Mechanical Engineering Commons^™

Effect Of Defects Part Ii: Multiscale Effect Of Microvoids, Orientation Of Rivet Holes On The Damage Propagation, And Ultimate Failure Strength Of Composites, Vahid Tavaf, Mohammadsadegh Saadatzi, Sourav Banerjee

Faculty Publications

Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. The nteraction of multiple cutouts like rivet holes, the repercussion of their configuration on crack propagation, and ultimate strength were predicted using Peridynamic method and the results are reported in this article. The effect of microscale defects at the vicinity of the cutouts on macroscale damage propagation were shown to have quantifiable manifestation. This study focused on two to four holes in unidirectional composite plates with 0°, 45°, and 90° fiber directions, while the vicinity of a hole was considered degraded. Numerical results were validated using …

Identification Of Active Surface Species In Molten Carbonates Using In Situ Raman Spectroscopy, Peng Zhang, Tao Wu, Kevin Huang

Faculty Publications

Here we report the results of a study on active surface species of a pristine and modified (Li-Na)₂CO₃ eutectic using in situ Raman spectroscopy technique. The effects of gas compositions, temperature, time, and alkaline earth have been systematically studied. The species of CO₄^2–, HCO₄^–, and C₂O₅^2– are identified as the three major active species on the surface of (Li-Na)₂CO₃ eutectic by a combined Raman spectroscopy and theoretical density functional theory calculations. The results further reveal that CO₄^2–, HCO₄^–, …

High-Order Wave-Damage Interaction Coefficients (Wdic) Extracted Through Modal Decomposition, Hanfei Mei, Victor Giurgiutiu

Faculty Publications

This paper presents a new technique for the extraction of high-order wave-damage interaction coefficients (WDIC) through modal decomposition. The frequency and direction dependent complex-valued WDIC are used to model the scattering and mode conversion phenomena of guided wave interaction with damage. These coefficients are extracted from the harmonic analysis of local finite element model (FEM) mesh with non-reflective boundaries (NRB) and they are capable of describing the amplitude and phase of the scattered waves as a function of frequency and direction. To extract the WDIC of each wave mode, all the possible propagating wave modes are considered to be scattered …

Impact Damage Ascertainment In Composite Plates Using In-Situ Acoustic Emission Signal Signature Identification, Robin James, Roshan Prakash Joseph, Victor Giurgiutiu

Faculty Publications

Barely visible impact damage (BVID) due to low velocity impact events in composite aircraft structures are becoming prevalent. BVID can have an adverse effect on the strength and safety of the structure. During aircraft inspections it can be extremely difficult to visually detect BVID. Moreover, it is also a challenge to ascertain if the BVID has in-fact caused internal damage to the structure or not. This paper describes a method to ascertain whether or not internal damage happened during the impact event by analyzing the high-frequency information contained in the recorded acoustic emission signal signature. Multiple 2 mm quasi-isotropic carbon …

Accelerated Controller Tuning For Wind Turbines Under Multiple Hazards, Aly Mousaad Aly, Milad Rezaee

Faculty Publications

During their lifecycle, wind turbines can be subjected to multiple hazard loads, such as high-intensity wind, earthquake, wave, and mechanical unbalance. Excessive vibrations, due to these loads, can have detrimental effects on energy production, structural lifecycle, and the initial cost of wind turbines. Vibration control by various means, such as passive, active, and semi-active control systems provide crucial solutions to these issues. We developed a novel control theory that enables semi-active controller tuning under the complex structural behavior and inherent system nonlinearity. The proposed theory enables the evaluation of semi-active controllers’ performance of multi-degrees-of-freedom systems, without the need for time-consuming …

Thermal Ignition Of A Combustible Over An Inclined Hot Plate, Salaika Parvin, Nepal Chandra Roy, Rama S. R. Gorla

Faculty Publications

In this study, the ignition characteristics and the flow properties of the mixed convection flow are presented. Detailed formulations of the forced, natural and mixed convection problems have been discussed. In order to avoid inconvenient switch between the forced and natural convection we introduce a continuous transformation in the mixed convection. We make a comparison between these situations which reveal a good agreement. For mixed convection flow, the ignition distance is explicitly expressed as a function of the Prandtl number, reaction parameter and wall temperature. It has been observed that owing to the increase of the aforesaid parameters, the thermal …

State Consistence Of Data-Driven Reduced Order Models For Parametric Aeroelastic Analysis, William C. Krolick, Jung I. Shu, Yi Wang, Kapil Pant

