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Effects of local mesostructure on the damage mechanisms in a fibre-reinforced polyamide composite studied by in situ laminography and digital volume correlation

Abstract : Core-shell mesostructure in a reinforced polymer composite could dramatically affect the damage mechanisms of the material during monotonic loading. A growing understanding of the damage scenario has been possible by the use of ex-situ and in-situ microtomography tests for non-destructive 3D investigation of the material bulk. Fibre orientation analysis has been extensively developed to describe the composite mesostructure. However, complexity of the damage mechanisms still makes it difficult to predict the mechanical response. This study is aimed to understand the effects of the local mesostructure on damage mechanisms and to assess the possibility to measure strains within the material. Flat notched specimens of a short glass fibre-reinforced polyamide 6,6 were used to perform in-situ fracture tests. Fibres local orientations and crack propagation features were studied and quantified using synchrotron radiation laminography, a technique adapted to image regions of interest in flat samples. Damage mechanisms were identified independently in the core and the shell zones. Displacement and strain fields were successfully calculated by a Digital Volume Correlation (DVC) method; then, the results were compared to the mesostructure/damage analysis. Using the DVC correlation residuals the cavitation quantification was possible. As expected, fibres in the specimen core were mainly orientated in the loading direction, whereas, in the shell, the fibres were mainly oriented perpendicularly to the loading direction, see Figure 1.a. The crack roughness and heterogeneity of the crack front showed a strong influence of the local fibre orientation. In Figure 1.b, the void volume fraction thickness-distribution seems to be linked to the local fibre orientation. Qualitative results from the DVC showed that the evolution of the void volume fraction follows the same trend as the fibre orientation gradient with faster void and crack growth in the specimen center. Thus, it may be concluded that the mesostructure gradient strongly influences the damage process.
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Contributor : Cristian Ovalle Connect in order to contact the contributor
Submitted on : Tuesday, January 4, 2022 - 10:57:29 AM
Last modification on : Thursday, January 6, 2022 - 3:43:47 AM

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  • HAL Id : hal-03509483, version 1

Citation

Cristian Ovalle, Julie Brun, Lukas Helfen, M Hurst, X Kong, et al.. Effects of local mesostructure on the damage mechanisms in a fibre-reinforced polyamide composite studied by in situ laminography and digital volume correlation. 1st Virtual ESIS TC4 Conference on Fracture of Polymers, Composites and Adhesives, Sep 2021, Les Diablerets (online), Switzerland. ⟨hal-03509483⟩

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