Engineering Commons^™

Investigating The Effect Of Bead Geometry On Fiber Orientation And Thermomechanical Properties For Large-Format Extrusion-Based Additive Manufacturing, Joanna F. Keaton

Electronic Theses and Dissertations

In large-format extrusion-based additive manufacturing of polymer composites, the relationship between material properties and processing parameters requires further investigation. This thesis focuses on the relationship between fiber orientation and thermomechanical properties for short fiber-filled thermoplastic polymer systems manufactured by extrusion-based additive manufacturing. Fiber orientation is particularly important in determining the thermomechanical properties of the composite material as properties in the direction of deposition are expected to be higher for highly aligned fibers than randomly aligned fibers. Fiber orientation distribution, which is related to processing parameters and deposition conditions, can be efficiently represented by the orientation tensor. The orientation tensor can …

A Study On Early Age Properties Of Concrete For Precast And 3d Printing, Debalina Ghosh

Doctoral Dissertations

Concrete is the second-most consumed material, leading the global Portland cement production of 4.1 billion tons in 2020 and 5-8% of global Carbon dioxide (CO₂) emission annually. As with any other material and practice, the construction industry is also ever-changing to meet market demand, evolving technology, and resource limitation. In the case of concrete construction, one of the main concerns is the lack of automation. In the last few decades, some new construction methods have risen to address this concern. Some of these economic and successful practices are precast construction, self-compacting concrete (SCC), and 3D printing of concrete(3DPC). …

Effects Of Fiber Orientation On The Coefficient Of Thermal Expansion Of Fiber-Filled Polymer Systems In Large Format Polymer Extrusion-Based Additive Manufacturing, José Luis Colón Quintana, Lucinda Slattery, Jon Pinkham, Joanna Keaton, Roberto A. Lopez-Anido, Keith Sharp

Civil Engineering Faculty Scholarship

Large format polymer extrusion-based additive manufacturing has been studied recently due to its capacity for high throughput, customizable bead size and geometry, and ability to manufacture large parts. Samples from three fiber-filled amorphous thermoplastic materials 3D printed using a Masterprint 3X machine from Ingersoll Machine Tools were studied, along with their neat counterparts. Characterization techniques included thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermo-mechanical analysis (TMA). TGA results showed that the fillers decreased the degradation temperature for most of the materials investigated, with a 30°C decrease for polycarbonate (PC) and a 12°C decrease for polyethylene terephthalate glycol (PETG). For …

Development Of The Uhpc Mix For 3d Printing, Buse Ilayda Oz

FIU Electronic Theses and Dissertations

This thesis utilizes the development of Ultra-High-Performance Concrete mix design for 3-Dimensional (3D) Printing purposes. 3D concrete printing offers many advantages such as the improvements in safety, quality, and productivity. Moreover, it holds a great advantage for the construction of structural elements that are difficult to construct by conventional methods. These advantages carry a huge potential for solving the aforementioned challenges.

Seven UHPC mixes have been designed and analyzed using various test setups for comparison purposes. Extrudability, flowability, buildability, and open time were measured using the fresh properties of the UHPC mixes. Mechanical properties were measured using compression test setups. …

Critical Evaluation Of Construction Industry-Related Additive Manufacturing Research: A Scientometric Analysis, Tyler J. Brunjes

Theses and Dissertations

Review of construction-related AM literature is used to identify the advantages, challenges, and current trends of the research. Using a scientometric analysis of 522 bibliographic records, this research systematically analyzed construction related AM research to determine the key research areas and trends. Results showed that starting in 2015, the field has been growing at an exponential rate. Recent AM research focused on materials and reinforcement topics, which matched the most notable challenges of AM, which are material rheology, reinforcement, and lacking construction standards. This study provides an insight into AM research and identifies areas requiring more innovation before its commercial …

Numerical Modeling And Experimental Investigation Of Effective Elastic Properties Of The 3d Printed Gyroid Infill, Philip Bean, Roberto A. Lopez-Anido, Senthil Vel

Civil Engineering Faculty Scholarship

A numerical homogenization approach is presented for the effective elastic moduli of 3D printed cellular infills. A representative volume element of the infill geometry is discretized using either shell or solid elements and analyzed using the finite element method. The elastic moduli of the bulk cellular material are obtained through longitudinal and shear deformations of a representative volume element under periodic boundary conditions. The method is used to analyze the elastic behavior of gyroid infills for varying infill densities. The approach is validated by comparing the Young’s modulus and Poisson’s ratio with those obtained from compression experiments. Results indicate that …

