PSI - Issue 38

Frédéric Kihm et al. / Procedia Structural Integrity 38 (2022) 12–29 Kihm, Miu, Bonato / Structural Integrity Procedia 00 (2021) 000 – 000

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Fig. 6. Comparison of the predictions between the temperature-only model and the temperature-plus-pressure model

The temperature-only model has a 29.9% relative absolute error (RAE), whereas the temperature-plus-pressure model has a 28.1% RAE. When displaying the absolute value of the residual as a function of the difference in prediction between the two models, it appears that the temperature-plus-pressure model seems to correct predictions the most where the difference in predictions is greater than 0.0001. The previous exercise was repeated by considering this time the effects of temperature and acceleration (the input least correlated with the output) on damage. The p-value of the acceleration damage slope is very high. This means that the slope can reasonably be zero, thereby having no effect on the output. In addition, the expected value of this slope is three orders of magnitude less than the slope of the temperature damage. Therefore, the effect of the acceleration on the output is minute and this can also be seen from the distribution of residuals which remains largely unchanged. It was observed that the predictions change very little by including the additional acceleration dimension. Finally and similarly, we investigate the effects of all input variables on strain damage, even though we’ve already seen that acceleration is not a good predictor in conjunction with temperature. The results of the Ordinary Least Squares function are presented in Table 6:

Table 6. OLS results.for the case with TemperatureDamage, PressureDamage and AccelerationDamage inputs Dep. Variable: StrainDamage R-squared 0.830 No. Observations 138 Adj. R-squared 0.826 Df Residuals 134 Prob (F-statistic): 2.44e-51 Df Model 3

coef

P value

[0.025 -0.001 0.010 0.000 -0.001

0.975] 0.000 0.011 0.002 0.001

const

-0.0001 0.0104 0.0010

0.654 0.000 0.006 0.888

TemperatureDamage

PressureDamage

AccelerationDamage

8.755e-05

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