PSI - Issue 18

Lobanov Dmitriy S. et al. / Procedia Structural Integrity 18 (2019) 347–352 Lobanov Dmitriy S. et al. / Structural Integrity Procedia 00 (2019) 000–000

350

4

E, GPa

σ, MPa

10 12 14 16 18 20 22 24 26

260 270 280 290 300 310 320 330 340

T/ t, °С / days

22 120/5 120/15 160/5 160/15 200/5 200/15

22 120/5 120/15 160/5 160/15 200/5 200/15

T/ t, °С / days

Fig. 3. Strength (a) and elastic modulus (b) for all groups of samples

a

c

b

120°С/ 5 days

normal

160°С/ 5 days

d

e

f

160°С/ 15 days

200°С/ 5 days 200°С/ 15 days Fig. 4. Microstructure of fracture surface at 100x times magnification for fiberglass samples after various aging modes

The photographs of fractures of fiberglass specimens tested after various temperature aging modes were analyzed. It is noted that at temperatures of 22 ºС and 120 ºС destruction occurs from breaking the fibers in the gauge length of the specimen. The destruction mechanisms of samples for temperatures of 22 ºC and 120 ºC are identical in nature. (fig.4, a, b). At 160 ° C the matrix is destroyed which accompanied by the appearance of interlayer cracks. It leads to a decrease in stiffness and a change in the mechanisms of destruction. A change in the color of the matrix to darker shades of yellow is observed. (fig.4, c, d). At 200 ° C, active destruction of the matrix and fiber is observed which accompanied by multiple delamination and increase in the matrix porosity. It is noted that the reinforcing elements and the matrix change color from white-yellow to brown (fig.4, e, f).