Engineering Commons^™

Seismic Analysis Of Geosynthetic-Reinforced Soil (Grs) Bridge Abutments With Modular Block Facing, Roonak Ghaderi

Theses and Dissertations

The response of Geosynthetic Reinforced Soil (GRS) bridge abutments to earthquake loading remains a concern despite their great success under static loads. In order to advance and implement this new technology, especially in seismically active regions, this study was undertaken to examine the performance of GRS bridge abutments under seismic loads in a rational and critical manner.

This research is focused on single span, simply supported bridges. The current seismic design methods, including pseudo-static and displacement methods, are not specifically developed for GRS bridge abutments where the foundation of the bridge superstructure is placed on the top surface of the …

Design And Analysis Of The Impact Diffusion Helmet Through A Finite Element Analysis Approach, Steven Paul Warnert

Master's Theses

By applying the finite element approach to the design and analysis of the impact diffusion helmet, many helmet configurations were able to be analyzed. Initially it was important to determine what design variables had an influence on the impact reducing abilities of the helmet design. The helmet was run through a series of Abaqus simulations that determined that a design with two oval shaped channels running along the length of the helmet was best. Next, these options were optimized to generate the helmet that produced the greatest impact reduction. The optimization simulations determined that a helmet that pushed the channels …

Effect Of Severe Corrosion On Lateral Strength Of Square Rc Bridge Columns, Sara Sotoud

Dissertations - ALL

Corrosion of reinforcing steel bars is the primary durability problem that causes degradation of reinforced concrete structures located in aggressive environments. Severe corrosion of steel bars decreases the lateral load-carrying capacity of reinforced concrete members, causes loss in the mechanical properties of reinforcement and cross-sectional area of steel bars and concrete cover, bond deterioration, reduces anchorage of steel bars, and decreases the confinement by transverse reinforcement. Consequently, corrosion results in drop in the lateral strength of columns. Therefore, studying response of corroded reinforced concrete columns subjected to lateral loads is necessary.

According to the Federal Highway Administration (FHWA) report in …

Design Optimization Of Permanent Magnet Machines Over A Target Operating Cycle Using Computationally Efficient Techniques, Alireza Fatemi

Dissertations (1934 -)

The common practices of large-scale finite element (FE) model-based design optimization of permanent magnet synchronous machines (PMSMs) oftentimes aim at improving the machine performance at the rated operating conditions, thus overlooking the performance treatment over the entire range of operation in the constant torque and extended speed regions. This is mainly due to the computational complexities associated with several aspects of such large-scale design optimization problems, including the FE-based modeling techniques, large number of load operating points for load-cycle evaluation of the design candidates, and large number of function evaluations required for identification of the globally optimal design solutions. In …

Design, Manufacture, Dynamic Testing, And Finite Element Analysis Of A Composite 6u Cubesat, Yanina Soledad Hallak

Master's Theses

CubeSats, specially the 6U standard, is nowadays the tendency where many developers point towards. The upscaling size of the standard and payloads entail the increase of the satellite overall mass. Composite materials have demonstrated the ability to fulfill expectations like reducing structural masses, having been applied to different types of spacecraft, including small satellites.

This Thesis is focused on designing, manufacturing, and dynamic testing of a 6U CubeSat made of carbon fiber, fiberglass, and aluminum.

The main objective of this study was obtaining a mass reduction of a 6U CubeSat structure, maintaining the stiffness and strength. Considering the thermal effects …

Finite Element Modeling Of Delamination Damage In Carbon Fiber Laminates Subject To Low-Velocity Impact And Comparison With Experimental Impact Tests Using Nondestructive Vibrothermography Evaluation, George Rodriguez Iv

Master's Theses

Carbon fiber reinforced composites are utilized in many design applications where high strength, low weight, and/or high stiffness are required. While composite materials can provide high strength and stiffness-to-weight ratios, they are also more complicated to analyze due to their inhomogeneous nature. One important failure mode of composite structures is delamination. This failure mode is common when composite laminates are subject to impact loading.

Various finite element methods for analyzing delamination exist. In this research, a modeling strategy based on contact tiebreak definitions in LS-DYNA^®was used. A finite element model of a low-velocity impact event was created to …

Improved Methodologies In Modeling And Predicting Failure In Aashto M-180 Guardrail Steel Using Finite Element Analysis - Phase I, Brandt M. Humphrey

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Steel guardrail systems have historic and widespread applications throughout the nation’s highways and roadways. However, catastrophic system failure can occur if the guardrail element ruptures, thus allowing an errant vehicle to pass uncontrolled through the system and potentially allow fractured ends to pierce the occupant compartment. To aid in the analysis and design of guardrail systems, further efforts are needed to develop and implement more reliable material failure criteria to predict and model guardrail steel rupture under all vehicle impact loading scenarios within impact simulation finite element method (FEM) software, such as LS-DYNA.

This Phase I study accomplished a number …

Wind Loading On Full-Scale Solar Panels, Zeinab Samani

Electronic Thesis and Dissertation Repository

Wind load governs the design of supporting structures of solar panels and constitutes approximately fifty percent of the total cost. There are various test scale related issues while testing solar panels (small structures) in boundary layer wind tunnel laboratories meant for tall buildings (large structures). Emergence of large testing facilities, however, is enabling testing full-scale solar panels. In this thesis an extensive experimental program is conducted at WindEEE Dome using full-scale solar panels and finite element modeling. The experimental program includes: (i) high resolution pressure tests to understand the sensitivity of pressure taps density and distribution; (ii) force balance test …

Finite Element Simulation Of Single-Lap Shear Tests Utilizing The Cohesive Zone Approach, Wilson A. Perez

Honors Undergraduate Theses

Many applications require adhesives with high strength to withstand the exhaustive loads encountered in regular operation. In aerospace applications, advanced adhesives are needed to bond metals, ceramics, and composites under shear loading. The lap shear test is the experiment of choice for evaluating shear strength capabilities of adhesives. Specifically during single-lap shear testing, two overlapping rectangular tabs bonded by a thin adhesive layer are subject to tension. Shear is imposed as a result. Debonding occurs when the shear strength of the adhesive is surpassed by the load applied by the testing mechanism. This research develops a finite element model (FEM) …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Characterization Of Fracture Initiation In Non-Cylindrical Buckle Folds Using 3d Finite Element Analysis, Eli Jacob Steinbeck

Masters Theses

"The spatial distribution of fracture sets associated with buckle folds has been well documented in field studies. There are difficulties, however, in placing accurate constraints on the timing of the initiation of individual fracture sets during the deformation history of the fold under in-situ conditions. This study investigates specific conditions that give rise to the initiation of various fracture sets in the hinge and limb of a pericline, based on an analysis of the effective stress evolution during the processes of buckling and erosional unloading. A 3D finite element modeling approach is used to simulate the effective stress evolution in …

Finite Element Modeling Of Active And Passive Behavior Of The Human Tibialis Anterior: A Preliminary Approach, David Joda

Dissertations, Master's Theses and Master's Reports

This research project serves as exploratory work in the field of computational human biomechanics. A connection between muscular force and intramuscular pressure (IMP) has been uncovered that could prove invaluable in medical diagnostics as a method to circumvent the use of electromyography.

Preliminary finite element simulations were conducted to model the human tibialis anterior muscle in passive lengthening and active contraction. These simulations, totaling over 50 unique runs, utilized a novel constitutive model developed within the IMP research group. Volumetric strain, reaction forces, and pressure gradients were compared to data acquired from ongoing in vivo human experiments. A mechanism for …