Issue 44

N.M. Khansari et alii, Frattura ed Integrità Strutturale, 44 (2018) 106-122; DOI: 10.3221/IGF-ESIS.44.09

Each initial population is created during a random process. The results of GA optimization for three different initial populations are presented in Tab. 5, Tab. 6 and Tab. 7. The aforementioned Tables are indicating that there are insignificant differences between the results for three different initial populations.

Rotational Speed (Rpm)

Forward Speed (Mm/Min)

tensile strength (MPa)

Initial Population

50 75

1104.2 1096.8 1107.8

94.338 94.573 94.651

461.01 462.23 462.52

100

Table 5 : GA optimization of AA2024 for different initial populations.

Rotational Speed (Rpm)

Forward Speed (Mm/Min)

tensile strength (MPa)

Initial Population

50 75

512.29 481.05 499.58

87.903 85.475 85.074

80.455

80.48

100

80.492

Table 6 : GA optimization of AA5050 for different initial populations.

Rotational Speed (Rpm)

Forward Speed (Mm/Min)

ultimate strength (MPa)

Initial Population

50 75

466.9

72.725 71.087 70.296

216.33 217.36 217.56

509.12 490.87

100

Table 7 : GA optimization of AA5050 for different initial populations.

Furthermore, tensile and ultimate strength as an objective function versus number of evaluations for three different initial populations have been demonstrated as well in Fig. 16 to Fig. 18.

Figure 16 : Tensile strength of AA2024 versus number of evaluations for three different initial populations.

As it shown in Figs. 15 to 17, for all three distinct initial populations, tensile strength data for AA2024 and AA5050 obtained approximately as 462 and 80.5 MPa respectively. In addition, the evaluation reported for ultimate strength of AA5050 is 217 MPa. In the following, convergence stability versus the number of generations for three initial populations has been investigated (see Fig. 19 and Fig. 20). The convergence stability criterion is based on mean and standard deviation of the output parameters. It means that, for stable population, the optimization is converged.

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