INTERFACIAL FRACTURE TOUGHNESS OF UNCONVENTIONAL SPECIMENS: SOME KEY ISSUES
Panayiotis Tsokanas
panayiotis.tsokanas@gmail.comDepartment of Mechanical Engineering and Aeronautics, University of Patras, Patras University Campus, GR-26504, Patras, Greece (Greece)
https://orcid.org/0000-0001-5110-0632
Paolo Fisicaro
University of Pisa, Department of Civil and Industrial Engineering, Largo Lucio Lazzarino 1, I-56122 Pisa, Italy (Italy)
https://orcid.org/0000-0002-9931-6149
Theodoros Loutas
University of Patras, Department of Mechanical Engineering and Aeronautics, Patras University Campus, GR-26504 Patras, Greece (Greece)
https://orcid.org/0000-0002-4092-6225
Paolo S. Valvo
University of Pisa, Department of Civil and Industrial Engineering, Largo Lucio Lazzarino 1, I-56122 Pisa, Italy (Italy)
https://orcid.org/0000-0001-6439-1926
Abstract
Laboratory specimens used to assess the interfacial fracture toughness of layered materials can be classified as either conventional or unconventional. We call conventional a specimen cut from a unidirectional composite laminate or an adhesive joint between two identical adherents. Assessing fracture toughness using conventional specimens is a common practice guided by international test standards. In contrast, we term unconventional a specimen resulting from, for instance, bimaterial joints, fiber metal laminates, or laminates with an elastically coupled behavior or residual stresses. This paper deals with unconventional specimens and highlights the key issues in determining their interfacial fracture toughness(es) based on fracture tests. Firstly, the mode decoupling and mode partitioning approaches are briefly discussed as tools to extract the pure-mode fracture toughnesses of an unconventional specimen that experiences mixed-mode fracture during testing. Next, we elaborate on the effects of bending-extension coupling and residual thermal stresses often appearing in unconventional specimens by reviewing major mechanical models that consider those effects. Lastly, the paper reviews two of our previous analytical models that surpass the state-of-the-art in that they consider the effects of bending-extension coupling and residual thermal stresses while they also offer mode partitioning.
Supporting Agencies
Keywords:
interlaminar cracking, non-standard specimen, laminated material, bending-extension coupling, residual thermal stresses, analytical modelingReferences
Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites, ASTM D5528-13, ASTM International, 2013.
Google Scholar
P. Manikandan and C. B. Chai, “Mode-I metal-composite interface fracture testing for fibre metal laminates,” Adv. Mater. Sci. Eng., vol. 2018, art. no. 4572989, 2018.
DOI: https://doi.org/10.1155/2018/4572989
Google Scholar
K. Dadej, J. Bieniaś, and P. S. Valvo, “Experimental testing and analytical modeling of asymmetric end-notched flexure tests on glass-fiber metal laminates,” Metals, vol. 10, no. 1, art. no. 56, 2020.
DOI: https://doi.org/10.3390/met10010056
Google Scholar
J. Rzeczkowski, S. Samborski, and P. S. Valvo, “Effect of stiffness matrices terms on delamination front shape in laminates with elastic couplings,” Compos. Struct., vol. 233, art. no. 111547, 2020.
DOI: https://doi.org/10.1016/j.compstruct.2019.111547
Google Scholar
V. Saseendran, C. Berggreen, and L. A. Carlsson, “Fracture mechanics analysis of reinforced DCB sandwich debond specimen loaded by moments,” AIAA J., vol. 56, no. 1, pp. 413–422, 2018.
DOI: https://doi.org/10.2514/1.J056039
Google Scholar
J. R. Reeder, K. Demarco, and K. S. Whitley, “The use of doubler reinforcement in delamination toughness testing,” Compos. Part A Appl. Sci., vol. 35, no. 11, pp. 1337–1344, 2004.
DOI: https://doi.org/10.1016/j.compositesa.2004.02.021
Google Scholar
P. Tsokanas, T. Loutas, G. Kotsinis, V. Kostopoulos, W. M. van den Brink, and F. Martin de la Escalera, “On the fracture toughness of metal-composite adhesive joints with bending-extension coupling and residual thermal stresses effect,” Compos. B. Eng., vol. 185, art. no. 107694, 2020.
DOI: https://doi.org/10.1016/j.compositesb.2019.107694
Google Scholar
C. Alía, J. M. Arenas, J. C. Suárez, R. Ocaña, and J. J. Narbón, “Mode II fracture energy in the adhesive bonding of dissimilar substrates: carbon fibre composite to aluminium joints,” J. Adhes. Sci. Technol., vol. 27, no. 22, pp. 2480–2494, 2013.
