PSI- Issue 9

Fatima Majid et al. / Procedia Structural Integrity 9 (2018) 229–234 Fatima MAJID et al / Structural Integrity Procedia 9 (2018) 229 – 234

232 232

Ep1 Ep2 Ep5 Ep6 Ep4 Ep3

0 10 20 30 40

Stress (MPa)

0

3,5

5,5

12

17

40

70

100

130

160

Elongation(mm)

190

Fig 2. Calculation of equivalent energy under the surface of the tensile curves of neat and aged HDPE specimens

The evolution of cumulative energy is linear function of tensile time.

y = a x + b

(3)

 y = 0,91 x + 8,5

(4)

 E(J) = t + 8,5

(5)

This evolution is because the maximum-recorded energy varies significantly from one specimen to another with proportional steps as shown in Figure 14.

100 150 200 250 300 350 400

y = 0,9161x + 8,559

Energy(J)

0 50

0

50

100

150

200

250

300

350

400

Time (s)

Fig 3. Evolution of maximum-recorded energy for neat and aged specimens

A representation of the evolution of the dissipated energy for each specimen, figure 4, shows a polynomial decrease that can be represented using a third degree polynomial.