Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 29 of 29
Full-Text Articles in Engineering
Towards Sustainable Additive Manufacturing: Assessment Of Cost, Greenhouse Gas Emission, And Recyclability, Lei Di
Industrial, Manufacturing, and Systems Engineering Dissertations
Additive Manufacturing technologies fabricate 3D objects layer by layer following a predesigned CAD model. Owing to the unique layer-wise production method, additive manufacturing offers competitive advantages in comparison with traditional subtractive manufacturing, such as shortened production time, increased design freedom, improved manufacturing capability and complexity, and reduced manufacturing waste. Numerous research studies have been conducted to design, understand, and improve additive manufacturing technologies in order to facilitate the implementation in the supply chain. On the other hand, with the rapid growth of additive manufacturing, sustainability issues that exist on both process level and supply chain level have started to receive …
Enhancing Microstructure, Composition Homogeneity, And Mechanical Properties In Laser Powder Bed Fused Metallic Alloys: Design, Fabrication, And Evaluation, Bahzad Farhang
Mechanical and Aerospace Engineering Dissertations
ABSTRACT: Over the past five decades, Nickel-based and Titanium-based alloys have become increasingly popular materials. As the manufacturing industry for these alloys has advanced, the demand for fabricating complex parts with enhanced mechanical properties at elevated temperatures has grown. Laser Powder Bed Fusion (LPBF), one of the most prevalent additive manufacturing techniques, has been employed successfully to produce these alloys. Nonetheless, there is still considerable effort being made to improve the microstructural, compositional, and mechanical properties of LPBF-processed components. In this study, we focused on adjusting the multi-scale microstructure and composition of LPBF-fabricated Nickel-based and Titanium-based alloys. The first objective …
Mechanical And Thermal Performance Of Additively Manufactured Digital Materials, Layth Muayyad Ahmad
Mechanical And Thermal Performance Of Additively Manufactured Digital Materials, Layth Muayyad Ahmad
Mechanical and Aerospace Engineering Theses
Over the past decades, additive manufacturing has become a critical material processing tool. All ranges of materials including polymers, composites, metals, and ceramics can be used to fabricate structures with complex geometries that are nearly impossible to build using conventional fabrication process. Recently, additive manufacturing methods to build polymeric structures have been advanced significantly. In particular, the emergence of multi-material printers has made it possible to seamlessly print hybrid and digital materials where materials components and compositions are digitally varied to construct fully tailored material system. In this work, using a commercially available polyjet printer (Stratasys J850 Prime 3D printer), …
Characterization Of Fatigue Strength Of Additively Manufactured Ti-6al-4v With Recoater Blade Interference Flaws And Residual Stresses Towards An Enhanced Fatigue Substantiation Methodology For Aerospace Structures Applications, Joshua Manyara Mochache
Mechanical and Aerospace Engineering Dissertations
This research characterized the fatigue strength of additively manufactured (AM) Ti-6Al-4V, through fatigue and static tests conducted using specimens with and without recoater blade interference flaws (RBIF), and thus further enhanced the fatigue substantiation methodology for AM parts by using combined fatigue strength knock-down-factors (KDF) developed from this study. Qualification and certification (Q&C) of metallic AM parts, through acceptable methods for fatigue and damage tolerance (F&DT) substantiation, is an area where significant gaps still exist. While progress has been made in design as well as materials and process standardization, Q&C of additively manufactured metallic structural parts, especially those in civil …
Characterization And Enhancement Of Fatigue And Fracture Properties In Thermoplastic Fff Parts Using In-Situ Annealing, Manjarik Mrinal
Characterization And Enhancement Of Fatigue And Fracture Properties In Thermoplastic Fff Parts Using In-Situ Annealing, Manjarik Mrinal
Mechanical and Aerospace Engineering Dissertations
Fused filament fabrication (FFF) show high anisotropy and reduced mechanical properties as compared to conventional manufacturing techniques. This happens due to the poor interlaminar bonding between the layers, as a result of premature halt of bond healing process. Previous research works show multiple approaches to improve the bond quality to enhance the mechanical properties of FFF parts, however these are complex and expensive techniques. In this work a novel print head assembly is presented to offer a simple and effective solution by applying a thermal field to the part as it is being printed to preheat the previously deposited layer, …
