Mechanical Engineering Commons^™

Mapping Chemical Selection Pathways For Designing Multicomponent Alloys: An Informatics Framework For Materials Design, Srinkant Srinivasan, Scott R. Broderick, Ruifeng Zhang, Amrita Mishra, Susan B. Sinnott, Surendra Saxena, James M. Lebeau, Krishna Rajan

Department of Mechanical and Materials Engineering

A data driven methodology is developed for tracking the collective influence of the multiple attributes of alloying elements on both thermodynamic and mechanical properties of metal alloys. Cobalt-based superalloys are used as a template to demonstrate the approach. By mapping the high dimensional nature of the systematics of elemental data embedded in the periodic table into the form of a network graph, one can guide targeted first principles calculations that identify the influence of specific elements on phase stability, crystal structure and elastic properties. This provides a fundamentally new means to rapidly identify new stable alloy chemistries with enhanced high …

Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi

FIU Electronic Theses and Dissertations

This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and …

A Novel Hip Implant Using 3d Woven Composite Material – Design And Analysis, Hari Kishore Adluru

FIU Electronic Theses and Dissertations

The present research focuses on analyzing the possibility of implementing three dimensional woven composite (3DWC) materials in hip implants. The integration of 3DWCs in hip implants has the possibility to both extend the life-time and improve patient outcomes; by spatially varying mechanical properties to meet both biological needs as well as required mechanical loading. In this study, the bulk material properties of 3DWCs were varied based on woven composite architecture and determined using physics based models, which reflect the realistic geometries of fibers in compaction and preform. The multi-digital chain method combined with Extended Finite Elemental Analysis (XFEA) are adopted …

Novel Ternary Magnesium-Tin Alloys By Microalloying, Sadegh Behdad

FIU Electronic Theses and Dissertations

The objective of this research was to explore the possibility of developing novel Magnesium-Tin alloys with improved mechanical properties by micro-alloying. Magnesium is the lightest of all structural metals. It can be machined faster and with almost half the power required for aluminum. There is a limitless supply of magnesium in sea water and it can also be recycled at 5% of initial energy requirements. These properties make magnesium an ideal green alternative to replace metals and polymers in automotive, aerospace, biomedical and defense sectors. The potential weight reduction in the US automotive market alone, leads to 100 billion gallons …

Heat-Driven Self-Cooling System Based On Thermoelectric Generation Effect, Robel Kiflemariam

FIU Electronic Theses and Dissertations

This research entails the first comprehensive and systematic study on a heat-driven, self-cooling application based on the thermoelectric generation effect. The system was studied using the first and second laws of thermodynamics to provide a solid and basic understanding of the physical principles governing the system. Multiphysics equations that relate heat transfer, fluid dynamics and thermoelectric generation are derived. The equations are developed with increasing complexity, from the basic Carnot heat engine to externally and internally irreversible engines. A computational algorithm to systematically use the fundamental equations has been presented and computer code is implemented based on the algorithm.

Experiments …

High Performance Li4ti5o12/Si Composite Anodes For Li-Ion Batteries, Chunhui Chen, Richa Agrawal, Chunlei Wang

Department of Mechanical and Materials Engineering

Improving the energy capacity of spinel Li4Ti5O12 (LTO) is very important to utilize it as a high-performance Li-ion battery (LIB) electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li+ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35) exhibited superior specific capacity (1004 mAh·g−1) at lower current densities (0.22 A·g−1) but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si …

Multi-Objective Analysis And Optimization Of Integrated Cooling In Micro-Electronics With Hot Spots, Sohail R. Reddy

FIU Electronic Theses and Dissertations

With the demand of computing power from electronic chips on a constant rise, innovative methods are needed for effective and efficient thermal management. Forced convection cooling through an array of micro pin-fins acts not only as a heat sink, but also allows for the electrical interconnection between stacked layers of integrated circuits. This work performs a multi-objective optimization of three shapes of pin-fins to maximize the efficiency of this cooling system. An inverse design approach that allows for the design of cooling configurations without prior knowledge of thermal mapping was proposed and validated. The optimization study showed that pin-fin configurations …

The Microstructure And The Electrochemical Behavior Of Cobalt Chromium Molybdenum Alloys From Retrieved Hip Implants, Christopher P. Emerson

FIU Electronic Theses and Dissertations

Because of their excellent mechanical, tribological, and electrochemical properties, Cobalt Chromium Molybdenum alloys have been used as the material for both the stem and head of modular hip implants. Corrosion is one mechanism by which metal debris, from these implants, is generated, which can lead to adverse events that requires revision surgery. Manufacturing process such as wrought, as-cast, and powder metallurgy influences the microstructure, material properties, and performance of these implants

The current research focuses on analyzing the microstructure of CoCrMo alloys from retrieved hip implants with optical and scanning electron microscopy. Additionally, energy disperse spectroscopy was utilized to determine …

In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, Jose Luis Gonzalez Jr

FIU Electronic Theses and Dissertations

The purpose of this study was to evaluate the incidence of corrosion and fretting in 48 retrieved titanium-6aluminum-4vanadium and/or cobalt-chromium-molybdenum modular total hip prosthesis with respect to alloy material microstructure and design parameters. The results revealed vastly different performance results for the wide array of microstructures examined. Severe corrosion/fretting was seen in 100% of as-cast, 24% of low carbon wrought, 9% of high carbon wrought and 5% of solution heat treated cobalt-chrome. Severe corrosion/fretting was observed in 60% of Ti-6Al-4V components. Design features which allow for fluid entry and stagnation, amplification of contact pressure and/or increased micromotion were also shown …

Acoustic Manipulation And Alignment Of Particles For Applications In Separation, Micro-Templating, And Device Fabrication, Kamran Moradi

FIU Electronic Theses and Dissertations

This dissertation studies the manipulation of particles using acoustic stimulation for applications in microfluidics and templating of devices. The term particle is used here to denote any solid, liquid or gaseous material that has properties, which are distinct from the fluid in which it is suspended. Manipulation means to take over the movements of the particles and to position them in specified locations.

Using devices, microfabricated out of silicon, the behavior of particles under the acoustic stimulation was studied with the main purpose of aligning the particles at either low-pressure zones, known as the nodes or high-pressure zones, known as …

Development Of New Structural Health Monitoring Techniques, Hadi Fekrmandi

FIU Electronic Theses and Dissertations

During the past two decades, many researchers have developed methods for the detection of structural defects at the early stages to operate the aerospace vehicles safely and to reduce the operating costs. The Surface Response to Excitation (SuRE) method is one of these approaches developed at FIU to reduce the cost and size of the equipment. The SuRE method excites the surface at a series of frequencies and monitors the propagation characteristics of the generated waves. The amplitude of the waves reaching to any point on the surface varies with frequency; however, it remains consistent as long as the integrity …

A Comparison Between Graphene And Ws2 As Solid Lubricant Additives To Aluminum For Automobile Applications, Sara Rengifo

FIU Electronic Theses and Dissertations

The purpose of this thesis was to compare graphene nanoplatelets (GNP) and WS₂ as solid lubricant additives to aluminum in order to reduce friction and wear. The central hypothesis of this work relied on lubricating properties of 2D materials, which consist layers that slip under a shear force.

Two aluminum composites were made (Al-2 vol.% GNP and Al-2 vol.% WS₂) by spark plasma sintering. Tribological properties were evaluated by ball-on-disk wear tests at room temperature (RT) and 200^°C.

WS₂ not only presented the lowest COF (0.66) but also improved the wear resistance of aluminum …