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  • Ph.D. Dissertation

    Wed, May 26, 2021 @ 02:00 PM - 04:00 PM

    Sonny Astani Department of Civil and Environmental Engineering

    Conferences, Lectures, & Seminars

    Speaker: An Xin, Ph.D. Candidate, Astani Department of Civil and Environmental Engineering

    Talk Title: Harness Microorganisms to Design Resilient Engineering Materials

    Abstract: Conventional engineering materials include ceramics, metal, polymers, and composites, which construct various artificial structures and applications. However, these engineering materials achieved the pinnacle of performance once they are made out and gradually become weaker with the cyclic loading, corrosion, and degradation caused by the ambient environment. Different from traditional engineering materials, natural organic inorganic composites are always perfectly designed with exceptional mechanical properties. Therefore, it is a fertile area of exploration to realize the biomimetic reproduction of biological materials. Emerging 3D printed ceramics, though showing unprecedented application potential, are typically vulnerable to fractures and unable to heal at room temperature. Inspired by the bone's healing mechanism, particular bacteria are employed to heal 3D printed porous ceramics at room temperature. The healing paradigm relies on bacteria-initiated precipitation of calcium carbonate to bridge fracture interfaces of ceramics. Taking this bacterial precipitation enabled healing as an example, we further construct a modeling framework to explain the bacteria assisted extrinsic healing mechanics. A model for the growth of crystal pillars is developed to explain the bacteria assisted growth of the CaCO3 crystal forest within the fracture interface. Except for autonomous remediation, self growing is another desired capability for traditional engineering materials. Although natural systems can form materials with sophisticated microstructures, harnessing living cells to grow materials with predesigned microstructures in engineering systems remains largely elusive. Therefore, we presented a method to grow bionic mineralized composites with ordered microstructures. The bionic composites exhibit outstanding specific strength and fracture toughness comparable to natural composites and exceptional energy absorption capability superior to both natural and artificial counterparts. In addition to self healing and self growing capabilities, the self enhancement of some biotic material allows them to allocate resources more effectively in different growth stages and environments. A modeling framework is proposed to understand and explain the mechanical behavior over time in the particle reinforced self strengthening composite systems. The studies open promising avenues for harnessing microorganisms to understand, fabricate, and design resilient engineering materials in the future.


    Location: Zoom:https://usc.zoom.us /j/8450644190 Meeting ID: 845 064 4190 Passcode: USC

    Audiences: Everyone Is Invited

    Contact: Evangeline Reyes


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