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Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams 2019 Iowa State University

Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams

Derrick K Rollins, Sr.

Understanding stress-strain behavior of asphalt pavement under repetitive traffic loading is of critical importance to predict pavement performance and service life. For viscoelastic materials, the stress-strain relationship can be represented by the dynamic modulus. The dynamic modulus test in indirect tension mode can be used to measure the modulus of each specific layer of asphalt pavements using representative samples. Dynamic modulus is a function of material properties, loading, and environmental conditions. Developing predictive models for dynamic modulus is efficient and cost effective. This article focuses on developing an accurate Finite Element (FE) model using mixture elastic modulus and asphalt binder ...


Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams 2019 Iowa State University

Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams

R. Christopher Williams

Understanding stress-strain behavior of asphalt pavement under repetitive traffic loading is of critical importance to predict pavement performance and service life. For viscoelastic materials, the stress-strain relationship can be represented by the dynamic modulus. The dynamic modulus test in indirect tension mode can be used to measure the modulus of each specific layer of asphalt pavements using representative samples. Dynamic modulus is a function of material properties, loading, and environmental conditions. Developing predictive models for dynamic modulus is efficient and cost effective. This article focuses on developing an accurate Finite Element (FE) model using mixture elastic modulus and asphalt binder ...


Efficient Solar-To-Thermal Energy Conversion And Storage With High-Thermal-Conductivity And Form-Stabilized Phase Change Composite Based On Wood-Derived Scaffolds, Bolin Chen, Meng Han, Bowei Zhang, Gaoyuan Ouyang, Behrouz Shafei, Xinwei Wang, Shan Hu 2019 Iowa State University

Efficient Solar-To-Thermal Energy Conversion And Storage With High-Thermal-Conductivity And Form-Stabilized Phase Change Composite Based On Wood-Derived Scaffolds, Bolin Chen, Meng Han, Bowei Zhang, Gaoyuan Ouyang, Behrouz Shafei, Xinwei Wang, Shan Hu

Shan Hu

Solar-to-thermal energy conversion is one of the most efficient ways to harvest solar energy. In this study, a novel phase change composite with porous carbon monolith derived from natural wood is fabricated to harvest solar irradiation and store it as thermal energy. Organic phase change material n-octadecane is physically adsorbed inside the porous structure of the carbonized wood, and a thin graphite coating encapsulates the exterior of the wood structure to further prevent n-octadecane leakage. The carbonized wood scaffold and the graphite coating not only stabilize the form of the n-octadecane during phase change, but also enhance its thermal conductivity ...


Liquid Metal-Elastomer Soft Composites With Independently Controllable And Highly Tunable Droplet Size And Volume Loading, Ravi Tutika, Steven Kmiec, A. B. M. Tahidul Haque, Steve W. Martin, Michael D. Bartlett 2019 Iowa State University

Liquid Metal-Elastomer Soft Composites With Independently Controllable And Highly Tunable Droplet Size And Volume Loading, Ravi Tutika, Steven Kmiec, A. B. M. Tahidul Haque, Steve W. Martin, Michael D. Bartlett

Michael Bartlett

Soft composites are critical for soft and flexible materials in energy harvesting, actuators, and multifunctional devices. One emerging approach to create multifunctional composites is through the incorporation of liquid metal (LM) droplets such as eutectic gallium indium (EGaIn) in highly deformable elastomers. The microstructure of such systems is critical to their performance, however, current materials lack control of particle size at diverse volume loadings. Here, we present a fabrication approach to create liquid metal-elastomer composites with independently controllable and highly tunable droplet size (100 nm ≦ D ≦ 80 μm) and volume loading (0 ≦ φ ≦ 80%). This is achieved through a combination ...


Predicting The Mechanical Properties Of Nanocomposites Reinforced With 1-D, 2-D And 3-D Nanomaterials, Scott Edward Muller 2019 University of Arkansas, Fayetteville

Predicting The Mechanical Properties Of Nanocomposites Reinforced With 1-D, 2-D And 3-D Nanomaterials, Scott Edward Muller

Theses and Dissertations

Materials with features at the nanoscale can provide unique mechanical properties and increased functionality when included as part of a nanocomposite. This dissertation utilizes computational methods at multiple scales, including molecular dynamics (MD) and density functional theory (DFT), and the coupled atomistic and discrete dislocation multiscale method (CADD), to predict the mechanical properties of nanocomposites possessing nanomaterials that are either 1-D (carbyne chains), 2-D (graphene sheets), or 3-D (Al/amorphous-Si core-shell nanorod).

