Mechanical Engineering Commons^™

The Future Is Now In Twisted Coil Polymer Actuators (Tcpa), Ryan Ronquillo

Electronic Theses and Dissertations

This thesis aimed to fabricate and test twisted coiled polymer actuators (TCPA) to understand the mechanical and thermal aspects of this artificial muscle fiber. The purpose of this thesis was to find a linear relationship using the LVDT sensor, fabricating TCPA fibers, and interpreting the data. The project tested whether nylon/polymer could be used as a better artificial muscle fiber.

This research accomplished three goals: (1) designing and fabricating a system capable of creating supercoiled muscle fibers consistently, (2) calibrating the Linear Variable Differential Transformer (LVDT) and Core, and (3) analyzing/interpreting the data of the Twisted Coiled Polymer Actuators (TCPA) …

Magnetic Properties Of Nd-Fe-B Permanent Magnets Under Thermal Experimentation, Géraldine Houis

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Neodymium-Iron-Boron (Nd-Fe-B) magnets were developed in the 1980s, and since then, they have appeared as a common component in many fields. From the industry to consumers or defense applications, from turbines, computers, cellphones to most audio systems, Nd-Fe-B magnets are present everywhere. But when Nd-Fe-B magnets are applied to the motors of electric vehicles and wind-turbine generators, their temperature rises, therefore Nd-Fe-B-Dy magnets are used. However, while the use of these magnets is common at low temperatures, their properties decrease dramatically with the increase of temperature. In this paper, the Nd-Fe-B-based samples used were prepared by using arc melting, melt …

Fracture Toughness Improvement Of ����� Ceramics By Grain Size Control And Ductile Phase Reinforcement, Kesong Wang

McKelvey School of Engineering Theses & Dissertations

This study used grain size control and ductile phase reinforcement to improve fracture toughness of ����� ceramics. Alpha alumina particles of 100 nm, 0.5-1 micrometers, and 10 micrometers were coated with 1-5 nm nickel by electroless nickel plating (ENP). The coated powders were consolidated at 1200℃-1500℃ by spark plasma sintering (SPS). The sintered samples were annealed at 1100 oC for 1.5 hours and 10 hours to determine the effect of post sintering annealing on hardness and fracture toughness. Density of the samples were measured by the standard Archimedes method using a 5 mL pycnometer. Hardness values were determined by Vickers …

Heat Of Fusion Of Primary Alcohol Confined In Nanopores, Harrisonn Griffin

Honors Theses

Melting behavior of physically confined 1-decanol in nano porous silica was probed using a Differential Scanning Calorimeter (DSC). In agreement with the Gibbs-Thomson prediction, we observe that the melting temperature of the confined 1-decanol scales inversely with the physical size of the pores. Contrary to the assumption used in developing the Gibbs-Thomson equation, however, the apparent heat of fusion decreases as the pore size decreases. Previously, several models have been proposed where interfacial layers of molecules do not participate in the phase transition and thereby would not contribute to the heat of fusion. While these could reconcile the seeming contradiction, …

Nanomechanical Characterization Of Cavity Growth And Rupture In Hydrogen-Implanted Single-Crystal Batio3., Young-Bae Park, Patrick Nardi, Xiaodong Li, Harry A. Atwater

Xiaodong Li

A thermodynamic model of cavitynucleation and growth in ion-implanted single-crystal BaTiO3 layer is proposed, and cavity formation is related to the measured mechanical properties to better understand hydrogen implantation-induced layer transfer processes for ferroelectric thin films. The critical radius for cavitynucleation was determined experimentally from blistering experiments performed under isochronal anneal conditions and was calculated using continuum mechanical models for deformation and fracture, together with thermodynamic models. Based on thermodynamic modeling, we suggest that cavitiesgrow toward the cracking criteria at a critical blister size whereupon gas is emitted from ruptured cavities. The main driving force for layer splitting is the …

A Case Study Of Heat Treatment On Aisi 1020 Steel, Sayed Shafayat Hossain, Md. Maksudul Islam, Md. Sajibul Alam Bhuyan

Md. Maksudul Islam

Proper heat treatment of steels is one of the most important factors in determining how they will perform in service. Engineering materials, mostly steel, are heat treated under controlled sequence of heating and cooling to alter their physical and mechanical properties to meet desired engineering applications. In this study we have chosen AISI 1020 steel as for our research work and we have tried to find out the mechanical properties (hardness) and micro structural properties (martensite formation, carbon self-locking region) by means of appropriate heat treatment process (annealing, normalizing & hardening). Here the steel specimens were heat treated in a …

Analysis Of Mechanically Milled Exchange Coupled Nanocomposite Permanent Magnets, Santanu Mukherjee

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Nanocomposite permanent magnets have recently evoked wide interest because of their interesting properties. They usually consist of a hard magnetic phase having superior coercivities and a soft magnetic phase having improved values of magnetization and when they are coupled together, we get a permanent magnet with enhanced values of both the parameters and thus can be put to a lot of applications. Also to make this possible we can take advantage of the principle of exchange interaction which has been discussed subsequently in detail.

