Mechanical Engineering Commons^™

Vibrating Flexoelectric Micro-Beams As Angular Rate Sensors, Yilin Qu, Feng Jin, Jiashi S. Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied flexoelectrically excited/detected bending vibrations in perpendicular directions of a micro-beam spinning about its axis. A set of one-dimensional equations was derived and used in a theoretical analysis. It is shown that the Coriolis effect associated with the spin produces an electrical output proportional to the angular rate of the spin when it is small. Thus, the beam can be used as a gyroscope for angular rate sensing. Compared to conventional piezoelectric beam gyroscopes, the flexoelectric beam proposed and analyzed has a simpler structure.

Vibrating Flexoelectric Micro-Beams As Angular Rate Sensors, Yilin Qu, Feng Jin, Jiashi S. Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied flexoelectrically excited/detected bending vibrations in perpendicular directions of a micro-beam spinning about its axis. A set of one-dimensional equations was derived and used in a theoretical analysis. It is shown that the Coriolis effect associated with the spin produces an electrical output proportional to the angular rate of the spin when it is small. Thus, the beam can be used as a gyroscope for angular rate sensing. Compared to conventional piezoelectric beam gyroscopes, the flexoelectric beam proposed and analyzed has a simpler structure.

Geometric Analysis Of Insect Wing Vein Network, Jacob White, Ying Hu, Sangjin Ryu, Seunghee Kim, Haipeng Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

An insect wing consists of a thin membrane supported by a system of veins, and flow of blood through the system of veins is critical for maintaining healthy insect wings. Better understanding of the insect wing vein circulation requires to know how the efficiency of blood flow in an insect wing relates to the geometric shape of the vein. Our investigation of the wing vein network of a dragonfly Anax junius follows the idea of Murray’s law, which is established in the study of efficiency of the vein network and the geometric shape of the vein. Instead of using the …

Manufacturing And Characterization Of Continuous Nanofiber-Reinforced Composites, Lucas Barry

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

Fiber-reinforced composite laminates are some of the most advanced structural materials available. However, delamination remains a critical challenge due to its prevalence in structures and ability to cause catastrophic failure. Recently, high-temperature composites are at the forefront of polymer-matrix composites research, but they are prone to microcracking followed by delamination. Nanoreinforcement of interfaces by continuous nanofibers has been proposed earlier at UNL and produced increased interlaminar fracture resistance in conventional advanced composites. However, no studies have yet been conducted on emerging high-temperature composites. Also, there is insufficient information on the translatability of observed modes I and II interlaminar fracture toughness …

Octopus-Inspired Adhesive Skins For Intelligent And Rapidly Switchable Underwater Adhesion, Sean T. Frey, A. B. M. Tahidul Haque, Ravi Tutika, Elizabeth V. Krotz, Chanhong Lee, Cole B. Haverkamp, Eric J. Markvicka, Michael D. Bartlett

Department of Mechanical and Materials Engineering: Faculty Publications

The octopus couples controllable adhesives with intricately embedded sensing, processing, and control to manipulate underwater objects. Current synthetic adhesive–based manipulators are typically manually operated without sensing or control and can be slow to activate and release adhesion, which limits system-level manipulation. Here, we couple switchable, octopus-inspired adhesives with embedded sensing, processing, and control for robust underwater manipulation. Adhesion strength is switched over 450× from the ON to OFF state in <50 ms over many cycles with an actively controlled membrane. Systematic design of adhesive geometry enables adherence to nonideal surfaces with low preload and independent control of adhesive strength and adhesive toughness for strong and reliable attachment and easy release. Our bio-inspired nervous system detects objects and autonomously triggers the switchable adhesives. This is implemented into a wearable glove where an array of adhesives and sensors creates a biomimetic adhesive skin to manipulate diverse underwater objects.