Thermal And Mechanical Numerical Modeling Of Extrusion-Based 3d Printed Reinforced Polymers For Selecting Manufacturing Process Parameters, Sunil Bhandari

Electronic Theses and Dissertations

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. …

3d Printed Concrete & Polymer Concrete For Infrastructure Applications, Daniel Heras Murcia

Civil Engineering ETDs

Additive manufacturing technology has been established as one of the fastest-growing building technologies worldwide. Three-dimensional concrete printing (3DCP) has developed an increasing interest in the last decade due to its prospects as a transformative technology for industries such as the concrete precast. Besides the improvements in automation technologies in construction, traditional construction has faced considerable challenges: high accident rates, labor dependency, significant potential for automation, and high costs associated with the use of traditional formwork. In this context, three-dimensional concrete, also referred to as physical prototyping, is a novel construction technique in which the concrete is extruded layer-to-layer. 3DCP is …

Extremely Low Cycle Fatigue Behavior Of Additively Manufactured 17-4ph Stainless Steel, Kaley Collins

Civil Engineering Undergraduate Honors Theses

Steel structures survive seismic loading thanks to components capable of dissipating large amounts of energy through large deformations. Future optimizations of these components include complex free-form geometries that are difficult to fabricate with traditional casting processes. Additive manufacturing (AM) is an alternative for producing optimized free-form geometries. AM material contains significant differences in microstructural characteristics and mechanical behavior compared to its wrought counterparts. Research has been conducted to understand the effect of microscopic features in the high cycle fatigue (HCF) and low cycle fatigue (LCF) regimes. This study focuses on the behavior of 17-4 Precipitation Hardening (PH) stainless steel in …

An Analysis Of The Viability Of 3d-Printed Construction As An Alternative To Conventional Construction Methods In The Expeditionary Environment, Jeneé A. Jagoda

Theses and Dissertations

Conventional construction is believed by some to have reached its technological limit of performance, making it increasingly difficult for conventional construction methods to meet the U.S. military’s core standards of quality, cost, and timeliness in the expeditionary environment. While still in its infancy, 3D-printed construction has the potential to revolutionize the way the military performs construction in deployed environments. This research conducts a systematic review of the viability of 3D-printed construction to investigate whether or not it is now or could be a viable replacement for conventional construction methods, specifically in remote environments where conventional construction capability may be limited. …

Mechanical Performance Of Structural Systems With Missing Members: From Buildings To Architected Materials, Panagiotis Pantidis

Doctoral Dissertations

Structural systems are potentially subjected to damage initiating scenarios throughout the course of their service time. Depending on the nature and extent of the damaging event, they may experience significant reduction or even complete loss of their mechanical performance. This dissertation delves into the mechanics of structural systems under the notion of missing members from their domain, investigating types of structural systems: a) multi-story steel framed buildings, and b) materials with a truss-lattice microstructure. Part I of the dissertation investigates the performance of multi-story steel framed buildings under a column removal scenario, developing an analytical framework for their quasi-static robustness …

Development Of Test Methods For Characterizing Extrudability Of Cement-Based Materials For Use In 3d Printing, Jonathan Thomas Kuchem

Masters Theses

"3D printing is the process of creating three-dimensional objects using an automated additive manufacturing process. The 3D printing process has been used with materials such as metals and polymers, but application with cement based materials for the construction industry has yet to be developed. In this research, two main problems were investigated for printing cement based composite materials: extrudability and tensile reinforcement. Fiber-reinforced concrete (FRC) was studied as an internal reinforcing system to increase tensile/flexural strength. First, FRC was studied to investigate mechanical properties and use of fibers from waste tires as an environmentally friendly option. A reference mixture with …

Crack Healing In 304l Stainless Steel Using Additive Manufacturing And Friction Stir Processing (Fsp), Cameron Scott Gygi

Theses and Dissertations

Continuing an investigation on using FSP to heal stress corrosion cracks (SCC) in welds on nuclear reactors, this study seeks to use AM in addition to FSP to aid crack repair. Previous studies address that current repair technology on nuclear reactors involves the use of TIG welding which can allow helium atoms to aggregate and form voids at the grain boundaries. This weakens the material and renders the repair ineffective. Another previous study evaluated the effectiveness of FSP alone in repairing SCC which did have defects depending on the parameters used during FSP. This study evaluated the use of AM …

Feasibility Of Using 3d Printed Molds For Thermoforming Thermoplastic Composites, Sunil Bhandari

Electronic Theses and Dissertations

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are:

1. a methodology for model-based performance evaluation of 3D printed structural parts, and
2. an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing.

The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D …