Mechanical Engineering Commons^™

An Axisymmetric Finite Element Model To Study The Earplug Contribution To The Bone Conduction Occlusion Effect, Martin K. Brummund, Franck Sgard, Yvan Petit, Frédéric Laville, Hugues Nélisse

Études primaires

An axisymmetric linear elasto-acoustic finite element (FE) model of an occluded human external ear is proposed to simulate the bone conduction occlusion effect (OE). The model consists of a cylindrical ear canal cavity surrounded by layers of biological tissues (skin, cartilage and bone) in which an earplug is inserted. Geometrical and material properties are taken from the literature. OEs are predicted for foam and silicone earplug FE-models using COMSOL Multiphysics (COMSOL®, Sweden). The FE-model is shown to predict the experimental OE measured in two healthy human reference groups wearing foam or silicone earplugs, satisfactorily. Deviations between model and experiment are …

High-Resolution Bottom-Loss Estimation Using The Ambient-Noise Vertical Coherence Function, Lanfranco Muzi, Martin Siderius, Jorge E. Quijano, Stan E. Dosso

Electrical and Computer Engineering Faculty Publications and Presentations

The seabed reflection loss (shortly "bottom loss") is an important quantity for predicting transmission loss in the ocean. A recent passive technique for estimating the bottom loss as a function of frequency and grazing angle exploits marine ambient noise (originating at the surface from breaking waves, wind, and rain) as an acoustic source. Conventional beamforming of the noise field at a vertical line array of hydrophones is a fundamental step in this technique, and the beamformer resolution in grazing angle affects the quality of the estimated bottom loss. Implementation of this technique with short arrays can be hindered by their …

Control Of Responses Of Smart Plate Structures Under Non-Stationary Random Excitations, Xiaojian Yang

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

This thesis is concerned with an investigation of the control of responses of plate structures with piezoelectric layers and under complicated excitations modeled as a non-stationary random process. The plate structures and piezoelectric layers are both discretized by the mixed formulation finite element method (FEM).

The investigation consists of three parts. The first part is a literature survey and theoretical development. The second part is the eigenvalue solution and computation of uncontrolled response statistics of laminated plate structures under nonstationary random excitations. The final part is the introduction and application of the stochastic central difference (SCD) method that was presented …

Wingtip Dynamics Simulator, Eugene Fox, Nick Rodriguez, Steven Rieber

Mechanical Engineering

Raytheon is a defense contracting company with an electronic warfare division that is developing a radio frequency signal triangulation system. Part of the focus in improving this technology is the need for accurate and real time locational knowledge of the signal receivers, which are located at the tips of aircraft wings. Due to turbulence during flight, the fluttering motion of the wings alter the distance and angle relationships of the two receivers and add noise to the received signal data, which negatively affect the triangulation estimates. To mitigate this error caused by the wing flutter, Raytheon is developing a software …

Experiment And Simulation Of The Acoustic Signature Of Fatigued-Cracked Gears In A Two-Stage Gearbox, Matthew James Ostiguy

Master's Theses

This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy …

The Icon Horn Loudspeaker, Vincent Phan

Mechanical Engineering

A horn loudspeaker in layperson terms is essentially taking a megaphone and integrating it into a standard speaker. Similar to a cheerleader yelling into a megaphone, the horn loudspeaker will amplify the sound from the speaker with no additional power needed. Using standard speaker horn theory, the geometry of the “megaphone” can be engineered to tune the acoustic performance tailored to loudness and/or specific acoustics frequencies. The horn contours are similar to traditional orchestra instruments such as the French horn, trumpet, and tuba. The iconic beauty of a horn married with the quantitative engineering theory creates an aesthetic yet functional …