A Pilot Study On The Nanoscale Properties Of Bone Tissue Near Lacunae In Fracturing Women, Wen Qian, Roman Schmidt, Joseph A. Turner, Sue P. Bare, Joan M. Lappe, Robert R. Recker, Mohammed P. Akhter

Department of Mechanical and Materials Engineering: Faculty Publications

The goal of this study is to investigate the causes of osteoporosis-related skeletal fragility in postmenopausal women. We hypothesize that bone fragility in these individuals is largely due to mineral, and/or intrinsic material properties in the osteocyte lacunar/peri-lacunar regions of bone tissue. Innovative measurements with nanoscale resolution, including scanning electron microscope (SEM), an atomic force microscope that is integrated with infrared spectroscopy (AFM-IR), and nanoindentation, were used to characterize osteocyte lacunar and peri-lacunar properties in bone biopsies from fracturing (Cases) and matched (Age, BMD), non-fracturing (Controls) postmenopausal healthy women. In the peri-lacunar space, the nanoindentation results show that the modulus …

Microfluidic Device For Localized Electroporation, Justin Brooks, Arian Jaberi, Ruiguo Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Electroporation is a common method of transfection due to its relatively low risk and high transfection efficiency. The most common method of electroporation is bulk electroporation which is easily performed on large quantities of cells yet results in variable levels of viability and transfection efficiency across the population. Localized electroporation is an alternative that can be administered on a similar scale but results in much more consistent with higher quality transfection and higher cell viability. This paper discusses the creation and use of a simple and cost-effective device using porous membrane for performing localized electroporation.

Phase Space Analysis Of Nonlinear Wave Propagation In A Bistable Mechanical Metamaterial With A Defect, Mohammed A. Mohammed, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

We study the dynamics of solitary waves traveling in a one-dimensional chain of bistable elements in the presence of a local inhomogeneity (`defect'). Numerical simulations reveal that depending upon its initial speed, an incoming solitary wave can get transmitted, captured or reflected upon interaction with the defect. The dynamics are dominated by energy exchange between the wave and a breather mode localized at the defect. We derive a reduced-order two degree of freedom Hamiltonian model for wave-breather interaction, and analyze it using dynamical systems techniques. Lobe dynamics analysis reveals the fine structure of phase space that leads to the complicated …

The Dark Annulus Of A Drop In A Hele-Shaw Cell Is Caused By The Refraction Of Light Through Its Meniscus, Sangjin Ryu, Haipeng Zhang, Carson Emeigh

Department of Mechanical and Materials Engineering: Faculty Publications

Knowing the meniscus shape of confined drops is important for understanding how they make first contact and then coalesce. When imaged from the top view by brightfield microscopy, a liquid drop (e.g., corn syrup) confined in a Hele-Shaw cell, surrounded by immiscible liquid (e.g., mineral oil), had a dark annulus, and the width of the annulus decreased with increasing concentration of corn syrup. Since the difference in the annulus width was presumed to be related to the meniscus shape of the drops, three-dimensional images of the drops with different concentrations were obtained using confocal fluorescence microscopy, and their cross-sectional meniscus …

Modular Cable - Driven Surgical Robots, Carl A. Nelson, Nicholas Nelson

Department of Mechanical and Materials Engineering: Faculty Publications

A surgical robot can be configured for minimally invasive surgery ( MIS ) and other types of surgery with modular link geometry and disposable components. In some examples, the surgical robot includes a cable driver comprising at least one drive motor configured for tensioning a cable. The surgical robot includes an articulated surgical tool coupled to the drive motor by the cable. The articulated surgical tool comprises at least first and second articulated links and a joint coupling the first and second articulated links. The cable passes through the joint, and the joint comprises an elastic antagonist biased in opposition …

Gross Positioning Device And Related Systems And Methods, Mark A. Reichenbach, Shane M. Farritor

Department of Mechanical and Materials Engineering: Faculty Publications

Disclosed herein are gross positioning systems for use with robotic surgical devices to provide gross positioning of the robotic surgical devices. The gross positioning systems have a base, a first arm link operably coupled to the base, a second arm link operably coupled to the first arm link, a third arm link operably coupled to the second arm link, and a slidable coupling component slidably coupled to the third arm link.

Monolithic Integration Of Hybrid Perovskite Single Crystals With Silicon For Highly Sensitive X - Ray Detectors, Jinsong Huang, Wei Wei

Department of Mechanical and Materials Engineering: Faculty Publications

Perovskite single crystal X - ray radiation detector devices including an X - ray wavelength - responsive active layer including an organolead trihalide perovskite single crystal, a substrate layer comprising an oxide, and a binding layer disposed between the active layer and the substrate layer. The binding layer including a binding molecule having a first functional group that bonds to the organolead trihalide perovskite single crystal and a second functional bonds with the oxide. Inclusion of the binding layer advantageously reduces device noise while retaining signal intensity.