DOI: https://doi.org/10.1080/01694243.2013.787516
Google Scholar
Z. Ouyang, G. Ji, and G. Li, “On approximately realizing and characterizing pure mode-I interface fracture between bonded dissimilar materials,” J. Appl. Mech., vol. 78, no. 3, art. no. 031020, 2011.
DOI: https://doi.org/10.1115/1.4003366
Google Scholar
T. Garulli, A. Catapano, D. Fanteria, J. Jumel, and E. Martin, “Design and finite element assessment of fully uncoupled multi-directional layups for delamination tests,” J. Compos. Mater., vol. 54, no. 6, pp. 773–790, 2020.
DOI: https://doi.org/10.1177/0021998319868293
Google Scholar
P. Tsokanas and T. Loutas, “Fracture mode partitioning: a literature review.” (to be submitted)
Google Scholar
J. N. Reddy, Mechanics of Laminated Composite Plates and Shells: Theory and Analysis, 2nd ed. Boca Raton, FL: CRC Press, 2003.
DOI: https://doi.org/10.1201/b12409
Google Scholar
P. S. Valvo, “On the calculation of energy release rate and mode mixity in delaminated laminated beams,” Eng. Fract. Mech., vol. 165, pp. 114–139, 2016.
DOI: https://doi.org/10.1016/j.engfracmech.2016.08.010
Google Scholar
P. Tsokanas and T. Loutas, “Hygrothermal effect on the strain energy release rates and mode mixity of asymmetric delaminations in generally layered beams,” Eng. Fract. Mech., vol. 214, pp. 390–409, 2019.
DOI: https://doi.org/10.1016/j.engfracmech.2019.03.006
Google Scholar
S. Bennati, P. Fisicaro, L. Taglialegne, and P. S. Valvo, “An elastic interface model for the delamination of bending-extension coupled laminates,” Appl. Sci., vol. 9, no. 17, art. no. 3560, 2019.
DOI: https://doi.org/10.3390/app9173560
Google Scholar
J. A. Nairn. “On the calculation of energy release rates for cracked laminates with residual stresses,” Int. J. Fract., vol. 139, no. 2, pp. 267–293, 2006.
DOI: https://doi.org/10.1007/s10704-006-0044-0
Google Scholar
T. Yokozeki, T. Ogasawara, and T. Aoki, “Correction method for evaluation of interfacial fracture toughness of DCB, ENF and MMB specimens with residual thermal stresses,” Compos. Sci. Technol., vol. 68, no. 3–4, pp. 760–767, 2008.
DOI: https://doi.org/10.1016/j.compscitech.2007.08.025
Google Scholar
T. Yokozeki, “Energy release rates of bi-material interface crack including residual thermal stresses: application of crack tip element method,” Eng. Fract. Mech., vol. 77, no. 1, pp. 84–93, 2010.
DOI: https://doi.org/10.1016/j.engfracmech.2009.09.018
Google Scholar
J. Wang and P. Qiao, “Interface crack between two shear deformable elastic layers,” J. Mech. Phys. Solids, vol. 52, no. 4, pp. 891–905, 2004.
DOI: https://doi.org/10.1016/S0022-5096(03)00121-2
Google Scholar
P. Tsokanas and T. Loutas, “Closed-form solution for interfacially cracked layered beams with bending-extension coupling and hygrothermal stresses,” Eur. J. Mech. A Solids, vol. 96, art. no. 104658, 2022.
DOI: https://doi.org/10.1016/j.euromechsol.2022.104658
Google Scholar
P. Tsokanas, T. Loutas, and A. P. Vassilopoulos, “Fracture toughness of elastically coupled laminates: evaluation of analytical solutions through digital image correlation,” in Proc. 20th Eur. Conf. Compos. Mater. (ECCM20), 2022, pp. 812–819.
Google Scholar
Authors
Panayiotis Tsokanaspanayiotis.tsokanas@gmail.com
Department of Mechanical Engineering and Aeronautics, University of Patras, Patras University Campus, GR-26504, Patras, Greece Greece
https://orcid.org/0000-0001-5110-0632
Authors
Paolo FisicaroUniversity of Pisa, Department of Civil and Industrial Engineering, Largo Lucio Lazzarino 1, I-56122 Pisa, Italy Italy
https://orcid.org/0000-0002-9931-6149
Authors
Theodoros LoutasUniversity of Patras, Department of Mechanical Engineering and Aeronautics, Patras University Campus, GR-26504 Patras, Greece Greece
https://orcid.org/0000-0002-4092-6225
Authors
Paolo S. ValvoUniversity of Pisa, Department of Civil and Industrial Engineering, Largo Lucio Lazzarino 1, I-56122 Pisa, Italy Italy
https://orcid.org/0000-0001-6439-1926
Statistics
Abstract views: 192PDF downloads: 160
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
All articles published in this journal are open access and distributed under the terms of the Creative Commons Attribution 4.0 International License.