Mechanical Engineering Commons^™

A Cfd-Dem Framework For Characterizing Nanoparticle Adhesion Effects On Creeping-Flow Permeability In Composite Manufacturing, Gavin Stoker

All Graduate Theses and Dissertations, Fall 2023 to Present

Modern aircraft, spacecraft, and high-performance vehicles are increasingly built from composite materials, engineered combinations of plastics and fibers that are lighter and stronger than traditional metals. Researchers are now pushing these materials further by mixing in microscopic particles thousands of times smaller than a human hair, called nanoparticles, to make them even tougher and more resistant to damage. The challenge is getting those nanoparticles distributed evenly. During manufacturing, liquid plastic resin is pumped through a network of tightly packed fibers, carrying the nanoparticles along with it. But nanoparticles tend to clump together and stick to surfaces as they travel, clogging …

Composite Carrier, Thomas W. Clarke, Kaden T. Guevarra, D'Anna M. Jennings, John F. Tomas

Mechanical Engineering

The Composite Carrier project developed and tested a proof-of-concept system to improve safety and accessibility in the Cal Poly Composites Lab. The system enables users to retrieve composite material rolls from elevated storage racks without using ladders, reducing fall hazards and improving material handling. The final design integrates rack-mounted rotary latches, a ground-level pulley release mechanism, and a custom Genie dolly attachment with a foldable cradle. Verification testing demonstrated that the prototype could securely retain representative roll loads, support repeated retrieval and placement, and improve operator safety, while also identifying future refinements such as reducing attachment width for improved rack …

Aerodynamic Design And Structural Evaluation Of A Global Minimum Torque Inspired Multirotor Propeller, Zeke Bukovansky

Master's Theses

This thesis develops a repeatable design, CAD, aerodynamic postprocessing, structural screening, and manufacturing feasibility workflow for a 22-inch global minimum torque inspired multirotor propeller. Matched MIL and GMT geometries were compared at a 35 N, 4000 rpm static-hover operating condition using BEMT/XFOIL aerodynamic postprocessing, with diameter, blade count, chord distribution, airfoil schedule, and target thrust held constant. The final modeled comparison predicted a modest 1.5% reduction in torque and shaft power for the GMT case while maintaining the same thrust target. CAD construction, MATLAB reduced-order beam model, Abaqus screening, and manufacturing planning were used to identify geometry level structural and …

Effect Of Environmental Conditions On Fracture Of Composite Materials And Thin Films, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Environmental conditions, i.e., temperature and moisture, affect mechanical properties of materials, including composites. In this paper, we concentrate on one of the aspects of the effect of environment on fracture in a composite lamina. The paper demonstrates an analytical approach to account for the effect of the changes in environment on the strain energy release rate of composite materials and thin films. These analytically determined strain energy release rates should be compared to fracture toughness to predict the susceptibility of the material to fracture. Numerical examples are presented for several polymeric and metal matrix composites using available experimental data for …

Enhancing Nasa Sounding Rocket Capabilities Through Composite Material Adoption, Robert Burth

Mechanical & Aerospace Engineering Theses & Dissertations

Sounding rockets are a suborbital research platform employed by NASA for heliophysics, astrophysics, geospace science investigations, and for technology development. They follow semi-parabolic trajectories and are launched using surplus military, and commercial, solid-propellant rocket motors. NASA sounding rocket payloads are comprised of standard, modular subassemblies, designed to perform specific functions critical to achieving specific mission success criteria.

Since the program’s inception, payload length and mass have trended upwards, limiting the capability of the platform to reach exospheric apogees and decreasing the time above critical altitudes to observe solar and celestial targets. To offset this trend, composite materials may be of …

Manufacturing And Material Property Verification Of Short Fiber Particle Reinforced Composites, Megan Elise Howell

Graduate Theses - Mechanical Engineering

This thesis investigates the manufacturing, testing, and material property verification of short fiber and particle reinforced polymer composites intended for use in flywheel energy storage systems. Composite tensile specimens were fabricated using controlled mold geometries and autoclave-assisted curing to improve consolidation quality and reduce void content. Short carbon fibers and particulate reinforcements were selected to balance mechanical performance, manufacturability, and isotropy for high-speed rotor applications. Tensile testing was performed using a tensile testing machine, and machine compliance effects were quantified and removed to obtain accurate elastic moduli. Experimental results were compared against analytical micromechanics predictions to evaluate stiffness trends and …

