Structures and Materials Commons^™

Buckling Analysis Of Auxetic Composite Laminates And Optimal Design Using Lamination Parameters And Machine Learning, Hans Bendon Maria Tamil Selvan

Mechanical and Aerospace Engineering Theses

Composite materials are widely used as structural panels in aerospace, automotive, and civil engineering applications, where buckling is often a critical failure mode. This thesis focuses on the analysis and design of composite laminates that maximize buckling performance under prescribed stiffness and thickness constraints.

The first part of the study investigates the buckling behavior of auxetic laminates, which exhibit a negative Poisson's ratio. While previous studies suggest that auxetic laminates can achieve higher critical buckling loads than non-auxetic laminates under simply supported boundary conditions with lateral restraint, the influence of other boundary conditions and plate aspect ratios has not been …

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 …

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 …

Experimental Investigations And Optimization Of 3d Printed Cellular Structures For Protection Against Traumatic Brain Injury, Aaron R. Jackson

Mechanical and Aerospace Engineering Dissertations - Archive

Traumatic Brain Injury (TBI) disrupts brain function due to head impacts, blast exposures, and ballistic penetrations. It is a significant cause of mental health issues and disability, particularly among military personnel. Historically, combat helmets were designed primarily to protect against fragments. However, recent data highlights the need for helmets that also protect against blast and blunt impacts. Effective TBI prevention requires helmets that address various energy threats while remaining lightweight. A critical metric in this effort is head acceleration, which is closely linked to injury across different scales of brain damage.

Four lattice structures were 3D printed using Digital ABS …

Development Of A 3d Printed Optimization-Driven Aeroelastically Scaled Wind Tunnel Model For High Aspect Ratio Flying Wings, Mikaela K. Leevy

Mechanical and Aerospace Engineering Theses - Archive

Design optimization coupled with 3D printing and parametric CAD offers a unique approach to investigating flutter phenomena by creating low-cost iterative aeroelastic wind tunnel models. Recently, there is an interest in studying flutter phenomena at low air speeds in flying wing configurations. The X-56 experimental flying wing was designed to investigate flutter phenomena and flutter suppression, which makes the X-56 a logical choice for the full-scale model. The goal of this work is to optimize, physically print, and geometrically characterize a scaled aeroelastic wind tunnel model. The 18% reduced scale X-56 model was optimized by matching the mode shapes to …

Parametric Analysis Of A Dynamic And Static Model For Low Velocity Impact Of Specially Orthotropic Laminates, Juan Daniel Ruiz

Mechanical and Aerospace Engineering Theses - Archive

The high specific strength and specific stiffness of composite materials makes them highly desirable for structural applications, but their laminated nature makes them susceptible to impact damage. Even low velocity impacts (LVI), generally, result in barely visible impact damage (BVID) and delamination, which can go unnoticed and grow during service, eventually leading to catastrophic failure. Due to this, the study of impact resistance and damage tolerance is typically studied through LVI followed by compression after impact (CAI) experiments. However, conducting LVI experiments are time consuming and expensive, as they require specialized equipment and extensive pre-test preparations.

In this study, the …

Image-Based Thermal And Mechanical Analysis Of Polymers, Yukti Shinglot

Mechanical and Aerospace Engineering Theses - Archive

In recent years, application of polymers have rapidly expanded across industries due to their versatility, cost-effectiveness, and adaptability to diverse manufacturing techniques, including 3D printing. Innovations in PolyJet technology enable the creation of complex geometries with tailored color combinations, transparency, and flexibility, broadening applications in medical, aerospace, and automotive sectors. Advances in processing viscoelastic rubbers like PDMS (Polydimethylsiloxane) have further enhanced its mechanical properties, expanding its use in biomedical devices and electronic components. However, polymers are susceptible to complex deformation and failure under thermal and mechanical stresses, which can impact their performance and safety. This research examines the thermal behavior …

Thermal Damage And Mechanical Failure Analysis Of Polymers, Tina Ko

Mechanical and Aerospace Engineering Theses - Archive

As the demand for more intricate and precise components increases, polymers continue to stand out for their flexibility, durability, and adaptability across numerous applications. From aerospace to biomedical engineering industries, polymers are valued for their versatility and customizability, enabling the creation of complex geometries or achieving specific material properties. Since polymers are widely used, analyzing their thermal and mechanical properties is essential to understand their behavior under high-energy exposure or defects. Two types of polymers were analyzed: Polydimethylsiloxane (PDMS) and 3D-printed digital materials. This thesis investigates the mechanical and thermal response of polymers through two distinct studies. The first part …

Graphene Reinforced Polymer Composite For Small-Scale Vertical Axis Wind Turbine Rotors, Kunal A. Bachim

Mechanical and Aerospace Engineering Theses - Archive

Polymers have evolved as an indispensable asset in various sectors ranging from packaging and construction to energy and aerospace. However, the accumulation of polymer waste poses a necessity to shift toward sustainable waste management processes. Mechanical recycling is a primary method in establishing a circular economy approach for polymers. However, a fundamental challenge arises in this process: a decrease in the mechanical performance of the recycled product compared to that of its pristine counterpart.

This project addresses the challenge of enhancing the recyclability of polyethylene terephthalate (PET) from discarded polymer material by incorporating graphene nanoparticles into the polymer matrix during …