Open Access. Powered by Scholars. Published by Universities.®

Mechanical Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 11401 - 11430 of 30089

Full-Text Articles in Mechanical Engineering

Impulsive Dynamics And Control Of The Inertia-Wheel Pendulum, Nilay Kant, Ranjan Mukherjee Oct 2018

Impulsive Dynamics And Control Of The Inertia-Wheel Pendulum, Nilay Kant, Ranjan Mukherjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The dynamics of the inertia-wheel pendulum, when subjected to impulsive inputs, can be described by algebraic equations. Optimal sequences of these inputs, that minimize their infinity norm, are designed for rest-to-rest maneuvers. The results are applied to the well-studied swing-up problem, and high-gain feedback is used for continuous approximation of the inputs and simulation of the impulsive dynamics. Analytical and simulation results establish a direct link between high wheel velocities during swing-up and control strategies that take the pendulum directly to the upright configuration. They also indicate that optimal trajectories resemble those of energy-based controllers and can be designed to …

Go to article

Slow Relaxation Dynamics In Binary Glasses During Stress-Controlled, Tension-Compression Cyclic Loading, Nikolai V. Priezjev Oct 2018

Slow Relaxation Dynamics In Binary Glasses During Stress-Controlled, Tension-Compression Cyclic Loading, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of cyclic loading on relaxation dynamics and mechanical properties of metallic glasses is studied using molecular dynamics simulations. We consider the Kob-Andersen three-dimensional binary mixture rapidly cooled across the glass transition and subjected to thousands of tension-compression cycles in the elastic range. It was found that during cyclic loading at constant pressure, the system is relocated to progressively lower levels of the potential energy, thus promoting greater densification and higher strength. Furthermore, with increasing stress amplitude, the average glass density increases and the minimum of the potential energy becomes deeper, while the elastic modulus is reduced. The typical …

Go to article

Explosive Dust Test Vessel Comparison Using Pulverized Pittsburgh Coal, Jacob Miller, Jay Schafler, Phillip R. Mulligan, Robert Eades, Kyle A. Perry, Catherine E. Johnson Oct 2018

Explosive Dust Test Vessel Comparison Using Pulverized Pittsburgh Coal, Jacob Miller, Jay Schafler, Phillip R. Mulligan, Robert Eades, Kyle A. Perry, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein …

Go to article

Revealing Particle-Scale Powder Spreading Dynamics In Powder-Bed-Based Additive Manufacturing Process By High-Speed X-Ray Imaging, Luis I. Escano, Niranjan D. Parab, Lianghua Xiong, Qilin Guo, Cang Zhao, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen Oct 2018

Revealing Particle-Scale Powder Spreading Dynamics In Powder-Bed-Based Additive Manufacturing Process By High-Speed X-Ray Imaging, Luis I. Escano, Niranjan D. Parab, Lianghua Xiong, Qilin Guo, Cang Zhao, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Powder spreading is a key step in the powder-bed-based additive manufacturing process, which determines the quality of the powder bed and, consequently, affects the quality of the manufactured part. However, powder spreading behavior under additive manufacturing condition is still not clear, largely because of the lack of particle-scale experimental study. Here, we studied particle-scale powder dynamics during the powder spreading process by using in-situ high-speed high-energy x-ray imaging. Evolution of the repose angle, slope surface speed, slope surface roughness, and the dynamics of powder clusters at the powder front were revealed and quantified. Interactions of the individual metal powders, with …

Go to article

Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren Oct 2018

Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren

Mechanical & Aerospace Engineering Faculty Publications

Modeling works which simulate the proton-exchange membrane fuel cell with the computational fluid dynamics approach involve the simultaneous solution of multiple, interconnected physics equations for fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts vary by how they treat the physics within and adjacent to the membrane-electrode assembly (MEA). Certain approaches treat the MEA not as part of the computational domain, but rather an interface connecting the anode and cathode computational domains. These approaches may lack the ability to consistently model catalyst layer losses and MEA ohmic resistance. This work presents an upgraded interface formulation …