Numerical And Machine Learning Based Recreation Of Damage Morphologies Of Barely Visible Impact Damage, Oscar A. Valdez

Mechanical and Aerospace Engineering Dissertations

Composite laminates are highly sought after in the aerospace industry as they provide strength without dramatically increasing the weight of manufactured structures. However, composite laminates are susceptible to barely visible impact damage caused by routine activities. This type of damage can easily go unnoticed while significantly reducing the load-carrying capability of the laminate. Current non-destructive evaluation techniques, such as ultrasonic scanning, can reveal the damage footprint but provide no insight into delamination through-the-thickness due to the shadowing effect. Micro-computed tomography offers ply-by-ply damage resolution but is unsuitable for field inspections and is constrained by specimen size. This study aims to …

Detecting And Repairing Conflicting Constraints In Co-Trained Physics-Informed Neural Networks For Composite Curing Processes, Cooper J. Evans

Dissertations, Master's Theses and Master's Reports

Composite materials have become a critical component of modern manufacturing, especially in the automotive and aerospace industries. The curing process for these composites has been modeled using a variety of partial differential equations representing the heat transfer and composite curing kinetics. Optimizing the applied temperature profile is critical for maximizing the efficiency and capacity of composite part manufacturers. Constraints must be placed on the inputs and outputs of the model, including but not limited to, the applied temperature profile, part temperature, and final degree of cure. Conflicting sets of constraints are easy to unknowingly impose due to the highly coupled …

Manufacturing And Performance Evaluation Of Carbon/Epoxy Laminated Composites Cured Using Single- And Six-Magnetron Microwave Applications, Nayan Pundhir

Doctoral Dissertations

Microwave curing is fast, energy-efficient, and a viable alternative to conventional thermal curing processes. It has been widely adopted for processing carbon fiber-reinforced polymer (CFRP) composites because the high electrical conductivity of carbon fibers enables strong microwave coupling, leading to rapid volumetric heating and reduced energy consumption. The aim of this study is to investigate the use of microwave curing for manufacturing CFRP composites. IM7/Cycom 5320-1 unidirectional prepreg was utilized to fabricate laminated composites in two thickness ranges: 16-layer laminates (2.5 mm thickness) and 64-layer laminates (9.2 mm thickness). Two lay-up configurations were examined: symmetric cross-ply and quasi-isotropic. Different curing …

Cold Spray On Fiber Reinforced Polymer Substrates For Composite Repair And Tooling Applications, Patrick Allen Bailey

Theses and Dissertations

Cold Spray technology was first developed in the 1980’s and is an additive manufacturing and repair technique. It works by heating a pressurized carrier gas upwards of 600 °C and inserting metal particles downstream such that when they impact a substrate, the energy transformation causes plastic deformation of the particles. This thesis presents a use case for metal and polymer CS powder on fiber reinforced and fused filament fabrication polymer substrates. The state of the art for CS discusses the most up-to-date research within the field, and where new investigations are required. This research investigates the required process parameters to …

Impact Of Composite Materials Research On Underrepresented Communities, Neil Mahesh Bedagkar, Ramanan Sritharan, Wyatt Barnes

Mechanical Engineering

This research assesses how advancements in composites material research affect communities from lower socioeconomic backgrounds, using a dual track strategy to quantitatively and qualitatively examine their impact. A keyword-based classification algorithm was applied to a sample of research papers from ScienceDirect spanning the last 24 years to quantify which engineering industries benefit most from this research. The findings indicate that the construction industry benefits the most, followed by the automotive, defense, renewable energy, and biomedical sectors. A broader qualitative analysis of the social implications of these industries was also conducted to provide context. Each sector were found to have either …

Application Of Polymer Nanocomposites In The Design Of Prosthetic Sockets That Feature Auxetic Meta-Structures, Sumit Suryakant Kolte, Vinayak Vijayan, Lihua Lou

