Multi-objective optimization of mechanical and microstructural characteristics in a stir casting process of MWCNTs/Al6082 composites using neutrosophic TOPSIS and GRA

The objective of this paper is to find optimum process parameters of stir casting process for multi-walled carbon nanotubes (MWCNTs) reinforced Al6082 composites in a multi-objective optimization context. In this work, output parameters include ultimate tensile strength (UTS), hardness, compressive strength (CS), and uniform distribution of MWCNTs. Among these, first three parameters can be measured, and data can be obtained in quantitative terms. However, uniformity of distribution of MWCNT is a qualitative variable, and hence neutrosophic sets are used in this work. Each of the four input process parameters, such as fraction weight of MWCNTs, stirring speed, furnace temperature, and stirring time, are taken at three levels each, and experiments are designed using Taguchi L27 array. Information entropy method is used to compute the weights of output parameters. TOPSIS method is used to normalize the quantitative data, and neutrosophic TOPSIS is applied for normalizing the data related to uniformity. It is found that MWCNT's percentage of 0.9, speed of 450 rpm, temperature of 800 degrees C, and time of 10 minutes, yield best output parameters. Neutrosophic gray relational analysis is also used to find optimum solution for above case, and the optimum values obtained from both methods are compared.