Assessment Of Noise-Induced Annoyance By Tones In Noise From Building Mechanical Systems, Joonhee Lee, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Prominent tones in noise generated by mechanical equipment in buildings can cause complaints from occupants in buildings. The ISO 1996-2 and ANSI S1.13 standards describe methodologies and metrics to quantify tonality perception, but the influence of tones in noise on human annoyance and performance is not fully understood yet. This paper investigates annoyance responses of humans while exposed to background noise with tonal components. Twenty participants completed digit span tasks while exposed to noise signals with differing levels of tones and overall loudness. Subjects were also asked to rate their annoyance after completing tasks under each noise signal. The subjective …

The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

The movement for improved classroom acoustics has primarily been grounded on studies that show how building acoustics (i.e. background noise levels and room reverberation) affect speech intelligibility, as determined by speech recognition tests. What about actual student learning, though? If students do not understand each spoken word in the classroom perfectly, can they still manage to achieve high scholastic success? This presentation will review two recent studies conducted at the University of Nebraska – Lincoln, linking classroom acoustic conditions to student learning outcomes and speech comprehension (rather than simply recognition). In the first, acoustic measurements in two public school districts …

Effects Of Room Acoustics On Comprehension Of Foreign-Accented Speech By Native And Non-Native English-Speaking Listeners, Zhao Peng, Kristin E. Hanna, Brenna N. Boyd, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

In a previous study by the authors, reverberation time (RT) and background noise level (BNL) were both found to have negative effects on native and non-native English-speaking listeners in comprehending English speech produced by native American-English-speaking talkers. Comprehension scores were adjusted for listeners’ baseline English proficiency levels. In the present study, instead of native English-speaking talkers, two native Mandarin Chinese talkers (one male, one female) with similar English spoken proficiency were recruited to produce the same speech materials used in the previous study. A similar methodology was adopted to conduct speech comprehension tests on three groups of listeners: 1) native …

Team Nathan Suspension, Frankie J. Wiggins, Alex D. Seitz, Justin P. Bautista

Mechanical Engineering

Nathan Cooper is an 8-year old boy with Spinal Muscular Atrophy (SMA). SMA has affected Nathan’s muscle development and requires him to use the Standing Dani™ mobility device. The Standing Dani is a motorized standing wheelchair, or Wheelstand. Nathan controls and uses it to get around. Though the Standing Dani performs well for most functions, it has some distinct issues. The primary issue that this project addresses is its lack of suspension and the discomfort that Nathan feels as a result. After talking with our client, we developed several specifications generally related to geometry, safety, vehicle dynamics, and reliability. Many …

Control Of A Spacecraft Using Mixed Momentum Exchange Devices, Blake J. Currie

Master's Theses

Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for …

Development Of Sound Quality Metrics For Gear Rattle In Diesel Engines, Brandon Sobecki

Open Access Theses

Sound quality is an important factor in the design of competitive diesel engines. The noise produced by specific components and mechanisms in the engine can play a significant role in determining the perceived quality of the overall noise and in turn the perceived quality of the engine. The goal of the present research is to characterize the sounds produced by the phenomenon known as gear rattle and to develop a model that can be used to assess gear rattle levels in a way that connects directly with human perception of rattle. Most previous work in this area has been focused …

Motion Control Of Robotic Arm With Command Shaping Method, Yumeng Wu, Peter H. Meckl, Alok Agrawal

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the manufacturing industry, lots of rapid point-to-point motion is required while the residual vibration is unfavorable. Residual vibrations caused by flexible elements are limiting the performance of mechanical system, especially when the system needs to make rapid point-to-point motion. As proved in earlier studies, avoiding natural frequencies of the mechanical system reduces the residual vibrations. This work is based on a non-linear, two-link flexible jointed robot with configuration dependent resonance. Command shaping method consisting different combinations of base functions and weighting factors are compared in this work. The compatibility of command shaping with classical feedback control structure allows a …

An Assessment Of Acoustic Contrast Between Long And Short Vowels Using Convex Hulls, Erin F. Haynes, Michael Taylor