The MD method is used to model Ni-graphene nanocomposites. The strength of a Ni-graphene nanocomposite is found to improve by increasing the gap between the graphene sheet and ...


Transferring Power Through A Magnetic Couple, Nickolas Cruz Villalobos Jr. 2019 Linfield College

Transferring Power Through A Magnetic Couple, Nickolas Cruz Villalobos Jr.

Senior Theses

Properties of several working magnetic coupled rotors have been measured and their performance compared to theoretical models. Axial magnetic couplers allow rotors to work within harsh environments, without the need for seals, proper alignment, or overload protection on a motor. The influence of geometrical parameters, such as distance from the center of the rotors, polarity arrangement, and the number of dipole pairs were experimentally tested. These results can be used to improve rotor designs, to increase strength and efficiency.


Advances In Design Methodology In Swelling Shale Rock In Southern Ontario, Thomas R.A. Lardner 2019 The University of Western Ontario

Advances In Design Methodology In Swelling Shale Rock In Southern Ontario, Thomas R.A. Lardner

Electronic Thesis and Dissertation Repository

As infrastructure requirements increase in southern Ontario, excavations within swelling rock formations will become more frequent and larger. The objective of this study is to advance design capability for structures in swelling rock through three aspects: i) developing a practical swelling model for design engineers, ii) investigate two crushable/compressible materials for the mitigation of swelling rock effects, and iii) observe and analyze the behaviour of swelling rock to current excavation techniques.

A swelling rock constitutive model has been developed. The swelling parameters include the horizontal and vertical free swell potential, threshold stress, and critical stress as well as a ...


Application Of Computational Tools To Spaghetti-Based Truss Bridge Design, Jin Xu, Jiliang Li, Nuri Zeytinoglu, Jinyuan Zhai 2019 Purdue University Northwest

Application Of Computational Tools To Spaghetti-Based Truss Bridge Design, Jin Xu, Jiliang Li, Nuri Zeytinoglu, Jinyuan Zhai

ASEE IL-IN Section Conference

Application of Computational Tools to Spaghetti-Based Truss Design

Statics and Strength of Materials are two foundational courses for Mechanical/Civil Engineering. In order to assist students in better understanding and applying concepts to a meaningful design task, SolidWorks and theoretical calculation were used for a spaghetti-bridge design contest with the constraints of given maximum weight and allowable support-material weight. As the first step of this iterative designing process, both extrude feature and structural member were introduced to model planar bridge trusses. Then SolidWorks’ Statics module was used to run FEA analysis of the structural performance in efforts to optimize the ...


Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang 2019 University of Nebraska–Lincoln

Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Annealing twins often form in metals with a face centered cubic structure during thermal and mechanical processing. Here, we conducted molecular dynamic (MD) simulations for copper and aluminum to study the interaction processes between {1 1 1}1/2 <1 1 0> dislocations and a three-dimensional annealing twin. Twin boundaries are characterized with Σ3{1 1 1} coherent twin boundaries (CTBs) and Σ3{1 1 2} incoherent twin boundaries (ITBs). MD results revealed that dislocation-ITB interactions affect slip transmission for a dislocation crossing CTBs, facilitating the nucleation of Lomer dislocation.


Strength And Plasticity Of Amorphous Silicon Oxycarbide, Kaisheng Ming, Chao Gu, Qing Su, Yongqiang Wang, Arezoo Zare, Don A. Lucca, Michael Nastasi, Jian Wang 2019 University of Nebraska-Lincoln

Strength And Plasticity Of Amorphous Silicon Oxycarbide, Kaisheng Ming, Chao Gu, Qing Su, Yongqiang Wang, Arezoo Zare, Don A. Lucca, Michael Nastasi, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Amorphous SiOC films were synthesized by magnetron sputtering at room temperature with/without radio frequency (RF) bias and further improved in terms of mechanical properties by ion irradiation. As-deposited SiOC films without RF bias exhibit catastrophic failure at a low stress and strain, which is ascribed to microstructural heterogeneities associated with the formation of voids during deposition, as evidenced by transmission electron microscopy. Ion irradiation unifies microstructure accompanied with eliminating the voids, resulting in a simultaneously increase in strength and plasticity (ultimate strength of 5–7 GPa and the strain to shear instability of over 20%). Homogeneous microstructures are demonstrated ...


