Engineering Commons^™

Analyzing The Effects Of Ultrafast Laser Processing On Mechanical Properties Of 3d-Printed Pla Parts, Darshan Pramodbhai Yadav

Theses and Dissertations

Recent advances in additive manufacturing technologies have already led to wide-scale adoption of 3D-printed parts in various industries. The expansion in choice of materials that can be processed, particularly using Fused Deposition Modeling (FDM), and the steady advancements in dimensional accuracy control have extended the range of applications far beyond rapid prototyping. However, additive manufacturing still has considerable limitations compared to traditional and subtractive manufacturing processes. This work addresses limitations associated with the as-deposited surface roughness of 3D-printed parts. The effects of roughness-induced stress concentrations were studied on ultimate tensile strength and fatigue life. The samples were manufactured using a …

Enhancing Compatibility And Mechanical Properties Of Natural Rubber Composites, Krisma Yessi Sianturi, Adam Febriyanto Nugraha, Belle Kristaura, Mochamad Chalid

Journal of Materials Exploration and Findings (JMEF)

Pure natural rubber (NR) exhibits low mechanical properties, necessitating the incorporation of additives like vulcanizing agents and fillers. Carbon black and silica, conventional fillers, are relatively expensive and not environmentally friendly. This study explores using Oil Palm Empty Fruit Bunch (OPEFB) fiber as an affordable, abundant, and biodegradable alternative filler for NR. However, compatibility issues arise between the nonpolar NR and the polar OPEFB fiber. A latex-starch hybrid coupling agent (CA (NR-St)) was added to the composite formulation to address this. NR, OPEFB fiber, and the coupling agent were mixed using an open roll mill with a 10 phr OPEFB …

Insect Antennae As Bioinspirational Superstrong Fiber-Based Microfluidics, Griffin J. Donley

All Theses

Nature is frequently turned to for inspiration for the creation of new materials. Insect antennae are hollow, blood-filled fibers with complex shape, and are cantilevered at the head. The antenna is muscle-free, but the insect can controllably flex, twist, and maneuver it laterally. To explain this behavior, a comparative study of structural and tensile properties of the antennae of Periplaneta americana (American cockroach), Manduca sexta (Carolina hawkmoth), and Vanessa cardui (painted lady butterfly) was performed. These antennae demonstrate a range of distinguishable tensile properties, responding either as brittle fibers (Manduca sexta) or strain-adaptive fibers that stiffen when stretched (Vanessa cardui …

An Investigation Into Energy-Material Properties Interaction In Additive Manufacturing Of Polymers., Pu Han

Electronic Theses and Dissertations

Additive manufacturing (AM), known as three-dimensional (3D) printing, is a fabrication process to build 3D objects layer by layer based on computer aided design (CAD) model or digital 3D model. Fused filament fabrication (FFF) has become a preferred method for additive manufacturing due to its cost-effectiveness and flexibility. However, the parts built using FFF process suffer from lower mechanical strength compared to that fabricated using traditional method and rough surface finish. With this motivation, this dissertation aims to develop and implement a novel in-process laser assisted technique on FFF to heal the microstructure of FFF built objects by enhancing reptation …

Determination Of Hydrogel Degradation By Passive Mechanical Testing, Avery Rosh-Gorsky

Honors Theses

This paper details a new technique to measure the mechanical properties of ETTMP PEGDA hydrogels using Hertz Contact Theory and simultaneously analyze both the model drug release and gel erosion in situ. This method involves curing a drug loaded hydrogel in a standard cuvette and placing a glass bead and phosphate buffer solution (PBS). Over time, the cross-linked network of the hydrogel breaks down, and, as a result, the ball sinks into the hydrogel. This method provides a macroscopic and inexpensive way to continuously and passively measure properties of the hydrogel as the hydrogel degrades. By plotting both the …

Influence Of Mechanical Properties Of Paper Coating On The Crack At The Fold Problem, Seyyed Mohammad Hashemi Najafi

Electronic Theses and Dissertations

Paper coating layers are subject to various stresses and deformations in many converting processes such as calendering, printing, slitting, and folding of the paper. In some cases, products may crack during folding to generate a defect called cracking at the fold (CAF). The parameters that influence these defects are not well understood. The overall goal of this thesis is to better understand the CAF behavior as related to material properties of the coating layer.

A method was developed to produce free-standing pigmented coating layers thick enough to be tested in bending as well as tension. The mechanical properties of these …

Covalently Crosslinked Organic/Inorganic Hybrid Biomaterials For Bone Tissue Engineering Applications, Dibakar Mondal

Electronic Thesis and Dissertation Repository

Scaffolds are key components for bone tissue engineering and regeneration. They guide new bone formation by mimicking bone extracellular matrix for cell recruitment and proliferation. Ideally, scaffolds for bone tissue engineering need to be osteoconductive, osteoinductive, porous, degradable and mechanically competent. As a single material can not provide all these requirements, composites of several biomaterials are viable solutions to combine various properties. However, conventional composites fail to fulfil these requirements due to their distinct phases at the microscopic level. Organic/inorganic (O/I) class II hybrid biomaterials, where the organic and inorganic phases are chemically crosslinked on a molecular scale, hence the …

Spray-Dried Cellulose Nanofibril-Reinforced Polypropylene Composites For Extrusion-Based Additive Manufacturing, Lu Wang

Electronic Theses and Dissertations

Compared to conventional manufacturing process, additive manufacturing (AM) offers free-form design, lighter and more ergonomic products, short lead time and less waste. Extrusion-based AM can be used to print thermoplastics. However, extrusion-based AM has processing challenges in printing semi-crystalline thermoplastics, for instance, polypropylene (PP). Cellulose nanofibrils (CNF) are one type of cellulose nanofibers that are produced from pulp fibers. CNF has extraordinary properties which make it an ideal candidate to reinforce polymers. Spray-dried CNF (SDCNF) is able to be incorporated into thermoplastic matrices without modifying conventional processing procedures.

