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

Acoustics, Dynamics, and Controls Commons

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

1848 Full-Text Articles 2860 Authors 299911 Downloads 52 Institutions

All Articles in Acoustics, Dynamics, and Controls

Faceted Search

1848 full-text articles. Page 1 of 32.

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy 2017 Iowa State University

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy

Stephen D. Holland

Fiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic NDE is the preferred method to identify the presence of defects (such as delaminations) in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. Hence, a framework to incorporate flaws and known damage models automatically into a finite element analysis (FEA) of composites will aid in accessing their ...


Ultrasound Scatter In Heterogeneous 3d Microstructures, Brady Engle, Ronald A. Roberts, Robert Grandin 2017 Iowa State University

Ultrasound Scatter In Heterogeneous 3d Microstructures, Brady Engle, Ronald A. Roberts, Robert Grandin

Robert Grandin

This paper reports on a computational study of ultrasound propagation in heterogeneous metal microstructures. Random spatial fluctuations in elastic properties over a range of length scales relative to ultrasound wavelength can give rise to scatter-induced attenuation, backscatter noise, and phase front aberration. It is of interest to quantify the dependence of these phenomena on the microstructure parameters, for the purpose of quantifying deleterious consequences on flaw detectability, and for the purpose of material characterization. Valuable tools for estimation of microstructure parameters (e.g. grain size) through analysis of ultrasound backscatter have been developed based on approximate weak-scattering models. While useful ...


Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy 2017 Iowa State University

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy

Robert Grandin

Fiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic NDE is the preferred method to identify the presence of defects (such as delaminations) in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. Hence, a framework to incorporate flaws and known damage models automatically into a finite element analysis (FEA) of composites will aid in accessing their ...


Modeling For Ut Inspection Of Anisotropic Materials, Robert A. Roberts, Robert Grandin, Andrew Downs 2017 Iowa State University

Modeling For Ut Inspection Of Anisotropic Materials, Robert A. Roberts, Robert Grandin, Andrew Downs

Robert Grandin

This presentation reports on the extension of an established CNDE ultrasound beam transmission model to accommodate transmission in generally anisotropic materials. Using principles of elastodynamic reciprocity, the model expresses the internal wave field as a surface integral over the radiating transducer, employing the full Green function (point force response function) for the combined body under inspection and the coupling medium. The model evaluates the Green function asymptotically for short wavelength, and is therefore referred to as an asymptotic Green function model (AGF). The integrand of the transducer integral is projected on to a discretely orthogonal Gaussian basis, leading to a ...


Surrogate Modeling Of Ultrasonic Testing Simulations Using Variable-Fidelity Models And Data-Driven Methods, Robert Grandin, Leifur Leifsson 2017 Iowa State University

Surrogate Modeling Of Ultrasonic Testing Simulations Using Variable-Fidelity Models And Data-Driven Methods, Robert Grandin, Leifur Leifsson

Robert Grandin

Ultrasonic testing (UT) is used to detect internal flaws in materials or to characterize material properties [1]. Computational simulations are an important part of the UT process. Having fast surrogate models for ultrasonic testing (UT) simulations is key for inverse analysis and model-assisted probability of detection (MAPOD) in the field of nondestructive evaluation. In fact, it is impractical to perform the aforementioned tasks in a timely manner using current simulation models directly. Fast surrogate models can make these processes computationally tractable. This paper presents investigations of using surrogate modeling techniques to create fast approximate models of UT simulator responses. In ...


Validation Of Utsim2, A New Ultrasonic Simulation Package, Robert Grandin, Timothy Gray 2017 Iowa State University

Validation Of Utsim2, A New Ultrasonic Simulation Package, Robert Grandin, Timothy Gray

Robert Grandin

The Center for NDE (CNDE) at Iowa State University has a long history of developing physics models for NDE and packaging these models into simulation tools which make the modeling capabilities accessible to CNDE’s industrial sponsors. Recent work at CNDE has led to the development of a new ultrasonic simulation package, UTSim2, which aims to continue this tradition of supporting industrial application of CNDE models. In order to meet this goal, UTSim2 has been designed as an extensible software package which can support previously-developed physics models as well as future models yet to be developed. Initial work has focused ...


