Multiaxial characterization of cross-ply and quasi-isotropic flax bio-composites using a modified Arcan fixture and digital image correlation

Bergant, Zoran (author), Kek, Tomaž (author), Maček, Andraž (author), Halilovič, Miroslav (author), Šturm, Roman (author)

This study investigates the mechanical behavior, stress–strain states and damage evolution of flax-fiber reinforced polymer composites under various loading angles using Arcan specimens with V-notches. Three stacking sequences, cross-ply [0/90]▫$_{4s}$▫, quasi-isotropic [45/−45/0/90]▫$_{2s}$▫, and angled cross-ply [45/−45]▫$_{4s}$▫, were examined to assess their response to combined tension and shear loading at angles of 0°, 45°, and 90°. Digital Image Correlation (DIC) was employed to capture detailed strain fields and principal strain orientations, enabling direct comparison with numerical predictions from finite element modelling. Results show that the [45/−45]▫$_{4s}$▫ laminate exhibits superior shear load-bearing capacity due to the transformation of shear into tensile and compressive stresses within ±45° plies. Notch sensitivity varied significantly among laminates, with the [45/−45/0/90]▫$_{2s}$▫ configuration showing greater damage tolerance, a smaller strength drop at off-axis angles, and a reduced notch effect compared to cross-ply laminates. The study reveals complex strain localization patterns and fiber-matrix interactions influencing crack initiation and propagation. These findings enhance the understanding of anisotropic damage mechanisms in natural fiber composites and provide valuable insights for optimizing biocomposite layups in structural applications subjected to multiaxial stress–strain states.

• Language: English
• Keywords: flax fiber, bio-epoxy, digital image correlation, finite element method
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 17 str.
• Numbering: Vol. 154, art. 109059
• PID: 20.500.12556/RUL-176482
• UDC: 620.1
• ISSN on article: 1873-2348
• DOI: 10.1016/j.polymertesting.2025.109059
• COBISS.SI-ID: 259435011
• Publication date in RUL: 02.12.2025

Record is a part of a journal

• Title: Polymer testing
• Publisher: Elsevier
• ISSN: 1873-2348
• COBISS.SI-ID: 23025669

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: lanena vlakna, bio-epoksi, digitalna korelacija slike, metode končnih elementov

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0270
• Name: Proizvodni sistemi, laserske tehnologije in spajanje materialov

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0263
• Name: Mehanika v tehniki