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Testing and
simulation of mixed-mode debond failure behaviour of a bonded
composite joint
Gang Li, Guillaume Renaud and Lucy Li |
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Vol. 20 (2025), No. 5, 529–552
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Abstract |
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This paper presents a study on test evaluation and corresponding finite element (FE) simulation performance for a bonded unidirectional composite specimen configuration under mixed-mode I/II loadings of 0.2, 0.4, 0.6, and 0.8. The test data sets were analyzed to identify the initial debond lengths and debond fracture toughness, specifically the critical strain energy release rates. The “effective” initial debond length was determined by correlating the initial stiffness with the debond length for each mode mixity. Subsequently, the quasistatic debond failure behaviour of the mixed-mode bending (MMB) specimens was modelled using either virtual crack closure technique (VCCT) and/or cohesive zone (CZ) elements. With the resulting “effective” initial debond lengths and appropriate mixed-mode analysis setups, the FE models generated predictions that were validated against test load-displacement curves. The performance of VCCT and cohesive zone elements was evaluated for selected mode mixities. VCCT models provided good predictions across all the assessed mode mixities, although they tended to slightly overestimate the peak load. Conversely, cohesive element models underestimated both the peak load and the displacement at peak load, with discrepancies increasing at the 0.8 mode mixity compared to the 0.2 mode mixity. Also, the effect of mode mixity on the load-displacement curve was explored numerically for two half-span lengths, with its implications for practical joint design discussed. Furthermore, a commentary for the practicality of the assessed modelling approaches is presented. |
Keywords
bonded composite specimen, cohesive elements, debond,
finite element, mixed-mode, virtual crack closure technique
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Milestones
Received: 18 February 2025
Revised: 21 July 2025
Accepted: 14 October 2025
Published: 21 November 2025
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Authors |
| Gang Li | |
| Aerospace Research Centre National Research Council Canada Ottawa, ON K1A 0R6 Canada |
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| Guillaume Renaud | |
| Aerospace Research Centre National Research Council Canada Ottawa, ON K1A 0R6 Canada |
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| Lucy Li | |
| Aerospace Research Centre National Research Council Canada Ottawa, ON K1A 0R6 Canada |
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| National Research Council Canada, under license to MSP (Mathematical Sciences Publishers). |
