Publications

Displaying 151 - 175 of 456

Determining Carbon Fiber Composite Loading with Flip-Chip Measurements to 110 GHz

September 1, 2018

Author(s)

Nina P. Basta, Aaron Hagerstrom, Jasper A. Drisko, James Booth, Edward Garboczi, Christian Long, Nathan Orloff

— Electrical properties of materials are a necessary part of any circuit design. With emerging applications at millimeter- wave frequencies, there is a need to characterize new materials before they come to market. At frequencies below about 67 GHz, it is

Numerical study of the initial particle parking structure of cement/geopolymer paste and dissolution of amorphous silica using real-shape particles

July 18, 2018

Author(s)

Edward Garboczi, Guang Ye, Zhiwei Qian, Yibing Zuo

Many particle-based numerical models have been used to simulate the hydration process of cementitious materials. But most of these models employ regular shape particles, like the commonly used spheres, to represent cement, slag or fly ash, which neglects

Experimental scattering matrix for lunar regolith simulant JSC-1A at visible wavelengths

March 8, 2018

Author(s)

Edward J. Garboczi, Ann C. Chiaramonti Debay, Thomas V. Lafarge, O Munoz, J Escobar-Cerezo, D Guirado, JC Gomez-Martin, Jay Goguen, F Moreno

We present the experimental scattering matrix as a function of the scattering angle of the lunar soil simulant JSC-1A. The measurements were performed at 488 nm, 520 nm and 647 nm, covering the range of scattering angles from 3o to 177o. The size

Freeze-Thaw Crack Determination in Cementitious Materials Using 3D X-ray Computed Tomography and Acoustic Emission

March 8, 2018

Author(s)

Edward Garboczi, Jason Weiss, Yaghoob Farnam, Yasmina Shields

Cracking in concrete due to freeze-thaw cycles is known to damage the structural integrity of materials and provides venues for water and ionic species to penetrate into concrete pores and create additional damage due to corrosion of reinforcement or

Simulation of the Influence of Intrinsic C-S-H Aging on Time-Dependent Relaxation of Hydrating Cement Paste

December 30, 2017

Author(s)

Xiaodan Li, Zachary Grasley, Edward Garboczi, Jeffrey W. Bullard

A numerical model has been developed that combines finite element methods with microstructure development algorithms to quantitatively predict the stress relaxation of cement paste due to intrinsic calcium silicate hydrate (C- S-H) viscoelasticity

Numerical study of the initial particle parking structure of cement/geopolymer pastes and dissolution of amorphous silica using real-shape particles

December 12, 2017

Author(s)

Edward Garboczi, Yibing Zuo, Zhiwei Qian, Guang Ye

Many particle-based numerical models have been used to simulate the hydration process of cementitious materials. But most of these models employ regular shape particles, such as spheres, to represent cement, slag or fly ash, which neglect the influence of

Shape and Size of Microfine Aggregates: X-Ray Microcomputed Tomography vs. Laser Diffraction

November 13, 2017

Author(s)

Sinan Erdogan, Edward Garboczi, D Fowler

Microfine aggregates are aggregates, formed naturally or in a crushing process, that pass a #200 ASTM sieve, so are considered to have an equivalent spherical diameter less than about 75 m. In this paper, for the first time we capture true 3-D shape and

Certification of SRM 2493:Standard Reference Mortar for Rheological Measurements

October 4, 2017

Author(s)

Alex Olivas, Chiara C. Ferraris, Nicos Martys, Edward Garboczi, Blaza Toman, William L. George

Rheological measurements are often performed using a rotational rheometer. In this type of rheometer, the tested fluid is sheared between two surfaces, one of which acts as the rotating surface [1]. Usually, the rotational velocity is imposed and the

A Multiscale Microstructure Model of Cement Paste Sulfate Attack by Crystallization Pressure

September 20, 2017

Author(s)

Pan Feng, Jeffrey W. Bullard, Edward Garboczi, Pan Feng

A recent microstructural model for simulating near-surface external sulfate attack on cement paste is modified to incorporate diffusive ionic transport between the surface and the interior of a macroscopic specimen. The model calculates the driving force

Electromagnetic Scattering from Individual Crumpled Graphene Flakes: A Characteristic Modes Approach

September 14, 2017

Author(s)

Edward J. Garboczi, Jack F. Douglas, Luis Fernando Vargas Lara, Ahmed M. Hassan, Deb Chatterjee, Kalyan Durbhakula, Md Gaffar

Graphene flakes in real composites are rarely perfectly flat, and often exhibit complicated crumpled shapes. Therefore, the goal of this work was to quantify the electromagnetic scattering characteristics of individual crumpled graphene flakes with shapes

Intrinsic conductivity, particle shape, and the Coulter particle counting method

September 4, 2017

Author(s)

Edward J. Garboczi

The Coulter particle counting method has been in use for more than five decades. It records a change in resistance when a particle flows from a large reservoir through a narrow orifice to another reservoir, where the flow direction is aligned with an

Effects of Powder Oxidation on Impact Toughness of Electron Beam Melt Ti-6Al-4V

August 25, 2017

Author(s)

Edward J. Garboczi, Enrico Lucon, William Grell, Z Loftus, Maciej Kumosa, E Solis-Ramos, Paul Predecki, E Clark

Powder quality in additive manufacturing (AM) electron beam melt (EBM) of Ti-6Al-4V components is crucial in determining the critical material properties of the end item. In this study, we report on the effect of powder oxidation on Charpy impact energy of

Quantifying the 3-Dimensional Shape of Lunar Regolith Particles Using X-Ray Computed Tomography and Scanning Electron Microscopy at sub-lambda Resolution

August 4, 2017

Author(s)

Ann C. Chiaramonti Debay, Jay D. Goguen, Edward J. Garboczi

We now know that, in addition to the size distribution, the specific shapes and orientations of regolith particles play a major role in determining the light scattering properties of lunar soil and other planetary regoliths. Our goal is to model light

Investigation of pore structure in cobalt chrome additively manufactured parts using X-ray computed tomography and three dimensional image analysis

July 15, 2017

Author(s)

Felix Kim, Edward Garboczi, Shawn P. Moylan, John Slotwinski

Pore structures of additively manufactured metal parts were investigated with X-ray Computed Tomography (XCT). Disks made of a cobalt-chrome alloy were produced using laser-based powder bed fusion (PBF) processes. The additive manufacturing processing

INVESTIGATION OF PORE STRUCTURE AND DEFECTS OF METAL ADDITIVE MANUFACTURING COMPONENTS USING X-RAY COMPUTED TOMOGRAPHY

July 14, 2017

Author(s)

Felix Kim, Edward Garboczi, Shawn P. Moylan, John Slotwinski

X-ray Computed Tomography (XCT) revealed pore structure and defects of additively manufactured metal parts produced with various processing parameters. A thresholding procedure involving a local thresholding algorithm was developed where the local

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