The mechanical properties of 3D printed plastic parts have been considered significantly …

Molecular Modeling Of Aerospace Polymer Matrices Including Carbon Nanotube-Enhanced Epoxy, Matthew Radue

Dissertations, Master's Theses and Master's Reports

Carbon fiber (CF) composites are increasingly replacing metals used in major structural parts of aircraft, spacecraft, and automobiles. The current limitations of carbon fiber composites are addressed through computational material design by modeling the salient aerospace matrix materials. Molecular Dynamics (MD) models of epoxies with and without carbon nanotube (CNT) reinforcement and models of pure bismaleimides (BMIs) were developed to elucidate structure-property relationships for improved selection and tailoring of matrices.

The influence of monomer functionality on the mechanical properties of epoxies is studied using the Reax Force Field (ReaxFF). From deformation simulations, the Young’s modulus, yield point, and Poisson’s ratio …

Study On Mechanical Properties Of Silicone Rubber Materials Used As Gaskets In Pem Fuel Cell Environment, Guo Li

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Mechanical And Electro-Mechanical Properties Of Crystalline Organic Semiconductors, Marcos A. Reyes-Martinez

Doctoral Dissertations

The study of the physical properties of organic crystalline semiconductors has allowed the advent of a new generation of high-performance organic electronic devices. Exceptional charge-transport properties and recent developments in large-area patterning techniques make organic single crystals (OSCs) excellent candidates for their utilization in the next-generation of electronic technologies, including flexible and conformable organic thin-film devices. In spite of the profound knowledge of the structural and electrical properties of OSCs, knowledge of the mechanical properties and the effects of mechanical strain is almost non-existent. This dissertation aims to bring new understanding of the intrinsic mechanical properties and the effect of …

Effect Of Heat Treatment On The Mechanical Properties In Natural Bamboo, Austin Levy, Mackenzie Kirkpatrick

Materials Engineering

Previous studies have shown that heat treatments have the ability to improve mechanical strength and stiffness in hardwood species. Compared to structural hardwoods, bamboo is a more sustainable and globally viable renewable resource. Therefore, Bambusoides vivax (timber bamboo) culms were fabricated into flat, rectangular cross-section samples with varying cellulose content to be heat treated and tested for mechanical properties. All samples were heat treated (HT) twice. The first HT was a normalization of all samples at 103 +/- 3 °C. The second HT was performed at various times and temperatures ranging from 130°C to 170°C for 0.5 to 3 hours. …

Synthesis, Characterization And Applications Of Lignin-Based Epoxy Resins, Fatemeh Ferdosian

Electronic Thesis and Dissertation Repository

Epoxy resin is one of the most versatile thermosetting polymers with diverse applications. Epoxy resins are mainly produced from the reaction of bisphenol-A (BPA) and epichlorohydrin. The consumption of bisphenol-A is facing growing concerns over its carcinogenic effects and its sustainability. Lignin can be a promising renewable substitute of bisphenol-A in the synthesis of epoxy resins.

In this thesis work, a novel method has been developed for the synthesis of bio-based epoxy resins with reduced side reactions, employing de-polymerized lignin from organosolv lignin (DOL), kraft lignin (DKL) and hydrolysis lignin (DHL) under alkaline condition in the presence of a phase …

Patterning And Mechanical Analysis Of Fiber-Based Materials, Samuel A. Pendergraph

Doctoral Dissertations

The ability to define and control the topography of a surface has been studied extensively due to its importance in a wide variety of applications. The control of a non-planar topography would be very valuable since a number of structures that are pervasive in artificial applications (e.g. fibers, lenses) are curved interfaces. This potential of enabling applications that incorporate non-planar geometries was the motivation for this thesis. The first study of this thesis comprises the study of patterning the circumference of micrometer sized fibers. Specifically, a unique technique was described to pattern the fiber with a periodic array of colloids. …

Sol-Gel Derived Biodegradable And Bioactive Organic-Inorganic Hybrid Biomaterials For Bone Tissue Engineering, Bedilu A. Allo

Electronic Thesis and Dissertation Repository

Treatments of bone injuries and defects have been largely centered on replacing the lost bone with tissues of allogeneic or xenogeneic sources as well as synthetic bone substitutes, which in all lead to limited degree of structural and functional recovery. As a result, tissue engineering has emerged as a viable technology to regenerate the structures and therefore recover the functions of bone tissue rather than replacement alone. Hence, the current strategies of bone tissue engineering and regeneration rely on bioactive scaffolds to mimic the natural extracellular matrix (ECM) as templates onto which cells attach, multiply, migrate and function.

In this …