Structures and Materials Commons^™

Experimental And Theoretical Fracture Analysis Of Additively Manufactured Orthotropic V-Notches, Venkata Siva Sainath Bavapuram

Theses and Dissertations

This study presents a comprehensive investigation into the fracture behavior of additively manufactured orthotropic V-notched components made of Acrylonitrile Butadiene Styrene (ABS) material. The research integrates both theoretical and finite element approaches to evaluate stress intensity factors (SIFs) in Modes-I and II, which are fundamental in characterizing stress field distributions around notches under applied loading conditions. Unlike isotropic materials, where stress fields depend only on geometry of the component, the anisotropic nature of 3D-printed ABS introduces a dependency on material properties that necessitate different approaches to include anisotropy of the material.

Tensile specimens are 3D-printed with specific material orientations to …

Mixed-Mode Fracture Analysis Of Additively Manufactured Periodic Orthotropic Functionally Graded Microcellular Materials, Behnam Shahbazian

Theses and Dissertations

The quest for safety, efficiency, and innovation in aerospace engineering demands a relentless focus on understanding how materials and structures behave under extreme and complicated loading conditions. Among the many challenges faced by engineers in this field, predicting and preventing structural failure stands out as both a fundamental necessity and a complex problem. Fracture mechanics, the science of how materials fail under stress, is a cornerstone of this effort. Whether it is the fuselage of an aircraft enduring cyclic loading or the lightweight components of a spacecraft resisting impact, the ability to accurately predict fracture behavior directly influences the reliability …

Experimental And Theoretical Fracture Analysis Of Rift Manufactured Carbon Fiber-Vinyl Ester Lamina, Daniel Joseph Longo

Theses and Dissertations

This thesis investigates the fracture behavior of unidirectional carbon fiber-vinyl ester (CFVE) laminates manufactured using the Resin Infusion with Flexible Tooling (RIFT) process, a cost-effective alternative to autoclave-based fabrication methods. Composite materials like CFVE are increasingly adopted in high-performance applications due to their high strength-to-weight ratio and corrosion resistance; however, their anisotropic nature presents challenges in predicting crack initiation and propagation. To address this, a comprehensive approach combining experimental testing, finite element modeling (FEM), and classical fracture mechanics was employed. Orthotropic mechanical properties were first determined through tensile and shear tests, providing critical properties for FEM simulations. A series of …

G.W.A.I.H.I.R. Guided Wing Aircraft For Intelligent Hybrid Insertion And Recovery, Abdirahman Ahmed Shirwa, Zach Richards, Derek Harwood, Alex Duncan

Senior Design Project For Engineers

The paper outlines the conceptual and preliminary design of a hybrid vertical takeoff and landing (VTOL) heavy lift unmanned aerial vehicle (UAV) for autonomous cargo transport missions. The primary design objective was to create an aircraft capable of carrying a 15 kg payload over a range of 33 km, achieving a top cruise speed of 45 km/h and maintaining an endurance capacity of at least 90 minutes.

A comprehensive literature review informed key design decision, including airfoil selection, structural material, propulsion system configuration, and control. Key requirements were established early in the design process, such as payload capacity, energy efficiency, …

40 - Design, Fabrication, And Installation Of Morphing Control Surfaces For Small-Scale Uas, Kyle Purser

Undergraduate Research Symposium

Morphing control surface technology, inspired by organic structures and compliant mechanisms, offers significant potential for enhancing the aerodynamic efficiency and performance of unmanned aerial systems (UAS). Despite these benefits, its adoption has been hindered by complexities in design, manufacturing, and installation, particularly when compared to traditional flap systems. This research explores the design, fabrication, and integration of morphing control surfaces for small-scale UAS using additive manufacturing techniques. To reduce costs and streamline the design process, fused deposition modeling (FDM) additive manufacturing was employed for component fabrication. An off-the-shelf Horizon Sport Cub S2 served as the testing platform, modified with a …

Engineering Anisotropic Porosity In Green Parts From Binder Jet 3d Printing, Reshma Chandrashekhar Kubsad

Doctoral Dissertations and Master's Theses

Binder Jet Additive Manufacturing (BJAM) is a promising metal additive manufacturing technique that enables the fabrication of complex geometries without the need for support structures. However, the inherent porosity in green parts, remains a challenge in achieving desired mechanical properties and performance. Instead of treating porosity as a limitation, this thesis explores engineering of anisotropic porosity engineering, where controlled variations in porosity in the green parts can be used to enhance functionality and efficiency in specific applications. The objective of this research is to investigate and analyze the key print parameters that influence green part density. By systematically varying layer …

Modeling The Dynamics Of Flexible Aerospace Vehicles Using The Theory Of Functional Connections, Carlo Lombardi

Doctoral Dissertations and Master's Theses

Modeling and control of flexible vehicles is a topic of high interest in the aerospace field and a key challenge lies in finding accurate mathematical representations of the flexible dynamics of continuous elastic structures that allow simple integration into estimation and control algorithms. The answer was found in approximating the dynamics of these systems with sets of coupled Ordinary Differential Equations (ODE) for which a well-established estimation and control theory is available. Each of the techniques employed to achieve this goal is characterized by its own strengths and limitations. Hence, the main objective of this research is to develop the …