Publications

This research evaluates the response of prosthetic sockets constructed using polymer nanocomposites and incorporating auxetic meta-structures. The prosthetic sockets feature lightweight meta-structures between the inner and outer walls of the socket. Three different prosthetic designs featuring chiral, reentrant hexagon, and honeycomb meta-structures are evaluated in this study. The prosthetic sockets were designed in SolidWorks and compared using finite element analysis. The polymer nanocomposites used in this study include polypropylene and ultra-high molecular weight polyethylene containing uniformly distributed inclusions of either titanium dioxide, zinc oxide, or graphene nanoplatelets. Our results show a favorable pressure profile at the interface between the prosthetic …

Engineering Of Metallic Interpenetrating Phase Composites For The Control Of Deformation And Failure Modes During Dynamic Events, David Kiyoshi Santacruz

Open Access Theses & Dissertations

Aerospace components, automotive structures, and ballistics armor are all engineered to withstand high strain rate service events through a combination of material selection and design choices. However, structural components may be less effective when their implementation is constrained by other factors such as weight or design limitations. To meet these challenges, the development of next-generation materials will need to increasingly rely on composite material systems rather than monolithic materials. This thesis presents the fabrication, dynamic characterization testing, and post-mortem analysis of 316L/A356 interpenetrating phase composites (IPCs) made from the PrintCasting methodology. These composites consist of additively manufactured 316L stainless steel …

Development And Tribological Characterization Of Uhmwpe-Tin Composite Coatings Deposited By Electrostatic Spraying, Jarrod Keith Perez

Theses and Dissertations

The increasing demand for inert, wear-resistant, cost-efficient, environmentally friendly, and low-friction coatings has driven extensive research into polymer-based solutions. Among these, ultra-high-molecular-weight polyethylene (UHMWPE) has emerged as a strong candidate due to its low density, anticorrosion properties, self-lubricating nature, affordability, and ease of processing. However, its low load-bearing capacity limits its widespread use in high-stress tribological applications. To overcome this limitation, this project investigates the development and characterization of UHMWPE composite coatings reinforced with titanium nitride (TiN) particles at varying concentrations (2.5, 5, and 10 wt%) to enhance their mechanical properties and wear resistance.

Exploring New Applications Of Municipal Solid Waste, Harrison Appiah, Ezra Bar Ziv, Jordan L. Klinger, Armando G. Mcdonald

Michigan Tech Publications

This study aimed to (i) characterize municipal solid waste (MSW) sourced from Utah and Michigan transfer stations and (ii) upcycle, produce, and evaluate composites derived from this MSW. Composition analysis showed that the MSW was composed of a variety of commodity plastics, paper/cardboard, and inorganic materials. Detailed chemical analysis for lignin, cellulose, hemicellulose, and lipids was performed. The plastics identified were mainly polyethylene, polypropylene, polystyrene, and poly (ethylene terephthalate). The compoundability of the MSW was assessed by torque rheometry. Composites were prepared by compounding the MSW in an extruder. A composite flexural strength of 29 MPa and a modulus of …

Characterization Of Cure And Temperature Dependent Properties Of Filament Wound Composite Structures, Aaron Riley Sinkler

Mechanical & Aerospace Engineering Theses & Dissertations

Residual stress development in filament wound composites presents a critical challenge for the fabrication of thick composite structures exposed to elevated temperatures during operation. This study focused on determining temperature and cure dependent material properties to aid in understanding the residual stress build-up during the cure. Material characterization of a filament wound composite materials was performed by investigating thermo-chemical shrinkages in resin, lamina, and bi-lamina configurations. The coefficient of thermal expansion (CTE) of both the neat resin and the fiber was measured, and the gel point and chemical shrinkage of the neat resin were investigated. A filament wound unidirectional laminate …

Biobased Acrylate Composites With Enhanced Strength For Additive Manufacturing, Nicole Wagner, Joseph Mcwherter

Engineering Faculty Articles and Research

With the expanding use of polymers in additive manufacturing, sustainable resins for use in vat photopolymerization are required to reduce their environmental impact. One promising approach to achieve this is to incorporate biobased fillers that replace the acrylates in photopolymer resins as ‘green’ alternatives. In this study, photopolymer composites consisting of a methacrylate resin with varying calcium carbonate powder content between 0 and 50 wt.% were investigated. A digital light processing technique was used to fabricate tensile test specimens for mechanical testing. Good printability, dimensional accuracy, and good interlayer adhesion were observed for composite resin formulations that incorporated calcium carbonate …

Application-Driven Materials Development Of Solid-State Conductive Composites Of Ultra-High Molecular Weight Polyethylene, Peder Solberg

Dartmouth College Ph.D Dissertations

Ultra-high molecular weight polyethylene (UHMWPE) is a linear long chain homopolymer valued for its toughness, wear resistance, and chemical inertness. In the medical field, these properties make it the material of choice for bearing surfaces despite recognized tradeoffs between wear resistance, toughness, and oxidation resistance. Electrically conductive composites of UHMWPE show promise to enable new types of smart and active load-bearing implants in a future of personalized medicine, if beneficial properties can be maintained with the addition of solid-state additives.