Faculty Publications

This paper investigates the state consistence of parametric data-driven reduced order models (ROMs) in a state-space form obtained by various system identification methods, including autoregressive exogenous (ARX) and subspace identification (N4SID), for aeroelastic analysis in varying flight conditions. The target flight envelop is first partitioned into discrete grid points, on each of which an aerodynamic ROM is constructed using system identification to capture the dependence of the generalized aerodynamic force on the generalized displacement of structural modes. High-fidelity aeroelastic modal perturbation simulations are used to generate the ROM training and verification data. Aerodynamic ROMs not on the grid point are …

First-Order Comprehensive Adjoint Sensitivity Analysis Methodology For Critical Points In Coupled Nonlinear Systems. I: Mathematical Framework, Dan Gabriel Cacuci

Faculty Publications

This work presents the novel first-order comprehensive adjoint sensitivity analysis methodology for critical points (1st-CASAM-CP), which enables the exact and efficient computation of the first-order sensitivities of responses defined at critical points (maxima, minima, saddle points) of coupled nonlinear models of physical systems characterized by imprecisely known parameters underlying the models, boundaries, and interfaces between the coupled systems. Responses defined at critical points are important in many applications, including system optimization, safety analyses and licensing. For the design and licensing of nuclear reactors, such essentially important responses include the maximum temperatures of the fuel and cladding in hot channels. The …

First-Order Comprehensive Adjoint Sensitivity Analysis Methodology For Critical Points In Coupled Nonlinear Systems. Ii: Application To A Nuclear Reactor Thermal-Hydraulics Safety Benchmark, Dan Gabriel Cacuci

Faculty Publications

Responses defined at critical points are particularly important for reactor safety analyses and licensing (e.g., the maximum fuel and/or clad temperature). The novel mathematical framework of the first-order comprehensive adjoint sensitivity analysis methodology for critical points (1st-CASAM-CP) is applied in this work to develop a reactor safety thermal-hydraulics benchmark model which admits exact closed-form expressions for the adjoint functions and for the first-order sensitivities of responses defined at critical points (maxima, minima, saddle points) in physical systems characterized by imprecisely known parameters, external and internal boundaries. This benchmark model is designed for verifying the capabilities and accuracies of computational tools …

User Guide For Dust Modeling Using Cmaq 5.3.1 And Wrf 4.2.1, Zachary D. Lawless, Ariel S. Cable, Cameron B. Van Dyke, Bradley R. Adams

Faculty Publications

Researchers at Brigham Young University (BYU) have developed a software framework for modeling dust emission and transport using the Community Multiscale Air Quality (CMAQ) modeling system in conjunction with the Weather Research and Forecasting (WRF) model and other utility programs. This framework uses meteorological data, land use data, and soil properties to predict dust concentrations for a specified area. This User Guide describes the start-to-finish process required to install and utilize relevant software to calculate and visualize dust concentrations. Note that the examples and figures provided in the guide are specific to Utah in the western United States, where this …

A Comparison Of Aerodynamic Models For Optimizing The Takeoff And Transition Of A Bi-Wing Tailsitter, Ryan Anderson, Jacob Willis, Jacob Johnson, Andrew Ning, Randal Beard

Faculty Publications

Electric vertical takeoff and landing (eVTOL) aircraft take advantage of distributed electric propulsion as well as aerodynamic lifting surfaces to take off vertically and perform long-duration flights. Complex aerodynamic interactions and a hard-to-predict transition maneuver from hover to wing-borne flight are one challenge in their development. To address this, we compare three different interaction models of varying fidelity for optimizing the transition trajectory of a biplane tailsitter. The first model accounts for simplified rotor-on-wing interactions using momentum theory, while the other two account for wing-on-wing interactions using a vortex lattice method and rotor-on-wing aerodynamic interactions using blade element momentum theory. …

Reducing Wind Farm Power Variance From Wind Direction Using Wind Farm Layout Optimization, Bertelsen Gagakuma, Andrew P.J. Stanley, Andrew Ning

Faculty Publications

This paper investigates reducing power variance caused by different wind directions by using wind farm layout optimization. The problem was formulated as a multi-objective optimization. The ε−constraint method was used to solve the bi-objective problem in a two-step optimization framework where two sequential optimizations were performed. The first was maximizing the mean wind farm power alone and the second was minimizing the power variance with a constraint on the mean power. The results show that the variance in power estimates can be greatly reduced, by as much as 30%, without sacrificing mean plant power for the different farm sizes and …

Optimization Of Turbine Tilt In A Wind Farm, James Cutler, Andrew P.J. Stanley, Jared J. Thomas, Andrew Ning

