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Full-Text Articles in Mechanical Engineering
Ultrasonic Non-Destructive Evaluation Of Additively Manufactured Polymer-Ceramic Composites, Christian Alexander Ruiz
Ultrasonic Non-Destructive Evaluation Of Additively Manufactured Polymer-Ceramic Composites, Christian Alexander Ruiz
Open Access Theses & Dissertations
Digital light processing (DLP) is an attractive additive manufacturing technique due to its ability to create ceramic parts with complex geometries. DLP uses ultraviolet light to polymerize a slurry comprised of ceramic powder and photosensitive resin in layers to create solid parts. Printing parameters such as light intensity and exposure time are critical when producing these parts. Improper parameters can lead to over or under-curing, adversely impacting print quality and strength. Samples were printed at varying layer exposure times and then tested using ultrasonics to determine the degree of conversion. Additionally, ultrasonics were used as a non-destructive technique to obtain …
Additive Manufacturing Of Composites For Sensing And Harsh Environments Application, Md Sahid Hassan
Additive Manufacturing Of Composites For Sensing And Harsh Environments Application, Md Sahid Hassan
Open Access Theses & Dissertations
Composite materials are made by combining two or more materials, such as fibers and resins to create a material system that has improved mechanical and physical properties compared to its individual components. The use of 3D printing technology in composite manufacturing allows for the creation of complex and custom shapes with precise control over the placement of the materials. This makes it possible to create composite parts with enhanced performance characteristics and reduced weight. The work presented in this dissertation lies in the design and development of highly flexible impact propagation sensor through material extrusion 3D printing technique. By using …
Characterization Of 3d Printed Parts Containing Integrated Functionality Via Ultrasonically Embedded Wires, David Abraham Sepulveda
Characterization Of 3d Printed Parts Containing Integrated Functionality Via Ultrasonically Embedded Wires, David Abraham Sepulveda
Open Access Theses & Dissertations
Material extrusion additive manufacturing has been widely adopted because it offers freedom of design, which allows complex geometry fabrication, and rapid prototyping. Interest in producing components with integrated functionality allowed forms of hybrid manufacturing to be developed such as the Multi3D system. This system produces parts with embedded components by combining additive, subtractive, soldering, dispensing, and embedding techniques. However, this involves pausing the printing process (which takes place in a controlled environment) and exposing it to ambient temperature where embedding takes places. In this research, the effect of embedding parts with 24 AWG copper for improved functionality was quantified mechanically. …
Synthesis And Advanced Manufacturing Of Polymer Structures And Their Composites, Bethany Rose Wilburn
Synthesis And Advanced Manufacturing Of Polymer Structures And Their Composites, Bethany Rose Wilburn
Open Access Theses & Dissertations
The following research work performed embodies three unique studies of polymer structures and their composites. In general, polymers are viscoelastic, insulative materials that are used for a wide variety of applications within industrial, aerospace, and biomedical fields. Polymers have been studied and optimized for any particular use by chemically synthesizing unique micro-structures, altering the physical properties through fabrication and post-processing, and utilizing 3D printing to achieve complex geometries. In the past decade, additive manufacturing (AM) has drawn extensive attention across academia, industry, and government agencies. It offers unprecedented advantages such as design freedom, rapid prototyping, and customization. In this work, …
Additive Manufactured Ear Pinna For Spatial Cue Preservation In Custom Hearing Devices, Carlos Felipe Acosta Carrasco
Additive Manufactured Ear Pinna For Spatial Cue Preservation In Custom Hearing Devices, Carlos Felipe Acosta Carrasco
Open Access Theses & Dissertations
Advancements in additive manufacturing/3D printing technologies has permitted the fabrication of intricate features such as the ones present in the human ear. The outer ear, also known as the pinna, allows for the spectral cues from incoming sound to be captured and identified. The hypothesis of the preservation of auditory localization and externalization relies on the fabrication of an ear pinna via additive manufacturing embedded into a headset for spectral cue preservation and hearing protection. Before exploring these custom circumaural hearing devices, a study on the fabrication process of AM pinnae was performed. The KEMAR system for acoustic research was …
Additive Manufacturing Of Multi-Functional Nanocomposites For Sensor And Energy Storage Devices, Hoejin Kim
Additive Manufacturing Of Multi-Functional Nanocomposites For Sensor And Energy Storage Devices, Hoejin Kim
Open Access Theses & Dissertations
The goal of this research is to develop novel 3D printing process and design nanocomposites for piezoelectric and dielectric devices using fused deposition modeling (FDM) and stereolithography (SL) 3D printing techniques for use in sensor and energy storage applications. Techniques for electric and corona assisted in-situ poling during 3D printing were developed to improve the piezoelectric property and ease of manufacture. Poly(vinylidene fluoride) (PVDF) and barium titanate (BaTiO3, BT) are well-known for their high piezo- and dielectric constants among polymers and ceramics, while multi-walled carbon nanotubes (CNTs) were introduced to improve efficiency of stress reinforcement and conductivity for charge carriers …
Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin
Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin
Open Access Theses & Dissertations
