This study explores the feasibility of using flax fiber-reinforced composites to design sustainable, high-performance I-beams as an alternative to traditional construction materials like steel and concrete. The motivation stems from the need to reduce the environmental impact of conventional materials, which contribute significantly to CO₂ emissions. Flax fibers, being renewable, biodegradable, and mechanically robust, present a promising eco-friendly alternative.

Methodology

1. Design Process:

   • Initially explored bridge designs but shifted focus to I-beams after generative design consistently produced I-beam-like structures.

   • Developed a double-webbed I-beam reinforced with flax fibers, combining woven and unidirectional flax layers for optimal strength.

2. Material Fabrication:

   • Flax fibers were sourced, woven (using a twill weave for durability), and combined with resin via vacuum infusion.

   • A foam mold was used to shape the beam, with flax layers strategically placed (three inner layers, two top/bottom layers, and one unidirectional layer at the bottom for tensile strength).

3. Mechanical Testing:

   • Hand calculations and simulations (Fusion 360) predicted performance under a 30 kN load, estimating:

     • Deflection: ~6.04 mm

     • Bending stress: ~122.55 MPa

     • Strain: ~0.942%

   • Physical 3-point bending test results:

     • Peak load: 25.96 kN (close to the target 30 kN)

     • Maximum deflection: 39.5 mm before test cessation

     • The beam showed elastic recovery, returning close to its original shape post-test.

Key Findings

• The flax fiber-reinforced I-beam demonstrated sufficient strength and stiffness for structural applications.

• The composite’s Young’s modulus (13 GPa) and tensile strength (~193 MPa) validate its viability as a steel/concrete alternative.

• The beam’s resilience and eco-friendly properties make it a compelling option for sustainable construction.