Also the microstructure plays a major role in obtaining good magnetic properties and the microstructure is …

Anomalous Loss Of Toughness Of Work Toughened Polycarbonate, Shawn E. Meagher

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Glassy polymers such as polycarbonate (PC) can be toughened through compressive plastic deformation. The increase in toughness is substantial, showing as much as a fifteen fold increase in the amount of dissipated energy during failure for samples compressed to 50% plastic strain. This toughness increase can be reversed through thermal aging at temperatures below the glass transition temperature (T_g = 147°C).

The combined effect of plastic compression and thermal aging has been studied using Charpy, Single Edge Notch Bending (SENB), and Compact Tension (CT) tests. The tests mapped the response of samples cut along different orientations relative to the …

Influence Of Ni Nanoparticle On The Morphology And Growth Of Interfacial Intermetallic Compounds Between

A.S. Md Abdul Haseeb

TiO2 thin films were deposited on unheated and heated glass substrates at an elevated sputtering pressure of 3 Pa by radio frequency (RF) reactive magnetron sputtering. TiO2 films deposited at room temperature were annealed in air for 1 h at various temperatures ranging from 300 to 600 °C. The structural and optical properties of the thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometry. XRD results show that as-grown and post-annealed TiO2 films have anatase crystal structure. Higher substrate and annealing temperatures result in a slight increase of crystallinity. TiO2 …

Effects Of Annealing Treatment On Optical Properties Of Anatase Tio 2 Thin Films

A.S. Md Abdul Haseeb

In this investigation, anatase TiO 2 thin films were grown by radio frequency magnetron sputtering on glass substrates at a high sputtering pressure and room temperature. The anatase films were then annealed at 300-600 °C in air for a period of 1 hour. To examine the structure and morphology of the films, X-ray diffraction (XRD) and atomic force microscopy (AFM) methods were used respectively. From X-ray diffraction patterns of the TiO 2 films, it was found that the as-deposited film showed some differences compared with the annealed films and the intensities of the peaks of the crystalline phase increased with …

Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications

A.S. Md Abdul Haseeb

For thermally stable LIGA materials for high temperature MEMS applications LIGA Ni-W layers and micro testing samples with different compositions (15 and 5 at% W) were electrodeposited. In order to investigate the thermal stability the Ni-W layers were annealed at different temperatures (300-700°C) and for different durations (1, 4, 16 h). Their microstructure and micro-hardness were than analysed after annealing and compared with those of as-deposited states. The observed microstructures show, in comparison to pure LIGA nickel, a small grain growth and a relatively stable structure up to 700°C. The micro-hardness values of the LIGA Ni-W layers are higher than …

Nanomechanical Characterization Of Cavity Growth And Rupture In Hydrogen-Implanted Single-Crystal Batio3., Young-Bae Park, Patrick Nardi, Xiaodong Li, Harry A. Atwater

Faculty Publications

A thermodynamic model of cavitynucleation and growth in ion-implanted single-crystal BaTiO₃ layer is proposed, and cavity formation is related to the measured mechanical properties to better understand hydrogen implantation-induced layer transfer processes for ferroelectric thin films. The critical radius for cavitynucleation was determined experimentally from blistering experiments performed under isochronal anneal conditions and was calculated using continuum mechanical models for deformation and fracture, together with thermodynamic models. Based on thermodynamic modeling, we suggest that cavitiesgrow toward the cracking criteria at a critical blister size whereupon gas is emitted from ruptured cavities. The main driving force for layer splitting is …

Synthesis And Characterization Of Cobalt-Platinum Thin Films, Priya David

LSU Master's Theses

Co-based alloy thin films have attracted a lot of interest, due to their excellent magnetic properties, that is essential in the field of magnetic recording media. Alloying Co with metals like Pt changes some of its intrinsic magnetic properties such as increasing the magnetocrystalline anisotropy constants of the alloy. Co-Pt thin films and multilayers are more suitable for ultra high-density magnetic recording media because they have high-magnetic anisotropy, chemical stability, excellent coercivity and resistance to corrosion. In the present study, Co-Pt alloy and Pt/Co multilayered films were deposited on Si substrate using dual electron beam co-evaporation. The Co-Pt alloy thin …