A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson 2019 Chinese Academy of Sciences

A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson

Mechanical & Materials Engineering Faculty Publications

The existing surgical robots for laparoscopic surgery offer no or limited force feedback, and there are many problems for the traditional sensor-based solutions. This paper builds a teleoperation surgical system and validates the effectiveness of sensorless force feedback. The tool-tissue interaction force at the surgical grasper tip is estimated using the driving motor’s current, and fed back to the master robot with a position-force bilateral control algorithm. The stiffness differentiation experiment and tumor detection experiment were conducted. In the stiffness differentiation experiment, 43 out of 45 pairs of ranking relationships were identified correctly, yielding a success rate of 96 ...


Interface Facilitated Reorientation Of Mg Nanolayers In Mg-Nb Nanolaminates, Y. CHen, Mingyu Gong, N. A. Mara, Jian Wang 2019 University of Minnesota, Minneapolis

Interface Facilitated Reorientation Of Mg Nanolayers In Mg-Nb Nanolaminates, Y. Chen, Mingyu Gong, N. A. Mara, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Mg/Nb nanolaminates synthesized through vapor deposition techniques exhibit high flow strength without conventional twinning in Mg. In this work, we investigated the influence of laminated microstructures on deformation mechanisms of Mg nanolayers. Using molecular dynamics simulations, we explored that (0001)-oriented Mg layers transform or re-orient to {10¯10}-oriented Mg layers through nucleation and growth of {10¯12} twins by atomic shuffling, instead of conventional {10¯12} twinning shear. Such a reorientation accommodates in-plane compressive strain and out-of-plane tensile strain when Mg/Nb laminates are subjected to compression parallel to the Mg/Nb interfaces. The nucleation of {10 ...


Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen 2019 University of Nebraska-Lincoln

Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen

Mechanical & Materials Engineering Faculty Publications

In this work, the peridynamic corrosion model is used for 3D simulation of pitting corrosion in stainless steel. Models for passivation and salt layer formation are employed to predict detailed characteristics of pit growth kinetic in stainless steels, such as lacy cover formation on top of the pit, and the diffusion-controlled regime at the pit bottom. The model is validated against an experimentally grown pit on 316L stainless steel in NaCl solution. Lacy covers in this model are formed autonomously during the simulation process. They are remarkably similar to the covers observed on top of the real pits.


High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang 2019 Purdue University

High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang

Mechanical & Materials Engineering Faculty Publications

Aluminum (Al) alloys have been widely used in the transportation industry. However, most highstrength Al alloys to date have limited mechanical strength, on the order of a few hundred MPa, which is much lower than the flow stress of high-strength steels. In this study, we show the fabrication of nanocrystalline Al alloys with high-density growth twins enabled by a few atomic percent of Co solute. In situ uniaxial compression tests show that the flow stress of Al–Co solid solution alloys exceeds 1.5 GPa, while good work hardening capability is maintained. This study provides a new perspective on the ...


Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu 2019 University of Nebraska - Lincoln

Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

The hemodynamic interference of serial stenoses poses challenges for identifying the functional severity using the fractional flow reserve (FFR) method. The instantaneous wave-free ratio (iFR), i.e., the distal-to-proximal pressure ratio at 75% of diastole, was recently proposed to overcome the disadvantages of the FFR. However, the underlying mechanism remained ambiguous due to the lack of quantitative definition of hemodynamic interference. The objective of this study is to quantitatively define the hemodynamic interference and then examine its role on the FFR and iFR measurements. Pressure distributions, velocity fields, and Q-criterion which identifies vortices, were obtained through the computational fluid dynamics ...


Fe Modeling Methodology For Load Analysis And Preliminary Sizing Of Aircraft Wing Structure, Jun Hwan Jang, Sang Ho Ahn 2019 Defense Acquisition Program Administration

Fe Modeling Methodology For Load Analysis And Preliminary Sizing Of Aircraft Wing Structure, Jun Hwan Jang, Sang Ho Ahn

International Journal of Aviation, Aeronautics, and Aerospace

It is a critical part at the basic design phase of aircraft structural design to build a finite element model and it will have a direct impact on time and cost for airframe structure development. In addition, the objective of finite element model will be varied depending on each design review phase and the modelling methodology varied accordingly. In order to build an effective and economic finite element model, it is required to develop adequate level of modelling methodology based on each design phase and its objectives. Therefore, in this paper, the finite element modeling methodology was presented for internal ...


