Mechanical Engineering Commons^™

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 …

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 …

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 …

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 …

Comprehensive Second-Order Adjoint Sensitivity Analysis Methodology (2nd-Asam) Applied To A Subcritical Experimental Reactor Physics Benchmark: V. Computation Of Mixed 2nd-Order Sensitivities Involving Isotopic Number Densities, Ruixian Fang, Dan Gabriel Cacuci

Faculty Publications

This work applies the Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to compute the mixed 2nd-order sensitivities of a polyethylene-reflected plutonium (PERP) benchmark’s leakage response with respect to the benchmark’s imprecisely known isotopic number densities and the other benchmark imprecisely known parameters, including: (i) the 6 × 180 mixed 2nd-order sensitivities involving the total microscopic cross sections; (ii) the 6 × 21,600 mixed 2nd-order sensitivities involving the scattering microscopic cross sections; (iii) the 6 × 60 mixed 2nd-order sensitivities involving the fission microscopic cross sections; and (iv) the 6 × 60 mixed 2nd-order sensitivities involving the average number of neutrons produced …

Impact Of Part Thickness And Drying Conditions On Saturation Limits In Binder Jet Additive Manufacturing, Nathan B. Crane

Faculty Publications

Binder jetting (BJ) is a high build-rate additive manufacturing process with growing commercial interest. Growth in BJ applications is driven by the use of finer powders and improved post-processing methods that can produce dense, homogenous final parts. However, understanding of the basic droplet/powder interaction is relatively limited. This paper considers the impact of in-process drying, part geometry, and droplet size on a key printing parameter: binder saturation. Parts of varying thicknesses are printed with a range of saturation levels under various heating conditions. The ratio of the printed part mass to the theoretical part mass is used to detect bleeding. …

Comprehensive Second-Order Adjoint Sensitivity Analysis Methodology (2nd-Asam) Applied To A Subcritical Experimental Reactor Physics Benchmark. Vi: Overall Impact Of 1st- And 2nd-Order Sensitivities On Response Uncertainties, Dan Gabriel Cacuci, Ruixian Fang, Jeffrey A. Favorite

Faculty Publications

: This work applies the Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to compute the 1st-order and unmixed 2nd-order sensitivities of a polyethylene-reflected plutonium (PERP) benchmark’s leakage response with respect to the benchmark’s imprecisely known isotopic number densities. The numerical results obtained for these sensitivities indicate that the 1st-order relative sensitivity to the isotopic number densities for the two fissionable isotopes have large values, which are comparable to, or larger than, the corresponding sensitivities for the total cross sections. Furthermore, several 2nd-order unmixed sensitivities for the isotopic number densities are significantly larger than the corresponding 1st-order ones. This work also presents …

Porous Silica Nanotube Thin Films As Thermally Insulating Barrier Coatings, Derric B. Syme, Jason M. Lund, Brian D. Jensen, Robert C. Davis, Richard R. Vanfleet, Brian D. Iverson

Faculty Publications

The fabrication and examination of a porous silica thin film, potentially for use as an insulating thin film, were investigated. A vertically aligned carbon nanotube (CNT) forest, created by chemical vapor deposition (CVD), was used as scaffolding to construct the porous film. Silicon was deposited on the CNT forest using low-pressure CVD (LPCVD) and then oxidized to remove the CNTs and convert the silicon to silica for electrical or thermal passivation (e.g., thermal barrier). Thermal conductivity was determined using a 1D heat-transfer analysis that equated radiative heat loss in a vacuum with conduction through the substrate and thin film stack. …

Comprehensive Second-Order Adjoint Sensitivity Analysis Methodology (2nd-Asam) Applied To A Subcritical Experimental Reactor Physics Benchmark: Iv. Effects Of Imprecisely Known Source Parameters, Ruixian Fang, Dan Gabriel Cacuci

