PSI - Issue 24

8

Michele Perrella et al. / Procedia Structural Integrity 24 (2019) 601–611 Perrella et al. / Structural Integrity Procedia 00 (2019) 000–000

608

By the experimental data of Fig. 5 and eq. (4) it was possible to evaluate each shift factor involved in the construction of the master curve, setting as corresponding temperature = 25 ° . The procedure for evaluating the shift factor for creep compliance at 30°C is presented in Fig. 7, whilst all the shift factors used for the master curve construction are reported in Table 5.

0.00025

T=25°C J(30°C; t(30°C)) J(30°C; tr(30°C))

0.00020

0.00005 Creep compliance J [ e /MPa] 0.00010 0.00015

0.00000

1E+03

1E+04

1E+05

1E+06

1E+07

log(time) [s]

Fig. 7. Shift factor evaluation at 30°C.

Table 5. Horizontal shift factor a T for experimental creep compliance curve. Temperature [°C] Time t r [s] Time t [s]

a T [-]

30 35 40

10000

120960 777600

0.08267 0.00463 0.00031

3600

12000

38880000

Shifting the individual creep compliance curve at 30°C with respect to the one at 25°C a final time of 70 days was reached. Then, shifting the J(t) curves at 35°C and 40°C was obtained a final time of about 3 and 40 years, respectively. The creep compliance master curve for epoxy resin Sikadur30 by Sika at the reference temperature of 25°C is plotted in Fig. 8. From this predicting curve, the long-term deformation after about 40 years can be derived.

0.00000 0.00020 0.00040 0.00060 0.00080 0.00100 0.00120 0.00140 0.00160 0.00180 1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 Creep compliance J [ e /MPa] log(time) [s] 25°C J(30°C; tr(30°C)) J(35°C; tr(35°C)) J(40°C; tr(40°C))

Fig. 8. Creep compliance master curve at 25°C.