Digital Commons Network^™

Predictive Models For Mechanistic Cutting Force Coefficients And Surface Roughness In Carbon Fiber Reinforced Polymers Milling With Tool Wear, Junbeom Son

Masters Theses

Machining carbon fiber composite materials poses significant challenges including rapid tool wear and decreased productivity. This research aims to address these challenges by developing a predictive model for surface roughness in carbon fiber composite milling operations using a cutting force-based approach.

This research applies a mechanistic cutting force model to force prediction in carbon fiber composite milling. Because tool wear can be significant in this application, the force model coefficients are defined as a function of the volume of material removed. This enables the cutting force growth with tool wear to be embedded within the model. Examples are provided for …

Damage Control Measures In Composites: Focus On Damage Tolerance Of Aerospace Structures, Kais Jribi

Doctoral Dissertations and Master's Theses

Barely Visible Impact Damage (BVID) in composite materials presents a stealthy yet significant risk to structural integrity, particularly challenging due to its elusive nature. The approach adopted here diverges from traditional methodologies, focusing on the novel application of Digital Image Correlation (DIC) to map surface area changes during in-situ Compression After Impact (CAI) tests. This technique allows for an in-depth analysis of planar strains along the x and y axes, shedding light on the material's behavior under stress.

A pivotal advancement lies in developing a method for precisely identifying when BVID-induced delamination recommences. By meticulously analyzing strain pattern deviations along …

The Effect Of Through Thickness Reinforcement Angle On The Disbonding Behavior In Skin-Stringer Configuration, Christopher John Morris

Mechanical & Aerospace Engineering Theses & Dissertations

Post-cure through thickness reinforcement is a method used to increase the mechanical properties of composite laminates in the transverse direction. This study conducted a test on skin-stringer structures bonded together in three configurations using an epoxy or thermoplastic adhesive at the interface with reinforcing pins inserted through the laminate thickness located at the edge of the stringer at differing angles between -30º and 30º. The fabrication of these samples in configurations B and C consisted of the use of carbon fiber prepeg laminate at a ply orientation of [0₂90₂]_2s for the skin and [0 90] …

Interfacial Thermomechanical Behavior Of Hybrid Carbon Fibers, Sriraj Srihari

Doctoral Dissertations and Master's Theses

The carbon fiber/epoxy interface is of great importance in composite design due to its load transfer mechanisms from the weak epoxy to the stronger fiber. Improving the strength of the interface reduces the risk of failure at the interface and improves the load transfer to the fiber. In this study, two types of nano-species ZnO nanowires and nickel-based metal organic frameworks were grown on carbon fibers to improve the interfaces. The interfacial mechanics of the enhanced fibers are evaluated using nanoindentation studies. Composite samples with Aeropoxy matrix and vertically aligned fibers are fabricated for this purpose. A Bruker TI-980 TriboIndenter …

Studies Of Damage Tolerance In Automated Fiber Placement Based Heterogeneous Meso-Architectured Carbon/ Epoxy Composite Laminates., Karan Kodagali

Theses and Dissertations

Traditional unidirectional (UD) carbon fiber-reinforced polymer matrix composites manufactured via automated fiber placement (AFP) are widely used in aerospace structures. While heterogeneous at the micro-scale, these materials are homogeneous at the meso-scale (ply-scale). The major limitation is its limited toughness, poor damage tolerance/impact resistance capability and the inability to sufficiently redistribute stresses, resulting in strength-toughness tradeoffs, making them susceptible to impact damage. From previous studies, there is an understanding that fiber architecture has a first order effect on the damage tolerance. Introducing new discontinuous/heterogeneous meso-scale architectures, through an optimal merger of material and structure, can result in unprecedented property improvements …

Investigation Of Fatigue Response With Analytical And Machine Learning Models And Hygroscopic Analysis Of Asymmetric Bistable Cfrp Composites, Shoab Ahmed Chowdhury

All Dissertations

Asymmetric bistable carbon fibre reinforced plastic (CFRP) composites enable a broad range of applications as they can sustain multiple stable configurations and have small snap-through load requirements. These unique features, coupled with their light strength-to-weight and stiffness-to-weight ratios, have made them preferred options for multifunctional systems. This study investigates the fatigue and hygroscopic response of 2-ply, [0/90] bistable CFRP laminates and proposes predictive modeling approaches for improved performance.

