PSI - Issue 10

N.M. Vaxevanidis et al. / Procedia Structural Integrity 10 (2018) 333–341 N.M. Vaxevanidis et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 7. Main effects and interactions plots for Fc, Ra and Rt.

conducted using Minitab ® 17 software with stepwise technique to eliminate the insignificant terms from the models. The models are given in equations 1, 2 and 3 for Fc, Ra and Rt respectively: Fc (N) = 69.7-0.0218*n-612*f+194.9*a+1283*f 2 -53.38*a 2 +0.135*n*f-65*f*a (1) Ra (μm) = 9.30-0.00413*n-3.1*f-2.55*a+29.1*f 2 +1.56a 2 +0.00494*n*f-0.00002*n*a-3.49*f*a (2) Rt (μm) = 75.3-0.0319*n-103*f-35.3*a+210*f 2 +13.5*a 2 +0.0512*n*f+0.00637*n*a-3.5*f*a (3) Outputs referring to the studied objectives; i.e., Fc, Ra and Rt where compared to those predicted by the corre sponded predictive models. From Figs.8,9 it is evident that a very good correlation has been achieved among experi mental and predicted results for all responses. The prediction model developed for Fc has an R 2 equal to 99.44%; the