Passivation Of Defects In Perovskite Materials For Improved Solar Cell Efficiency And Stability, Jinsong Huang, Xiaopeng Zheng

Department of Mechanical and Materials Engineering: Faculty Publications

Semiconductor devices , and methods of forming the same , include a cathode layer , an anode layer , and an active layer disposed between the cathode layer and the anode layer , wherein the active layer includes a perovskite layer . A passivation layer is disposed directly on a surface of the active layer between the cathode layer and the active layer , the passivation layer including a layer of material that passivates both cationic and anionic defects in the surface of the active layer .

Rheological Behavior Of Dspc-, Dbpc-, And Dppc-Oxygen Microbubbles And Their Effectiveness In Improving Survival In A Rat Model Of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome, Riaz Ur Rehman Mohammed

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

Acute respiratory distress syndrome (ARDS) causes 75,000 deaths in the U.S., annually. It is characterized by hypoxemia and damage to the lung alveoli. ARDS Management strategies involve extracorporeal membrane oxygenation (ECMO) and mechanical ventilation, but none of these methods improve the mortality rates. Oxygen microbubbles (OMBs) consist of a lipid shell with an oxygen core and have potential to augment oxygenation to manage ARDS. Previous studies demonstrated significant improvements in systemic oxygenation and mortality upon administering OMBs.

We replicated an ARDS rat model by intratracheal administration of lipopolysaccharide at a 24 mg/kg dose. After inducing the disease in rats, the …

Design Of Path Correction For Improved Gait Rehabilitation, Zvonimir Pusnik

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

Following a serious neurological injury or disease, such as a spinal cord injury or multiple sclerosis, many patients develop impaired gait (the ability to walk). There are many different pieces of equipment to help rehabilitate people with impaired gait, ranging from over ground walking with exoskeletons to treadmills with partial bodyweight support. Since the 1990s and 2000s, elliptical trainers have entered the rehabilitative field as a machine with low impact forces and gait-like motion. This led researchers at Madonna Rehabilitation Hospitals to collaborate with the University of Nebraska-Lincoln to create the Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE).

While the ICARE …

Understanding The Nonlinear Dynamics Governing Vertical-Lift Vehicles With Variable-Speed, Fixed Rotors, Stephanie Vavra, Micah Busboom, Aleea Stanford, Keegan Moore

UNL Student Research Days Posters, Undergraduate

Problem: Traffic significantly limits travel in urban areas. • The NASA Urban Air Mobility Project is developing an air taxi as an alternative mean of transportation (Fig. 1).

Challenge: Operating rotors at different frequencies may cause the cabin to vibrate at high amplitudes. Such effects are currently unknown.

Objective: Understand the effect of variable speed rotors on passenger comfort.

From the reduced-order modeling simulations, it can be assumed that counteracting the rotor speed in-balances can reduce the displacement and vibrations experienced at the center of the wing. In other words, should a rotor not maintain its optimal operation speed, reducing …

The Effect Of Store-To-Store Energy Transfers On The Global Dynamics Of Aircraft, Guilherme Mainieri Eymael, Keegan J. Moore

UNL Student Research Days Posters, Undergraduate

This study analyzes the energy transfer mechanisms when nonlinear devices (stores) are attached to a linear model airplane. For that, a reduced-order model (ROM) was derived to simulate the first two flexible modes of vibration of the primary structure (aircraft) with one store in each wing. Each store can either be locked or unlocked. When locked, it only contributes as mass-effect, and when unlocked, it adds nonlinearity to the system. Simulations were then performed with either both stores locked, one store unlocked, or both stores unlocked. It was found that the attachment of nonlinear stores in the ROM changes the …

Polyaniline/Cobalt Nanoparticle Composite Films, Rifat Mahbub

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

Polymer nanocomposites have been gaining attention because of the enhanced properties of the element materials it can offer. These composites have been used in biological sector as well as quantum computing and memory devices. These are also used as different kind of sensors. Polymer composites incorporated with magnetic nanoparticles can modify the magnetic property of the nanoparticles and that has huge potential to be used in different sort of applications.