The focus of this research was twofold, such as development of defect free fabrication parameters for laser powder bed fusion (LPBF) processing of crack prone or difficult to process metallic materials, and study of the temperature dependence of emissivity for some commonly used metal alloy powders in LPBF process. The later objective extends to the implementation of multiwavelength (MW) pyrometer technology for in situ true surface temperature measurement in LPBF process. LPBF is an additive manufacturing (AM) process capable of layer-by-layer manufacturing by successive laser melting of each layer according to CAD data. AM manufacturing has the inherent advantages of …
Process Development And Characterization Of Smart Parts Fabricated Using Powder Bed Fusion Additive Manufacturing Technologies, Mohammad Shojib Hossain
Process Development And Characterization Of Smart Parts Fabricated Using Powder Bed Fusion Additive Manufacturing Technologies, Mohammad Shojib Hossain
Open Access Theses & Dissertations
The fields of modern energy conversion, e.g., fossil fuel, natural gas, and coal power plants, are in increased need of health monitoring and data collection (temperature, pressure, and flow rate) to improve process efficiency and satisfy the demand for clean energy. In situ process monitoring can lead to a robust automated system to achieve the goal. The monitoring equipment or sensors in energy systems components (e.g., pressure tube, turbine blade, and fuel injector) undergo high temperature, high pressure, and corrosive environments; for example, combustion inlet conditions can reach up to 810 K and 2760 kPa [1]. Therefore, a reliable, accurate, …
Manufacturing And Mechanics Of Polymer Matrix Composites, Md Shariful Islam
Manufacturing And Mechanics Of Polymer Matrix Composites, Md Shariful Islam
Open Access Theses & Dissertations
Fiber-reinforced composite materials are widely used in the aerospace and automobile industries. Their strength-to-weight and stiffness-to-weight ratios make them suitable to be used in spacecraft, especially as cryogenic tank materials. One of the focus of this dissertation is to investigate the application of woven carbon and Kevlar® fiber composites as cryogenic tank materials. Tensile, bending and short beam shear tests are performed on rectangular specimens at room temperature and after cryogenic exposure (-196°C). It is found that the mechanical properties of these composite materials do not degrade significantly due to cryogenic exposure. It is observed that the failure mode took …
Design Optimization Of Sandwich Core, Mohammad Tauhiduzzaman
Design Optimization Of Sandwich Core, Mohammad Tauhiduzzaman
Open Access Theses & Dissertations
Ultralight sandwich structures comprising of low-density core with stiff facings have attracted significant research interest for their considerable weight saving applications. The aircraft industries are focusing on decreasing the structural mass to lower the manufacturing and operating costs. Design analysis of the sandwich cores using finite element analysis has been developed as a promising concept to feature sandwich structures with maximum strength, stiffness, and reduced weight. To obtain multifunctional behavior of sandwich panels, a profound investigation of geometrical and mechanical properties in the transverse plane is required because it is very susceptible to any kind loadings. Structural optimization is one …
Characterization Of High-Purity Niobium Structures Fabricated Using The Electron Beam Melting Process, Cesar Adrian Terrazas
Characterization Of High-Purity Niobium Structures Fabricated Using The Electron Beam Melting Process, Cesar Adrian Terrazas
Open Access Theses & Dissertations
Additive Manufacturing (AM) refers to the varied set of technologies utilized for the fabrication of complex 3D components from digital data in a layer-by-layer fashion. The use of these technologies promises to revolutionize the manufacturing industry. The electron beam melting (EBM) process has been utilized for the fabrication of fully dense near-net-shape components from various metallic materials. This process, catalogued as a powder bed fusion technology, consists of the deposition of thin layers (50 - 120µm) of metallic powder particles which are fused by the use of a high energy electron beam and has been commercialized by Swedish company Arcam …
Fabrication Of A Nickel-Based Superalloy In Electron Beam Melting And Process Improvements Using Thermal Feedback From A Multi-Wavelength Pyrometer, Jonathan Minjares
Fabrication Of A Nickel-Based Superalloy In Electron Beam Melting And Process Improvements Using Thermal Feedback From A Multi-Wavelength Pyrometer, Jonathan Minjares
Open Access Theses & Dissertations
The focus of this research was to fabricate parts composed of a nickel-based superalloy containing high levels of aluminum and titanium (NSAT) by using electron beam melting (EBM) additive manufacturing (AM) technology and utilizing thermal feedback from a multi-wavelength pyrometer to perform process improvements leading to near defect-free parts. EBM is an AM technology that utilizes metal powder to fabricate parts in layer-by-layer manner. A multi-wavelength pyrometer was implemented in an Arcam S12 (Arcam AB, Sweden) EBM system to observe and record surface temperatures throughout fabrication. Temperature data from the EBM system and the multi-wavelength pyrometer were graphed using MATLAB …
Process Study And Control Of Electron Beam Melting Technology Using Infrared Thermography, Jorge Mireles
Process Study And Control Of Electron Beam Melting Technology Using Infrared Thermography, Jorge Mireles
Open Access Theses & Dissertations
An IR camera was installed in an Arcam A2 system (Arcam AB, Mölndal, Sweeden) and layer-by-layer image acquisition was achieved. The camera's capability to detect manufacturing defects was evaluated by implementing computer vision techniques using LabVIEW measurement and programming software (National Instruments, Austin, TX). Thermal maps acquired by the IR camera allowed layer-by-layer part temperature to be recorded. A core objective of this research was to study the impact of processing temperature on EBM-fabricated Ti-6Al-4V parts and achieve controlled mechanical properties. In this research, build variations were achieved by modifying parameters that change processing temperature from the standard processing temperature. …