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Full-Text Articles in Engineering
Collapse Vulnerability And Fragility Analysis Of Substandard Rc Bridges Rehabilitated With Different Repair Jackets Under Post-Mainshock Cascading Events, Mostafa Fakharifar, Genda Chen, Ahmad Dalvand, Anoosh Shamsabadi
Collapse Vulnerability And Fragility Analysis Of Substandard Rc Bridges Rehabilitated With Different Repair Jackets Under Post-Mainshock Cascading Events, Mostafa Fakharifar, Genda Chen, Ahmad Dalvand, Anoosh Shamsabadi
Civil, Architectural and Environmental Engineering Faculty Research & Creative Works
Past earthquakes have signaled the increased collapse vulnerability of mainshock-damaged bridge piers and urgent need of repair interventions prior to subsequent cascading hazard events, such as aftershocks, triggered by the mainshock (MS). The overarching goal of this study is to quantify the collapse vulnerability of mainshock-damaged substandard RC bridge piers rehabilitated with different repair jackets (FRP, conventional thick steel and hybrid jacket) under aftershock (AS) attacks of various intensities. The efficacy of repair jackets on post-MS resilience of repaired bridges is quantified for a prototype two-span single-column bridge bent with lap-splice deficiency at column-footing interface. Extensive number of incremental dynamic …
Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks
Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during …
Cardinal Raúl Silva Henríquez Bridge During The 2010 Chile Earthquake, Zuocai Wang, Genda Chen, W. Phillip Yen, Ian G. Buckle
Cardinal Raúl Silva Henríquez Bridge During The 2010 Chile Earthquake, Zuocai Wang, Genda Chen, W. Phillip Yen, Ian G. Buckle
Civil, Architectural and Environmental Engineering Faculty Research & Creative Works
This paper presents a case study of the Cardinal Raúl Silva Henríquez Bridge, which experienced significant damage during an earthquake that occurred in Chile on February 27, 2010. Supported by reinforced concrete and steel columns of varying heights, the superstructure of the bridge consisted of 22 steel-girder spans, with one intermediate expansion joint located at the middle of the bridge. At each end of the bridge, the bottom flanges of the girders were welded to their bearing steel plates, which were embedded and anchored into the bridge abutment. Two, three-dimensional, finite element models (global versus local) with beam and solid …
Condition Assessment Of Bill Emerson Memorial Cable-Stayed Bridge Under Postulated Design Earthquake, Dongming Yan, Wenjian Wang, Genda Chen, Bryan A. Hartnagel
Condition Assessment Of Bill Emerson Memorial Cable-Stayed Bridge Under Postulated Design Earthquake, Dongming Yan, Wenjian Wang, Genda Chen, Bryan A. Hartnagel
Civil, Architectural and Environmental Engineering Faculty Research & Creative Works
In this study, a three-dimensional finite element model of the Bill Emerson Memorial cable-stayed bridge was developed and validated with the acceleration data recorded during the M4.1 earthquake of May 1, 2005, in Manila, Arkansas. The model took into account the geometric nonlinear properties associated with cable sagging and soil-foundation-structure interaction. The validated model was used to evaluate the performance of a seismic protective system, the behavior of cable-stayed spans, and the accuracy of two simplified bridge models that have been extensively used by the structural control community. The calculated natural frequencies and mode shapes correlated well with the measured …
Aperture Modeling Using A Hybrid Method For Rfi Analysis, Liehui Ren, Zhenwei Yu, Gang Feng, Francesco De Paulis, Yaojiang Zhang, Jun Fan, Xiaopeng Dong, Jason A. Mix, Daniel Hua, Kevin P. Slattery
Aperture Modeling Using A Hybrid Method For Rfi Analysis, Liehui Ren, Zhenwei Yu, Gang Feng, Francesco De Paulis, Yaojiang Zhang, Jun Fan, Xiaopeng Dong, Jason A. Mix, Daniel Hua, Kevin P. Slattery
Electrical and Computer Engineering Faculty Research & Creative Works
A hybrid method is proposed for radio frequency interference (RFI) prediction of a metal enclosure with an aperture on the top wall. The structure is divided into several segments. While the fields in rectangular segments are described by cavity model, the segments with apertures are modeled by the commercial finite element solver (HFSS). Tangential field continuities along the common boundaries of different segments are enforced by the voltages and currents of boundary ports. Good agreement has been achieved between the hybrid method and full wave simulation.
Spice-Compatible Cavity And Transmission Line Model For Power Bus With Narrow Slots, Gang Feng, Yaojiang Zhang, James L. Drewniak, Lin Zhang
Spice-Compatible Cavity And Transmission Line Model For Power Bus With Narrow Slots, Gang Feng, Yaojiang Zhang, James L. Drewniak, Lin Zhang
Electrical and Computer Engineering Faculty Research & Creative Works
Segmental lumped circuits are derived from coupled transmission line model for a narrow slot on the power bus. Both electric and magnetic coupling are taken into account by distributed inductances and capacitances. Then a SPICE- compatible circuit model for the power bus with the narrow slot is proposed. In this model, the segmental lumped circuits are connected to the equivalent circuit, which is derived by a hybrid cavity model and segmentation method for irregular power/ground planes. The model is validated by comparing with the calculations of finite element method (FEM) for the self or mutual impedances of the two port …
Machine Design Considerations For The Future Energy Challenge, Jonathan W. Kimball, Marco Amrhein
Machine Design Considerations For The Future Energy Challenge, Jonathan W. Kimball, Marco Amrhein
Electrical and Computer Engineering Faculty Research & Creative Works
Motors consume a significant fraction of electricity in the United States and in the world. As part of the International Future Energy Challenge, student teams are endeavoring to improve the efficiency of fractional-horsepower machines. The present work summarizes the motor design and construction process for a 500 W prototype induction machine targeting efficiency above 80%. Analytical and finite-element results are shown.
