STRENGTH THE

OF

A

GLASS-REINFORCED

SHORT-TERM

ACTION

G. A. Grigorovich, and A. A. Kritsuk

V.

UNDER

PLASTIC

OF

CERTAIN

MEDIA

V.

Lushchik, UDC 6 7 8 : 5 3 9 . 4 . 0 1 9 . 3

E a r l i e r d e t e r m i n a t i o n s [1] h a v e b e e n m a d e of t h e e f f e c t of f r e s h w a t e r , s o l a r oil, and o t h e r m e d i a on t h e c o m p r e s s i v e s t r e n g t h and t h e s p e c i f i c s h o c k v i s c o s i t y of a g l a s s c r o s s - r e i n f o r c e d p l a s t i c with an e x p o s u r e t i m e up to 90 d a y s . T h e a i m of t h e p r e s e n t w o r k w a s to d e t e r m i n e t h e e f f e c t of k e r o s e n e w i t h w a t e r in t h e r a t i o of 3 : 1 and of s e a w a t e r on t h e t e n s i l e a n d b e n d i n g s t r e n g t h s of a u n i d i r e c t i o n a l r e i n f o r c e d g l a s s p l a s t i c . T h e e f f e c t of t h e s e m e d i a on t h e p r o p e r t i e s of t h e g l a s s - r e i n f o r c e d p l a s t i c w a s i n v e s t i g a t e d in s a m p l e s p r e v i o u s l y h e l d in t h e s e m e d i a up to 100 h, and t h e n t e s t e d with s h o r t - t e r m l o a d i n g . T h e s a m p l e s f o r t h e b e n d i n g t e s t s (80 x 10 x 6 ram) w e r e c u t f r o m p l a t e s p r e p a r e d by t h e m e t h o d of t h e w i n d i n g of a g l a s s - f i b e r f i l l e r ( g l a s s f i l a m e n t N S - 5 5 / 6 , GOST [ A l l - U n i o n S t a t e S t a n d a r d ] 8 3 2 5 - 6 1 ) , s a t u r a t e d with an E F B - 4 p o l y m e r b i n d e r , on a m e t a l l i c m a n d r e l . R i n g - t y p e s a m p l e s ( d i a m e t e r 100 r a m , w i d t h 10 r a m , t h i c k n e s s 1 r a m ) , d e s t i n e d f o r t e n s i l e s t r e n g t h t e s t s , w e r e o b t a i n e d by w i n d i n g on a c o m p o s i t e c y l i n d r i c a l m a n d r e l . H a r d e n i n g of t h e p l a t e s and t h e r i n g s was c a r r i e d out in a d e s i c c a t o r u n d e r c o r r e s p o n d i n g c o n d i t i o n s . T a k i n g a c c o u n t of a c e r t a i n d e g r e e of n o n u n i f o r m i t y in t h e t h i c k n e s s of t h e f i l a m e n t s d u r i n g t h e p r o c e s s of p r e p a r i n g t h e r i n g s t h e n u m b e r of t u r n s w a s m o n i t o r e d , which, f o r a l l t h e s a m p l e s TABLE 1 Form of load

Medium

Tensile strength, kg/mm z

Time of action of medium, h

1st group 108,6

Seawater

Elonga -

111,2 105,4

50 75 100 96

103,9

Variance coeff., qo

2nd group

92;1 95,1 88,2

Change in / strength, %

.

+4,8 ~6,0 _+5,1 +2,3 • 9,6 -6,2 •

100 100 102,4 97,0 103,2 95,7 95,8

+7,0 _+6,0 _+10,6 _+13,5 +9,8 •

100 100 96,0 96,1 107,5 106,6

tion 106,7

Kerosene with oil

50 75 100

,

101,4 102,5

2,41 Seawater

50 75 100

2,51 2,34 2,29

92,I 99,6 97.2 1,84

+4,5 + 19,1 +4,1 _+10,5

1,36

• 11,3

1,84

--b4,5 +19,1 •

@2r

I

I

100 100. 104,1 97,1 % ,o

94,1

Bending 2,41 Kerosene with oil

50 75 100

2,42 2,56 2,48

, 1,75

_+ 3,6

_+3,5 _+28.1

100

10o lO0 106,2 lO2.9 95,1

I n s t i t u t e of M e c h a n i c s , A c a d e m y of S c i e n c e s of t h e U k r a i n i a n SSR, K i e v . T r a n s l a t e d f r o m F i z i k o K h i m i c h e s k a y a M e k h a n i k a M a t e r i a l o v , Vol. 8, No. 4, pp. 119-120, J u l y - A u g u s t , 1972. O r i g i n a l a r t i c l e s u b m i t t e d N o v e m b e r 12, 1970. 9 197l Consuhants Bureau, a division o f Plenum Publishing Coq)omttion, 227 ffest 17th Street, \"eu: )'or],, \:. )'. 10011. :\"o port o f this publication may De reproduced, stored in a retrieval .system. or tr.nsmitted, in . n ) /~)rm or b) uny metros, electronieo mechanical, photocopying, microfilming, recording, or otherwi.se. ~cithout written permission o / t h e p.blisher. 1 copy of thi.s article is avcfilable from tt~e publisher for .5"15.00.