Clinical need-finding conducted through Dartmouth’s Training Program in Surgical Innovation revealed several potential applications for conductive, load-bearing polymers. These include: …

Degradation Of Polymers And Polymer Composites In Extreme Environments, Ben T. Jewell

Dissertations, Master's Theses and Master's Reports

Polymeric materials are widely used in engineering applications due to their high strength-to-weight ratio, easy manufacturability, and cost-effectiveness. When incorporated into composites, they provide further performance enhancements, enabling use in demanding structural applications. However, long-term exposure to harsh environments including elevated temperatures, UV radiation, harsh chemicals, and radiation, can drive degradation processes that alter the material’s network structure, and in turn, degrade its mechanical performance. Exposure to thermo-oxidative conditions is one of the most common environments driving polymer degradation, leading to chain scission and crosslinking events, with the resulting oxidative products causing discoloration, reduced ductility, and changes in glass transition …

Evaluation Of Impact Energy In Composites Using Acoustic Emission Sensing Technique, Li Ai, Tanner Mesaric, Sydney Flowers, Sydney Houck, Joshua Widawsky, Paul Ziehl

Faculty Publications

A major challenge faced by composite materials is impact, which can result in unexpected damage and degradation. Impact events can cause significant structural damage that may not be immediately visible, leading to a reduction in the material’s mechanical properties and overall performance. This paper presents an impact assessment method using acoustic emission (AE) sensing technology. The primary goal of this approach is to determine the extent of impact damage on composite components by analyzing AE signals produced under operating stress conditions. An advanced algorithm is proposed to predict the probability that the damage falls into various damage categories, providing a …

Finite Element Analysis And Verification Of Transverse Mechanical Properties Of Generally Cylindrical Orthotropic Constitutive Modeling Of 3-Phase Nanocomposite Unit Cell, Christopher J. Hawkins

Master's Theses

Fiber-reinforced composites are increasingly popular due to their specific strength and stiffness, making them ideal for high-performance applications. However, these materials primarily exhibit superior properties in-plane, while their out-of-plane characteristics remain comparatively weaker. Previous research has shown that the most effective method to enhance out-of-plane properties involves the incorporation of carbon nanotubes. Experimental tests have demonstrated significant improvements in properties such as tension, flexural, short beam shear, and fracture toughness. Alongside these experimental studies, analytical equations have been developed to predict the behavior of these composites under various loading conditions, including tension, bending, shear, and fracture. Existing models primarily address …

Multiscale Analysis Of Thermal Barrier Coated Cfrp Composites Under Thermal Loading, Devin Nielsen, Trenton M. Ricks, Juhyeong Lee

Mechanical and Aerospace Engineering Student Publications and Presentations

Carbon-fiber reinforced polymer (CFRP) composites are commonly used in high performance applications. Although offering several advantages (i.e., superior specific properties and improved structural rigidity), traditional CFRP composites often exhibit poor thermal stability due to a low matrix thermal decomposition temperature. The effective operating temperature of the CFRP composites can be raised by applying an outermost, protective thermal barrier coating (TBC) layer. Prefabricated high void content ceramic TBCs are ideal for composite applications due to their high thermal stability and relatively low thermal conductivity. In this paper, the thermo-mechanical response of the TBCCFRP composite laminate subjected to 500°C are assessed through …

Critical Comparison Of Potential Machine Learning Methods For Lightning Thermal Damage Assessment Of Composite Laminates, Juhyeong Lee, Scott L.J. Millen, Xiaodong Xu