Faculty Publications

Wind farm power production is significantly affected by upstream turbines creating wakes of slower wind speeds that overlap the rotor swept areas of downstream turbines. By optimizing the tilt angle of the turbines in a farm, wakes may be deflected away from downstream turbines, increasing the overall energy production. In this study, we optimized the tilt angle of turbines in a wind farm to maximize energy production. We used an analytic wake model modified for gradient-based optimization to consider wake deflection from tilt. We considered optimizing the tilt angle of each turbine assuming that it remained fixed for the lifetime …

Spectral Absorption Coefficient Of Additive Manufacturing Materials, Nicholas J. Wallace, Matthew R. Jones, Nathan B. Crane

Faculty Publications

Active thermography techniques are of interest for quality assurance of additive manufacturing processes. However, accurate measurements of thermophysical properties of materials are required to successfully implement active thermography. In particular, the spectral absorption coefficient of materials commonly used in additive manufacturing must be known to accurately predict the spatial distribution of thermal energy generated from absorption of power emitted by a laser or pulsed flash lamp. Accurate measurements of these optical properties are also needed to develop greater understanding of additive manufacturing processes that rely on radiative heat transfer to fuse powders. This paper presents spectral absorption coefficient measurements and …

Experimental Investigation Of Transverse Loading Behavior Of Ultra-High Molecular Weight Polyethylene Yarns, Karan Deepak Shah, Subramani Sockalingam

Faculty Publications

Ultra-high molecular weight polyethylene (UHMWPE) Dyneema^® SK-76 fibers are widely used in personnel protection systems. Transverse ballistic impact onto these fibers results in complex multiaxial deformation modes such as axial tension, axial compression, transverse compression, and transverse shear. Previous experimental studies on single fibers have shown a degradation of tensile failure strain due to the presence of such multi-axial deformation modes. In this work, we study the presence and effects of such multi-axial stress-states on Dyneema^® SK-76 yarns via transverse loading experiments. Quasi-static transverse loading experiments are conducted on Dyneema^® SK-76 single yarn at different starting angles …

Analytical And Experimental Study Of Fatigue-Crack-Growth Ae Signals In Thin Sheet Metals, Roshan Joseph, Victor Giurgiutiu

Faculty Publications

The acoustic emission (AE) method is a very popular and well-developed method for passive structural health monitoring of metallic and composite structures. AE method has been efficiently used for damage source detection and damage characterization in a large variety of structures over the years, such as thin sheet metals. Piezoelectric wafer active sensors (PWASs) are lightweight and inexpensive transducers, which recently drew the attention of the AE research community for AE sensing. The focus of this paper is on understanding the fatigue crack growth AE signals in thin sheet metals recorded using PWAS sensors on the basis of the Lamb …

Impact Of Sintering Time And Temperature On Mechanical Properties In Projection Sintering Of Polyamide-12, Justin Nussbaum, Taranjot Kaur, Julie Harmon, Nathan B. Crane

Faculty Publications

In powder bed fusion additive manufacturing (AM), the fusing process is temperature and time dependent. However, little work has been done to understand how different processing temperatures and times might impact the mechanical properties at longer sintering times than are typical in laser sintering (LS) systems. Prior results with projection sintering have shown that heating for longer times (>1s) improves part toughness compared to laser sintering. In this work, Large Area Projection Sintering (LAPS) is used to sinter entire layers of material simultaneously over the course of a few seconds with spatial control of layer temperature. This work evaluates …

3d Interdigitated Vertically Aligned Carbon Nanotube Electrodes For Electrochemical Impedimetric Biosensing, Benjamin J. Brownlee, Jonathan C. Claussen, Brian D. Iverson

Faculty Publications

Advances in nanomaterials, combined with electrochemical impedance spectroscopy (EIS), have allowed electrochemical biosensors to have high sensitivity while remaining labe-lfree, enabling the potential for portable diagnosis at the point-of-care. We report porous, 3D vertically aligned carbon nanotube (VACNT) electrodes with underlying chromium electrical leads for impedance-based biosensing. The electrodes are characterized by electrode height (5, 25, and 80 μm), gap width (15 and 25 μm), and geometry (interdigitated and serpentine) using scanning electron microscopy, cyclic voltammetry, and EIS. The protein streptavidin is functionalized onto VACNT electrodes for detection of biotin, as confirmed by fluorescence microscopy. EIS is used to measure …

First-Order Comprehensive Adjoint Method For Computing Operator-Valued Response Sensitivities To Imprecisely Known Parameters, Internal Interfaces And Boundaries Of Coupled Nonlinear Systems: Ii. Application To A Nuclear Reactor Heat Removal Benchmark, Dan Gabriel Cacuci

