Mechanical Engineering Commons^™

Improving Sizing Resolution Of Particle Impactors In The Nanoparticle Range, Shivuday Kala

All Dissertations

The application of particle size measurement extends across many fields: air quality measurement, pharmaceutical studies, paint and coating production, and nanoparticle formulation to name a few. Therefore, accurate measurement of nanoparticles is critical to aerosol science. While devices currently exist that can size and count nanoparticles such as electrical mobility spectrometers, dynamic light scattering devices, and small angle X-ray scattering devices, their high costs, complex operation, and lack of outdoor usability, restrict their use in practical applications. Among the devices that can size aerosols down to the nanoscale, cascade impactors stand out because of their robustness, relatively simple design, low …

Thermoplastics 3d Printing Using Fused Deposition Modeling On Fabrics, Maxwell M. Blais

Electronic Theses and Dissertations

The creation of objects with integrated flexibility is desired and this can be achieved by additive manufacturing on fabric. We propose to use a textile fabric as a flexible joint and create to create an entire object with smaller parts called segments. Such a novel technique will bring integrated flexibility and folded assemblies using extrusion based additive manufacturing machines. The proposed process allows segments to be created flat one at a time on a continuous fabric, which will be suitable for flat to folded assemblies and eliminate size limitations of the 3D printer. Techniques considering object segmentation were used to …

Nanoscratch Study Of Diamond-Like Carbon Coatings With A Polydopamine + Sio2 Adhesive Underlayer, Anna Fisher

Mechanical Engineering Undergraduate Honors Theses

Diamond-like carbon (DLC) coatings have a wide array of desirable characteristics such as low friction, high hardness, and scratch resistance. Due to high residual stress and thermal mismatch, DLC films experience adhesion difficulties when bonded with metallic substrates, leading to cracking and delamination. In this study, the properties of a new coating with a polydopamine underlayer and silica nanoparticles bonded to a stainless-steel substrate (PDA+SiO2/DLC) were studied alongside three other samples, one with a polydopamine underlayer (PDA/DLC), one with a trimethylsilane (TMS) underlayer (TMS/DLC), and one with no underlayer (DLC only). Nanoscratch tests were performed with a 1 μm spheroconical …

Adhesion And Deformation Mechanisms Of Polydopamine And Polytetrafluoroethylene: A Multiscale Computational Study, Matthew Brownell

Graduate Theses and Dissertations

Polydopamine (PDA) has been shown to bond via covalent bonding, van der Waals forces, and hydrogen bonding and is known to adhere strongly to almost any material. The application of PDA between a substrate and a PTFE surface coating has resulted in low friction and a greatly reduced wear rate. Previous research probing the capabilities and limitations of PDA/PTFE films have studied the wear and mechanical properties of the film, but the overall adhesive and deformation mechanisms remain unclear.

In this research, we investigate the tribological properties of PDA and PTFE molecules and composites from the atomic to the microscale …

The Design, Manufacture, And Testing Of A Novel Adhesion System For A Climbing Vehicle, Michael William Schier

Master's Theses

We present the design and fabrication of a prototype wall-climbing vehicle employing a unique combined locomotion and adhesion system in which the adhesive vacuum is transmitted through moving, perforated treads. Implementing the adhesion/drive system involved a broad range of design challenges, including: developing reliable sealing of sliding and static interfaces, understanding the frictional interactions between the drive treads and various vehicle components and surfaces on which they ride, as well as designing for lightness, manufacturability, and adjustability. The clean sheet design presented in this thesis was taken from concept to functioning prototype in less than 6 months, requiring a considered …

Fabrication And Characterization Of Thiol-Acrylate Based Polymer For Bone Tissue Engineering Application, Anoosha Forghani

LSU Master's Theses

Thiol-acrylate materials have been demonstrated to have therapeutic potential as biocompatible scaffolds for bone tissue regeneration due to their osteoconductivity, biodegradability, and well-suited mechanical properties. This study connects the mechanical properties and stability of thiol-acrylate polymer with cell adhesion and proliferation of human adipose derived stromal cells. The polymer presented in this study, trimethylolpropane ethoxylate triacrylate-co-trimethylolpropane tris (3-mercaptopropionate) (TMPeTA-co-TMPTMP), was synthesized by an amine-catalyzed Michael addition reaction. Physical, mechanical, and chemical characterizations were performed on the polymeric scaffold, followed by preliminary in vitro cytocompatibility tests. Live/dead staining assays showed significant differences in cell adhesion for TMPeTA (692 and 912 MW). …