Mechanical Engineering

An alternative to the spectral overlap assessment metric (SOAM), first introduced by Wassink [(2006). J. Acoust. Soc. Am. 119(4), 2334–2350], is introduced. The SOAM quantifies the intra- and inter-language differences between long–short vowel pairs through a comparison of spectral (F1, F2) and temporal properties modeled with best fit ellipses (F1 × F2 space) and ellipsoids (F1 × F2 × duration). However, the SOAM ellipses and ellipsoids rely on a Gaussian distribution of vowel data and a dense dataset, neither of which can be assumed in endangered languages or languages with limited available data. The method presented in this paper, called …

Development And Applications Of The Expanded Equivalent Fluid Method, Bharath Kumar Kandula

Dissertations

Ocean acoustics is the study of sound in the oceans. Electromagnetic waves attenuate rapidly in the water medium. Sound is the best means to transmit information underwater. Computational numerical simulations play an important role in ocean acoustics. Simulations of acoustic propagation in the oceans are challenging due to the complexities involved in the ocean environment. Different methods have been developed to simulate underwater sound propagation. The Parabolic-Equation (PE) method is the best choice in several ocean acoustic problems. In shallow water acoustic experiments, sound loses some of its energy when it interacts with the bottom. An equivalent fluid technique was …

Feedback Speed Control Of A Small Two-Stroke Internal Combustion Engine That Propels An Unmanned Aerial Vehicle, Paul D. Fjare

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unmanned aerial vehicles (UAV) require intelligent control of their power source. Small UAV are typically powered by electric motors or small two-stroke internal combustion (IC) engines. Small IC engines allow for longer flight times but are more difficult to control and cause significant ground noise. A hybrid operation that uses the engine at high altitudes and the electric motors at low altitudes is desired. This would allow for extended flight with acceptable ground noise levels. Since the engine can not be restarted in the air it must be able to remain at idle for an extended time without stalling. A …

Acoustic Testing Of Generator/Alternator Fans, Jacob Kriesel

Culminating Projects in Electrical Engineering

The intent of this project was to fill in a gap of the testing knowledge possessed for acoustics of an alternator within a generator set. The objective was to build a test fixture that would allow the user to test the acoustics of alternators without the driving force of an engine, which is a high acoustic source during testing. Eliminating the engine from the equation would allow for more accurate data of the product line, allowing for better utilization of acoustic tools when implementing sound source dampening. At the end of the project, it was found that the test fixture …

Determining Annoyance Thresholds Of Tones In Noise, Jennifer M. Francis, Joonhee Lee, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Building services equipment often produces noise signatures with significant tones in them that can lead to complaints in the built environment. Previous studies have investigated prominence levels of assorted tonal frequencies, but it is still unclear what prominence of the tones across varying tonal frequencies can lead to human annoyance. This project seeks to apply two different methods towards defining annoyance thresholds of tones in noise at two tonal frequencies: 125 Hz and 500 Hz. In the first, subjects are asked to perform a task, while exposed to ten minutes of a broadband noise spectrum with a specific level of …

The Prediction Of Airborne And Structure-Borne Noise Potential For A Tire, Nicholas Sakamoto

Open Access Theses

Tire/pavement interaction noise is a major component of both exterior pass-by noise and vehicle interior noise. The current testing methods for ranking tires from loud to quiet require expensive equipment, multiple tires, and/or long experimental set-up and run times. If a laboratory based off-vehicle test could be used to identify the airborne and structure-borne potential of a tire from its dynamic characteristics, a relative ranking of a large group of tires could be performed at relatively modest expense. This would provide a smaller sample set of tires for follow-up testing and thus save expense for automobile OEMs. The focus of …

Experimental And Numerical Investigation Of The Mechanism Of Blast Wave Transmission Through A Surrogate Head, Yi Hua, Praveen Akula, Linxia Gu, Jeff Berg, Carl A. Nelson