Go to article

Coordinated, Multi-Arm Manipulation With Soft Robots, Dustan Paul Kraus Oct 2018

Coordinated, Multi-Arm Manipulation With Soft Robots, Dustan Paul Kraus

Theses and Dissertations

Soft lightweight robots provide an inherently safe solution to using robots in unmodeled environments by maintaining safety without increasing cost through expensive sensors. Unfortunately, many practical problems still need to be addressed before soft robots can become useful in real world tasks. Unlike traditional robots, soft robot geometry is not constant but can change with deflation and reinflation. Small errors in a robot's kinematic model can result in large errors in pose estimation of the end effector. This error, coupled with the inherent compliance of soft robots and the difficulty of soft robot joint angle sensing, makes it very challenging …

Go to article

Ultra-Thin Coating And Three-Dimensional Electrode Structures To Boosted Thick Electrode Lithium-Ion Battery Performance, Jie Li, Yan Gao, Xinhua Liang, Jonghyun Park Oct 2018

Ultra-Thin Coating And Three-Dimensional Electrode Structures To Boosted Thick Electrode Lithium-Ion Battery Performance, Jie Li, Yan Gao, Xinhua Liang, Jonghyun Park

Chemical and Biochemical Engineering Faculty Research & Creative Works

This paper reports a multiscale controlled three‐dimensional (3D) electrode structure to boost the battery performance for thick electrode batteries with LiMn1.5Ni0.5O4 as cathode material, which exhibits a high areal capacity (3.5 mAh/cm2) along with a high specific capacity (130 mAh/g). This excellent battery performance is achieved by a new concept of cell electrode fabrication, which simultaneously controls the electrode structure in a multiscale manner to address the key challenges of the material. Particles with ultrathin conformal coating layers are prepared through atomic layer deposition followed by a nanoscale‐controlled, thermal diffusion doping. The particles …

Go to article

T-Shirt Square Cutter, Austin Chawgo, Kendall Weishaar, Samir Lopez Oct 2018

T-Shirt Square Cutter, Austin Chawgo, Kendall Weishaar, Samir Lopez

Mechanical Engineering Design Project Class

Each year, Americans waste millions of pounds of textiles in the form of clothing that is thrown away. Professor Mary Ruppert-Stroescu from the Sam Fox School of Design seeks to combat this by reusing the old fabric from discarded clothes and creating new, fashionable clothing. To do this, her and her students cut up donated shirts into small squares, by hand, using scissors and fabric cutters and sew them together using a method developed by her.. This process is very time consuming and limits the commercial viability of this process. The T-shirt Cutter design, detailed below, has the potential to …

Go to article

Universal Tube Fixture, Griffin Kivitz, Matthew Whitehill, Jason Hsu Oct 2018

Universal Tube Fixture, Griffin Kivitz, Matthew Whitehill, Jason Hsu

Mechanical Engineering Design Project Class

The goal of this design project was to create a device that can aid in the assembly of glue joints between concentric tubes. In many medical devices, whether they be laser probes, retractable injectors, or other devices with actuating parts, there are often concentric glue joints. The problem we are trying to solve is controlling where the 2 tubes are relative to one another when they are glued.

Go to article

Group T Asme Design Challenge Project, Thomas Orgielewicz, Hayden Von Hoffmann, Michael Chirumbole Oct 2018

Group T Asme Design Challenge Project, Thomas Orgielewicz, Hayden Von Hoffmann, Michael Chirumbole

Mechanical Engineering Design Project Class

Design and build a RC Robot eligible to compete in the 2019 ASME Challenge, the "Pick-and-Place Race"

Go to article

Pick And Place Bot: Asme Design Challenge, Steven Mumford, Josh Clark, Stephan Meyer Oct 2018

Pick And Place Bot: Asme Design Challenge, Steven Mumford, Josh Clark, Stephan Meyer

Mechanical Engineering Design Project Class

Design a bot that meets the standards of and is able to compete in the 2019 ASME Design Challenge.

Go to article

Group L: T-Shirt2 Cutter, Sophie Anderson, Avery German, Taylor Tuleja Oct 2018

Group L: T-Shirt2 Cutter, Sophie Anderson, Avery German, Taylor Tuleja

Mechanical Engineering Design Project Class

The T-shirt square cutter was commissioned by fashion design professor at Washington University, Dr. Mary RuppertStroescu who has developed a method of turning T-shirts that might have otherwise been thrown away into a unique, woven fabric. Dr. Ruppert-Stroescu cuts T-shirts into either strips or squares that she then quilts together, she uses this fabric to make one-of-a-kind clothes, bags, and rugs. Though she is proficient at weaving the fabric scraps together, cutting the Tshirts was a very time-consuming process – it takes her at least 20 minutes to cut a T-shirt into squares by hand. Our team was tasked with …

Go to article

Tendon Rehabilitator, David Ricks, Lucas Parisot, Benjamin Wang Oct 2018

Tendon Rehabilitator, David Ricks, Lucas Parisot, Benjamin Wang

Mechanical Engineering Design Project Class

Our goal was to provide a cheap, portable and easy way for those suffering from medial epicondylitis tendinosis, or golfers elbow, to perform rehabbing exercises.