Highly Transparent, Self-Cleaning, And Antireflective Nanoparticle Coatings, Corey Seth Thompson

Graduate Theses and Dissertations

Current solar panel technologies require a sheet of glass to serve as both mechanical support and to protect the cells from the environment. The reflection from the glass sheet can reflect up to 8% of the incident light, reducing the power output of the panel. Antireflective coatings can be used to allow more light to enter the panel to be converted into usable electricity. However, no solid thin film materials exhibit a low enough index of refraction to serve as antireflective coatings for common solar glass. The main goal of this research was to investigate the self-cleaning, antifogging, and antireflective …

Scaling Reversible Adhesion In Synthetic And Biological Systems, Michael David Bartlett

Open Access Dissertations

Geckos and other insects have fascinated scientists and casual observers with their ability to effortlessly climb up walls and across ceilings. This capability has inspired high capacity, easy release synthetic adhesives, which have focused on mimicking the fibrillar features found on the foot pads of these climbing organisms. However, without a fundamental framework that connects biological and synthetic adhesives from nanoscopic to macroscopic features, synthetic mimics have failed to perform favorably at large contact areas. In this thesis, we present a scaling approach which leads to an understanding of reversible adhesion in both synthetic and biological systems over multiple length …

Numerical Evaluation And Analysis Of The Adhesion Phenomena In Thermal Barrier Coating Systems Through Bio-Mimicking Plasma Process, Naser Imran Hossain

LSU Master's Theses

Thermal Barrier Coatings or TBCs when abbreviated are an imperative part of the thermal protection system of expensive equipment and machinery in the automobile and aeronautics industry. They provide protection to expensive alloy materials upto a temperature of 2700° C without expensive metallurgical additions. Unfortunately, the problem of coating adhesion has plagued the TBC field for years, leading to catastrophic failures in critical TBC systems. Efforts to chemically improve bond strength has not been entirely successful, so the only other efficient way to do this would be some kind of mechanical interlocking that occurs at micro/nano scales. This research work …

Interface Engineered Diamond Coatings For Dry Machining Applications, Humberto Arturo Gomez Vega

USF Tampa Graduate Theses and Dissertations

Several studies have been propose to improve the adhesion of diamond films on cemented carbide tool materials, however a systematic study in identifying the role of the factors that affect the final diamond adhesion and the resulting machining performance of the tool under real manufacturing conditions is still unexplored. CVD diamond film's extraordinary qualities bring little benefit if the film fails to adhere sufficiently to the substrate. Inadequate adhesion undermines tool performance and longevity, causing unpredictable behavior under load and possibly leading to unexpected failure of the tool in the production line. This dissertation investigates the effects of different surface …

Direct Simulations Of Cells Motions And Deformations In Flow, Quan Jin

Dissertations

Direct numerical simulations (DNS) are used to study the motions and deformations of blood cells, especially leukocytes, in pressure driven flows in parallel plate channels with both smooth and uneven walls under adhesion force between the leukocytes and the channel wall.

Leukocytes are represented by two composite fluid models. The first model is the compound-drop model in which the cytoplasm and the nucleus are modeled as fluids, and the second one is the drop-rigid-particle model in which the cytoplasm is modeled as a fluid and the nucleus as a rigid particle. The adhesion force is computed using two adhesion force …

Modeling The Mechanical Effects Of Liquid Mediated Adhesion Between The Human Vocal Folds, Gifford Zach Decker

Theses and Dissertations

The vocal folds are a complex self-oscillating biological system. In the current research, an equation was developed to model viscous adhesion forces that occur when the collision of the vocal folds results in the formation of a liquid bridge. The adhesion equation was validated using experimental data, and simplified to a one-dimensional approximation with an included correction factor that adjusted the predicted pressure in situations where the one-dimensional approximation was invalid. A non-oscillating vocal fold model with a modeled liquid bridge was used to study stress resulting from viscous adhesion. The vertical normal stress magnitude ranged from about 80 to …