The Impact Of Three Interfaces For 360-Degree Video On Spatial Cognition, Wutthigrai Boonsuk, Stephen B. Gilbert, Jonathan W. Kelly 2017 Iowa State University

The Impact Of Three Interfaces For 360-Degree Video On Spatial Cognition, Wutthigrai Boonsuk, Stephen B. Gilbert, Jonathan W. Kelly

Stephen B. Gilbert

In this paper, we describe an experiment designed to evaluate the effectiveness of three interfaces for surveillance or remote control using live 360-degree video feeds from a person or vehicle in the field. Video feeds are simulated using a game engine. While locating targets within a 3D terrain using a 2D 360-degree interface, participants indicated perceived egocentric directions to targets and later placed targets on an overhead view of the terrain. Interfaces were compared based on target finding and map placement performance. Results suggest 1) non-seamless interfaces with visual boundaries facilitate spatial understanding, 2) correct perception of self-to-object relationships is ...


Hierarchical Feature Extraction For Efficient Design Of Microfluidic Flow Patterns, Kin Gwn Lore, Daniel Stoecklein, Michael Davies, Baskar Ganapathysubramanian, Soumik Sarkar 2017 Iowa State University

Hierarchical Feature Extraction For Efficient Design Of Microfluidic Flow Patterns, Kin Gwn Lore, Daniel Stoecklein, Michael Davies, Baskar Ganapathysubramanian, Soumik Sarkar

Baskar Ganapathysubramanian

Deep neural networks are being widely used for feature representation learning in diverse problem areas ranging from object recognition and speech recognition to robotic perception and human disease prediction. We demonstrate a novel, perhaps the first application of deep learning in mechanical design, specifically to learn complex microfluidic flow patterns in order to solve inverse problems in fluid mechanics. A recent discovery showed the ability to control the fluid deformations in a microfluidic channel by placing a sequence of pillars. This provides a fundamental tool for numerous material science, manufacturing and biological applications. However, designing pillar sequences for user-defined deformations ...


Full Wave Modeling Of Ultrasonic Scattering Using Nystrom Method For Nde Applications, Praveen Gurrala, Kun Chen, Jiming Song, Ron Roberts 2017 Iowa State University

Full Wave Modeling Of Ultrasonic Scattering Using Nystrom Method For Nde Applications, Praveen Gurrala, Kun Chen, Jiming Song, Ron Roberts

Jiming Song

Approximate methods for ultrasonic scattering like the Kirchhoff approximation and the geometrical theory of diffraction (GTD) can deliver fast solutions with relatively small computational resources compared to accurate numerical methods. However, these models are prone to inaccuracies in predicting scattered fields from defects that are not very large compared to wavelength. Furthermore, they do not take into account physical phenomena like multiple scattering and surface wave generation on defects. Numerical methods like the finite element method (FEM) and the boundary element method (BEM) can overcome these limitations of approximate models. Commercial softwares such as Abaqus FEA and PZFlex use FEM ...


Semi-Autonomous Golf Cart, Daniel T. Garza, Richard S. Emeott, Matthew E. May, Valerie A. Cherry, Brooke Davidson 2017 University of Tennessee, Knoxville

Semi-Autonomous Golf Cart, Daniel T. Garza, Richard S. Emeott, Matthew E. May, Valerie A. Cherry, Brooke Davidson

University of Tennessee Honors Thesis Projects

No abstract provided.


Room Acoustics: Measurement And Correction With A Portable Digital Signal Processor, Azad Jalali 2017 University of Southern Maine

Room Acoustics: Measurement And Correction With A Portable Digital Signal Processor, Azad Jalali

Thinking Matters

The frequency response of a listening space is often of great interest to anyone pursuing an accurate and undistorted listening experience. Here we successfully implement sine- sweep deconvolution on a hardware platform to demonstrate an easy, digitized way to measure and guide improvements to the audio dynamics of a room.


