# Advances on Mechanics, Design Engineering and Manufacturing

## A introduction of Advances on Mechanics, Design Engineering and Manufacturing :

The improvements in the design of structural components are often reached by an iterative approach driven by the designer experience. Even if this represents a key aspect of the design process, an approach that is completely based on experience, usually, can lead to only marginal improvements and would take quite a long time.

A complementary approach is what makes use of structural optimization methods [1,2] to determine the optimal characteristics, topology and/or shape of an object. In the recent years, structural optimisation has considerably developed and the interest concerning its practical applications is steadily growing in many engineering fields [3-8]. Of course, the improvements of the information technology tools have strongly contributed to the spreading of the numerical analysis methods, like FEM or BEM, which can be effectively used during the optimization process of a structure. Advances on Mechanics, Design Engineering and Manufacturing.

In the past, many research activities related to the optimization methods were focused primarily on mathematical aspects of the problem, trying to adapt the available analytical and numerical methods to solve particular structural problems. These kinds of problems, in fact, are quite difficult
to solve making use of non-convex functions with several variables (continuous and discrete). Practical applications of these optimization methods usually forces the designer to simplify the problem, often dramatically, with a consequent lost of reliability.Advances on Mechanics, Design Engineering and Manufacturing.

Therefore, in the engineering field, the need for new optimization procedures (alternative to classic mathematical approaches) has arisen during years. These alternative approaches would allow maintaining some generality and accuracy in the description of real complex problems, but leading to solutions reasonably similar to those considered rigorously optimal. Consequently, since the early 1990s, different new optimization methodologies, based on numerical approaches [3, 8, 9], have been proposed. In this scenario, the Evolutionary Structural Optimization (ESO) has become one of the most interesting and known technique [6, 10, 11]. Advances on Mechanics, Design Engineering and Manufacturing.

Following the ESO approach, the optimal solution is searched basing
on heuristic rules. Unlike traditional methods, the evolutionary strategy has shown a high degree of efficiency for different typologies of structural problems [11]. The solutions found using the ESO approach, however, might be influenced by the chosen optimization parameters [10, 11]. Although several papers are found in literature concerning the ESO approach, to the authors knowledge, much little information is available regarding the effect of the parameters on the optimal solution.Advances on Mechanics, Design Engineering and Manufacturing.

In this work, it has been investigated how the main control parameters, used in an evolutionary optimization process, can affect the result. One of the main advantages of the proposed approach concerns the comparison between two of the most commonly used efficiency criteria. The goal is to provide useful guidelines that can lead designers to obtain the best result for every (particular) optimization problem.