Thermal Stability Analysis Of Aqueous Ionic Amines For Sustainable Co2 Capture, Li Hua Zang, Keegan Everitt, Kevin West, Brooks D. Rabideau, Breanna Dobyns, James Davis

Shelby Hall Graduate Research Forum Posters

In closed air cabin atmospheres such as those of spacecraft, CO₂ accumulation jeopardizes crew respiratory function and may gradually affect sensitive equipment, making effective air revitalization critical. Traditional CO₂ capture methods like monoethanolamine (MEA) efficiently capture CO₂ but suffer from high volatility, leading to solvent loss and unpleasant odor, as well as corrosion and degradation, requiring frequent replacement. These flaws demand eco-friendly, durable alternatives. This study addresses these limitations by exploring a series of aqueous ionic amines (AIAs), salts similar to MEA in CO₂ capture efficiency but with improved thermal stability—crucial for preventing degradation under high regeneration temperatures and prolonged …

Mechanical Response Of Triply Periodic Minimal Surface Gyroid Structures Under Combined Loading, Jay B. Patel

Theses and Dissertations

This work explored combined tensile and torsional loads applied to additively manufactured Inconel 718 specimens employing Triply Periodic Minimal Surface (TPMS) structures. The gyroid TPMS unit cell was selected with two variations of cylindrical cell maps, a rectangular cell map, and a spherical cell map. All four variants were tested in an axial-torsion test frame at room temperature using equal parts of vertical and angular displacement control until failure. The combined loading in these tests utilized tension and torsion. The data from the tests were compared to finite element analysis (FEA) models to visualize when yielding was predicted. Finally, the …

Graphene-Polymer Nanocomposite For Electromagnetic Interference Shielding, Ravi Venkata Surya Sai Mogilisetti

Mechanical and Aerospace Engineering Theses - Archive

Polymers have widespread usage in most industries, such as aerospace, automotive, telecommunications, and medicine, mainly because they have a positive lightweight nature and excellent mechanical properties. One significant advantage of polymeric materials is their ability to combine nano-fillers, greatly enhancing their mechanical, electrical, and thermal properties. In the category of polymer matrices, polypropylene (PP) is notable for its low cost, ease of processing, and balanced mechanical properties. However, its relatively lower modulus and strength limit their applications in high-performance engineering. This research explores the addition of graphene into polypropylene to improve its mechanical properties and establish a conductive network for …

Linking Molecular Structure Evolution To Mechanical Degradation During Environmental Aging In Conventional And Recyclable Epoxy Systems, Ben T. Jewell

Dissertations, Master's Theses and Master's Reports

The long-term performance of polymeric materials in extreme environments is governed by complex chemical and physical aging processes that alter their molecular structure and mechanical integrity. Conventional thermoset epoxies, while widely used in structural applications, are particularly susceptible to oxidative degradation at elevated temperatures, leading to embrittlement and loss of structural integrity. In the first part of this work, diffusion-limited oxidation (DLO) in a bulk structural epoxy was systematically investigated to establish the link between heterogeneous microstructural evolution and macroscopic mechanical degradation. High-temperature oxidation experiments were conducted in a controlled environmental chamber, and the resulting chemical, thermal, and mechanical changes …

Investigation Of Subsurface Thermal Radiation Phenomena In Fibrous Thermal Protection Systems, Colby L. Gore

Theses and Dissertations--Science, Technology, Engineering, and Mathematics (STEM) Education

Atmospheric re-entry induces intense thermal stress upon vehicles through a high-enthalpy boundary layer that encompasses the craft. To protect these vehicles, numerous insulative methods, known as thermal protection systems (TPS), are deployed to protect the craft during re-entry. The TPS materials insulate the craft from intense thermal transmission that would terminate a mission. In hypersonic environments, vast temperature gradients exist, enforcing the exponential effect of thermal radiation. However, TPS materials are commonly low-density fibrous materials that allow for the potential to be penetrated by thermal radiation. A series of arc-jet tests was completed to replicate enhanced radiative conditions in a …

Smart Material Actuated Flap, James Lyons, Kristofer Johnson

Williams Honors College, Honors Research Projects

The objective of this project is to develop and evaluate a smart material actuated aerodynamic control surface to determine the viability of these new systems as alternatives to conventional electromechanical and hydraulic systems. The research will begin with the selection of a control surface and actuator design. The concept will then be tailored to create an experimental model for the purposes of this project. Smart materials that suit the model requirements will be selected and procured. Next, the actuators will be shape trained and characterized to meet the model requirements. Then, a benchtop model will be produced for design verification, …

Analyzing Micrometeoroid And Orbital Debris Shield Performance For Sample Return Spacecraft, William P. Schonberg, Michael Squire

