Digital Commons Network^™

Development Of Novel, Microscale Fracture Toughness Testing For Adhesives, Dillon S. Watring

FIU Electronic Theses and Dissertations

The purpose of this thesis was to develop microscale fracture toughness tests to be performed in situ based off previously used macroscale fracture toughness tests. The thesis also was to use these tests to perform in situ analysis and imaging of reinforced adhesives during crack propagation. Two different fracture toughness tests were developed for this thesis through developing fixtures and sample geometry. A microscale double cantilever beam (DCB) test was developed for mode I fracture (opening mode). A microscale end notch flexure (ENF) test was developed for mode II fracture (sliding mode).

Three different types of materials were used as …

Drawing And Twisting Of Graphene Fibers, Gregory T. Lane, Robert J. Sekerak, Isaias Diaz

Mechanical Engineering

The aim of this project was to develop a more automated process for drawing and twisting of graphene fibers than was currently in place. This was implemented by having two chemical baths with variable speed rollers at either end, and intermediate roller to spool fiber between stages, and a twisting cylinder with integral spool to twist the fiber as it is collected. The goal was to have this first iteration deliver a working prototype, however due to manufacturing delays and timing constraints, that will be missed. A second follow-on project would be able to continue the work presented here and …

The Effect Of Biocomposite Material In A Composite Structure Under Compression Loading, Benjamin Andrew Sweeney

Master's Theses

While composite structures exhibit exceptional strength and weight saving possibilities for engineering applications, sometimes their overall cost and/or material performance can limit their usage when compared to conventional structural materials. Meanwhile ‘biocomposites’, composite structures consisting of natural fibers (i.e. bamboo fibers), display higher cost efficiency and unique structural benefits such as ‘sustainability’. This analysis will determine if the integration of these two different types of composites are beneficial to the overall structure. Specifically, the structure will consist of a one internal bamboo veneer biocomposite ply; and two external carbon fiber weave composite plies surrounding the bamboo biocomposite. To acquire results …

Advances In Composite Manufacturing Of Helicopter Parts, Tobias A. Weber, Hans-Joachim K. Ruff-Stahl

International Journal of Aviation, Aeronautics, and Aerospace

This study investigates and compares different methods for improving standard autoclave composite manufacturing in order to find suitable approaches to a more efficient composite production. The goal is not only a reduction in manufacturing times and costs but also quality enhancement. Improved part quality while decreasing costs enables a manufacturer of composite parts to expand its market share, especially in the helicopter market, which has been constantly shrinking over the last two years. Various approaches such as improved tooling technology, the use of automated systems for lamination as well as outsourcing are examined to provide an overview of possible advancements …

Formula Sae Intake System, Esa Mahmood, Arman Sarwar, Michael R. Smith

Capstone Design Expo Posters

The Formula SAE Intake System is intended to optimize the airflow into a restricted 600cc engine. The intake system is designed, fabricated, and installed in accordance with the FSAE rule book with a focus on maximizing the vehicle’s acceleration. It is directly responsible for determining the drivability of the car and how much horsepower the flow restricted engine produces.

Design of the intake was conceptualized based on researching a number of factors including venturi diffusion angles, plenum volumes, and runner lengths. Initial tests were performed utilizing computational fluid dynamics for a total of 367 flow simulations and 261 running hours …

Flexural Creep Behavior Of Adhesively Bonded Metal And Composite Laminates, Hasan M. Nuwayer

Wayne State University Dissertations

Adhesively bonded structures exhibit time dependent behavior when subjected to constant load (creep). In this investigation, long-term creep behavior of adhesively bonded aluminum and carbon fiber composite beams under flexural loading was investigated. Three point bending test was selected because of its simplicity and the fact that bending stresses are quite common. In this study, two types of adhesively bonded beam specimens were tested: specimens prepared by adhesively bonding two aluminum beams and specimens prepared by adhesively bonding two unidirectional carbon fiber laminated beams. Accelerated creep tests were performed at higher temperatures up to 60 °C and deflection was measured …

Multiscale Modeling: Thermal Conductivity Of Graphene/Cycloaliphatic Epoxy Composites, Sorayot Chinkanjanarot

Dissertations, Master's Theses and Master's Reports

The thermal property of epoxy as the binder in the Carbon Fiber (CF) composites, especially thermal conductivity is important to achieve the advance technology and to improve the performance of materials. Multiscale modeling including molecular dynamic (MD) modeling and micromechanical modeling is used to study the properties of neat Cycloaliphatic Epoxies (CE) and Graphene nanoplatelet (GNP)/CE with and without covalent functionalization.

The thermal properties (glass-transition temperature, thermal expansion coefficient, and thermal conductivity) and mechanical properties of CE system are investigated by MD modeling using OPLS-All Atom force field. A unique crosslinking technique is developed to achieve the cured CE models …

Controllable Energy Absorption Of Double Sided Corrugated Tubes Under Axial Crushing, Hozhabr Mozafari, Shengmao Lin, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

To maximize the controllable energy absorption of corrugation troughs as observed in the single sided corrugated (SSC) tube, we proposed and tested a new structure design, i.e., double-sided corrugated (DSC) tube made of Al 6060-T6 aluminum alloy or CF1263 carbon/epoxy composite. Finite element models were developed to test the mechanical advantage of the DSC tube in comparison with both SSC and classical straight (S) tubes under axial crushing. Results have shown that the total absorbed energy of the DSC aluminum tube with 14 corrugations was 330% and 32% higher than that of the SSC tube with 14 corrugations and the …

Organic-Inorganic Graphite And Transition Metal Dichalcogenide Based Composites For 3d Printing, Jorge Alfredo Catalan Gonzalez

Open Access Theses & Dissertations

This project was multipronged to help fuse together topics of additive manufacturing and two-dimensional (2D) layered materials, and studying the mechanical and electrical properties of the composites produced. The composites are made from the thermoplastic polymer acting as a matrix and the graphite and 2D transition metal dichalcogenides (TMDs) serving as the filler or reinforcement. Different concentrations of TMD's were added to the matrix to study the effect of composition on the mechanical and electrical properties. To shed insights into the mechanical properties, test coupons were produced as "dog bone" structures for tensile testing using the ASTM D638 type 5 …

Non-Destructive Evaluation Of Composites: Predictive Ultrasonic Guided-Waves Modeling, Non-Destructive Material Characterization, And The Application To Aerospace Structures, Darun Barazanchy

Theses and Dissertations

To predict guided wave dispersion curves, it is common to use different solution approaches depending on the material type (isotropic or anisotropic) of the medium in which the wave propagates. The two different solution methods are defined in different domains, frequency-phase velocity domain for isotropic materials and wavenumber-phase velocity domain for anisotropic materials. This may lead to difficulties and unsatisfying results when predicting the dispersion curves for hybrid laminates which contain both isotropic and anisotropic materials. Therefore, a unified formulation defined in the wavenumber-phase velocity domain to accomodate both isotropic and anisotropic materials, as well as hybrid combinations, is desired. …

Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa

Masters Theses

"Benefits of a functionally graded core increasing wrinkling stability of sandwich panels have been demonstrated in a recent paper [1] where a several-fold increase in the wrinkling stress was observed, without a significant weight penalty, using a stiffer core adjacent to the facings. In the present paper wrinkling is analyzed in case where the facings are subject to biaxial compression and/or in-plane shear loading and the core is arbitrary graded through-the-thickness. Two issues addressed are the effect of biaxial or in-plane shear loads on wrinkling stability of panels with both graded and ungraded core and the verification that functional grading …