Department of Mechanical and Materials Engineering: Faculty Publications

This work is to develop an experiment-validated numerical model to elucidate the wave transmission mechanisms through a surrogate head under blast loading. Repeated shock tube tests were conducted on a surrogate head, i.e., water-filled polycarbonate shell. Surface strain on the skull simulant and pressure inside the brain simulant were recorded at multiple locations. A numerical model was developed to capture the shock wave propagation within the shock tube and the fluid-structure interaction between the shock wave and the surrogate head. The obtained numerical results were compared with the experimental measurements. The experiment-validated numerical model was then used to further understand …

Phonon Confinement Using Spirally Designed Elastic Resonators In Discrete Continuum, Sourav Banerjee, Raiz U. Ahmed

Faculty Publications

Periodic and chiral orientation of microstructures, here we call phononic crystals, have extraordinary capabilities to facilitate the innovative design of new generation metamaterials. Periodic arrangements of phononic crystals are capable of opening portals of non-passing, non-dispersive mechanical waves. Defying conventional design of regular periodicity, in this paper spirally periodic but chiral orientation of resonators are envisioned. Dynamics of the spirally connected resonators and the acoustic wave propagation through the spirally connected multiple local resonators are studied using fundamental physics. In present study the spiral systems with local resonators are assumed to be discrete media immersed in fluid. In this paper …

Uncertainty Quantification Driven Predictive Multi-Scale Model For Synthesis Of Mycotoxins, Sourav Banerjee, Gabriel A. Terejanu, Anindya Chanda

Faculty Publications

Many toxic molds synthesize and release an array of poisons, termed mycotoxins that have an enormous impact on human health, agriculture and economy [1]. These molds contaminate our buildings, indoor air and crops, cause life threatening human and animal diseases and reduce agricultural output [2]. In order to design appropriate approaches to minimize the detrimental effects of these fungi, it is essential to develop diagnostic methodologies that can rapidly and accurately determine based on fungal strains and their growth patterns, the extent of mycotoxin mediated damage caused to the environment.Here we developed a novel multi-scale predictive mathematical model that could …

A Study On The Vibrational Performance Characteristics Of An E22 Isolator After Outgassing And Bake-Out, Alma Melendez

Master's Theses

The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It …

Automated Foosball Table, Jim R. Stefani, Alex J. Herpy, Brett Gordon Jaeger, Kevin S. Haydon, Derek Alan Hamel

Mechanical Engineering

This project is the second iteration of an automated foosball table for Yaskawa America as a trade show display. The table is meant to provide an interactive experience which highlights the speed and precision of the Yaskawa hardware. The first iteration of the project was mainly focused on creating the physical hardware for the system and to begin the basic programming for the system. This phase of the project was focused on finalizing the physical hardware of the system, implementing the vision system and to continue the basic programing of the system AI. A third team will be assigned to …

Autonomous Indoor Localization For Fire Safety And Resource Location Via Field Mapping Techniques, Jaeyoung Kim, Kartik Ariyur, Yan Cui, Benjamin D. Branch, Joshua Ebung Umo

Libraries Faculty and Staff Presentations

An overall result of this collaboration between the Mechanical Engineering Dept. and the Purdue University Libraries (PUL) should result in building a big data framework that make have knowledge transfer for similar large scale geospatial data implementations. Such may promote best practices of data management where the library skill sets may aid faculty research and student learning. Here, the PUL is concerned with advancing the Mechanical Engineering‘s STEM pipeline capacity with this type of research, collaboration and data management engagement.

Autonomous Indoor Localization For Fire Safety And Resource Location Via Field Mapping Techniques (Android Version), Joshua Ebung Umo, Yan Cui, Kartik Ariyur, Benjamin D. Branch, Jaeyoung Kim

Libraries Faculty and Staff Presentations

An overall result of this collaboration between the Mechanical Engineering Dept. and the Purdue University Libraries (PUL) should result in building a big data framework that make have knowledge transfer for similar large scale geospatial data implementations. Such may promote best practices of data management where the library skill sets may aid faculty research and student learning. Here, the PUL is concerned with advancing the Mechanical Engineering‘s STEM pipeline capacity with this type of research, collaboration and data management engagement.

