Multi-objective optimization of converting process of auxetic foam using three different statistical methods

This paper studies the optimization of converting process parameters of conventional foam into the auxetic. The control factors of converting process are heat temperature, pressure and time. The aim of this study is to achieve an optimum combination of these control factors for obtaining maximum stiffness and minimum negative Poisson's ratio as the desired responses. A series of experiments were implemented based on the Taguchi orthogonal array design. In order to determine the optimum control factors level, three different multi-objective optimization methods i.e. grey relational analysis, fitness function and desirability function were employed. The optimum combinations achieved form all methods were verified through the confirmation tests. Although outcomes of all these methods, in the case of both Poisson's ratio and stiffness, were in a good agreement with the confirmation tests, however the result of grey relational analysis had the minimum mean error percentage. Also, all these methods reported the pressure, heat temperature and time as the first, second and third level of significance, respectively. This study allows manufacturer to select the optimization procedure appropriately and produce the auxetic foam with minimum waste material.