Analysis of the efficiency of advanced methods of in-plane shear testing of highstrength CFRP specimens

The mechanical testing performed to determine shear characteristics of advanced carbon fiber-reinforced plastics (CFRP) can involve significant problems. First of all, this is due to the difficulties in providing uniform distribution of shear stresses in the working area of the specimens, particularly in determining the strength characteristics of advanced polymer composite materials based on high-modulus or highstrength carbon fibers with the ±45° layup, where the material properties depend not only on the matrix but also on the fiber properties, unlike unidirectional composites. In addition, one can mention a large number of shear test methods and related standards of in-plane shear testing. At the same time, the results of the tests performed according to various standards generally do not comply with each other. In this study the analysis of CFRP shear characteristics obtained from various test methods was performed. The calculated and experimental data of stress-strain distribution for various specimen types were obtained. The experimental results of determining the strength and elastic characteristics of CFRP in the in-plane shear were obtained during the testing of 125 flat specimens made of four brands of CFRP reinforced with the ±45° plies. None of the standard methods discussed in this study was found to provide uniform distribution of shear stresses in the working area of the test specimen. The strength values closest to the predicted ones were obtained from the specimens made according to ASTM D7078 (GOST R 57207) based on the method of V-notch plate distortion. At the same time, the method of plate distortion in the four-bar linkage (GOST 24778, ASTM D2719) and the losipescu method (ASTM D5379, GOST R 56799) cannot definitely be used to reliably determine the shear strength characteristics of advanced CFRP reinforced with the ±45° plies.

1. Tarnopolskiy Yu. М., Kintsis Т. Ya. Static test methods for reinforced plastics. 3rd edition. — Moscow: Khimiya, 1981. — 272 p. [in Russian].

2. Adams D. F. A comparison of shear test methods. Composites World. 2009. https://www.compositesworld.com/ articles/a-comparison-of-shear-test-methods

3. Adams D. F. V-notched shear testing of composites. Composites World. 2015. https://www.compositesworld.com/articles/vnotched-shear-testing-of-composites

4. Arnautov A., Bax T. Determination of in-plane shear characteristics of composite materials with [±45°] layup / Mekh. Kompozit. Mater. 1996. Vol. 32. N 2. E 256 - 264 [in Russian].

5. Popov A. G., Matyushevsky N. V. Abstracts of the XX International scientific and technical conference "Structures and technologies of production from nonmetallic materials". — Obninsk, 2013. E 146 - 148 [in Russian].

6. Park S. Y., Choi W. J. Review of material test standardization status for the material qualification of laminated thermosetting composite structures / J. Reinforced Plast. Composites. 2020. Vol. 40. N 5 - 6. E 235 - 258. DOE 10.1177/0731684420958107

7. Taheri-Behrooz F, Moghaddam H. S. Nonlinear numerical analysis of the V-notched rail shear test specimen / Folymer Testing. 2018. Vol. 65. E 44 - 53. DOE 10.1016/j.polymertesting.2017.11.008

8. Alfutov N. A., Zinoviev P. A., Popov В. G. Calculation of multilayered plates and shells. — Moscow: Mashinostroenie, 1984. — 264 p. [in Russian].

9. Polovyi A. O., Lisachenko N. G. Approximation of non-linear in-plane shear stress-strain diagrams of unidirectional and cross-ply reinforced polimer matrix composites / Zavod. Lab. Diagn. Mater. 2022. Vol. 88. N 4. E 48 - 57 [in Russian]. DOI: 10.26896/1028-6861-2022-88-4-48-57

10. Ilichev A. V, Gubin A. M., Akmeev A. R., Ivanov N. V Definition of area of the maximum shear deformations for CFRP samples on Iosipescu method, with use of optical system of measurements / Tr. VIAM. 2018. N 6(66). E 99 - 109 [in Russian]. DOI: 10.18577/2307-6046-2018-0-6-99-109

11. Tan W., Falzon B. G. Modelling the nonlinear behaviour and fracture process of AS4/PEKK thermoplastic composite under shear loading / Compos. Sci. Technol. 2016. Vol. 126. E 60 - 77. DOI: 10.1016/j.compscitech.2016.02.008

