Healing of complex damage modes in model composites

Lauer, Andrew Robert

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https://hdl.handle.net/2142/99441 Copy

Description

Title

Healing of complex damage modes in model composites

Author(s)

Lauer, Andrew Robert

Issue Date

2017-12-15

Director of Research (if dissertation) or Advisor (if thesis)

Sottos, Nancy R.

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Composites
• Self-healing
• Model composites
• Microcapsules
• Carbon fiber

Abstract

Self-healing has potential to extend the usable lifetime of composite materials. Introducing self-healing systems to fiber reinforced composites has proven to be difficult due to the high temperatures and pressures of processing as well as the requirement that the delivery scheme for the healing agent must exist in the interstitial regions between fibers. Additionally, assessment of self-healing performance for composites poses a challenge as many damage modes occur during composite failure including matrix cracking and fiber-matrix debonding. In this thesis, a tow-level model composite test is developed with a view towards simplifying characterization and improving understanding of capsule-based self-healing in fiber reinforced composites. The tow-level test is intended to allow for testing of potential healing without requiring manufacture of a complex composite panel. A modified compact tension is developed with a carbon fiber tow running orthogonally to the advancing crack plane. Initial testing of a non-healing control system reveals that the tow can survive crack propagation and that debonding of the matrix and tow occurs. Additionally, the size of the debonding damage correlates to the magnitude of energy released. Healing studies utilized a phase-separated thermoplastic-epoxy matrix with solvent filled microcapsules. Initial reference tests with the matrix but no microcapsules showed high healing efficiency of over 100% when the solvent was injected manually. However, no mechanical healing response could be observed when microcapsules were incorporated to deliver healing agent to the crack. Attempts were made at altering the healing agent delivery scheme as well as the healing conditions to increase healing response, but no combination of conditions was shown to be suitable for self-healing to occur.

Graduation Semester

2017-12

Type of Resource

text

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http://hdl.handle.net/2142/99441

Copyright and License Information

Copyright 2017 Andrew R. Lauer

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