Issue 45

S. Harzallah et al, Frattura ed Integrità Strutturale, 45 (2018) 147-155; DOI: 10.3221/IGF-ESIS.45.12

n

1

   i



2



(10)

RMSE

y x

i

n 

i 1

1 n



n





2

y x 

i

i

i 1 





rRMSE

100

(11)

1



n i i 1 x 

N

Depth of crack estimated Length of cracks estimated

Depth of crack

Stocking data base

 z

ANN

Direct Model by FEM

Length of cracks

X position

Figure 6 : Inverse problem RN with two inputs and two outputs.

The ranges of rRMSE define the model performance as: Excellent if: rRMSE < 10% Good if: 10 % < rRMSE < 20% Fair if: 12 % < rRMSE < 30% Poor if: rRMSE > 30%

1

n i 1 





y x 

MAE

(12)

i

i

N

n i 1 n i 1  

 

 

  y x ² y y ²   i i



R

²

(13)

i

i

y is the average of estimated values and N is data number.

and x i

are the estimated and the measured values, i

where: y i

Figure 7 : Cost function (MSE) vs. number of iterations.

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