12. An Q., Merzkirch M., Forster A. Characterizing Fiber Reinforced Polymer Composites Shear Behavior with Digital Image Correlation. — American Society for Composites. 33rd Technical Conference Proceedings. — Seattle, 2018. DOI: 10.12783/ASC33/25914

13. Bru Т., Hellstrom P., Gutkin R., et al. Characterisation of the mechanical and fracture properties of a uni-weave carbon fibre/epoxy non-crimp fabric composite / Data in Brief. 2016. Vol. 6. E 680 - 695. DOI: 10.1016/j.dib.2016.01.010

14. Adams D. F. The Picture Frame Shear Test method. Composites World. 2014. https://www.compositesworld.com/articles/the-picture-frame-shear-test-method

15. Chaterjee S., Adams D., Oplinger W. D. Test Methods for Composites: A Status Report. Vol. 3. Shear Test Methods. DOT/FAAICT-93/1 7, III. Final Report. National Technical Information Service. — Springfield, VA, 1993. — 117 p.

16. Polilov A. N. Etudes on Composite Mechanics. — Moscow: Fizmatlit, 2015. — 320 p. [in Russian].

17. Baere I. D., Paepegem W., Degrieck J. Design of a modified three-rail shear test for shear fatigue of composites / Polymer Testing. 2008. N 27. E 346 – 359. DOI: 10.1016/j.polymertesting.2007.12.006

18. Hussain A. K., Adams D. F. Experimental Evaluation of the Wyoming-modified Two-rail Shear Test Method for Composite Materials / Exp. Mech. 2004. Vol. 44. N 4. E 354 - 364. DOI: 10.1177/0014485104044317

19. Iosipescu N. New Accurate Procedure for Single Shear testing of Metals / J. Mater. 1967. Vol. 2. N 3. E 537 - 566.

20. Walrath D. E., Adams D. F. The Iosipescu Shear Test as Applied to Composite Materials / Exp. Mech. 1983. Vol. 23. N 1. E 105 - 110. DOI: 10.1007/BF02328688

21. Adams D. F., Walrath D. E. Further Development of the Iosipescu Shear Test Method / Exp. Mech. 1987. Vol. 27. N 2. P 113 - 119. DOI: 10.1007/BF02319461

22. Crossan M. Mechanical Characterization and Shear Test Comparison for Continuous-Fiber Polymer Composites. Electronic Thesis and Dissertation Repository. — Ontario, Canada, 2018. — 118 p. https://ir.lib.uwo.ca/etd/5408

23. Ifju P. G. The Shear Gage: For Reliable Shear Modulus Measurements of Composite Materials / Exp. Mech. 1994. Vol. 34. N 4. E 369 - 378. DOI: 10.1007/BF02325152

24. Conant N. R., Odom E. M. An improved Iosipescu shear test fixture / J. Compos. Technol. Res. 1995. Vol. 17. N 1. E 50 - 55. DOI: 10.1520/CTR10513J

25. Adams D. O., Moriarty J. M., Gallegos A. M., Adams D. F. Development and Evaluation of the V-Notched Rail Shear Test for Composite Laminates. DOT/FAA/AR-03/63. Final Report. National Technical Information Service. — Springfield, VA, 2003. — 90 p.

26. Adams D. F V-Notch Rail Shear test (ASTM D 7078-05). Composites World. 2009. https://www.compositesworld.com/articles/v-notch-rail-shear-test-astm-d-7078-05

27. Litz D. J. Development of the Combined Loading Shear Test Method and Shear Strain Measurement in the V-Notched Rail Shear Test. MS Thesis. — Department of Mechanical Engineering. University of Utah, 2012. — 126 p.

28. Adams D. O., Moriarty J. M., Gallegos A. M., Adams D. F. The V-Notched Rail Shear Test / J. Composite Mater. 2007. Vol. 41. N 3. E 281 - 297. DOI: 10.1177/0021998306063369

29. Liu G., Zhang L., Guo L., et al. A modified V-notched beam test method for interlaminar shear behavior of 3D woven composites / Composite Struct. 2017. Vol. 181. E 46 - 57. DOI: 10.1016/j.compstruct.2017.08.056