While previous studies widely researched and documented the fatigue of general composites in axial loading, fatigue analysis of asymmetric bistable composites in the out-of-plane snap-through direction is inadequate. This study performs fatigue …

Chemical And Physical Interaction Mechanisms And Multifunctional Properties Of Plant Based Graphene In Carbon Fiber Epoxy Composites, Daniel W. Mulqueen

Mechanical & Aerospace Engineering Theses & Dissertations

Graphene has generated substantial interest as a filler due to its exceptional strength, flexibility, and conductivity but faces obstacles in supply and implementation. A renewable, plant-based graphene nanoparticle (pGNP) presents a more accessible and sustainable filler with the same properties as mineral graphenes. In this study, the mechanisms of graphene reinforcement in carbon fiber reinforced plastic (CFRP) were examined, along with the resulting improvements to mechanical strength, resistance to crack propagation, electrical and thermal conductivity at elevated temperatures. pGNP, produced from renewable biomass, was shown to have a graphitic structure with flakes 3-10 layers thick and a median lateral size …

Composite And Polymer Formulation Employing Sulfur And Bio-Olefin Feedstocks, Claudia V. Lopez

All Dissertations

Environmental sustainability represents a challenge for society since industrial growth has a direct impact on natural resources and waste production. New technologies that effectively incorporate waste into renewable resources are critical to the development of a sustainable and circular economy. The manufacturing of structural materials like Portland cement (OPC) is responsible for >8% of the global anthropogenic emissions of carbon dioxide, with ~ 1 kg of CO₂ released to the atmosphere for every kilogram of OPC produced. For instance, the development of sustainable structural materials is a key factor to reduce the greenhouse emissions and to attenuate the climate …

Northrop Grumman Collaboration Project, Nikkia Psomas-Sheridan, Santiago Robles, Ben Elkayam, Benjamin Ulfhake

Mechanical Engineering

The Northrop Grumman Collaboration Project (NGCP) is a collaborative club project sponsored by Northrop Grumman for the students of Cal Poly San Luis Obispo (CPSLO) and Cal Poly Pomona (CPP) to create a fleet of vehicles to aid in the simulated rescue of stranded hiker. The CPSLO club is responsible for delivering an autonomous flight vehicle that can suppress a fire and retrieve a payload. Mechanical Design Team of the CPSLO team was responsible for the design of the frame, electronics housing, and payload and fire suppression systems.

Development Of An Affordable Hybrid Golf Shaft Using Sustainable Materials, Kenyon Pelletier

Honors Theses

As with many industries, technology is improving in the golf world, but sacrifices made to improve performance have resulted in polluting materials and manufacturing processes. These cutting-edge designs support the specifications and playing abilities of a small professional minority while exceeding the needs of much of the golf community. To minimize the emissions created through golf shaft manufacturing, it was hypothesized that the needs of the amateur player could still be satisfied through a less capable yet more sustainable material. Research on and eventual introduction of these materials into commercial golf shafts will significantly improve the sustainability of the sport. …

The Modernization Of Large Power Transformer Tanks, Babajide O. Williams

Electronic Theses and Dissertations

Due to the current demands placed on the power grid in terms of climate change, increasing urbanization, and terrorist attacks, the U.S. government in response to these demands, mandated that all the grid components be modernized in order to increase their reliability. As a critical component of the grid, Large Power Transformers (LPTs) play a key role in ensuring sustainable power generation and distribution. A literature search performed in this work and the analysis of data retrieved from the search showed that the tanks of these LPTs are critical to their durability, longevity, and reliability. Therefore, the reliability of LPTs …

Study Of A Carbon Fiber Reinforced Polymer Composite Using A Biobased Polyurethane As A Thermosetting Resin, Teddy Mageto

Electronic Theses & Dissertations

Carbon Fiber Reinforced Polymer composites (CFRP) have garnered increasing interest in recent years especially in the aerospace and automobile industries where they are gradually replacing metals as structural materials. This is owing to their light weight, high strength, high modulus, and excellent strength-to-weight ratio. Polymers are typically used as thermosetting resins in these composites. However, the synthesis of polymers currently is conducted via petrochemical processes which leads to adverse effects on the environment. To this end, in this work a biobased Polyurethane (PU) was used as a thermosetting resin in a CFRP. The biobased PU was synthesized by the reaction …

A Predictive Analysis Of The Influence Of Thickness And Length On The Curvature Of Square Bistable Carbon Fiber Reinforced Composite Laminates, Stephan Terry

All Theses

This thesis presents a predictive analysis of the stability of square bistable carbon fiber reinforced composite laminates under various loading conditions. The stability of these laminates is essential to their performance and longevity and is influenced by factors such as thickness and length. Analytical and numerical techniques are used to model the behavior of these laminates, and experimental tests are conducted to validate the models. The findings of this research have implications for the design and optimization of square bistable carbon fiber reinforced composites.

