Six criteria (C1, C2, . . ., C6) are contemplated to com- pare the alternatives. The weights ‘assignment  Procedure

calculated by Chang and based on the Fuzzy AHP technique (Chang, 1996) (Table 2).

The alternatives by the Complex proportional assessment method are ranked according to their Qi values, and the alternative having the maximum value of Qi is the best. In respect to the case-study Q1 =

Alternatives by MOORA method are ranked also accord- ing to the value of Qi, and the alternative with the peak value of Qi  is  the  supreme  alternative.  In  respect  to our case-study Q1 = 0.303, Q2 = 0.239, Q3 = 0.308, Q4 = 0.139, Q5 = 0.259, Q6 = 0.294.

According to the TOPSIS method, the relative closeness of these six different alternatives to the ideal one results to be C1 = 0.830, C2 = 0.637, C3 = 0.827, C4 = 0.217, C5 = 0.693 and

This method levels the alternatives allowing to the signif- icance of three different scalar quantities like Si, Ri        and

Table 2 Choice criteria of connecting rod.

Criteria Orientation Symbol

Cost (TL/kg) Minimization property C

Tensile strength (N/mm2) Maximization property TS

Fatigue limit (N/mm2) Maximization property FL

Fracture toughness (N/mm2) Maximization property FT

Machining Maximization property PM

First fracture brittleness Maximization property FFB

A comparative study of some prominent multi criteria decision making methods 549

Conclusions

In the present study the choice of material has been inspected and examined for a connecting rod with the help of different MCDM methods. This study collates five illus- trious MCDM techniques to a specific case study. Actually this paper explored the authentic materiality and cogency of these decision making techniques for the focused task. The study also analyzes frontiers and benefits associated with the application of the opted methods. TOPSIS and VIKOR, methods results to be the most advisable to the focused

Qi. For each criterion Cj, the best a∗  and inferior a−    per- decision making, because the adequacy to supervise all type formances amongst all the six alternatives firstly have    to be determined. After that the values Si, Ri and Qi have to be evaluated. In respect to the case-study Q1 = 0.509, Q2 = 0.425, Q3 = 0, Q4 = 1, Q5 = 0.951, Q6 = 0.533.

ARAS method

Additive ratio assessment method is recently contemplated MCDM method. In ARAS method, the most suitable choice is resolute according to the degree of utility Qi, and this can be determined by using the formula: Qi = Si/S0; i = 1, 2, 3,

. . ., m. Where Si is the ‘‘overall performance index’’ of ith alternative, S0 is ‘‘overall performance index’’ of optimal alternative, and S0 has a value which equals to 1. In respect to the study Q1 = 0.233, Q2 = 0.199, Q3 = 0.231, Q4 = 0.149, Q5 = 0.212, Q6 = 0.233.

Results and discussion

Chapter and verse regarding the validity of every above MCDM methods to the material selection problem of con- necting rod is resumed in Table 3. All the five applied methods are very useful for the specific decision making problem.

In the table, it is not so much astonishing that pearlite and bainite are the most assertive materials for connecting rod. Where FRACTIM and 70MnSV4 are the next alternatives for the connecting rod materials, but tempered Martensite and Martensite is not an acceptable choice for a crackable connecting rod.

of acumen criterion and variables, the precision of their results and chop down the obscurity in dealing among param- eters and preferences they engross are commendable. Both the methods administer a perse ranking file. The top- ranked alternative by VIKOR method is very much nearer to the ideal solution. However, top-ranked alternative by TOP- SIS is the finest in terms of the ranking index, which does not mean that is always nearest to the ideal solution. In addition to ranking, the VIKOR method asserts a compromise solution with a dominance rate.