P26. Global Exponential Stabilization On So(3), Soulaimane Berkane 2017 sberkane@uwo.ca

P26. Global Exponential Stabilization On So(3), Soulaimane Berkane

Western Research Forum

Global Exponential Stabilization on SO(3)


Performance Evaluation Of The Fbg Sensing Device And Comparison With Piezoelectric Sensors For Acoustic Emission Detection, Chuang Zhang, Leonard J. Bond 2017 Hebei University of Technology

Performance Evaluation Of The Fbg Sensing Device And Comparison With Piezoelectric Sensors For Acoustic Emission Detection, Chuang Zhang, Leonard J. Bond

Leonard J. Bond

In-service structural health monitoring (SHM) of engineering structures has assumed a significant role in assessing their safety and integrity. As the most mature technique in fiber-optic field, Fiber Bragg Grating (FBG) sensors have emerged as a reliable, in situ and nondestructive tool for monitoring and diagnostics in large-scale structure. Main objectives of this work are to evaluate and compare the acoustic emission (AE) sensing characteristics simultaneously with FBG sensor array and piezoelectric (PZ) sensors. The pencil-lead-break (PLB) test, ball dropping test and the excitation from the PZ transducer are treated as the AE source which conducted on the platy and ...


Higher Order Acoustoelastic Lamb Wave Propagation In Stressed Plates, Ning Pei, Leonard J. Bond 2017 Iowa State University

Higher Order Acoustoelastic Lamb Wave Propagation In Stressed Plates, Ning Pei, Leonard J. Bond

Leonard J. Bond

Residual stresses can be generated during fabrication processes, such as, welding, forging, rolling etc[1-3] . They have obvious influence on the performance of the material, like cracking and corrosion. To better control residual stresses, the initial distribution of them in materials must be clear. Ultrasonic methods can be used as a good tool for residual stress detection, and this approach is non-destructive and costs are modest. Methods which utilize longitudinal critically refracted (LCR) waves are receiving increased attention and it can be used on thick material. However, there have only been a limited number of studies which consider the acoustoelastic ...


Constraints On Acoustic Signaling Among Birds Breeding In Secondary Cavities: The Effects Of Weather, Cavity Material, And Noise On Sound Propagation, John P. Swaddle, Caitlin R. Kight, Saji Perera, Eduardo Davila-Reyes, Shena Sikora 2017 College of William and Mary

Constraints On Acoustic Signaling Among Birds Breeding In Secondary Cavities: The Effects Of Weather, Cavity Material, And Noise On Sound Propagation, John P. Swaddle, Caitlin R. Kight, Saji Perera, Eduardo Davila-Reyes, Shena Sikora

John Swaddle

Increasing evidence suggests that anthropogenic noise from urbanization affects animal acoustic communication. We investigated whether the begging calls of nestling Eastern Bluebirds (Sialia sialis) varied along a disturbance gradient of ambient noise. Contrary to our prediction and the results of a previous study of nestling Tree Swallows (Tachycineta bicolor), we found that nestling Eastern Bluebirds did not increase the amplitude or structural characteristics—including frequency, rate, and duration—of their vocalizations in response to ambient noise. However, we found that prevalent temperature and humidity conditions attenuated begging calls. Specifically, in warmer, more humid weather, vocalizations of nestling Eastern Bluebirds attenuated ...