Faculty Publications

This work illustrates the application of a comprehensive first-order adjoint sensitivity analysis methodology (1st-CASAM) to a heat conduction and convection analytical benchmark problem which simulates heat removal from a nuclear reactor fuel rod. This analytical benchmark problem can be used to verify the accuracy of numerical solutions provided by software modeling heat transport and fluid flow systems. This illustrative heat transport benchmark shows that collocation methods require one adjoint computation for every collocation point while spectral expansion methods require one adjoint computation for each cardinal function appearing in the respective expansion when recursion relations cannot be developed between the corresponding …

First-Order Comprehensive Adjoint Method For Computing Operator-Valued Response Sensitivities To Imprecisely Known Parameters, Internal Interfaces And Boundaries Of Coupled Nonlinear Systems: I. Mathematical Framework, Dan Gabriel Cacuci

Faculty Publications

This work presents the first-order comprehensive adjoint sensitivity analysis methodology (1st-CASAM) for computing efficiently the first-order sensitivities (i.e., functional derivatives) of operator-valued responses (i.e., model results) of general models of coupled nonlinear physical systems characterized by imprecisely known or and/or uncertain parameters, external boundaries, and internal interfaces between the coupled systems. The explicit mathematical formalism developed within the 1st-CASAM for computing the first-order sensitivities of operator-valued response to uncertain internal interfaces and external boundaries in the models’ phase–space enables this methodology to generalize all of the previously published methodologies for computing first-order response sensitivities. The computational resources needed for using …

Experimental Demonstration Of Heat Loss And Turn-Down Ratio For A Multi-Panel, Actively Deployed Radiator, Rydge B. Mulford, Samuel D. Salt, Lance P. Hyatt, Kyle S. Meaker, Vivek H. Dwivedi, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Origami-inspired, dynamic spacecraft radiators have been proposed which utilize an expandable/collapsible surface capable of large variations in emitting surface area. In this work, an experimental prototype of this concept is realized and its performance is analyzed. In particular, we demonstrate the capability of maintaining a spacecraft component at a desired operating temperature through the expansion and contraction of a collapsible radiator to control radiative heat loss. Four aluminum panels are connected via a flexible hinge constructed from interwoven copper wires and suspended from an actuating framework. The radiator panels are connected to a heated aluminum block. The radiator is placed …

Gradient-Based Optimization Of Solar-Regenerative High-Altitude Long-Endurance Aircraft, Taylor Mcdonnell, Andrew Ning

Faculty Publications

This paper uses gradient-based optimization to minimize the mass of a solar-regenerative high-altitude long-endurance (SR-HALE) flying-wing aircraft while accounting for nonlinear aeroelastic effects. The aircraft is designed to fly year round at 35° latitude at 18 km above sea level and subjected to energy capture, energy storage, material failure, local buckling, stall, longitudinal stability, and coupled flight and aeroelastic stability constraints. The optimized aircraft has an aspect ratio of 54.52, a surface area of 73.56 m2 , a mass of 349.5 kg, exhibits little aeroelastic deflection at the design airspeed, and is primarily stability constrained. Several parameter sweeps are performed …

Large-Scale Flow In Micro Electrokinetic Turbulent Mixer, Keyi Nan, Zhongyan Hu, Wei Zhao, Kaige Wang, Jintao Bai, Guiren Wang

Faculty Publications

In the present work, we studied the three-dimensional (3D) mean flow field in a micro electrokinetic (μEK) turbulence based micromixer by micro particle imaging velocimetry (μPIV) with stereoscopic method. A large-scale solenoid-type 3D mean flow field has been observed. The extraordinarily fast mixing process of the μEK turbulent mixer can be primarily attributed to two steps. First, under the strong velocity fluctuations generated by μEK mechanism, the two fluids with different conductivity are highly mixed near the entrance, primarily at the low electric conductivity sides and bias to the bottom wall. Then, the well-mixed fluid in the local region convects …

Data Quality And Reliability Assessment Of Wearable Emg And Imu Sensor For Construction Activity Recognition, Srikanth Sagar Bangaru, Chao Wang, Fereydoun Aghazadeh

Faculty Publications

The workforce shortage is one of the significant problems in the construction industry. To overcome the challenges due to workforce shortage, various researchers have proposed wearable sensor-based systems in the area of construction safety and health. Although sensors provide rich and detailed information, not all sensors can be used for construction applications. This study evaluates the data quality and reliability of forearm electromyography (EMG) and inertial measurement unit (IMU) of armband sensors for construction activity classification. To achieve the proposed objective, the forearm EMG and IMU data collected from eight participants while performing construction activities such as screwing, wrenching, lifting, …

