PSI - Issue 50

Kirill Guseinov et al. / Procedia Structural Integrity 50 (2023) 105–112 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

108

4

(a)

(b)

Fig. 2. Cubic (a) and V-notched (b) specimens loading schemes

2.3. Combined compression-shear loading in the new fixture The previously developed fixture and appropriate V-notched specimen (Figure 2,b) developed by Guseinov et al. (2022) were used for an alternative assessment of the interlaminar shear properties of woven CFRP. Two plates were used to fix V-notched specimens. The specimen was glued for strong fixation. The combination of transversal compressive and interlaminar shear stresses in the tests was varied by rotating the plates in the supports through angle α. The displacement of the lower support in one plane was implemented using rollers. The Well known Iosipescu and butterfly-shaped specimens (see ASTM D5379/D5379M-12 (2019), Arcan et al. (1978)) formed the basis for the choice of the specimen configuration for testing in the new fixture. This specimen configuration makes it possible to implement an almost uniform shear-stress distribution in the gauge section between the notches. Through-thickness compression and interlaminar shear stresses in the gauge section of the specimen are defined as follows:

cos( ) P l t   

3 



(3)

,

sin( ) P l t   





13

(4)

.

2.4. Test procedure The biaxial tests were carried out on a universal testing machine INSTRON 5900R with 100 kN load cell. All tests were performed at the crosshead speed of 1 mm/min. Two types specimens were tested by varying loading angle α in the range from 15° to 45°. All specimens were loaded to failure. The s train distribution was recorded using the VIC-2D software. The digital monochrome 8-bit camera GRAS-50S5M-C with Schneider lens - Kreuznach Xenoplan 1.4/17 had a resolution of 2048×2048 pixels. The images were captured at a frequency of 4 frames per second. The full-fields deformations of the specimens in the local coordinate system of the material are defined as follows:

2 sin      

2

cos

0,5 sin2

  



(5)

,

3

x

y

xy

sin2

sin       2

cos2





x 



(6)

.

13

y

xy