Faculty Publications

By applying the Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to the polyethylene-reflected plutonium (PERP) benchmark, this work presents results for the first- and second-order sensitivities of this benchmark’s leakage response with respect to the spontaneous fission source parameters. The numerical results obtained for these sensitivities indicate that the 1st-order relative sensitivity of the leakage response to the source parameters for the two fissionable isotopes in the benchmark are all positive, signifying that an increase in the source parameters will cause an increase in the total neutron leakage from the PERP sphere. The 1st- and 2nd-order relative sensitivities with respect to …

Multi-Mode Guided Wave Detection Of Various Composite Damage Types, Hanfei Mei, Robin James, Victor Giurgiutiu

Faculty Publications

This paper presents a new methodology for detecting various types of composite damage, such as delamination and impact damage, through the application of multimode guided waves. The basic idea is that various wave modes have different interactions with various types of composite damage. Using this method, selective excitations of pure-mode guided waves were achieved using adjustable angle beam transducers (ABTs). The tuning angles of various wave modes were calculated using Snell’s law applied to the theoretical dispersion curves of composite plates. Pitch–catch experiments were conducted on a 2-mm quasi-isotropic carbon fiber-reinforced polymer (CFRP) composite plate to validate the excitations of …

Operational Planning Of Supply Chains In A Production And Distribution Center With Just-In-Time Delivery, Pablo Biswas, Bhaba Sarker

Faculty Publications

Purpose: A supply chain consists of raw material suppliers, manufacturers and retailers where inventory of raw materials and finished goods are involved, respectively. Therefore, it is important to find optimal solutions, which are beneficial for both supplier, manufacturer and retailer.

Design/methodology/approach: This research focuses on a semi-continuous manufacturing facility by assuming that the production of succeeding cycle starts immediately after the production of preceding cycle. In reality, the inventory of a supply chain system may not be completely empty. A number of products may be left over after the deliveries are made. These leftover inventories are added to the next …

Internet Of Things In Sustainable Energy Systems, Abdul Salam

Faculty Publications

Our planet has abundant renewable and conventional energy resources but technological capability and capacity gaps coupled with water-energy needs limit the benefits of these resources to citizens. Through IoT technology solutions and state-of-the-art IoT sensing and communications approaches, the sustainable energy-related research and innovation can bring a revolution in this area. Moreover, by the leveraging current infrastructure, including renewable energy technologies, microgrids, and power-to-gas (P2G) hydrogen systems, the Internet of Things in sustainable energy systems can address challenges in energy security to the community, with a minimal trade-off to environment and culture. In this chapter, the IoT in sustainable energy …

Efficient Incorporation Of Fatigue Damage Constraints In Wind Turbine Blade Optimization, Bryce Ingersoll, Andrew Ning

Faculty Publications

Wind turbine design is a challenging multidisciplinary optimization problem, where the aerodynamic shapes, structural member sizing, and material composition must all be determined and optimized. Some previous blade design methods incorporate static loading with an added safety factor to account for dynamic effects. Others incorporate dynamic loading, but in general limit the evaluation to a few design cases. By not fully incorporating the dynamic loading of the wind turbine, the final turbine blade design is either too conservative by overemphasizing the dynamic effects or infeasible by failing to adequately account for these effects. We propose an iterative method that estimates …

Influence Of Droplet Velocity, Spacing, And Inter-Arrival Time On Line Formation And Saturation In Binder Jet Additive Manufacturing, Trenton Colton, Nathan B. Crane

Faculty Publications

Binder Jetting (BJ) is a low-cost Additive Manufacturing (AM) process that uses inkjet technology to selectively bind particles in a powder bed. BJ relies on the ability to control, not only the placement of binder on the surface but also its imbibition into the powder bed. This is a complex process in which picoliter-sized droplets impact powder beds at velocities of 1-10 m/s. However, the effects of printing parameters such as droplet velocity, size, spacing, and inter-arrival time on saturation level (fraction of pore space filled with binder) and line formation (merging of droplets to form a line) are unknown. …