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Quantifying Bonding Characteristics Between Uhpc And Normal-Strength Concrete For Bridge Deck Application, Sriram Aaleti, Sri Sritharan 2019 University of Alabama - Tuscaloosa

Quantifying Bonding Characteristics Between Uhpc And Normal-Strength Concrete For Bridge Deck Application, Sriram Aaleti, Sri Sritharan

Civil, Construction and Environmental Engineering Publications

Ultrahigh performance concrete (UHPC) is an advanced cementitious material which has excellent mechanical and durability properties, making it appropriate for the rehabilitation of concrete structures. This paper investigates the usage of a thin layer of UHPC overlaying a normal strength concrete (NC) deck. The behavior of the interface connection will have a significant impact on the overall structural and durability performance of the UHPC-NC composite deck system. An integrated experimental and analytical study was conducted to understand the influence of several variables, such as normal concrete strength, interface roughness, and curing condition on the shear transfer behavior across the interface ...


Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong 2019 Iowa State University

Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong

Valery I. Levitas

In this paper, phase transformations (PTs) in silicon were investigated through molecular dynamics (MD) using Tersoff potential. In the first step, simulations of PTs in single crystal silicon under various stress-controlled loading were carried out. Results shows that all instability points under various stress states are described by criteria, which are linear in the space of normal stresses. There is a region in the stress space in which conditions for direct and reverse PTs coincide and a unique homogeneous phase transition (without nucleation) can be realized. Finally, phase transition in bi-crystalline silicon with a dislocation pileup along the grain boundary ...


Quantifying Bonding Characteristics Between Uhpc And Normal-Strength Concrete For Bridge Deck Application, Sriram Aaleti, Sri Sritharan 2019 University of Alabama - Tuscaloosa

Quantifying Bonding Characteristics Between Uhpc And Normal-Strength Concrete For Bridge Deck Application, Sriram Aaleti, Sri Sritharan

Sri Sritharan

Ultrahigh performance concrete (UHPC) is an advanced cementitious material which has excellent mechanical and durability properties, making it appropriate for the rehabilitation of concrete structures. This paper investigates the usage of a thin layer of UHPC overlaying a normal strength concrete (NC) deck. The behavior of the interface connection will have a significant impact on the overall structural and durability performance of the UHPC-NC composite deck system. An integrated experimental and analytical study was conducted to understand the influence of several variables, such as normal concrete strength, interface roughness, and curing condition on the shear transfer behavior across the interface ...


Soft-Matter Damage Detection Systems For Electronics And Structures, Michael D. Bartlett, Eric J. Markvicka, Ravi Tutika, Carmel Majidi 2019 Iowa State University

Soft-Matter Damage Detection Systems For Electronics And Structures, Michael D. Bartlett, Eric J. Markvicka, Ravi Tutika, Carmel Majidi

Materials Science and Engineering Publications

Soft-matter technologies are essential for emerging applications in wearable computing, human-machine interaction, and soft robotics. However, as these technologies gain adoption in society and interact with unstructured environments, material and structure damage becomes inevitable. Here, we present a robotic material that mimics soft tissues found in biological systems to identify, compute, and respond to damage. This system is composed of liquid metal droplets dispersed in soft elastomers that rupture when damaged, creating electrically conductive pathways that are identified with a soft active-matrix grid. This presents new opportunities to autonomously identify damage, calculate severity, and respond to prevent failure within robotic ...


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 ...


Design Of A Carburizing Treatment Of Steel Base Gear In The Materials Science Course, Jiliang Li, Jin Xu, Nuri Zeytinoglu, Jinyuan Zhai 2019 Purdue University Northwest

Design Of A Carburizing Treatment Of Steel Base Gear In The Materials Science Course, Jiliang Li, Jin Xu, Nuri Zeytinoglu, Jinyuan Zhai

ASEE IL-IN Section Conference

Diffusion PDE Application to Carburizing Treatment of Steel Base Gear

An introductory materials-science course is required in the mechanical engineering curriculum of many universities. This article describes an example effort to incorporate programming, diffusion transfer, heat treatment process and mechanical-property determination as an integral part of the materials-science course instruction. This effort was undertaken in order to give students additional experience in Fick’s 1st and 2nd laws and in-depth understanding of physics and mathematics involved in diffusion analysis. We chose to focus on Fick’s second law because its applications are not restricted to the materials-science field ...


Latex Modified Concrete - Very Early Strength, Bobby Steele 2019 Purdue University

Latex Modified Concrete - Very Early Strength, Bobby Steele

Purdue Road School

INDOT came out with specifications for a very early strength concrete to use on bridge deck overlays. This concrete is fast setting, which allows overlays to be performed over a weekend and benefits the traveling public with a short duration of traffic interference. Cure time to reach the strength requirement is 3 hours. E&B Paving performed the first application with the new spec on August 26, 2018. Many changes were also made to the INDOT Specification Section 722.