The study investigates the relationships between the side length and thickness of square laminates for bistability. …

Fusion Bonding Behavior Of 3d Printed Pa6/Cf Composites Via Post Fabrication Compaction, Gonzalo Fernandez Mediavilla

Mechanical & Aerospace Engineering Theses & Dissertations

Additive manufacturing (AM) is becoming a robust production technology for aerospace, healthcare, and construction industries among others. Fused Deposition Modelling (FDM) is one of the methods most used to 3D print products. FDM has limitation due to interlayer adhesion and restriction imposed by the printing direction. Specially with AM composites, as reinforced nylon PA6 with short fibers, parts show more strength along the direction of the filament due to the alignment of the carbon fibers, but weaker in other directions. The proposed method to solve this issue is to print parts separately and join them together by fusion bonding. PA6/CF …

Dispersion Study Of Metal-Organic Frameworks And Synthesis Of Mof-High-Density Polyethylene Fibers, Sathvika Gondi

Material Science and Engineering Theses

Metal-Organic Frameworks (MOFs) are a highly versatile class of materials with a wide range of potential applications in gas storage, separation, catalysis, drug delivery, and sensing. The ability to tailor the properties and functionalities of MOFs by varying the organic linkers and inorganic nodes makes them highly attractive for a wide range of applications. The unique properties of MOFs also make them promising materials for fundamental studies in materials science and chemistry. The current investigation focuses on the dispersion study of MOFs and the synthesis of MOF-Polymer composites. The dispersions of MOFs in various organic solvents like ethanol, isopropanol, tetrahydrofuran, …

Fatigue Performance Modeling In Advanced Out-Of-Autoclave Composites For Aerospace Applications, Grayson Reid Curry

Mechanical and Aerospace Engineering Theses

Increased application of composite materials in the military and civil applications renewed the interest to development of high-fidelity methodologies for predicting their performance characteristics. Besides the traditional autoclave processed structural composites such as IM7/8552 and IM7/977-3 widely used on various platforms, novel materials such IM7/5320-1 suitable for Out-of-Autoclave (OoA) cure became of interest. Static and fatigue performance prediction of Open-Hole quasi-isotropic laminates made from IM7/5320-1 was performed in this work by using the Finite Element Analysis software BSAM. Progressive failure simulation including delaminations, matrix cracks and fiber failure was performed. Regularized eXtended Finite Element Methods (RXFEM) was used for mesh …

Effects Of Metal Organic Frameworks In Polyether Block Amide Elastomer, Joe Alex

Mechanical and Aerospace Engineering Theses

Metal-organic frameworks (MOFs) are highly porous materials that find extensive applications in gas absorption and separation in recent years. These hybrid materials can be designed with specific pore sizes and voids to selectively filter gases. PEBAX (MV 1074) is a commercially available polyether block amide copolymer generally used in gas separation applications. In this study, we characterize two different MOFs by means of a dispersion study and create a medium for them to be evenly dispersed into the aforementioned copolymer matrix. Polymer composite fibers are extruded using a twin-screw extruder and a winding unit at pre-determined parameters for winding speed …

Shape Memory Polymer-Based Multifunctional Syntactic Foams, Siavash Sarrafan

LSU Doctoral Dissertations

With the increase in popularity of shape memory polymers (SMPs), especially in applications such as aerospace, textile, biomedical engineering, and even structures, the weight of the material and the devices made with it has always been a crucial factor. Using the shape memory polymer as a matrix to make a syntactic foam is one of the best and most affordable approaches to creating a lighter material that still has the shape memory effect. The addition of particles of different stiffness, strength, and size, with variable fractions, creates a composite that enables engineering the mechanical, as well as other physical and …