Characterization And Enhancement Of Mechanical Properties In Thermoplastic Fff Parts Using In-Situ Annealing, Rhugdhrivya Rane
Characterization And Enhancement Of Mechanical Properties In Thermoplastic Fff Parts Using In-Situ Annealing, Rhugdhrivya Rane
Mechanical and Aerospace Engineering Dissertations
Fused filament fabrication is one of the most common and widely used additive manufacturing techniques. Owing to its ease of use, availability and cheap feedstock it provides a significant advantage over other AM techniques. But these advantages are overshadowed by the fact that FFF parts show high anisotropy and reduced mechanical properties as compared to conventional manufacturing techniques. Literature review of previous research works show multiple approaches to enhance the mechanical properties of FFF parts but each of these techniques have limitations to either the geometries that can be printed or involve complex expensive setups. In one such technique a …
Evaluating The Thermal Performance Of Topology Optimized Low-Cost 3d Printed Heat Sink Made Of Copper, Bilal Taha
Evaluating The Thermal Performance Of Topology Optimized Low-Cost 3d Printed Heat Sink Made Of Copper, Bilal Taha
Mechanical and Aerospace Engineering Theses
The performance of a heat sink is highly dependent on the overall surface area available for heat transfer. Designing heat sinks with greater surface areas meant bigger size, weight, and volume of heat-exchanger thus making it unfeasible to produce. Design and manufacture of compact-sized heat sinks is a difficult task, as it would require the use of complex surface modeling and complex surface cutting. But with the advent of 3D printing technology, it has become easier to manufacture heat sinks having complex designs producing larger surface areas as they add material layer by layer rather than cutting it away. The …
Investigation On Microstructure And Mechanical Properties Of Porous Structures Processed By Laser Powder Bed Fusion, Samarth Ramachandra
Investigation On Microstructure And Mechanical Properties Of Porous Structures Processed By Laser Powder Bed Fusion, Samarth Ramachandra
Mechanical and Aerospace Engineering Theses
Inconel 718 (i.e., IN718) is a prominent nickel-based, precipitation-hardening superalloy which exhibits exceptionally stable mechanical and corrosion resistant properties, even at temperature range of 650ºC to 700ºC, making it suitable for a wide range of applications such as aerospace, nuclear reactors, tooling, turbines, oil and gas applications. The high toughness and work hardening offered by this superalloy, however, greatly limits the choice of machinability. The presence of low levels of aluminum permits good weldability which further allows the use of laser-based additive manufacturing (AM) to efficiently fabricate IN718 parts without the limitations associated with conventional manufacturing methods. Thanks to AM …
Investigation Of The Microstructural And Mechanical Properties Of Selectively Laser Melted In718 Overhangs Fabricated Without Support Structures, Manjunath Hanumantha
Investigation Of The Microstructural And Mechanical Properties Of Selectively Laser Melted In718 Overhangs Fabricated Without Support Structures, Manjunath Hanumantha
Mechanical and Aerospace Engineering Theses
Additive manufacturing is a new manufacturing technology that allows for extreme design freedom as well as the simultaneous production of many parts with high complexities. IN718 is a high-strength, corrosion-resistant super alloy of nickel and chromium. It is ideal for high-end applications such as rocket nozzles and turbines because it can handle exceptionally high pressure and heat. Because of its high stiffness qualities, conventional manufacturing of complex IN718 geometries is challenging. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) because of its potential to produce near-perfect parts at a low cost when working …
Experimental Investigation Of Effect Of Support Structure Geometry On The Microstructure And Metallurgical Properties Of In718 Parts Fabricated By Selective Laser Melting, Sourabh Hemant Thakare
Experimental Investigation Of Effect Of Support Structure Geometry On The Microstructure And Metallurgical Properties Of In718 Parts Fabricated By Selective Laser Melting, Sourabh Hemant Thakare
Mechanical and Aerospace Engineering Theses
Additive Manufacturing is a modern manufacturing technique that provides extreme design freedom and the ability to manufacture multiple parts with high complexities at the same time. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) due to its ability to provide near-perfect parts at low cost while being able to work with a wide range of materials. In SLM, the part is manufactured, layer-by-layer, by melting and solidification of powder material under controlled inert conditions. The fabrication of complex geometries is not possible without proper allocation of support structures for the part, which keeps …