Bridge Damage Detection Using Spatiotemporal Patterns Extracted From Dense Sensor Network, Chao Liu, Yongqiang Gong, Simon Laflamme, Brent M. Phares, Soumik Sarkar 2017 Iowa State University

Bridge Damage Detection Using Spatiotemporal Patterns Extracted From Dense Sensor Network, Chao Liu, Yongqiang Gong, Simon Laflamme, Brent M. Phares, Soumik Sarkar

Simon Laflamme

The alarmingly degrading state of transportation infrastructures combined with their key societal and economic importance calls for automatic condition assessment methods to facilitate smart management of maintenance and repairs. With the advent of ubiquitous sensing and communication capabilities, scalable data-driven approaches is of great interest, as it can utilize large volume of streaming data without requiring detailed physical models that can be inaccurate and computationally expensive to run. Properly designed, a data-driven methodology could enable fast and automatic evaluation of infrastructures, discovery of causal dependencies among various sub-system dynamic responses, and decision making with uncertainties and lack of labeled data ...


Development Of An Excel® Rocket Simuator For Application In Middle School, High School, And University Stem Education, Melvin Lee Hortman 2017 Central Washington University

Development Of An Excel® Rocket Simuator For Application In Middle School, High School, And University Stem Education, Melvin Lee Hortman

All Master's Theses

Water rocket activities are one of the most popular STEM activities used in primary, secondary, and higher education yet are void of engineering, though engineering is heavily implied in the STEM acronym. This study investigated the amount of engineering present in water rocket activities, and options for emphasizing engineering more in water rocket activities using an open-platform flight simulator for use by educators to enable students to predict flight parameters of a water rocket they designed, and test those predictions against experimental data. The simulator was constructed in Excel® with many functions, but the function validated in this study was ...


Optimization Of Acoustic Soundboard Through Modal Analysis And Material Selection, Noah C. Nicholas, Cody Gruber, Nicholas Hartman 2017 The University Of Akron

Optimization Of Acoustic Soundboard Through Modal Analysis And Material Selection, Noah C. Nicholas, Cody Gruber, Nicholas Hartman

Honors Research Projects

The purpose of this design project was to determine if it is plausible to design an acoustic top plate assembly made of a non-traditional material which is equivalent in sound quality to that of a standard wooden guitar. Since wood must be crafted by skilled luthiers, the overall cost of producing the completed product is fairly high. To reduce the cost of a finished acoustic guitar, we proposed to alter the material to that of one that is easier to manufacture, such as plastics and composites.

Based on our research, our team chose to test both ABS plastic and carbon ...


Advanced Uses For Carbon Nanotubes: A Spherical Sound Source And Hot-Films As Microphones, Micaela M. Thiery 2017 Michigan Technological University

Advanced Uses For Carbon Nanotubes: A Spherical Sound Source And Hot-Films As Microphones, Micaela M. Thiery

Dissertations, Master's Theses and Master's Reports

Super-aligned carbon nanotube (CNT) thin-film is used to create thermophones. The thermal properties of CNT film allow it to rapidly heat and cool when supplied AC power producing temperature and pressure gradients and, therefore, audible sound. The advantages of CNT thermophones include eliminating all moving components of traditional speakers and reducing the weight of the speaker itself by using CNT film, which is nearly weightless. Additionally, the flexibility of CNT film provides the unique opportunity to construct loudspeakers of various sizes and geometries. In this work, a spherical CNT thermophone is designed, manufactured, and tested for directivity with the overall ...


Electroencephalographic Signal Processing And Classification Techniques For Noninvasive Motor Imagery Based Brain Computer Interface, Md Erfanul Alam 2017 Georgia Southern University

Electroencephalographic Signal Processing And Classification Techniques For Noninvasive Motor Imagery Based Brain Computer Interface, Md Erfanul Alam

Electronic Theses & Dissertations

In motor imagery (MI) based brain-computer interface (BCI), success depends on reliable processing of the noisy, non-linear, and non-stationary brain activity signals for extraction of features and effective classification of MI activity as well as translation to the corresponding intended actions. In this study, signal processing and classification techniques are presented for electroencephalogram (EEG) signals for motor imagery based brain-computer interface. EEG signals have been acquired placing the electrodes following the international 10-20 system. The acquired signals have been pre-processed removing artifacts using empirical mode decomposition (EMD) and two extended versions of EMD, ensemble empirical mode decomposition (EEMD), and multivariate ...


Digital Commons powered by bepress