Autonomous Indoor Localization Via Field Mapping Techniques, With Agricultural Big Data Application, Yan Cui, Kartik Ariyur, Benjamin D. Branch

Libraries Faculty and Staff Presentations

This joint collaboration between the library, the Mechanical Engineering department shows the current research of localizing an Android smartphone using big data collection and sensor fusion techniques. The original work is Autonomous Indoor Localization via Field Mapping Techniques which primarily designed as indoor fire and safety aid.

For Agricultural Big Data Use, the Android smartphone is being applied to in indoor greenhouse fire, safety and data knowledge design. Such may aid big data tool value to greenhouse fire and safety design and any data that may be important fieldwork considerations.

The indoor agricultural mapping application may be application to greenhouses …

Using Acoustic Emission Monitoring For Energy-Based Fatigue Life Prediction, Sepehr Nesaei

Electronic Theses and Dissertations

The study of fatigue and fracture mechanics is crucial to the health monitoring and overall safety of aerospace and civil structures. The materials used to manufacture these industry parts have inherent anomalies that eventually grow under cyclic loadings during regular operation. The ASTM and/or military testing guidelines used to analyze and qualify structures and materials for use are costly and time consuming. Therefore, any additional methods or knowledge that can be used to reduce the number of tests will be useful to the industry to avoid unnecessary costs. Acoustic emission (AE) monitoring is currently used in many applications to assess …

Low Frequency Energy Scavenging Using Sub-Wave Length Scale Acousto-Elastic Metamaterial, Raiz U. Ahmed, Sourav Banerjee

Faculty Publications

This letter presents the possibility of energy scavenging (ES) utilizing the physics of acousto-elastic metamaterial (AEMM) at low frequencies (<∼3KHz). It is proposed to use the AEMM in a dual mode (Acoustic Filter and Energy Harvester), simultaneously. AEMM’s are typically reported for filtering acoustic waves by trapping or guiding the acoustic energy, whereas this letter shows that the dynamic energy trapped inside the soft constituent (matrix) ofmetamaterials can be significantly harvested by strategically embedding piezoelectric wafers in the matrix. With unit cell AEMM model, we experimentally asserted that at lower acoustic frequencies (< ∼3 KHz), maximum power in the micro Watts (∼35µW) range can be generated, whereas, recently reported phononic crystal based metamaterials harvested only nano Watt (∼30nW) power against 10KΩ resistive load. Efficient energy scavengers at low acoustic frequencies are almost absent due to large required size relevant to the acoustic wavelength. Here we report sub wave length scale energy scavengers utilizing the coupled physics of local, structural and matrix resonances. Upon validation of the argument through analytical, numerical and experimental studies, a multi-frequency energy scavenger (ES) with multi-cellmodel is designed with varying geometrical properties capable of scavenging energy (power output from ∼10µW – ∼90µW) between 0.2 KHz and 1.5 KHz acoustic frequencies.

Applying Spiking Neural Network Simulation To Neuromodulatory Autonomous Robot Control, Cameron Muhammad

Phi Kappa Phi Research Symposium (Archived)

In this paper, simulation of the brain based on an artificial spiking neuron model is used to create a self-learning algorithm. The spiking neuron simulation is used to demonstrate a neuromodulation program in which the reward seeking properties of dopamine, the risk-adverse effects of serotonin, and the attention-focusing effects of the cholinergic and noradrenergic systems are applied to a mobile robotic platform as it moves autonomously throughout an environment. External stimuli is recorded by the program as spiking “events” that result in corresponding amounts of dopamine and serotonin influenced spiking patterns. These spiking patterns affect how the robot adapts to …