512

o @

80t

,

0

25

~

r

____i

5o

~5

t , h

Fig. 1

0

i

i

2S

50

iS t , h

Fig. 2

Fig. '1. Change in the tensile strength of samples of a g l a s s r e i n f o r c e d plastic after p r e l i m i n a r y holding in seawater (a) and in k e r o s e n e with oil (b). Fig. 2. Change in the strength of samples of g l a s s - r e i n f o r c e d plastic a f t e r p r e l i m i n a r y holding in s e a w a t e r (a) and in k e r o s e n e with oil (b). was maintained constant. Before a test, the samples were cleaned, numbered, and m e a s u r e d with an a c c u r a c y up to 0.01 ram. A medium simulating s e a w a t e r was p r e p a r e d in the laboratory, in a c c o r d a n c e with the formula of [2]27.2 g / l i t e r NaC1, 3.8 MgC12, 1.7 MgSO4, 0.1 MgBr2, 0.9K2SO4, 0.1 CaCO3, 1.2 g / l i t e r CaSO 4. The second m e dium was obtained by mixing k e r o s e n e (GOST 1842-52) and oil for p r e s s e s (GOST 5519-50) in a ratio of 3 : 1 by volume. The samples (rings and p r i s m s ) , whose s u r f a c e s were completely exposed were placed in open v e s s e l s with the media, up to complete i m m e r s i o n . The media acted on the samples from all sides. Out of each group (10 pieces) of r i n g - t y p e samples, 6-8 pieces were held in the medium; the r e m a i n der were held u n d e r room conditions (moisture content 65 ~- 5%, t e m p e r a t u r e 20 =~2~ and were used for control t e s t s . The control samples were grouped with r e s p e c t to time, out of s e v e r a l groups. The tests of the ring-type samples for tensile strength, using h a l f - d i s c s , were c a r r i e d out in an RH-30 universal machine. The rate of application of the load was 2000-3000 k g / ( c m 2 9rain). During the experiments, the failure load was r e c o r d e d , and the tensile strength was determined using the formula or= P / 2 F , where 1~ is the value of the failure load, kg; 2F is the a r e a of a t r a n s v e r s e c r o s s section of a ring, m m 2. The experiment r e s u l t s were analyzed statistically and are presented in Table 1 as well as in the form of curves in Fig. 1. F o r each point, 5-10 samples were tested. The bending tests of the samples were c a r r i e d out in an AS-102 machine, with a maximal load of 250 kg, a distance between supports of 60 ram, and a rate of Poisson shift equal to 20 ram/rain. The s a m ples were brought up to f a i l u r e and the failure load r e c o r d e d . The samples which failed under bending passed through a neutral l a y e r as a result of the shift between l a y e r s . The tangential s t r e s s e s were c a l c u lated using the formula v = 3 P / 4 b h , where P is the value of the failure load, kg; b,h are the width and thickness of the sample, ram. The test data a r e presented in Table 1 as well as in Fig. 2. The results of the investigation showed that the strength of samples of g l a s s - r e i n f o r c e d plastic subjected to the action of the above media for a period of 100 h changes only slightly (on the a v e r a g e ~ 7% from the starting value). The deviations lie within the limits of the s c a t t e r of the experimental data. Thus, with the action of a g g r e s s i v e media on u n s t r e s s e d samples of unidirectional g l a s s - r e i n f o r c e d plastic for a period of 100 h, t h e i r tensile and bending strength do not change; however, with an i n c r e a s e in the holding time in the media, t h e r e is a tendency toward a lowering of the strength, which is in a g r e e m e n t with the results of other articles [1, 2]. LITERATURE 1.

2.

CITED

V. S. Gumenyuk and V. V. Lushchik, Mekhan. P o l i m e r o v , No. 4 (1967). G. V. Akimov, The T h e o r y and Methods of Investigating the C o r r o s i o n of Metals [in Russian], Izd. AN SSSR (1945).

513