Microwave Self-Healing Technology As Airfield Porous Asphalt Friction Course Repair And Maintenance System, Amir Tabakovic, Declan O'Prey, Drew McKenna, David Woodward 2019 Technological University Dublin

Microwave Self-Healing Technology As Airfield Porous Asphalt Friction Course Repair And Maintenance System, Amir Tabakovic, Declan O'Prey, Drew Mckenna, David Woodward

Articles

A problem increasingly faced by airport authorities is the maintenance of runways. Due to their large aircraft loadings associated with take-off and landing operations, runways experience surface deterioration. Poor quality runway surfaces cannot be tolerated in such an environment. Maintenance issues must be carried out to maximise safety and minimise the risk of aircraft damage. A recent development has been the introduction of self-healing technologies such as rejuvenator encapsulation, induction and microwave heating to address these issues. This paper summarises a laboratory investigation to determine the effectiveness of microwave self-healing for crack repair of Porous Friction Course (PFC) used for ...


Reactive Ion Etching Selectivity Of Si/Sio2: Comparing Of Two fluorocarbon Gases Chf3 And Cf4, Meiyue Zhang, Pat Watson 2019 Singh Center for Nanotechnology

Reactive Ion Etching Selectivity Of Si/Sio2: Comparing Of Two fluorocarbon Gases Chf3 And Cf4, Meiyue Zhang, Pat Watson

Protocols and Reports

Two reactive ion etching (RIE) processes were studied to show the relative etch selectivity between SiO2 and Si using two fluorocarbon gases, CF4 and CHF3. Results show that CHF3 gives better selectivity (16:1) over CF4 (1.2 :1). On the other hand, the etch rate of SiO2 of CF4 is approximately 52.8 nm/min, faster than CHF3 (32.4 nm/min).


On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins 2019 Iowa State University

On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins

Materials Science and Engineering Publications

Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a ...


Magneto-Active Slosh Control System Using Free Floating Membrane For Cylinderical Propellant Tanks Read More: Https://Arc.Aiaa.Org/Doi/Abs/10.2514/6.2019-2177, Pedro Llanos 2019 Embry-Riddle Aeronautical University - Daytona Beach

Magneto-Active Slosh Control System Using Free Floating Membrane For Cylinderical Propellant Tanks Read More: Https://Arc.Aiaa.Org/Doi/Abs/10.2514/6.2019-2177, Pedro Llanos

Pedro J. Llanos (www.AstronauticsLlanos.com)

The phenomenon of sloshing is a substantial challenge in propellant management, particularly in reduced gravity where surface tension-driven flows result in large slosh amplitudes and relatively long decay time scales. Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes are often employed to counteract motion of the free surface. In the present study, we investigate an active PMD that utilizes a free-floating membrane that, under an applied static magnetic field, becomes rigid and suppresses slosh. This semi-rigid structural layer can thereby replace bulky baffle structures and reduce the overall weight of the tank. In this paper, the ...


3d Textile Preforms And Composites For Aircraft Strcutures: A Review, Abbasali Saboktakin 2019 University of sistan and baluchestan, Zahedan, Iran

3d Textile Preforms And Composites For Aircraft Strcutures: A Review, Abbasali Saboktakin

International Journal of Aviation, Aeronautics, and Aerospace

Over the last decades, the development of 3D textile composites has been driven the structures developed to overcome disadvantages of 2D laminates such as the needs of reducing fabrication cost, increasing through-thickness mechanical properties, and improving impact damage tolerance. 3D woven, stitched, knitted and braided preforms have been used as composites reinforcement for these types of composites. In this paper, advantages and disadvantages of each of them have been comprehensively discussed. The fabric architects and their specification in particular stitched preforms and their deformation mode for aerospace applications have been reviewed. Exact insight into various types of damage in textile ...


Modeling And Simulation Of The Thermoforming Process In Thermoplastic-Matrix Composite Materials, Philip M. Bean 2018 University of Maine

Modeling And Simulation Of The Thermoforming Process In Thermoplastic-Matrix Composite Materials, Philip M. Bean

Electronic Theses and Dissertations

Thermoplastic-matrix composite materials have unique advantages over traditional thermosets including faster processing, improved fracture toughness, and recyclability. These and other benefits have caused increasing interest in the use of these materials in both aerospace and automotive industries. Due to the differences in behavior, these materials require a different type of manufacturing process to thermoset matrix composites. This manufacturing process generally involves using pre manufactured tape-layers. These layers, containing both thermoplastic-matrix and fiber-reinforcement, are aligned to the desired orientation, and stacked up into a “tailored blank” using an automated tape layup machine. They are then heated to the thermoplastic melting temperature ...


Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke 2018 University of New Mexico - Main Campus

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was ...


