LIBRARY ı6ıul 0) - Cranfield University

Table 6.3 - Coefficients of Ogunbiyi's models obtained for BDH-550
Regression Coeffic ients
Variable E . No a S SE R"
Imean (3.1) 53.6415 24.65153
-0.41327 9.933 0.9830
TSI (3.2) 3.4557 -0.006043 -0.034601 0.2543 0.7585
Imean (3.3) 0.324805 0.693878
-
15.8588 0.996
VbkJVea (3.4)
-0.335025 0.002398 0.040318 0.1121 0.8545
Vbk (3.5)
PR (3.10)
-30.78784 -0.031138 2.26504 1.0091 0.9921
-0.92147 -2.8511E-6 0.068592 0.0433 0.9818
Obs.: The coefficients of the models shown in equations (3.6) to (3.9) were kept the same as shown
in Table 3.1
SE standard error of the model
R2 coefficient of determination of the model
Note that the coefficients used for predicting the bead geometry using
equations 3.6 and 3.7 were developed for fillet welds carried out in the horizontal-
vertical position (see Table 3.1). The welding trials in this work were carried out in
the flat welding position. Thus, the average values of both predicted and measured
geometrical features were used in order to apply a calibration model to the original
prediction models. Table 6.4 shows the predicted and measured geometrical features
for the chosen specimens.
Figure 6.4 shows the plot of the measured average leg length against the
predicted average leg length. A linear function was chosen to fit the data (see
equation (6.2)).
Lee. sso
= 0.8802
" Le ä 32Ö
+0.623
R2 = 0.9435
SE=0256
(6.2)
where 20 Leg length predicted by using equation 3.6 with the coefficients from
Table 3.1
Predicted leg length adjusted to the BDH550 power source
RZ Coefficient of determination of the model
SE Standard error of the model
Figure 6.5 shows the plot of the measured average weld penetration against
the predicted average weld penetration calculated by using equation 3.7. Also, a linear
function was chosen to fit the data. (see equation (6.3))
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