Mechanical and Aerospace Engineering Faculty Publications

The present study assesses the potential of using machine learning (ML) methods to predict the extent of lightning thermal damage in fiber-reinforced composite laminates using three supervised machine learning (SML) algorithms: (1) linear regression (LR), (2) decision tree (DT)-based, and (3) MLP models. These models were based on the 10 most significant factors that influence the severity of lightning damage, including three current waveform parameters, four material configurations, and three orthogonal electrical conductivities of each composite. All models demonstrated good performance with coefficient of determination (R²) values between 0.84 ~ 0.96. The multilayer perceptron (MLP) regression model trained …

Natural Fiber Reinforced Composites For Sustainable Additive Manufacturing., Athira Nair Surendran

Electronic Theses and Dissertations

Carbon fiber is widely known for its exceptional strength, making it a sought-after material in composite manufacturing, especially with thermosets and thermoplastics. Its major applications span aerospace, wind turbines, sports equipment, automotive interior and exterior parts, robotics and medical equipment. Recently, carbon fiber filament manufacturing has gained attention due to the availability of desktop 3D printers and the versatility and customizability that comes with the realm of 3D printing. Commercial carbon fiber production, primarily from polyacrylonitrile (PAN), is energy-intensive and derived from crude oil, contributing to significant environmental impacts and poor recyclability. Alternatively, lignocellulosic natural fibers present a possible sustainable …

A Survey On Fused Filament Fabrication To Produce Functionally Gradient Materials, Arup Dey, Monsuru Ramoni, Nita Yodo

Manufacturing & Industrial Engineering Faculty Publications

Fused filament fabrication (FFF) is a key extrusion-based additive manufacturing (AM) process for fabricating components from polymers and their composites. Functionally gradient materials (FGMs) exhibit spatially varying properties by modulating chemical compositions, microstructures, and design attributes, offering enhanced performance over homogeneous materials and conventional composites. These materials are pivotal in aerospace, automotive, and medical applications, where the optimization of weight, cost, and functional properties is critical. Conventional FGM manufacturing techniques are hindered by complexity, high costs, and limited precision. AM, particularly FFF, presents a promising alternative for FGM production, though its application is predominantly confined to research settings. This paper …

Process Modeling Of Composites For Automated Fiber Placement, Von Clyde Jamora

Mechanical & Aerospace Engineering Theses & Dissertations

Fiber-reinforced composites are available in various material systems, each requiring specific manufacturing techniques to exploit their unique properties fully. Systems such as woven fabrics and preimpregnated fibers employ distinctive methods to harness these properties effectively. For instance, non-crimp fabrics (NCF) use high-pressure resin transfer molding and prepregs, like IM7-8552, use manufacturing method called automated fiber placement (AFP). However, these manufacturing processes often introduce deposition features that can evolve into defects. Their occurrence and impact on morphology must be predicted using experimentally informed finite element models. The research began with compaction experiments on NCF fabric, leading to the development of a …

Kissing Bond Assessment In Adhesive Bonded Carbon Fiber Reinforced Composites Using Dielectric Spectroscopy, Minhazur Rahman

Mechanical and Aerospace Engineering Dissertations - Archive

The widespread use of fiber-reinforced composites in industries such as space, aviation, automobiles, and construction necessitates the formation of robust composite joints between critical structural components. Although adhesive-bonded joints are superior with improved load distribution and reduced weight, they are often overlooked in favor of bolted joints and mechanical fasteners due to the lack of reliable Non-Destructive Evaluation (NDE) techniques for adhesive-bonded composites. The anisotropic nature of the substrate and the intricate interfacial interactions between the adherend and adhesive material present significant challenges for conventional NDE methods. Moreover, weak adhesive bonds can result from uncontrolled manufacturing parameters, such as accidental …

A Review Of Polymer – Particles Composite Materials, Ismail Ibrahim Marhoon, Ayad Abbood Abdul Al-Hassan, Mohammed Ali Abdulrehman

Al-Esraa University College Journal for Engineering Sciences

In several engineering applications traditional materials are replacedby composite materials. Filled composite materials consist of the continuousmatrix and the filling particles. The primary purpose of introducing inorganicsolid particles into polymers is to essentially increase mechanical and physicalproperties. The wear properties of polymer composite can be changed to agreater degree by modifying the process of preparing the filled compositematerials. In the present review, a large-scale research has been conductedon the effect of wear on the composites of polymers. The effect of filler onthe polymer composites wear behavior has been thoroughly explained

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 …

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] …