Go to article

Residential Automatic Door Opener, Steven Downs, Ardian Pollo, Ethan Bredemeier Oct 2018

Residential Automatic Door Opener, Steven Downs, Ardian Pollo, Ethan Bredemeier

Mechanical Engineering Design Project Class

This project proposes an innovative design for an automatic door opener intended for external doors of residential homes. The intended customers are elderly and disabled people who may benefit from such a device while entering and exiting their homes. The goal is to create an affordable product to compete with existing products that are relatively expensive to make such devices more accessible.

Go to article

Lacrosse Ball Passing Machine, William Galik, Daniel Finer, Matt Jenkins Oct 2018

Lacrosse Ball Passing Machine, William Galik, Daniel Finer, Matt Jenkins

Mechanical Engineering Design Project Class

Design and build a lacrosse ball passing machine that utilizes an automated ball sorting mechanism to shoot balls up to 60 mph with 80 percent accuracy at a 1 square yard target.

Go to article

Group V: Color Mixer, Kate Baskin, Mark Livshin, Andy Johnston Oct 2018

Group V: Color Mixer, Kate Baskin, Mark Livshin, Andy Johnston

Mechanical Engineering Design Project Class

This project was an exercise in product design, modeling, and prototyping. The result of this process was a partially functional prototype which successfully met two of the three design goals.

Go to article

Group B: Polar Coordinate Whiteboard Writer, Dylan Wu, Zexin Han, Keon Kim, Jiahao Wei Oct 2018

Group B: Polar Coordinate Whiteboard Writer, Dylan Wu, Zexin Han, Keon Kim, Jiahao Wei

Mechanical Engineering Design Project Class

From the initial funding of $250.00, our group attempted to make a polar coordinate whiteboard writer that was to be used in educational settings. Market for polar coordinate whiteboard writer is a blue ocean. Having a successful prototype will allow us to find a niche place in a market that shares border with the global education market.

Go to article

Anisotropic Tissue Maker, Jake Ireland, Jaryd Huffman, Sarah Mohrmann, Daniel Cano Oct 2018

Anisotropic Tissue Maker, Jake Ireland, Jaryd Huffman, Sarah Mohrmann, Daniel Cano

Mechanical Engineering Design Project Class

Traumatic brain injury (TBI) is a common injury that is not thoroughly understood. Data on brain mechanics and motion are not abundant during the time of impact. In order to accumulate more data and achieve a better understanding of how the injury occurs tissue mimics can be made.

Go to article

Autonomous Ground Photographer, Sylvia Tan, Nicholas C. Smith, Kate Padilla, Elise Ashley Oct 2018

Autonomous Ground Photographer, Sylvia Tan, Nicholas C. Smith, Kate Padilla, Elise Ashley

Mechanical Engineering Design Project Class

Dr. Penczykowski, a biology professor at Washington University in St. Louis, researches the effects of powdery mildew on three plant species. Her lab currently collects data in the field by manually counting the number of infected plants with the assistance of a simple PVC grid. Therefore, this projects aims to automate this process by capturing images that can then be processed in her lab after.

Go to article

Group O - Lacrosse Ball Passer, Mackenzie Gordon, Jake Mennemeier, Conor Pellas Oct 2018

Group O - Lacrosse Ball Passer, Mackenzie Gordon, Jake Mennemeier, Conor Pellas

Mechanical Engineering Design Project Class

The goal of our design group was to make a lacrosse ball passer that could be used in a team practice or individual setting. Wayne Jaekle, WashU’s head lacrosse coach defined major customer needs as producing a consistent pass speed and angle, an interactive interface allowing an automatic time interval between passes, and being easy to load. These needs lead to our main design goals: 1. A ball capacity of 30, 2. A minimum pass speed of 30 mph, and 3. A 5 second time interval between passes. Mock ups and brainstorming exercises led to our team’s selection of a …