High-Fidelity Modeling Of Multirotor Aerodynamic Interactions For Aircraft Design, Eduardo Alvarez, Andrew Ning

Faculty Publications

Electric aircraft technology has enabled the use of multiple rotors in novel concepts for urban air mobility. However, multirotor configurations introduce strong aerodynamic and aeroacoustic interactions that are not captured through conventional aircraft design tools. In this paper we explore the capability of the viscous vortex particle method (VPM) to model multirotor aerodynamic interactions at a computational cost suitable for conceptual design. A VPM-based rotor model is introduced along with recommendations for numerical stability and computational efficiency. Validation of the individual rotor is presented in both hovering and forward-flight configurations at low, moderate, and high Reynolds numbers. Hovering multirotor predictions …

Additive Manufacturing And Characterization Of Agi And Agi–Al2O3 Composite Electrolytes For Resistive Switching Devices, Benjamin J. Brownlee, Lok-Kun Tsui, Karthik Vempati, John B. Plumley, Brian D. Iverson, Thomas L. Peng, Fernando H. Garzon

Faculty Publications

This work investigates the electrochemical dynamics and performance of additively manufactured composite electrolytes for resistive switching. Devices are comprised of a Ag/AgI–Al₂O₃/Pt stack, where the solid state electrolyte is additively manufactured using extrusion techniques. AgI–Al₂O₃ composite electrolytes are characterized by x-ray diffraction and electrochemical impedance spectroscopy. The ionic conductivities of the electrolytes were measured for different concentrations of Al₂O₃, observing a maximum conductivity of 4.5 times the conductivity of pure AgI for composites with 20 mol. % Al₂O₃. There was little change in activation energy …

Advances In Materials Design For All-Solid-State Batteries: From Bulk To Thin Films, Gene Yang, Yuxi Ma, Myoungseok Lee, Evan Helfrick, Dahyun Oh, Dongkyu Lee

Faculty Publications

All-solid-state batteries (SSBs) are one of the most fascinating next-generation energy storage systems that can provide improved energy density and safety for a wide range of applications from portable electronics to electric vehicles. The development of SSBs was accelerated by the discovery of new materials and the design of nanostructures. In particular, advances in the growth of thin-film battery materials facilitated the development of all solid-state thin-film batteries (SSTFBs)—expanding their applications to microelectronics such as flexible devices and implantable medical devices. However, critical challenges still remain, such as low ionic conductivity of solid electrolytes, interfacial instability and difficulty in controlling …

Tracking Joint Angles During Whole-Arm Movements Using Electromagnetic Sensors, Ryan Clark, Taylor Dickinson, Johnfredy Loaiza, Daniel W. Geiger, Steven Knight Charles

Faculty Publications

Electromagnetic (EM) motion tracking systems are suitable for many research and clinical applications, including in-vivo measurements of whole-arm movements. Unfortunately, the methodology for in vivo measurements of whole-arm movements using EM sensors is not well described in the literature, making it difficult to perform new measurements and all but impossible to make meaningful comparisons between studies. The recommendations of the International Society of Biomechanics (ISB) have provided a great service, but by necessity they do not provide clear guidance or standardization on all required steps. The goal of this paper was to provide a comprehensive methodology for using EM sensors …

Introducing The Journal Of Nuclear Engineering: An Interdisciplinary Open Access Journal Dedicated To Publishing Research In Nuclear And Radiation Sciences And Applications, Dan Gabriel Cacuci

Faculty Publications

Note: In lieu of an abstract, this is an excerpt from the first page.

In 1938, Strassmann, Hahn and Meitner discovered neutron-induced nuclear fission in uranium, forever changing our world and opening multiple paths to developing nuclear energy, nuclear medicine, instrumentation, space propulsion, environmental monitoring, remediation and nuclear security [...]

Fatigue-Crack Detection And Monitoring Through The Scattered-Wave Two-Dimensional Cross-Correlation Imaging Method Using Piezoelectric Transducers, Wenfeng Xiao, Lingyu Yu, Roshan Joseph, Victor Giurgiutiu

Faculty Publications

Piezoelectric transducers are convenient enablers for generating and receiving Lamb waves for damage detection. Fatigue cracks are one of the most common causes for the failure of metallic structures. Increasing emphasis on the integrity of critical structures creates an urgent need to monitor structures and to detect cracks at an early stage to prevent catastrophic failures. This paper presents a two-dimensional (2D) cross-correlation imaging technique that can not only detect a fatigue crack but can also precisely image the fatigue cracks in metallic structures. The imaging method was based on the cross-correlation algorithm that uses incident waves and the crack-scattered …