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

349

3

to 350ºС. The longitudinal deformations of the samples were measured by an AVE Instron 2663-821, video extensometer, whose operation is based on determining the coordinates of contrasting (white or black) labels of the measuring base, marked the working part of sample, by means of a digital high-resolution video camera. In the course of the test, the AMSY-6 system continuously recorded acoustic emission signals. Two types of broadband sensors with different frequency bands (450-1150 kHz and 100-500 kHz) were used, the preamplifier with a gain of 34 dB. Analysis of changes in the structure (development of macrocracks, shell formation and destruction of the binder, etc.) of the composite material due to temperature aging after mechanical tests was performed using a Carl Zeiss SteREO Discover V12 stereomicroscope. The photo of the sample in the grips of the testing machine with attached acoustic emission sensors is shown in Figure 2.

a

b

Fig. 2. The photo of the sample in the grips of the testing machine with attached acoustic emission sensors

3. Results and discussions 3.1. Mechanical test results

The results of the mechanical tests of fiberglass after various temperature aging modes are shown in Table 2 and Fig. 3. A certain average strength and average elastic modulus for all groups of samples. Photos of fractures of samples surface after mechanical tests are presented in Figure 4.

Table 2. Mechanical performance of fiberglass after various modes of aging Temperature aging, °С Number of days Average strength (MPa)

Average elastic modulus (GPa)

Without thermal exposure

-

282,8±18,7 313,2±13,3 330,5±5,5 319,0±8,5 300,0±11,5 318,3±12,5 306,3±6,4

16,8± 1,6 20,0±1,8

120 120 160 160 200 200

5

15

21±1,4

5

20,4±0,6 19,4±0,7 20,9±2,1 21,3±0,9

15

5

15