Asymmetric Four Point Bend Test Method for Interlaminar Shear Strength in Ceramic Matrix Composites

Abstract:

Asymmetrical Four Point Bend test method is proposed for measurement of interlaminar shear strength in continuous fiber reinforced ceramic composites. The current standard ASTM test method (ASTM C1425) for interlaminar shear strength of composites uses a double edge notched compression (DNC) coupon. Large variation in measured strength is observed with the standard ASTM test method, possibly due to machining variability and damage at the notches. The proposed test AFPB method for ILSS is adapted from ASTM C1469 Standard Test Method for Shear Strength of Joints of Advanced Ceramics. This test method does not require any machining of notches and the sample size requirement is much smaller than the ASTM test method. The shear loading in this method is similar to the standard short beam shear test (ASTM D2344) with higher shear to tensile ratio compared to SBS with AFBP. Using finite element analysis, coupon geometry and the distance between the loading and support pins was optimized to maximize shear and minimize tensile and compressive stresses on the specimen. It was found that the variability in the measured ILSS strength was lower with this method compared to the ASTM standard method using the DNC specimen. In addition, the value of ILSS measured using AFPB method was found to be consistently higher than that measured using DNC coupons. It was also found that specimen preparation (cutting, polishing, etc.) did not have significant effect on the measured strength.

• Periodical: Materials Science Forum (Volume 1094)
• Pages: 19-24
• DOI: https://doi.org/10.4028/p-zN31vp
• Online since: July 2023
• Authors: Prakash Jadhav*, Chhaya Lande
• Keywords: Ceramic Matrix Composites, CMC, Shear Strength, Test Method Development

References

[1] M. Li, R. Matsuyama and M. Sakaib, Carbon, (1999), vol. 37, p.1749–1757.

[2] Prakash Jadhav, Innovative designs of embedded foam inserts in aerospace composite structures, Materials today proceedings, (2020), vol 21, 1164-1168

DOI: 10.1016/j.matpr.2020.01.066

[3] P. Samyn, S. L. Van, J. Leendertz, V. P. W, B. P. De and D. J, ASTM Journal of Testing and Evaluation, (2007), vol. 35, no. 3, pp.310-320.

[4] Prakash Jadhav, Effect of ply drop in aerospace composite structures, Key engineering materials, (2020), 847, pp.46-51.

DOI: 10.4028/www.scientific.net/kem.847.46

[5] E. Lewis, Adams and DF, An evaluation of composite material shear test methods, University of Wyoming at Laramie, Laramie, (1991).

[6] Prakash Jadhav and Lakshmi Yella Gruha, IOP Conference Series: Materials science and engineering, (2021), vol 1126

DOI: 10.1088/1757-899X/1126/1/012036

[7] ASTM Standard D2344: Standard test method for apparent interlaminar shear strength of parallel fiber composites by short-beam method, (2016)

[8] Prakash Jadhav, Failure criteria for composite blades with wavy edge in aerospace applications, Advances in materials and mechanical engineering, Springer,(2021)

DOI: 10.1007/978-981-16-0673-1_9

[9] ASTM Standard D3846: Standard test method for in-plane shear strength of reinforced plastics, American society for testing and materials, (2016)

[10] Prakash Jadhav, Design Methodologies for Composite Structures in Aircraft Engines, Advanced composites in aerospace engineering applications, (2022), Springer, 93-108

DOI: 10.1007/978-3-030-88192-4_4

[11] ASTM Standard D5379, Standard test method for shear properties of composite materials by the V-notched beam method, American society for testing and materials, (2019)

[12] Prakash Jadhav, Wavy trailing edge feasibility for aircraft engine composite fan blade, Material science forum, (2022), 1060, 51-56

DOI: 10.4028/p-4ubl99

[13] In-Plane Shear Test for Composite Materials, Slepetz, J.M., Zagaeski, T.F., Novelle, R.F, AMMRC-TR-78-30, Army Materials and Mechanics Research Center, MA, (1979).

[14] ASTM C 1469 – 00: Standard Test Method for Shear Strength of Joints of Advanced Ceramics at Ambient Temperature, (2015).

[15] Fok and J Smart, The notched beam in asymmetric four-point bending for brittle material testing, The Journal of Strain Analysis for Engineering Design, (1994), 29(4):289-298.

DOI: 10.1243/03093247v294289