Fiber Bridging and Interface

1. Learning objectives

• Explain fiber bridging after cracking.
• Compare pullout and rupture.
• Connect interface and dispersion to composite tensile behavior.

2. Key concepts

• Fiber bridging law
• Single-fiber pullout
• Chemical bond
• Frictional bond
• Fiber orientation
• Fiber dispersion

3. Minimal theory

After cracking, bridging fibers transfer stress across the crack. Interface should be strong enough for bridging but not so strong that fibers rupture before useful pullout.

4. Source-grounded evidence

• Main node: 02_concepts/fiber_bridging_law.md.
• Pullout node: 05_experiments/single_fiber_pullout.md.
• Lab evidence: Lee 2009/2010, Choi 2015/2020/2021, Hwang 2025.

5. Representative papers

• Yang et al. 2008.
• Lee 2009 fiber dispersion.
• Lee 2010 image-based bridging prediction.
• Hwang 2025 selvage fiber pullout.

6. Figures/tables to show later

• Single-fiber pullout curve.
• Fiber orientation distribution.
• Pullout vs rupture schematic.

7. Discussion questions

1. Why is very strong bond sometimes harmful?
2. How does fiber diameter affect statistical stability?
3. Why must recycled fibers be checked by pullout and dispersion?

8. Assignment idea

Compare two fibers and predict strain-hardening potential from strength, diameter, bond, and elongation.

9. Linked Atlas nodes

• 02_concepts/fiber_bridging_law.md
• 02_concepts/interface_properties.md
• 02_concepts/fiber_dispersion.md
• 05_experiments/single_fiber_pullout.md

10. Suggested reading path

1. 02_concepts/fiber_bridging_law.md
2. 02_concepts/interface_properties.md
3. 06_lab_position/recycled_selvage_fiber_position.md

Evidence files

• 07_visualization/foundational_papers_claim_evidence_matrix.csv
• 07_visualization/extreme_ductility_extension_claim_evidence_matrix.csv
• 07_visualization/sustainable_ecc_extension_claim_evidence_matrix.csv
• 07_visualization/by_lee_lab_publications_claim_evidence_matrix.csv