Evaluations Of Frp Composite Coupons Under Impact And Puncture, Lekhnath Bhandari

Graduate Theses, Dissertations, and Problem Reports

Evaluations of FRP Composite Coupons Under Impact and Puncture

Lekhnath Bhandari

Railroad tank cars are the main mode of transportation for carrying flammable liquids and other hazardous materials, in any mode of ground transportation system. These tank cars, if punctured during derailments may explode releasing large amounts of hazardous materials and posing serious threats to human life and leading to economic losses. To minimize such catastrophes, in 2015, United States Department of Transportation (USDOT) proposed to improve the thermal and puncture performances of these tank cars and introduced two new design specifications: DOT-117 and DOT-117R. Tank cars with 9/16 inches …

Study Of The Processing-Structure-Property Relationship In Recycled Thermoplastic Composites, Carlos Gerardo Angulo Ruiz

All ETDs from UAB

The quest for sustainable materials and manufacturing techniques has spurred research into distinct composite materials that utilizes recycled thermoplastics in combination with natural hemp fibers and recycled carbon fibers. This dissertation delves into the processing of recycled high-density polyethylene (rHDPE) with hemp fiber and separately, with recycled carbon fiber (rCF), scrutinizing their suitability as environmentally friendly and economically viable materials. The study focuses on distinct processing methods used for hemp fiber and recycled carbon fiber: compression molding with hemp mats as well as extrusion compression molding, additive manufacturing, and injection molding for recycled carbon fiber, while the recycled carbon fiber …

Investigation Of Manufacturing Techniques For Magnetorheological Elastomers To Expand Feasibility In A Diverse Array Of Applications, Austin S. Robbins

Electronic Theses and Dissertations

Magnetorheological elastomers, or MREs, are smart composite materials with controllable physical and mechanical properties when introduced to an external stimulus of a magnetic field. The controllability of these properties is highly tunable by the selection of the elastomeric matrix, concentration of magnetically permeable particles, introduction of additives, and the alignment of the constituents during the curing process. The fabrication of MREs typically calls for a mold that is filled with an MRE mixture to create the final desired geometry after curing. These molds are frequently placed under a magnetic field which orients the micron sized magnetic particles along the magnetic …

Anisotropic Material Behavior Of 3d Printed Fiber Composites, Jordan Garcia

Theses and Dissertations--Mechanical Engineering

Literature has shown that 3D printed composites may have highly anisotropic mechanical properties due to variation in microstructure as a result of filament deposition process. Laminate composite theory, which is already used for composite products, has been proposed as an effective method for quantifying these mechanical characteristics. Starting with the analysis of comparing the printing orientation of premanufactured carbon fiber reinforced filament, the mechanical properties of 3D printed objects were examined. The mechanical properties changed not only as a result of machine choice, but how the sample is oriented along the printing bed. The analysis continued with looking at the …

Northrop Grumman Collaboration Project, Nikkia Rae Psomas-Sheridan, Santiago Robles, Ben Elkayam, Benjamin Ulfhake

Mechanical Engineering

The Northrop Grumman Collaboration Project (NGCP) is a collaborative club project sponsored by Northrop Grumman for the students of Cal Poly San Luis Obispo (CPSLO) and Cal Poly Pomona (CPP) to create a fleet of vehicles to aid in the simulated rescue of stranded hiker. The CPSLO club is responsible for delivering an autonomous flight vehicle that can suppress a fire and retrieve a payload. Mechanical Design Team of the CPSLO team was responsible for the design of the frame, electronics housing, and payload and fire suppression systems.

Surface Preparation Study, Ryan Ferguson

Williams Honors College, Honors Research Projects

This work explores a custom air atmospheric pressure plasma treatment (APPT) machine’s effectiveness in cleaning and chemically activating a CFRP surface. It is explore by implementing water contact angle (WCA) measurements, water-break free (WBF) testing, and adhesive tubular lap-joint (TLJ) tensile testing. An 8x3 test matrix of different machine parameters is defined with the bounding conditions being the machine’s capabilities and industry standard recommendations. Each configuration of the test matrix is explored after treatment at multiple time intervals up to 2 weeks afterwards to gain insight into the outlife of the treatments with the intention of adhesively bonding to the …

