student and faculty conducting research

PhD Students and Post-Doctoral Researchers

Sang Yup Kim

  • Advisor:
      • Scott R. White
  • Departments:
    • Aerospace Engineering
    • Materials Science and Engineering
    • Mechanical Science and Engineering
  • Areas of Expertise:
      • self-healing composite
      • composite manufacturing
      • fracture mechanics
      • solid mechanics
      • fiber-reinforced polymer composite

  • Thesis Title:
      • Self-healing fiber-reinforced composite for high performance applications
  • Thesis abstract:
      • Fiber-reinforced composites are often exposed to severe user conditions which can result in complex damage consisting of matrix cracks, fiber-matrix interfacial debond, and fiber failure. The complex damage modes of composites limit broadening of their application because damage is difficult to detect and repair and can lead to catastrophic failure. Self-healing composites have been proposed as a solution that recovers damage autonomously, and makes the composite more reliable over extended service life. One typical method to provide self-healing functionality to a material is to incorporate microcapsules which sequester a healing agent. The healing agent in the microcapsule is autonomously released to the damaged site by a capillary force when damage occurs and causes rupture of the microcapsules. Capsule-based self-healing materials have been well studied in a bulk polymer, however, little research has been done in fiber-reinforced composites because of difficulties in fabrication. Microcapsules interfere with composite processing by increasing resin viscosity, being filtered through a fibers, and rupturing prematurely. As a result, self-healing composites inherently possess a low fiber volume fraction (Vf) around 40 vol% and non-uniform distribution of the microcapsules. This research is dedicated to developing a fabrication technique for a self-healing fiber-reinforced polymer composite with high performance. To obtain high performance, the microcapsules will be uniformly distributed throughout the composite, and its Vf as well as glass transition temperature (Tg) will be increased. A composite with a uniform microcapsule distribution and high Vf was efficiently fabricated by preparing a self-healing prepreg; a sheet of resin pre-impregnated fiber preform with dispersed microcapsules. A lab-sized prepregger was developed, and the prepregging procedure was optimized to fabricate the self-healing prepreg. Two types of the self-healing prepreg will be proposed in this research: a room temperature cured epoxy and high temperature cured thermoplastic-toughened epoxy.
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