Student: Prithvi Akella
Professor/Sponsor: Professor Oliver O’Reilly
Mentor: Evan Hemingway
Research Project Title: Analysis of Static and Dynamic Beam Deformation through Euler-Bernoulli and Timoshenko Beam Theories.
My research details the theory behind both Euler-Bernoulli and Timoshenko beam deformation for both the static and vibrational cases. This document is meant to be used in conjunction with its accompanying Mathematica code to help inform the user about beams deform in general. The first half of my paper will describe Euler-Bernoulli beam theory and attempt to reference the code whenever possible to as to make the gist of the code clear; the second half will proceed likewise with Timoshenko Beam Theory. That being said, while this document will reference the code, it may be used standalone to understand either theory as well.
Student: Nicholas Corral
Professor/Sponsor: Professor Carlos Fernandez-Pello
Mentor: James Urban
Research Project Title: The flaming ignition of aluminum particles.
The increasing rates of unplanned fires in both wild and urban settings, especially in the Western portion of the United States, has brought about the need for research concerning the cause of such tragic events. This research project specifically concerns the effects of spot fire ignition on characteristic combustible materials, and modeling them. The grinding or cutting of metal can create metal sparks which can chemically react with the oxygen in the atmosphere. This can cause an increase in their temperature which makes them a potential source for ignition. In the Combustion Fire Processes Laboratory, a computational model has been developed to simulate the reaction process and the distances these sparks travel. This involves solving the equations of motion and the heat and mass transfer to and from the particle. By making models like this, the fire risk posed by metal cutting and other spark producing processes can be better evaluated preventing dangerous and costly fires.
The ignition of combustible material by hot metal particles is an important pathway by which wildland and urban spot fires are started. Upon impact with combustible material (e.g. vegetation, cellulosic industrial material or polymer foams), these particles can initiate spot fires. In spite of interest in the subject, there is little work published that addresses the ignition capabilities of hot metal particles landing on natural fuels. This work is an experimental study of how the flaming ignition propensity of fuel beds in contact with hot aluminum particles is affected by the characteristics of the fuel bed. Two fuel beds were tested: pine needles and a fine powder formed by grinding the pine needles which are representative of forest litter and duff respectively. Comparing the ignition characteristics of these fuels will give insight into the effects of fuel macrostructure on the conditions which could initiate spot fires from metal particles. Thus, influential variables are monitored through frequent sampling such as the fuel bed moisture content and lab conditions (e.g. temperature, humidity, etc.). In the experiments, aluminum particles ranging from 2 – 8mm in diameter are heated to various temperatures between 575 – 1100oC and dropped into the different fuel beds.
I conducted, acquired, and analyzed the data for the various experiments used in the presentation of the spot project. The various parameters such as the particle diameter, temperature, particle ignition, etc. were recorded after every run of the experiment. The tests also involved constant moderation to keep the particles from melting within the furnace and therefore the real-world imitation for these tests became a bit less accurate than for others. Afterward, I would assist James by writing code in Jupyter/Python to visualize the results and improve the speed of the calculations. The results show that the pine needle powder fuel was capable of ignition at lower temperatures, but the flame spread faster on the pine needle fuels. As for the pine straw grass and powder, fire ignition seldom occurred even with large particles and smolder occurred just as infrequently.
Student: Thomas Mackey
Professor/Sponsor: Professor Tony Keaveny
Research Project Title: Computer Simulation of Hip Fracture
Around 200,000 cases of hip fracture occur in the United States each year, however the mechanics of what causes these hip fractures are not well understood. In particular, 90% of hip fractures are the result of falls, yet it is difficult to see how variables such as angle of impact, impact speed, muscle properties etc. affect the stress distribution in the hip. Woochol Joseph Choi and Stephen N. Robinovitch conducted research on how both muscle activation and the angle of impact affect the force, moments and stress in the hip. While their research determined that “increases in muscle force were protective (caused a reduction in bending moment, and peak compressive and tensile stress) at zero degree and anterior impact angles, and dangerous (caused an increase in bending moment and peak stresses) for posterior impact angles” certain limitations on their research study could cause uncertainty and inaccuracy in their results. Particularly, they modeled the muscle forces as point loads which we believe could significantly increase the amount of stress experienced in the hip. We feel that by simulating the muscle forces as distributed loads we will see much lower peak stresses than that obtained from their research. In addition, the model of soft tissue used was symmetric with respect to angle of impact, and thus not representative of real world scenarios. We feel that by using ANSA and LS Dyna to model the complex geometry of the soft tissue, we can see if the extra cushioning in the posterior negates the increased stress caused by muscle activation. Choi and Robinovich also only tested the impact at one specific location, we would like to see if their results hold true for other locations of impact. Finally in Choi and Robinovich’s paper only 7 different angles were tested. In order to have a better understanding of the relationship between angle of impact and stress in the hip we wanted to test more angles.
Student: Charlene Shong
Professor/Sponsor: Professor Hayden Taylor
Mentor: Brett Kelly
Research Project Title: Failure Case Studies for Continuous Liquid Interface Production
Student: Ganesh Vurimi
Professor/Sponsor: Professor Hayden Taylor
Mentor: Zachary Yun
Research Project Title: NanoHUB Composite Filament Modeling Project
For this project, we looked at making a computer simulation in order to be able to output the electrical properties of a nanocomposite material. Nanocomposites are materials where nanowires/nanoparticles are added to a polymer matrix in order to create a new material with certain desired properties. For this project, we are interested in the electrical properties of a such a material. A composite material can be made conductive with the addition of conductive nanowires, such as silver nanowires. However, designing these materials is expensive, as nanowires are still expensive and running numerous experiments to achieve a material with desired properties can be inefficient and time consuming. An application of this material is cheaper, electrically conductive 3D printing filaments. It is the goal of our simulation to be able to take in parameters such as nanowire material, length, diameter, the dimensions of the polymer and the volume percent of nanowires being added to the polymer and accurately output various electrical properties such as resistivity of the material, thus speeding up the design process.
The simulation is being coded in Python and will be put on the NanoHUB, an open source platform for nanotechnology related tools. It randomly generates the correct number of nanowires, represents it as a graph and then creates a circuit out of the ones that form a path across the polymer. We then use a circuit solver to solve the circuit and output resistance, from which the other properties can be calculated. In order to make sure the values outputted are accurate, a Monte Carlo simulation is run and the average values are returned. The first trials unfortunately gave us values up to two orders of magnitude different from the published experimental results. However, after going back and adding things to the model such as contact resistance, out values are now within the same order of magnitude in the preliminary testing. This will at least give designers a good ballpark of what a material’s electrical properties may be and hopefully we can continue to narrow the discrepancy. In addition to accuracy, we are continuing to optimize the simulation to run within a reasonable amount of time, especially as the number of nanowires in the polymer grows significantly for larger volumes.
Student: Kriya Wong
Professor/Sponsor: Professor Grace Gu
Mentor: Zhizhou Zhang, Kahraman Demir
Research Project Title: OwlFoil: Development of Bio-Inspired Multimaterial Composites
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.