Exploring dynamic mechanical properties in fibre-reinforced composites using spatial mapping techniques
Topic(s) : Experimental techniques
Co-authors :
Fanny PELISSON (FRANCE), Ugarak FEHIMA (FRANCE), Pauline BUTAUD (FRANCE), Alexis MOSSET (FRANCE), Vincent LAUDE , Yves GAILLARD , Vincent PLACET (FRANCE), Morvan OUISSE (FRANCE)Abstract :
Driven by growing environmental concerns, there is a clear shift towards developing lighter, safer and eco-friendly structures. In this context, rapid progress is being made in the field of composites, especially in the development of bio-based composites. These advancements aim not only to address ecological concerns, but also to improving mechanical properties, specifically damping [1-2]. However, understanding the damping mechanisms within bio-based composites presently remains a significant challenge of main importance [2]. Therefore, the objective of this study is to obtain a spatial mapping of a composite structure, to quantify and assess damping sources within it, in order to facilitate a comprehensive understanding of damping properties.
To understand the origins of damping, it is mandatory to better understand the sources of energy dissipation at the micro-scales, including the intricate interplay between fibre structure, fibre-matrix and fibre-fibre interfaces, and matrix damping. The proposed approach uses mapping methods that leverage mechanical and physical spectroscopic tools, such as nanoindentation, and Brillouin spectroscopy, to observe and evaluate damping within composites. A previous study using Brillouin spectroscopy shed light on biobased fibres [3]. However, that study primarily explored these fibres along their transverse direction and isolated from the matrix, leading to incomplete information regarding their behaviour within composite materials. Extending this analysis to composite materials enables the construction of a comprehensive damping map of biobased composites. Another technique used for this mapping is nanoindentation tests using harmonic force which can offer valuable insights into damping [4]. For methodological precision, the validation of these techniques across various types of fibres remains critical. Hence, the investigation in this study specifically targets flax, glass, and PA11 fibres. Two distinct sample preparation protocols are employed. The first protocol involves the manufacturing of micro-specimens representing a REV (Representative Elementary Volume). Each specimen consists of a single fibre of each type embedded in a small volume of Greenpoxy matrix. This approach facilitates property mapping through Brillouin spectroscopy. The second protocol involves the utilization of a conventional composite specimen, on the cross-section of which a nanoindentation grid method is applied.
Both approaches enable a comprehensive evaluation encompassing fibre, matrix, and interface properties for biobased composites. Specifically, nanoindentation highlights a loss factor of 4% of the fibre wall, comparable to that of the cellulose fibre wall measured by Brillouin spectroscopy [3].
To understand the origins of damping, it is mandatory to better understand the sources of energy dissipation at the micro-scales, including the intricate interplay between fibre structure, fibre-matrix and fibre-fibre interfaces, and matrix damping. The proposed approach uses mapping methods that leverage mechanical and physical spectroscopic tools, such as nanoindentation, and Brillouin spectroscopy, to observe and evaluate damping within composites. A previous study using Brillouin spectroscopy shed light on biobased fibres [3]. However, that study primarily explored these fibres along their transverse direction and isolated from the matrix, leading to incomplete information regarding their behaviour within composite materials. Extending this analysis to composite materials enables the construction of a comprehensive damping map of biobased composites. Another technique used for this mapping is nanoindentation tests using harmonic force which can offer valuable insights into damping [4]. For methodological precision, the validation of these techniques across various types of fibres remains critical. Hence, the investigation in this study specifically targets flax, glass, and PA11 fibres. Two distinct sample preparation protocols are employed. The first protocol involves the manufacturing of micro-specimens representing a REV (Representative Elementary Volume). Each specimen consists of a single fibre of each type embedded in a small volume of Greenpoxy matrix. This approach facilitates property mapping through Brillouin spectroscopy. The second protocol involves the utilization of a conventional composite specimen, on the cross-section of which a nanoindentation grid method is applied.
Both approaches enable a comprehensive evaluation encompassing fibre, matrix, and interface properties for biobased composites. Specifically, nanoindentation highlights a loss factor of 4% of the fibre wall, comparable to that of the cellulose fibre wall measured by Brillouin spectroscopy [3].