Go to article

Arliss Competition Canister Vehicle, Jessie Goldberg, Nicholas Cornejo, Tyler Smith, Rachel Kershner Oct 2018

Arliss Competition Canister Vehicle, Jessie Goldberg, Nicholas Cornejo, Tyler Smith, Rachel Kershner

Mechanical Engineering Design Project Class

For our project, we designed a canister vehicle that fits the design specifications of the ARLISS competition. For the ARLISS competition, the vehicles are loaded into a rocket, launched approximately 10,000 feet into the air, released, and then must autonomously navigate to a predetermined target on the ground. Because of our time restraint, we are focused on designing a vehicle of the correct dimensions (a maximum mass of 1050g, a maximum diameter of 146mm, and a maximum height of 240mm) that can simply travel on the ground over multiple types of terrain. Additionally, we designed a parachute release mechanism so …

Go to article

Asme Design Competition - Group H, Melanie Self, Ben Tattersfield, Joshua Emde Oct 2018

Asme Design Competition - Group H, Melanie Self, Ben Tattersfield, Joshua Emde

Mechanical Engineering Design Project Class

This document presents our solution for the ASME pick-and-place design competition. In brief, the challenge is to collect balls from an arena and return them to a ‘home base’. The specifics of the competition are elaborated on within. The document walks through the design decisions that went into the prototype; the Goalkeeper concept that we ultimately landed on best solved the problems presented by the challenge statement as interpreted by our customer, Dr. James Jackson Potter. Several of the design choices were made by applying mathematical relationships, with the math and results included to illuminate our methods. We include a …

Go to article

Topological Conduction And Investigation On Multi Occurrence Of Dirac Cone, Mustahseen Mobashwer Indaleeb Oct 2018

Topological Conduction And Investigation On Multi Occurrence Of Dirac Cone, Mustahseen Mobashwer Indaleeb

Theses and Dissertations

The unique phenomena in acoustic metamaterial at the Dirac-like cone, and at the exceptional spawning ring could transform the field of engineering with multiple new applications that were never possible before. Localized conical dispersion called Dirac cone at the Brillouin Zone boundaries are the well-known phenomena demonstrated by photonics and phononic metamaterials. However, Dirac cone-like dispersion at the center of the Brillouin zone (where wave number, k = 0) [1] is rare and only happens due to accidental degeneracy at finite frequencies in two-dimensional periodic crystals (PCs), with or without microarchitectures. Accidental degeneracies are generally the ‘sweet spots’ where the …

Go to article

Study Of The Femtosecond Laser Processed Surfaces, Imprinting, And Casting For Changing The Wettability Of Surfaces, Yingxiao Song Oct 2018

Study Of The Femtosecond Laser Processed Surfaces, Imprinting, And Casting For Changing The Wettability Of Surfaces, Yingxiao Song

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Femtosecond Laser Surface Processing (FLSP) is a technology to fabricate micro/nano surface structures. These patterned surface structures show great importance in many applications, especially in controlling the wettability of the surface. Imprinting is a typical method for manufacturing large volumes of surfaces. This study combines two processes (FLSP and stamping) together to produce a surface structure similar to the original FLSP surface. In the first step, micro/nano structured surface mounds were fabricated by femtosecond laser processing. Then, these FLSP surfaces served as molds for subsequent imprinting to replicated the “negative” surface on a blank material. Surface morphology and peak-to-valley roughness …

Go to article

Experimental Investigation Of Two-Phase (Gas/Liquid) Flow In Intermediate Sized, Horizontal And Inclined Pipes, Noble C. Anumbe Oct 2018

Experimental Investigation Of Two-Phase (Gas/Liquid) Flow In Intermediate Sized, Horizontal And Inclined Pipes, Noble C. Anumbe

Theses and Dissertations

Multiphase flow models and correlations are indispensable tools for the design and operation of vital flow systems that power various industries. The development, validation and tuning of these flow models & correlations depend on the availability of reliable and accurate data. This dissertation reports on an experimental campaign that not only generated crucial two-phase flow data but also evaluated the effect of inclination angle on several flow parameters of interest. The report details the experimental investigation of upward, adiabatic, co-current two-phase (gas/liquid) flow through a 101.6 mm inner diameter (ID) pipe. Experimental data for the investigation were acquired using an …