Heat Transfer Measurements And Enhancement For Materials And Processes In Polymer Extrusion Based Additive Manufacturing, Hardikkumar Mangaldas Prajapati
Heat Transfer Measurements And Enhancement For Materials And Processes In Polymer Extrusion Based Additive Manufacturing, Hardikkumar Mangaldas Prajapati
Mechanical and Aerospace Engineering Dissertations
Additive manufacturing (AM) is a burgeoning method for manufacturing over the subtractive manufacturing methodologies. Among the various method of polymer additive manufacturing the fused deposition modeling (FDM) also known as 3D printing is the most popular technique. In this technique, a rastering extruder dispenses a thermoplastic material on to a bed at a temperature greater than its glass transition temperature to build the part. Due to the additive nature of the process, AM introduces several challenges related to functional properties such as strength, thermal conductivity, etc of the eventual part. Measurement of thermal conductivity of additively manufactured polymer samples in …
Material Characterization And Fracture Prediction Of Fdm Printed Parts, Sanchita Sheth
Material Characterization And Fracture Prediction Of Fdm Printed Parts, Sanchita Sheth
Mechanical and Aerospace Engineering Theses
In order to take advantage of the design freedom that Additive Manufacturing offers, most applications require reliable material characterization. This can ensure that a design performs within its environment and life requirements. This work discusses two models. One investigates the raster angle dependency of stiffness properties and the other numerically predicts fracture in Fused Deposition Modeling (FDM) printed polymer parts. Pre-processing of FDM geometry was done in Abaqus CAE (SIMULIA TM). FEA and post-processing was done in BSAM, which is a damage prediction software developed for composites. BSAM uses a regularized extended finite element approach of Discrete Damage Modeling. In …
Design And Optimization Of Additively Manufactured Heat Sink And Heat Spreader For Microelectronics Cooling, Aditya Krishna Ganesh Ram
Design And Optimization Of Additively Manufactured Heat Sink And Heat Spreader For Microelectronics Cooling, Aditya Krishna Ganesh Ram
Mechanical and Aerospace Engineering Theses
High performance cooling is a critical requirement for modern microprocessors that generate large amounts of non-uniformly distributed heat. Metal heat spreaders and heat sinks have been traditionally used for thermal management. While the design of these components has traditionallly been restricted by manufacturability, in recent years, additive manufacturing has offered the capability to manufacture almost any design. This work analyzes and optimizes the performance of an additively manufactured heat sink and heat spreader. Computational heat transfer simulations were carried out to understand the variation of chip temperature and pressure drop for various designs. Discussion of key findings include the thermal …
Characterization Of 3d Printed Pla With The Help Of Mechanical, Di-Electric And X-Ray Diffraction Techniques, Sai Sri Nidhi Munaganuru
Characterization Of 3d Printed Pla With The Help Of Mechanical, Di-Electric And X-Ray Diffraction Techniques, Sai Sri Nidhi Munaganuru
Mechanical and Aerospace Engineering Theses
Additive manufacturing (AM) revolutionized many industries, i.e., Automotive, Biomedical, Aerospace and Defense. As opposed to traditional manufacturing methods, a part is manufactured layer by layer from 3D CAD models in AM. Though the vision of AM is impressive, there are many challenges that are hindering the widespread use of these complex parts. One of the main challenges is its strength that varies with different manufacturing parameters. We are going to investigate the effect of build parameters on the mechanical, electrical and crystalline properties of the additively manufactured heterogeneous material system. The goal of the thesis is to find a correlation …
Process Calibration For Elastically Scaled 3d Printed Models Using Fused Deposition Modeling, Edgar Bernardo Mares
Process Calibration For Elastically Scaled 3d Printed Models Using Fused Deposition Modeling, Edgar Bernardo Mares
Mechanical and Aerospace Engineering Theses
With the increase in additive manufacturing capabilities the use of 3D printed models characterize a critical point for evaluating aerodynamic and aeroelastic properties on aircraft configuration. An experimental and computational approach beginning with elastically scaled 3D printed models enables for a case to be defined, developed, and extracted to match aeroelastic test behavior. The basis of this work is supported by aeroelastic tailoring and scaling methods in the application of 3D printed models. To accomplish this, stiffened 3D printed plates are scaled from elastically scaled 3D printed models for stiffness through geometric configurations, different build orientations, and bead thickness as …
