Simultaneous topology and size optimization of structures by genetic algorithm using minimal length chromosome

Abstract

PurposeLayout optimization of structures aims to find the optimal topology and member sizes in an integrated manner. For this purpose, the most successful attempts have addressed the outstanding features of the genetic algorithms.Design/methodology/approachThis paper utilizes a direct index coding (DIC) in a way that the optimization algorithm can simultaneously integrate topology and size in a minimal length chromosome in order to seek the true optimum in an efficient and reasonable manner. Proper genetic operators are adopted for this special kind of encoding together with some modifications in the topological mutation aiming to improve the convergence of the algorithm.FindingsThe present DIC, has the following features: enforcing one‐to‐one correspondence between discrete genotype space and the problems' phenotype space; avoiding any out‐of‐bound parameter addressing and limiting the GA search only to necessary genotypes; reduction in the size of genotype search space to increase the algorithm convergence and the possibility of leading to the global optimum; dealing with direct genetic operators so that the GA parameters can be purely controlled to tune the desired balance between convergence and escaping from local optima.Originality/valueEmploying direct index chromosome makes it possible to eliminate the additional topological bits in treated examples.

Dynamic selective pressure using hybrid evolutionary and ant system strategies for structural optimization

“…In the first attempt, two-point crossover and a population of size 40 were employed. Both these first and second sample runs resulted in the global optimum mentioned in the literature [20] (Table III), but it took less computational effort for the proposed method of DSP as indicated in Table IV. For the second attempt, uniform crossover and a smaller population size were applied to a randomly generated set of individuals as initial population.…”

“…As a benchmark example, the well-known 6-node truss of Figure 1 is treated here [20,[37][38][39][40][41][42][43]. Material properties are taken as E = 68.95 GN/m 2 , = 27.1 kN/m 3 , allowable axial stress is a = ± 172 MN/m 2 and nodal displacements are confined to | a,y | 0.0508 m. In this example, optimal integrated topology and size is searched provided that each of P 1 and P 2 is applied as a separate loading condition [43].…”

“…For this purpose, the authors developed a special type of integer coding that deals with section indices as the character alphabet assignable to genes [19,20]. For the case of topology optimization, a zero index is added to such a list to indicate elimination of the corresponding member group in the structural model [20]. Another interesting feature of such a direct index coding (DIC), is revealing the definition of mutation band and then controlling it in an adaptive manner [21].…”

Optimizing the layout of rectangular hull tiles

“…Now it is able to lay them based on the computerized three-dimensional surface model. The optimum (Guo et al, 2003;Yu et al, 2003;Wu et al, 2007;Kaveh and Shahrouzi, 2006;Pugsley et al, 2006) layout design of the rectangular tiles is necessary because it influences the layout quality denoted by the deformation of them and the layout workload denoted by the number of fixing bolts and the amount of stuffing. Therefore, they could impact the ship construction period and costs.…”

Optimización estructural y topológica de estructuras morfológicamente no definidas mediante algoritmos genéticos

“…Kaveh y Shahrouzi [198] emplearon un Algoritmo Genético binario donde utilizaron una codificación indexada mediante una tabla de correspondencias en lugar de la tradicional codificación binaria, obteniendo un comportamiento más eficiente del algoritmo comparado con una codificación binaria tradicional. Aplicaron el algoritmo a la clásica estructura de diez barras, con un resultado aceptable, así como a la también clásica estructura de 25 barras.…”