High-Temperature Thermal, Tribological And Mechanical Properties Of High-Entropy Alloys And Alloys Composites, Tri D. Vo

University of Wollongong Thesis Collection 2017+

The discovery of High-Entropy Alloys (HEAs) has been a significant development in the field of Materials Science. In 2004, Cantor introduced the concept of single solid solution alloys containing several elements in equal or near equal proportions. The concept was also introduced by Yeh and co-workers, who coined the term ‘HEA’. This challenged conventional thinking about how alloys could be designed and opened up new possibilities for creating materials with unique properties. In 2014, Yiping Lu and his team proposed the concept of dual-phase eutectic HEAs, which has enabled the development of improved HEAs with both high strength and high …

Fabrication, Characterization, And Simulation Of Graphene-Copper Electrical Conductors, Raju Prasad Ghimire

Nanoscience and Microsystems ETDs

The addition of nanocarbons to copper (Cu), specifically in the form of graphene (GN), has been shown to enhance copper's properties. GN-Cu nanocomposites can potentially achieve higher electrical, mechanical, and thermal properties compared with copper. These characteristics make GN-Cu materials interesting for several applications including but not limited to interconnects, high voltage lines, and rotating machines. Copper’s microstructure and nanoscale interfacial phenomena between the GN and Cu control charge conduction in GN-Cu materials. In this work, we investigated the possibilities of conductivity enhancement in multi-layered GN-Cu composites both theoretically (classical, quantum, and atomistic models) and experimentally.

Additionally, our work elucidates …

Direct Ink Write And Thermomechanical Characterization Of Thermoset Composites, Sergio Dante Favela

Open Access Theses & Dissertations

This research will be divided into two sections. The first section discusses direct ink writing and thermomechanical characterization for thermoset composites. The thermoset ink is prepared with fillers aiding the printing process by modifying the rheology of the ink and geometry retention by allowing for the part to have an initial UV cure step. Three specimen formulations with different weight percentages were printed by material extrusion in the shape of tensile specimens following ASTM standard D638 to characterize the mechanical properties at room temperature, 100â?? and 200â??. Furthermore, the ink resin was characterized through DSC, TGA, and rheology testing. The …

Effects Of Graphene In High-Density Polyethylene Microfibers, Ashish Lal Sivadas Anilal

Material Science and Engineering Theses

High-Density Polyethylene uniquely can induce banded spherulites as it is crystallized from its melt. We studied the effects of graphene in the crystallography of banded HDPE by examining parameters such as the extent of twisting, spherulitic growth, and nucleation density. The application of graphene as a multifunctional filler in polymer matrices is a great topic of interest because graphene at low concentrations can bring many improvements in mechanical, electrical, and thermal properties. We synthesized graphene oxide by chemical oxidation of graphite and further studied its effects in the twisted crystallography of HDPE. Three batches of fibers were extruded: two batches …

Towards Modeling Of Induction Welding Of Thermoplastic Laminates With A Mixed Finite Element Boundary Element Approach, Florentius Johannes Van Zanten

Theses and Dissertations

There is an increased interest in induction welding of carbon fiber reinforced thermoplastic composite laminates within the aerospace industry. Currently, optimal manufacturing process parameters (e.g., current, power, and frequency settings, coil movement speed, etc.) are determined through an experimental trial-and-error approach. To reduce the need for an experimental approach that can determine the manufacturing process parameters, which would be expensive in both time and money, accurate and computationally efficient numerical tools are desired. This research is focused on improving the existing numerical tool, WelDone, in regard to its speed and accuracy.

WelDone utilizes a hybrid element formulation that combines traditional …

Contact Dewatering Of Cellulose Nanofibers For Biopolymer Composite Applications, Alexander Collins

Electronic Theses and Dissertations

Cellulose Nanofibrils (CNFs) are promising materials for reinforcement of polymer matrices attributable to their impressive physical and mechanical properties, as well as their biodegradability. However, the utilization of these materials in composites is made challenging by the water content of CNF slurries, the tendency of CNFs to agglomerate as they dry, and incompatibility between hydrophilic CNFs and hydrophobic polymer matrices. The most commercially viable drying methods to produce small-scale dry CNFs, such as spray drying, are very energy intensive, can only dry the materials down to micron-scale agglomerates, and do not preserve fibrillar aspect ratios. “Contact dewatering,” or the removal …