain the modal analysis that we will use in this paper. A modal model will be used to analyse the hollow parts of the structure. The modal analysis of the whole structure will be performed using substructuring and "double modal synthesis" proposed by Jezequel. Secondly, we will explainthe how to obtain effective modal parameters and their use for optimization. Finally, we will show the efficiency of these parameters through the optimization of a complex structure, using two types of optimization methods.
An optimality criterion method for dynamic optimization of structures
International Journal for Numerical Methods in Engineering, 1989
This paper presents an optimality criterion method for the determination of the least weight design of a structural system which satisfies a specific frequency requirement plus upper and lower bounds on the design variables. The design algorithm is an iterative solution of the Kuhn-Tucker optimality criterion based on choosing a single value of the Lagrange multiplier which minimizes the sum o f the squares of residuals. The method has been applied to a variety of structures. Results assert that the method is capable of locating the optimal design in a small number of redesign cycles. The method avoids the scaling of design variables. It can treat non-structural masses and is applicable to structural elements with a wide variety of size-stiffness. The procedure has been completely automated in a computer program on an IBM-PC microcomputer.
Transactions of the Korean Society of Mechanical Engineers A, 2006
Nonlinear Response Optimization using the Equivalent Static Loads (NROESL) method/algorithm is proposed to perform optimization of non-linear response structures. The conventional method spends most of the design time on nonlinear analysis. The NROESL algorithm makes the equivalent static load cases for each response and repeatedly performs linear response optimization and uses them as multiple loading conditions. The equivalent static loads are defined as the loads in linear analysis, which generate the same response fields as those in non-linear analysis. The algorithm is validated for the convergence and the optimality. The NROESL algorithm is applied to several structural problems with geometric and/or material nonlinearity. Conventional optimization with sensitivity analysis using the finite difference method is also applied to the same examples. The results of the optimizations are compared. The proposed NROESL method is found to be very efficient and good solutions are derived.
Optimal structural design under dynamic loads
International Journal for Numerical Methods in Engineering, 1977
This paper presents an algorithm for optimal design of elastic structures, subjected to dynamic loads. Finite element, modal analysis and a generalized steepest descent method are employed in developing a computational algorithm. Structural weight is minimized subject to constraints on displacement, stress, structural frequency, and member size. Optimum results for several example problems are presented and compared with those available in the literature.
Optimization of structures subjected to dynamic load: deterministic and probabilistic methods
REM - International Engineering Journal, 2016
This paper deals with the deterministic and probabilistic optimization of structures against bending when submitted to dynamic loads. The deterministic optimization problem considers the plate submitted to a time varying load while the probabilistic one takes into account a random loading defined by a power spectral density function. The correlation between the two problems is made by one Fourier Transformed. The finite element method is used to model the structures. The sensitivity analysis is performed through the analytical method and the optimization problem is dealt with by the method of interior points. A comparison between the deterministic optimisation and the probabilistic one with a power spectral density function compatible with the time varying load shows very good results.
Optimization in Structural Analysis and Design
2009
Two main tasks of a structural engineer, as for many other branches of engineering, are analysis and design. Among these two, the latter needs more knowledge, skill and experience. It even comprises completely the first one, that is, a designer must already have the capacity of analysis.
Structural Design Optimization-Numerical and Simulation Approaches
2019 ASEE Annual Conference & Exposition Proceedings
is a graduate of Elizabeth City State University, acquiring a Bachelor Degree of Science in Engineering Technology, focus on Mechanics and Automation. Momen also minored in Mathematics, as he desired to be versatile and knowledgeable in the Engineering world. His research interest are in structural engineering, bridges, and aspires further education in those fields.