Effects Of Open Stubs Associated With Plated Through-Hole Vias In Backpanel Designs, Shaowei Deng, Jingkun Mao, Todd H. Hubing, James L. Drewniak, Jun Fan, James L. Knighten, Norman W. Smith, Ray Alexander, Chen Wang
Effects Of Open Stubs Associated With Plated Through-Hole Vias In Backpanel Designs, Shaowei Deng, Jingkun Mao, Todd H. Hubing, James L. Drewniak, Jun Fan, James L. Knighten, Norman W. Smith, Ray Alexander, Chen Wang
Electrical and Computer Engineering Faculty Research & Creative Works
Plated through-hole (PTH) vias are commonly used in printed circuit boards. They usually leave open stubs if the signal(s) does not transition the entire depth of the board. These open stubs can have a negative impact on signal transmission. This summary reports the investigation of the impact of the open via stubs in a typical backpanel design.
Application Of Higher-Order Fem Elements To The Analysis Of Microstrip Structures, H. Wang, C. L. Guo, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff
Application Of Higher-Order Fem Elements To The Analysis Of Microstrip Structures, H. Wang, C. L. Guo, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff
Electrical and Computer Engineering Faculty Research & Creative Works
Microstrip structures, formed by metal traces printed on a dielectric substrate above a reference plane, are frequently the object of electromagnetic modeling. In this paper, hybrid FEM/MoM formulations employing conventional Whitney elements and newly developed linear-tangent/linear-normal (LT/LN) tangential vector finite elements (TVFEs) are applied to the analysis of microstrip structures with thin traces. This paper shows that the variation of the electric field below the trace is a significant issue to be addressed in microstrip structure modeling. Different mesh methods are investigated and the advantages of the LT/LN TVFEs are discussed.
Application Of A Hybrid Fem/Mom Method To A Canonical Pcb Problem, Yun Ji, J. Chen, Todd H. Hubing, James L. Drewniak
Application Of A Hybrid Fem/Mom Method To A Canonical Pcb Problem, Yun Ji, J. Chen, Todd H. Hubing, James L. Drewniak
Electrical and Computer Engineering Faculty Research & Creative Works
A hybrid FEM/MOM method was used to solve a canonical printed circuit board (PCB) problem. The PCB is populated with three traces. One is a signal line and the other two are I/O lines that extend beyond the boundary of the board. The finite element method (FEM) was used to model the fields in the volume around the on-board trace. The method of moments (MOM) was employed to model the equivalent surface currents on the board and the current on the off-board traces. The FEM and MOM equations were coupled by forcing the continuity of tangential fields on the dielectric …
Emc Applications Of The Emap5 Hybrid Fem/Mom Code, Yun Ji, Todd H. Hubing, Mohammad Wares Ali
Emc Applications Of The Emap5 Hybrid Fem/Mom Code, Yun Ji, Todd H. Hubing, Mohammad Wares Ali
Electrical and Computer Engineering Faculty Research & Creative Works
EMAP5 is a numerical software package designed to model electromagnetic problems. It employs the finite element method (FEM) to analyze three-dimensional volumes, and the method of moments (MOM) to analyze the current distribution on the surface of these volumes. The two methods are coupled through the fields on the dielectric surface. This paper describes the formulation of the EMAP5 code and demonstrates how it can be used to analyze simple printed circuit board configurations
A Hybrid Fem/Mom Technique For Electromagnetic Scattering And Radiation From Dielectric Objects With Attached Wires, Mohammad Wares Ali, Todd H. Hubing, James L. Drewniak
A Hybrid Fem/Mom Technique For Electromagnetic Scattering And Radiation From Dielectric Objects With Attached Wires, Mohammad Wares Ali, Todd H. Hubing, James L. Drewniak
Electrical and Computer Engineering Faculty Research & Creative Works
A hybrid formulation is presented, which combines the method of moments (MOM) with the edge-based vector finite element method (FEM) to solve electromagnetic radiation problems from structures consisting of an inhomogeneous dielectric body of arbitrary shape attached to one or more perfectly conducting bodies. While either method alone fails to model these structures efficiently, a combination of both finite element and moment methods provides an excellent way to solve these problems. The FEM is employed to handle the interior domain of inhomogeneous dielectric bodies and the method of moments is used to develop surface integrals that relate the field quantities …
An Expert System Approach To Emc Modeling, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Navin Kashyap
An Expert System Approach To Emc Modeling, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Navin Kashyap
Electrical and Computer Engineering Faculty Research & Creative Works
Existing computer software for EMC analysis can be divided into three categories. Analytical modeling codes employ closed form expressions to solve problems of general interest to EMC engineers or circuit designers. Numerical modeling codes use numerical techniques to solve Maxwell's equations subject to specific boundary conditions. EMC rule checkers search a design for features that violate basic EMC design guidelines. This paper outlines the relative advantages and limitations of each of these three approaches and describes an expert system EMC modeling approach. The new approach combines analytical models, numerical models, and EMC rule-checking in order to evaluate designs in much …