This work aims to develop a polymeric nanocomposite incorporating a conducting polymer and magnetic nanoparticles. The influence of the conducting polymer on the magnetic property of the nanoparticles was investigated. …

Ultra-Broadband And Polarization-Insensitive Metasurface Absorber With Behavior Prediction Using Machine Learning, Shobhit K. Patel, Juveriya Parmar, Vijay Katkar, Fahad Ahmed Al-Zahrani, Kawsar Ahmed

Department of Mechanical and Materials Engineering: Faculty Publications

The solar spectrum energy absorption is very important for designing any solar absorber. The need for absorbing visible, infrared, and ultraviolet regions is increasing as most of the absorbers absorb visible regions. We propose a metasurface solar absorber based on Ge₂Sb₂Te₅ (GST) substrate which increases the absorption in visible, infrared and ultraviolet regions. GST is a phase-changing material having two different phases amorphous (aGST) and crystalline (cGST). The absorber is also analyzed using machine learning algorithm to predict the absorption values for different wavelengths. The solar absorber is showing an ultra-broadband response covering a 0.2–1.5 …

The Effect Of Store-To-Store Energy Transfers On The Global Dynamics Of Aircraft, Guilherme Mainieri Eymael

Honors Program: Senior Projects (Public)

This study analyzes the energy transfer mechanisms when nonlinear devices (stores) are attached to a linear model airplane. For that, a reduced-order model (ROM) was derived to simulate the first two flexible modes of vibration of the primary structure (aircraft) with one store in each wing. Each store can either be locked or unlocked. When locked, it only contributes as mass-effect, and when unlocked, it adds nonlinearity to the system. Simulations were then performed with either both stores locked, one store unlocked, or both stores unlocked. It was found that the attachment of nonlinear stores in the ROM changes the …

Development Of Controller Area Network Bus Programming For Quarter-Scale Tractor Pulling Sled, Brittani Wacker

Honors Program: Senior Projects (Public)

Usage of Controller Area Network (CAN) technology has allowed for advancements in many industries, including agriculture. Most importantly, its application is useful for refining data acquisition methods. With support from the Quarter-scale Tractor Design Team at UNL, this project united a CAN bus with the team’s current tractor pulling sled. The objectives were to install new instrumentation needed for the CAN bus and to program the updated system utilizing CAN data. The program needed to give the pulling sled functionality and the ability to read and log important pulling data. These goals were all accomplished by implementing new sensors, coding …

Closed-Loop Control Of Meltpool Temperature In Directed Energy Deposition, Ziyad M. Smoqi, Ben Bevans, Aniruddha Gaikwad, James Craig, Alan Abul-Haj, Brent Roeder, Bill Macy, Jeffrey E. Shield, Prahalada K. Rao

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this work is to mitigate flaw formation in powder and laser-based directed energy deposition (DED) additive manufacturing process through close-loop control of the meltpool temperature. In this work, the meltpool temperature was controlled by modulating the laser power based on feedback signals from a coaxial two-wavelength imaging pyrometer. The utility of closed-loop control in DED is demonstrated in the context of practically inspired trapezoid-shaped stainlesssteel parts (SS 316L). We demonstrate that parts built under closed-loop control have reduced variation in porosity and uniform microstructure compared to parts built under open-loop conditions. For example, post-process characterization showed that …

Recent Advances In Biosensors For Detection Of Covid-19 And Other Viruses, Shobhit K. Patel, Jaymit Surve, Juveriya Parmar, Kawsar Ahmed, Francis M. Bui, Fahad Ahmed Al-Zahrani

Department of Mechanical and Materials Engineering: Faculty Publications

This century has introduced very deadly, dangerous, and infectious diseases to humankind such as the influenza virus, Ebola virus, Zika virus, and the most infectious SARS-CoV-2 commonly known as COVID-19 and have caused epidemics and pandemics across the globe. For some of these diseases, proper medications, and vaccinations are missing and the early detection of these viruses will be critical to saving the patients. And even the vaccines are available for COVID-19, the new variants of COVID-19 such as Delta, and Omicron are spreading at large. The available virus detection techniques take a long time, are costly, and complex and …

Tractor Test 2252: John Deere 9rx 540, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Tractor Test 2251: John Deere 9rx 490, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Tractor Test 2250: John Deere 9rt 570, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Tractor Test 2249: John Deere 9rt 520, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Tractor Test 2248: John Deere 9rt 470, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 2261: John Deere 6140m, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 2259: John Deere 9r 440, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …