INTERFACIAL FRACTURE TOUGHNESS OF UNCONVENTIONAL SPECIMENS: SOME KEY ISSUES

Panayiotis Tsokanas

panayiotis.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

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

Visiting Fellows Programme 2022 - University of Pisa

Keywords:

interlaminar cracking, non-standard specimen, laminated material, bending-extension coupling, residual thermal stresses, analytical modeling

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Published
2023-02-09

Cited by

Tsokanas, P., Fisicaro, P., Loutas, T., & Valvo, P. S. (2023). INTERFACIAL FRACTURE TOUGHNESS OF UNCONVENTIONAL SPECIMENS: SOME KEY ISSUES. Journal of Technology and Exploitation in Mechanical Engineering, 9(1), 1–10. https://doi.org/10.35784/jteme.3361

Authors

Panayiotis Tsokanas 
panayiotis.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 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

Authors

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

Authors

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

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