PSI - Issue 30

M.P. Lebedev et al. / Procedia Structural Integrity 30 (2020) 76–81 M.P.Lebedev et al / Structural Integrity Procedia 00 (2020) 000–000

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Table 1 (continued). Examples of an abnormal decrease of mechanical parameters of exposed PCM. № PCM Test site Ageing time , yrs.

Index, MPa

Symbols, R in (1)

R t / k R in (1) after ageing

Initial value in (1)

4

CFRP T-300/E-788

V A V A B

1 1 1 1 5 5 1 1 1 1 5 5 1 1 5 5 5 5 5 5 3 3 3 3 3 3 1 1

σ c σ c

872 872 77.4 77.4 410 410 1300 1300 1000 1000 1600 1600 1400 1400

883/1.01 837/0.96 78.7/1.02 71.7/0.93 410 / 1.0 365 / 0.89 1200 / 0.92 1060 / 0.82 930 / 0.93 850 / 0.85 1700 / 1.06 1470 / 0.92 1294 / 0.92 1170 /0.4 200 / 0.80 190 / 0.76 120 / 0.71 110 / 0.65 720 / 0.90 710 / 0.88 480 / 0,79 455 / 0.75 275 / 0.45 255 / 0.42 500 / 0.89 400 / 0.71 930/0.93 850/0.85 1090/0.90 780/0.65

τ τ

5

CFRP KMU-3 CFRP KMU-4e CFRP VKU-39 Fiberglass VPS-31 Fiberglass VPS-31 К 60 OP Organite 16 Т -Rus

σ c σ c σ t σ t σ b σ b σ b σ b σ b σ b σ c σ c

Ya

6

S

Ya

7

G

Ya

8

S

Ya

9

S

Ya

250 250 170 170 800 800 610 610 610 610 560 560

10

S

Ya

о С ) о С )

S

σ c (150 σ c (150

Ya

11

Hybrid composite GKM-1(m) CFRP KMKU-2m.120.

S

σ b σ b

Ya

о С ) о С ) о С ) о С )

σ b (120 σ b (120 σ b (120 σ b (120

12

G

S

M

Ya

S

σ c σ c σ b σ b σ b σ b

Ya

1000 1000 1210 1210

13

Fiberglass VKU-39

G

Ya

14

Basalt Plastic ED-22

G

2,5 2,5

Ya

Generally, alterations of k R should be extrapolated by the function in agreement with environmental factors and material properties:

k f T t 

t Q t q t H t WS t W t

( ), ( ), ( )] t 

.

(2)

[ ( ), ( ), ( ), ( ), ( ), 

R

i

Effects of each factor indicated in the function f (2) depend both on the type of a climate by Urzhumtsev (1986), and on individual characteristics of PCM by Kablov (2018). They contribute to the overall balance of physical and chemical transformations (plasticization, swelling, hydrolysis, post-hardening of polymer matrices activated by moisture, destruction under effects of ultraviolet radiation and oxygen, structural relaxation of the filler, binder, and their interfaces, formation of pores, microcracks on the surface and in the volume of samples, etc.) that determine k R .