Engineering Material Biointerfaces to Advance Biomedical Applications

Dynamic interfaces between materials and biological systems are found throughout the body and occur in both healthy and diseased states. I have taken inspiration from these naturally occurring biointerfaces to engineer how materials respond to their biological surroundings and how biological environments interact with materials. I used this bioinspired approach to advance applications in disease diagnostics, antimicrobial drug delivery, and regenerative engineering. During my graduate work at UC Berkeley, I developed a new class of xenon NMR/MRI turn-on probes that respond to disease microenvironments and biomarkers. As a postdoc at UCSF, I engineered drug carrier biointerfaces to treat bacterial lung infections. I developed polymeric particles that permeate mucus barriers, adhere to sites of infection, and deliver combinations of synergistic antimicrobials. I further utilized biointerface design to engineer networks of high aspect ratio particles to direct colloidal assembly dynamics for applications in regenerative medicine. Biointerface engineering will be a centerpiece of my future research program, as my lab will take inspiration from bacteria as dynamic living materials to develop biofunctional materials to study and treat bacterial infections, target tumor microbiota to overcome drug resistance, and improve the oral delivery of therapeutic bacteria and probiotics.

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"ZOOM" SEMINAR
SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Monday, November 9, 2020 at 14:00

Experimental and numerical investigation of failure initiation in pultruded composites using Phase Field Methods

Shirly Cherevatsky
M.Sc. student under the supervision of Prof. Zohar Yosibash

Fiber-reinforced polymer composites (FRPs), and especially pultrusions are of high interest in UAVs. Delamination (separation between the individual plies) for example can significantly reduce the strength and stiffness of the material leading to structural failure. The effect of delamination on the mechanical behavior of the unidirectional pultruded carbon/epoxy composite under compression was examined through experimental and numerical investigation.
Compressive experiments on 4-layered pultruded carbon/epoxy specimens with small circular delamination and large rectangular delamination were performed. The influence of small circular delamination was relatively small and the failure load was almost unaffected by the presence of circular delamination. On the other hand, the failure load in the presence of large rectangular delamination was considerably small compared to specimens with circular delamination.
Finite element analyses (FEA) were performed to estimate the compressive strength of the specimens and to investigate the influence of boundary conditions and imperfections in the experimental setting and initial geometry of the specimen. The FEA results compared to experiments showed higher critical loads due to modeling assumptions.
The relatively novel phase-field model (PFM) is an emerging topic that allows to model complex failure mechanisms problems. Preliminary PFM algorithms were implemented in the FE commercial code Abaqus via a user element (UEL) subroutine to investigate failure propagations in unidirectional FRPs. The PFM was found to be a convenient and effective method for predicting crack propagation in 2D domains.
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https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09 The meeting will be recorded and made available on the School’s site.