Deformation Correlations And Machine Learning: Microstructural Inference And Crystal Plasticity Predictions, Michail Tzimas 2019 West Virginia University

Deformation Correlations And Machine Learning: Microstructural Inference And Crystal Plasticity Predictions, Michail Tzimas

Graduate Theses, Dissertations, and Problem Reports

The present thesis makes a connection between spatially resolved strain correlations and material processing history. Such correlations can be used to infer and classify prior deformation history of a sample at various strain levels with the use of Machine Learning approaches. A simple and concrete example of uniaxially compressed crystalline thin films of various sizes, generated by two-dimensional discrete dislocation plasticity simulations is examined. At the nanoscale, thin films exhibit yield-strength size effects with noisy mechanical responses which create an interesting challenge for the application of Machine Learning techniques. Moreover, this thesis demonstrates the prediction of the average mechanical responses ...


Relative Contributions Of Intracranial Pressure And Intraocular Pressure On Lamina Cribrosa Behavior, Junfei Tong, Deepta Ghate, Sachin Kedar, Linxia Gu 2019 University of Nebraska - Lincoln

Relative Contributions Of Intracranial Pressure And Intraocular Pressure On Lamina Cribrosa Behavior, Junfei Tong, Deepta Ghate, Sachin Kedar, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

Purpose. To characterize the relative contributions of intraocular pressure (IOP) and intracranial pressure (ICP) on lamina cribrosa (LC) behavior, specifically LC depth (LCD) and LC peak strain. Methods. An axially symmetric finite element model of the posterior eye was constructed with an elongated optic nerve and retro-orbital subarachnoid space ensheathed by pia and dura mater. -e mechanical environment in LC was evaluated with ICP ranging from 5 to 15mmHg and IOP from 10 to 45 mmHg. LCD and LC peak strains at various ICP and IOP levels were estimated using full factorial experiments. Multiple linear regression analyses were then applied ...


The Role Of Low-Level Image Features In The Affective Categorization Of Rapidly Presented Scenes, L. Jack Rhodes, Matthew Rios, Jacob M. Williams, Gonzalo Quinones, Prahalada K. Rao, Vladimir Miskovic 2019 State University of New York at Binghamton

The Role Of Low-Level Image Features In The Affective Categorization Of Rapidly Presented Scenes, L. Jack Rhodes, Matthew Rios, Jacob M. Williams, Gonzalo Quinones, Prahalada K. Rao, Vladimir Miskovic

Mechanical & Materials Engineering Faculty Publications

It remains unclear how the visual system is able to extract affective content from complex scenes even with extremely brief (< 100 millisecond) exposures. One possibility, suggested by findings in machine vision, is that low-level features such as unlocalized, two-dimensional (2-D) Fourier spectra can be diagnostic of scene content. To determine whether Fourier image amplitude carries any information about the affective quality of scenes, we first validated the existence of image category differences through a support vector machine (SVM) model that was able to discriminate our intact aversive and neutral images with ~ 70% accuracy using amplitude-only features as inputs. This model allowed us to confirm that scenes belonging to different affective categories could be mathematically distinguished on the basis of amplitude spectra alone. The next question is whether these same features are also exploited by the human visual system. Subsequently, we tested observers’ rapid classification of affective and neutral naturalistic scenes, presented briefly (~33.3 ms) and backward masked with synthetic textures. We tested categorization accuracy across three distinct experimental conditions, using: (i) original images, (ii) images having their amplitude spectra swapped within a single affective image category (e.g., an aversive image whose amplitude spectrum has been swapped with another aversive image) or (iii) images having their amplitude spectra swapped between affective categories (e.g., an aversive image containing the amplitude spectrum of a neutral image). Despite its discriminative potential, the human visual system does not seem to use Fourier amplitude differences as the chief strategy for affectively categorizing scenes at a glance. The contribution of image amplitude to affective categorization is largely dependent on interactions with the phase spectrum, although it is impossible to completely rule out a residual role for unlocalized 2-D amplitude measures.


Monolithic Heat-Transfer Device, Sidy Ndao, George Gogos, Dennis Alexander, Troy Anderson, Craig Zuhlke 2019 Lincoln, NE

Monolithic Heat-Transfer Device, Sidy Ndao, George Gogos, Dennis Alexander, Troy Anderson, Craig Zuhlke

Mechanical & Materials Engineering Faculty Publications

A monolithic heat-transfer device can include a container wall configured to retain a working fluid, where the container wall is formed of a single material. The container wall also includes an interior surface configured to be in fluid communication with the working fluid. The monolithic heat-transfer device also includes a channel disposed in the interior surface of the container wall, where the channel comprises a microstructure and a nanostructure. The microstructure and the nanostructure are materially contiguous with the single material forming the container wall. In some embodiments, the nanostructure comprises one or more layers of nanoparticles. The monolithic heat-transfer ...


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