Young’S Modulus As A Measurement To Estimate Damage Related With Alkali-Silica Reaction In Concrete., Anazaria J. Ortega Gonzalez 2018 University of Arkansas, Fayetteville

Young’S Modulus As A Measurement To Estimate Damage Related With Alkali-Silica Reaction In Concrete., Anazaria J. Ortega Gonzalez

Civil Engineering Undergraduate Honors Theses

The main purpose of this research is to compare two nondestructive methods to assess Alkali-Silica reaction (ASR) in concrete. Fifteen concrete prisms were cast using aggregates with different Alkali-Silica reactivity such as Jobe sand and Van Buren sand. The change in strain, shear wave velocity and Young’s modulus were determined according to ASTM C129 and ASTM C215, respectively. This data was collected by Dillon K Self, who determined that the shear wave velocity and strain are inversely proportional. However, when single cracking in the concrete specimen transition to map cracking, the shear wave velocity dropped significantly, whereas the strain ...


Reinventing The Wheel, Esther K. Unti, Ahmed Z. Shorab, Patrick B. Kragen, Adam M. Menashe 2018 California Polytechnic State University, San Luis Obispo

Reinventing The Wheel, Esther K. Unti, Ahmed Z. Shorab, Patrick B. Kragen, Adam M. Menashe

Mechanical Engineering

Reinventing the Wheel selected tires and designed wheels for the 2018 Cal Poly, San Luis Obispo Formula SAE combustion vehicle. Available tire options were evaluated for steady-state and transient performance as well as vehicle integration. A single-piece composite wheel with hollow spokes was designed to meet stiffness, strength, and tolerance requirements. A detailed study of wheel loading and geometric structural efficiency was performed. Finite element analysis was used to iterate the geometry and laminate. A two-piece male mold was designed and machined to manufacture the wheel. Removable silicone inserts were used to create the hollow spokes.


Compensation Of Vertical Position Error Using A Force–Deflection Model In Friction Stir Spot Welding, Jinyoung Yoon, Cheol-Hee Kim, Sehoon Rhee 2018 Korea Institute of Industrial Technology

Compensation Of Vertical Position Error Using A Force–Deflection Model In Friction Stir Spot Welding, Jinyoung Yoon, Cheol-Hee Kim, Sehoon Rhee

Mechanical and Materials Engineering Faculty Publications and Presentations

Despite increasing need for friction stir spot welding (FSSW) for high-temperature softening materials, system deflection due to relatively high plunging force remains an obstacle. System deflection results in the vertical position error of a welding tool and insufficient plunge depth. In this study, we used adaptive control to maintain plunge depth, the plunging force was coaxially measured, and the position error was estimated using a force–deflection model. A linear relationship was confirmed between the force and deflection; this relationship is dependent on the stiffness of the welding system while independent of process parameters and base materials. The proposed model ...


Prediction Of Metal Sample Failure From Scanning Electron Microscope Images Using Deep Learning Neural Network, Lawrence Madriaga, Ivan Novikov, Morteza Nurcheshmeh 2018 Western Kentucky University

Prediction Of Metal Sample Failure From Scanning Electron Microscope Images Using Deep Learning Neural Network, Lawrence Madriaga, Ivan Novikov, Morteza Nurcheshmeh

Posters-at-the-Capitol

We present the preliminary results on using a deep learning neural network to predict a metal sample failure based on a set of images obtained with a Scanning Electron Microscope.

Various metal alloy samples were prepared according to ASTM E8/E8M-11 standards for a tensile test. Each sample was prepared for circle grid analysis and then stressed on a tensile machine. Stress and strain values were obtained for each position along the sample by measuring dimensions of each elongated circle. Increasing stress and strain values were found closer to the breakage of the sample with low values found at the ...


Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti 2018 University of New Mexico, Albuquerque

Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti

Shared Knowledge Conference

Ultrasonic monitoring in cementitious materials is challenging due to the high degree of attenuation. In wellbore environments, monitoring becomes more challenging due to inaccessibility. Meta materials, also known as acoustic bandgap materials, exhibit an interesting feature of forbidding the propagation of elastic/sound waves and isolate vibration in a certain frequency band. Traditionally, acoustic bandgap materials are developed with inclusions such as tin, aluminum, gold, steel in a polymer matrix. In this study, we present the development of three-dimensional cementitious sensors capable of exhibiting stopbands in the acoustic transmission spectra using carbon nanotubes. Relatively wide stopbands were engineered using Floquet-Bloch ...


Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson 2018 Ames Laboratory

Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson

Aerospace Engineering Publications

The density functional theory was employed to study the stress-strain behavior and elastic instabilities during the solid-solid phase transformation (PT) when subjected to a general stress tensor, as exemplified for semiconducting Si I and metallic Si II, where metallization precedes the PT, so stressed Si I can be a metal. The hydrostatic PT occurs at 76 GPa, while under uniaxial loading it is 11 GPa (3.7 GPa mean pressure), 21 times lower. The Si I → Si II PT is described by a critical value of the phase-field’s modified transformation work, and the PT criterion has only two parameters ...


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