Student: Sofia Arevalo
Professor/Sponsor: Professor Lisa Pruitt
Research Project Title: Nanoindentation of Ultra High Molecular Weight Polyethylene (UHMWPE) infused with alpha-tocopherol, UHMWPE Cross-Linked and UHMWPE 1050 and Nanoidentation Troubleshooting
Abstract:
Ultra high molecular weight polyethylene (UHMWPE) has been the main material utilized in joint arthroplasty because of its biocompatibility and desirable mechanical properties. However, wear has been a large problem that decreases the life of the joint replacement. Wear can result in failure of the implant and particles may be released into the bloodstream. The body’s response to remove the debris may lead to osteolysis and aseptic loosening of the device.
Characterization of surface mechanical properties may offer new insights to wear behavior and fracture mechanisms. The surface’s of Ultra High Molecular Weight Poly-Ethylene (UHMWPE) infused with Vitamin E, UHMWPE 1050, UHMWPE Cross-linked re-melted were indented to characterize the surface mechanical properties and correlate the relationship between the bulk and surface mechanical properties and its behavior in vivo.
The nanoindentations were performed with a conospherical tip with a loading range of 150-600 µN at a loading/unloading rate of 30 µN per second. The parameters were chosen such that the indentations remain within the surface regime of the material.
Student: Bernard Kim
Professor/Sponsor: Professor Paul Wright
Research Project Title: A Fully Printed, Integrated Supercapacitor with an Ionic Liquid Electrolyte
Abstract:
Stencil casting provides a highly rheologically-tolerant and scalable printing method for fabrication of electrochemical energy storage devices. The supercapacitor is designed to augment onboard batteries in small wireless sensors by providing the large power draws over short periods of time that would reduce the cycle life and health of the battery. The effects of different carbon-based materials of varying particle size on device performance and cyclability are investigated. In addition, the device is fabricated on a printed nickel-based current collector to eliminate the need for conductive substrates. The supercapacitor electrodes are composed of mesocarbon microbeads or activated carbon particles suspended in a poly(vinylidene fluoride-cohexafluoropropene) binder, and the current collector is composed of ball-milled nickel particles in the same binder. The electrolyte is composed of the same binder and 1-butyl-3- methylimidazolium tetrafluoroborate, a room temperature ionic liquid. All layers are printed successively on top of each other, with the binder providing enough mechanical support to separate each layer and hold the device together. The electric conductivities of the current collector and carbon electrodes with respect to mechanical stability were optimized to be 308.9 S/cm and 0.3660 S/cm respectively, and the fully assembled device demonstrated adequate preliminary cyclability.
Student: Qiaohao Liang
Area: Materials, MEMS/Nano
Professor/Sponsor: Professor Liwei Lin
Mentor: Emmeline Kao
Research Project Title: Electropolymerized Devices for Photocatalytic Hydrogen Gas Harvesting
Abstract
Student: Rian Mc Donnell
Professor/Sponsor: Professor Costas Grigoropoulos
Mentor: Yoonsoo Rho
Research Project Title: Graphene Exfoliation and Laser Treatment
Abstract
Student: Rian Mc Donnell
Professor/Sponsor: Professor Costas Grigoropoulos
Mentor: Yoonsoo Rho
Research Project Title: 2D Material Exfoliation and Laser Processing
Abstract
Student: Cynthia Tan
Professor/Sponsor: Professor George Johnson
Sub Area: Design Research Project Title: Energy absorption properties of a regular Weaire-Phelan open-cell foam under compression
Abstract:
This study investigates the mechanical behaviors and energy absorption properties of a regular open-cell foam under quasi-static and dynamic impact loads. The main motivation for this research is to provide an alternative approach to foam design and to the manufacturing process of protective gear and impact-resistant parts. In this study, the foams are comprised of a periodic lattice of tessellated cells that use the Weaire-Phelan structure as the primitive cell. The geometry of the foams, or the thickness of the edges, was changed to vary relative density, all designed to be less than 30 %. Foams of different relative densities were fabricated through selective laser sintering (SLS) of nylon powder. Compressive behaviors of the foam was modeled through simulations using LS-DYNA and experimentally tested in the Werner Goldsmith Impact Lab. Finite element analysis of the Weaire-Phelan foam, meshed through MATLAB, provided a predictive model as to how the part would respond experimentally. Simulated results showed layer-by-layer collapse of the cells during deformation, which was also observed during quasi-static compression in experiments. For each relative density and strain rate, numerical results provided responses that quantitatively matched those of the experiments in the elastic regime, but predicted higher stiffness for the foam. To improve simulations, coupon testing of the SLS nylon material for different build orientations was performed to collect more information on the material’s strain-rate dependencies and on the effects of the printing parameters on the SLS material properties. Impact loading of the foam will be conducted by shooting a projectile at speeds of around 30 m/s with a high-pressure pneumatic gas gun. The higher the relative density, the more energy the foam will absorb. Hence, experiments will provide a model of the absorbed energy as a function of relative density and geometry. It should be noted that initial stages of this research project are purely basic, but better understanding of the material properties of foam as a function of geometry may lead to improvements in both functional foam designs and the manufacturing process of cellular parts.
Student: Kriya Wong
Professor/Sponsor: Professor Grace Gu
Mentor: Zhizhou Zhang, Kahraman Demir
Research Project Title: OwlFoil: Development of Bio-Inspired Multimaterial Composites
Abstract:
The power of silent flight achieved by owls extends further than simple domination of the evolutionary arms race between predator and prey. Successful modeling and printing of wings have the potential to reform turbine and aerodynamic technology in terms of both energy efficiency and noise reduction. The characteristics of owl wings that render them silent are primarily the leading edge feathers and the trailing fringe of the wing, which work jointly to break up oncoming air currents and channel them along an invariant surface, minimizing the sound during flight. The leading edge feathers, which are typically smaller and more circular in shape, are lined with tiny serrations along the feather that are called pennula, whose primary purpose is to create roughness and texture along the wing that will break up the air currents into smaller streams called micro-turbulences, which raise the noise frequency of the air rushing over the wing to a higher frequency that is not detectable by prey and also humans. The trailing fringe further differentiates the owl from other birds in that the substructure of these feathers allow them to mesh into one another when the wings unfold, such that when the feathers spread, the outer fringe of the feathers create almost a single sheet with very little overlap, maximizing area and creating smoother surface which reduces noise and tapers out into larger, less densely packed barbule areas that break the air currents further into smaller streams to reduce noise. This project aims to create a base model for the computer-aided design (CAD) of synthetic, multi-material bird feathers, specifically of the male barn owl for the rapid prototype and development of 3D-printed feathers. Using an online database of primary feathers collected from the barn owl, three models from different regions of the wing were generated taking into account external feather spline, rachis or stem characteristic, curvature and barbule density. The properties of owls’ silent flight deemed to be the most impactful have been determined to be the comb-like pennula on the leading edge feathers and the fluid-like trailing fringe of the lower wing feathers, which work together to break air currents into smaller pockets as well as smooth the underside of the wing. The successful modeling and 3D-printing of these characteristic feathers unique to the owl have the potential to transform airfoil and turbine technology. As a crucial step towards the modeling of an entire wing, this project defines the parameters necessary for the realistic multi-material generation of owl flight feathers.
Student: Gregory Zaborski
Professor/Sponsor: Professor Kameshwar Poolla
Mentor: Professor Ian Sharp, Dr. Gideon Segev, Dr. Chang-Ming Jiang
Research Project Title: Investigation of opposite trends between charge transport and catalytic properties between CVO phases
Abstract