Abstract:

Nowadays the structures of satellites, aircrafts and vehicles will be optimized with regard to various criteria. This can be mass, stiness or other parameters. However at the same time some demands - also called restrictions - must be met. Typical examples of these demands are stress, natural frequency and cost. Therefore in recent years robust design has been more important as a result of structural optimization, which can be also insensitive to small changes. One approach to assess the robustness of the design is fuzzy set theory. The response parameters (mass, stress, etc.) will be represented as Fuzzy Numbers, which don't have a xed value but a range of variation. These parameters must be compared with allowable values (e.g. allowable stress) during the optimization. Hence it's impossible for an easy "greater/equal/less" classication. And the comparison method plays a decisive role when design parameters and allowable values (restriction) are compared to each other. In this paper about twenty dierent comparison methods will be discussed. With the aid of the implemented codes of these methods in MatLab the methods will be compared to each other and then a best method will be selected to be validated in the real optimization problem "Ten Bar Truss".