Go to article

Ultrasonic Analysis And Tools For Quantitative Material State Awarness Of Engineered Materials, Subir Patra Oct 2018

Ultrasonic Analysis And Tools For Quantitative Material State Awarness Of Engineered Materials, Subir Patra

Theses and Dissertations

The objective of this research is to devise new methods and tools to generate real time awareness of the material state of composite and metallic structures through ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) at its very early stage of failure. To device new methodology it is also important to verify the method through virtual experiments and hence computational NDE is getting popular in the recent years. In this thesis, while experimental methodology is developed to understand the material state at its early stage of failure, a new peridynamic based Peri-Elastodynamic (PED) computational method is also developed for …

Go to article

Electrochemical Hydrogenation Of Acetone To Produce Isopropanol Using A Polymer Electrolyte Membrane Reactor, Chen Li, Ashanti M. Sallee, Xiaoyu Zhang, Sandeep Kumar Oct 2018

Electrochemical Hydrogenation Of Acetone To Produce Isopropanol Using A Polymer Electrolyte Membrane Reactor, Chen Li, Ashanti M. Sallee, Xiaoyu Zhang, Sandeep Kumar

Civil & Environmental Engineering Faculty Publications

Electrochemical hydrogenation (ECH) of acetone is a relatively new method to produce isopropanol. It provides an alternative way of upgrading bio-fuels with less energy consumption and chemical waste as compared to conventional methods. In this paper, Polymer Electrolyte Membrane Fuel Cell (PEMFC) hardware was used as an electrochemical reactor to hydrogenate acetone to produce isopropanol and diisopropyl ether as a byproduct. High current efficiency (59.7%) and selectivity (>90%) were achieved, while ECH was carried out in mild conditions (65 degrees C and atmospheric pressure). Various operating parameters were evaluated to determine their effects on the yield of acetone and …

Go to article

A Deterministic-Stochastic Method For Computing The Boltzmann Collision Integral In O(Mn) Operations, Alexander Alekseenko, Truong Nguyen, Aihua W. Wood Oct 2018

A Deterministic-Stochastic Method For Computing The Boltzmann Collision Integral In O(Mn) Operations, Alexander Alekseenko, Truong Nguyen, Aihua W. Wood

Faculty Publications

We developed and implemented a numerical algorithm for evaluating the Boltzmann collision integral with O(MN) operations, where N is the number of the discrete velocity points and M < N. At the base of the algorithm are nodal-discontinuous Galerkin discretizations of the collision operator on uniform grids and a bilinear convolution form of the Galerkin projection of the collision operator. Efficiency of the algorithm is achieved by applying singular value decomposition compression of the discrete collision kernel and by approximating the kinetic solution by a sum of Maxwellian streams using a stochastic likelihood maximization algorithm. Accuracy of the method is …

Go to article

The Development Of A Novel Motion Cuing Algorithm For Flight Training Simulators Employing Objective Metrics For Evaluation, Ahmad Qasim Momani Sep 2018

The Development Of A Novel Motion Cuing Algorithm For Flight Training Simulators Employing Objective Metrics For Evaluation, Ahmad Qasim Momani

Link Foundation Modeling, Simulation and Training Fellowship Reports

The value of a dynamic motion platform to the flight simulator is a controversial issue within the flight training community. The motion of the flight simulator platform has been shown to affect pilot performance and behavior. Moreover, its ability to provide the operator with the appropriate motion cues is essential for pilot training or research. Unwanted cues can cause the operator to develop inappropriate control behavior strategies that are not useful or might be dangerous in real flight. Performance studies show that the operator’s performance is enhanced when introducing motion which might indicate that the operator experiences a sensation closer …

Go to article

Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian Sep 2018

Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian

Dissertations and Theses

Ozone in indoor environments can pose a health risk to human occupants; around half of exposure to this pollutant occurs inside buildings. One approach to reducing indoor O3 levels is to mitigate O3 as it enters a building via outdoor air ventilation supply. Often, mechanical systems that introduce outdoor air into buildings are placed on building rooftops. At the urban scale, greenery has been shown to reduce levels of some harmful pollutants, including ozone and cities like Portland, OR, are mandating green roofs be built on large commercial buildings to increase urban green surfaces. We investigate if rooftop …

Go to article

First Prev Next Last