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Sample-return missions typically seek to collect and return samples from extraterrestrial locations to Earth for analysis. The return of samples from certain locations in the solar system represents a potential hazard to Earth's biosphere from foreign microorganisms. One way this could occur would be a break-up of the returning capsule during entry (which would disperse the samples through the air) due to undetected damage to the capsule thermal protection system (TPS). As a result, missions that plan to return payloads from some destinations are likely to have certain design requirements for the TPS surrounding their returning capsules, which may include …

Extending The Applicability Of Thermal Protection System Ballistic Limit Equations Beyond The Testable Regime, William P. Schonberg, Michael D. Squire

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Spacecraft use thermal insulation in their design, which is usually placed on their exterior. As such, it is susceptible to high-speed impacts by meteoroids and orbital debris, which can damage it to a point where the protection it offers is below acceptable limits. It is important to be able to characterize expected levels of damage stemming from such high-speed impacts. In this paper, we extend the applicability of a previously developed ballistic limit equation (BLE) for one such thermal insulation material using the results of a series of Smooth Particle Hydrodynamics Code (SPHC) impact simulations at velocities in excess of …

Characterizing Intralaminar Distal Crack And Delamination In Multidirectional Laminates Under Low Velocity Impact: Modeling Approach With Ultrasound Testing Validation, Niildiip Chandraa, Rachel Van Lear, Arief Yudhanto, Yuqing Zhao, David A. Jack, Douglas E. Smith

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multidirectional laminated composites are essential for load-bearing structures, especially under frequent impact loading. While existing modeling techniques simulate various impact damage modes, our understanding of the underlying mechanisms, specifically the initiation and progression of intralaminar distal cracks and interlaminar delamination, needs improvement. Validating these mechanisms is crucial for enhancing modeling accuracy and expediting the design process. In this work, we propose a three-dimensional finite element modeling (3D FEM) approach aimed at elucidating the impact damage mechanisms in multidirectional carbon fiber reinforced polymer (CFRP). Our model incorporates cohesive zone models (CZM) to simulate the behavior of intralaminar cracks at distal points …

Ground Testing Of A Magnetic-Electrostatic Separation System For Lunar Regolith Beneficiation, Peter Bachle, Charles Wood, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han

Materials Science and Engineering Faculty Research & Creative Works

The separation of lunar regolith by mineral composition and size category is useful forin-situ resource utilization (ISRU). The research presented herein discusses the designing and development of equipment that has the potential to separate lunar regolith into aluminum, iron-titanium, and magnesium-iron ores. Along with the metal ore separation, this equipment shows the potential to separate regolith by size categories. The combined effect of these separation methods generates output that is valuable to subsequent use in metal and oxygen extraction, additive manufacturing, and regolith sintering processes. The designed equipment uses a dual-strength magnet system with N42 and N52 neodymium magnets for …

Novel Design And Fabrication Of A High-Speed Transient Heat Flux Sensor For Application To Rotating Detonation Engines, Zachary Todd Tallman

Graduate Theses, Dissertations, and Problem Reports (ETD)

Rotating detonation engine (RDE) combustion systems have been a topic of interest in the pressure gain combustion community for their benefits over traditional gas turbine engine combustors. However, cooling requirements for these engines are significantly higher and less predictable than those of non-detonating engines. To understand and quantify the high-speed heat transfer dynamics within an RDE, a novel high-frequency heat flux sensor is presented. This study aims to design a robust, single-sided sensor that can withstand the high temperature and harsh environment of an RDE for extended durations. Screen printing is used to deposit a layered, platinum-yttria-stabilized zirconia (YSZ) film …

Mars Sample Return Earth Entry System Uncertainty Analysis, Michael D. Squire, Victor Cabrera, Eric Christiansen, Alan Jenkin, Kevin Hoffman, Quincy Mckown, Peter Parker, Glenn Peterson, Bruno Victorino Sarli, William P. Schonberg, Katie Steward, Brian Tulaba, Joel Williamsen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Spacecraft designers and operators use micrometeoroid and orbital debris (MMOD) risk assessments to predict the probability that an MMOD particle impact will cause a critical failure to their systems. An important aspect of MMOD risk and associated requirements is the treatment of uncertainty, often difficult to quantify, or even estimate, for many elements of MMOD risk. This paper describes recent efforts to estimate uncertainties in inputs to the MMOD risk assessment process for a portion of the planned Mars Sample Return (MSR) campaign. The uncertainty bounds developed were used to examine their effect on overall mission MMOD risk.

Additive Manufacturing Of Multifunctional Materials And Composites, John Michael Pappas

Doctoral Dissertations

"This research focused on developing fundamental knowledge of process-material interactions for additive manufacturing of multifunctional materials that are highly desirable in high-tech industries for potential weight and space savings. Multifunctional materials are very sensitive to defects, which severely hinder performance. Thus, defect formation was systematically studied to develop strategies and methodologies to efficiently fabricate high-performance materials and composites. Blown-powder-based laser additive manufacturing of transparent spinel ceramics was investigated to reduce porosity and cracking, defects that hindered transparency and mechanical properties. A systematic study of processing parameters revealed that laser power and powder flow rate had the largest effects on defect …