Enhancing Tensile Strength Of Fdm Parts Using Thermal Annealing And Uniaxial Pressure, Rhugdhrivya Rane
Enhancing Tensile Strength Of Fdm Parts Using Thermal Annealing And Uniaxial Pressure, Rhugdhrivya Rane
Mechanical and Aerospace Engineering Theses
Additive manufacturing has been a revolutionary and disruptive technological development in the field of design and manufacturing with Fused deposition modelling (FDM) being at the forefront of this technology. But it is seen that parts printed using FDM suffer from an inherent deficiency of weak tensile strength in the out of plane direction (z-direction) thus limiting their application. This issue of weak z-direction strength is due to the weak Inter-bead bond strength of adjacent polymer interfaces. The purpose of this work is to increase this Inter-Bead bond strength thus increasing the overall tensile strength of the part. In this work, …
A Study Of Effect Of Bond Length On Bond Strength Using Transient Heat Transfer Analysis, Junaid Mohamed Baig
A Study Of Effect Of Bond Length On Bond Strength Using Transient Heat Transfer Analysis, Junaid Mohamed Baig
Mechanical and Aerospace Engineering Theses
It is important to understand the mechanical properties of the bonding between the adjacent layers of 3D printed parts build by fused deposition modeling. The bonding process is highly nonlinear and depends on various geometrical and thermal process parameters. This work aims to quantify the degree of bonding by calculating bond potential between the extruded layers using finite element heat transfer analysis. Successive transient analysis were carried out using this model by constantly updating the boundary conditions and geometric model during the deposition of the extruded bead. Temperatures at critical points were calculated over a period to calculate the bond …
Predicting Mechanical Behavior Of 3d Printed Structures Using Mechanics Of Composites And Fracture, Megha Tangri
Predicting Mechanical Behavior Of 3d Printed Structures Using Mechanics Of Composites And Fracture, Megha Tangri
Mechanical and Aerospace Engineering Theses
Recently, additive manufacturing, or 3D printing as it is more commonly called, has taken a big leap in the manufacturing industry. This technology is rapidly moving from prototyping to manufacturing using metals, polymers, concrete and even composites. Unlike subtractive methods of manufacturing, additive manufacturing can be used to manufacture parts with highly directional mechanical properties. This research focuses on predicting tensile failure of 3D printed polymer structures in different raster orientations using composites lamination theory. Previously it was found experimentally that tensile strengths of 3D printed specimens decrease when raster orientations changes from 0° to 90°. The proposed model developed …
On The Development And Integration Of Pneumatic Extrusion Module And A Methodology To Identify Process Parameters For Additive Manufacturing Using Machine Learning, Kashish Dhal
Mechanical and Aerospace Engineering Theses
Commonly used additive manufacturing platforms have a single extrusion module based on Fused Filament Fabrication (FFF) and their processing software generates G-Codes for this FFF module using defined process parameters. These platforms and software do not accommodate different processing modules such as viscous extruders or Direct Ink Writing (DIW). This research is focused on the development of a Pneumatic Extrusion Module (PEM) capable of dispensing viscous materials such as gels or slurries controlled through a digital pneumatic valve. A PEM is developed, integrated and its performance is evaluated on a multi-modality additive manufacturing platform in the MARS Lab. The operation …
Additive Manufacturing Process Investigation For The Fabrication Of Composite Scaffolds For Soft Tissue Application, Parimal Patel
Additive Manufacturing Process Investigation For The Fabrication Of Composite Scaffolds For Soft Tissue Application, Parimal Patel
Mechanical and Aerospace Engineering Theses
Additive manufacturing has been investigated and employed in the bio-medical domain for the fabrication of various devices and scaffolds. In various soft tissue engineering applications, multi-functional multi-material scaffolds are required for cell proliferation, structural integrity, bio-compatibility and tissue regeneration. In this research, an additive manufacturing methodology is developed to allow the fabrication of bio-composite scaffolds using a multi-modality in-house built platform. The researched materials for printing are Poly-L-Lactic Acid (PLLA) and a newly developed photo-curable radiopaque polymer called Rylar (Poly glycerole sebacate fumarate gadodiamide) mixed with a cross-linking agent Poly (Ethylene glycol) diacrylate (PEGDA). The developed methodology uses a Fused …
A Design Methodology For Continuous Fiber Additive Manufacturing Using Advanced Computer Aided Engineering Techniques, Nicholas Venter
A Design Methodology For Continuous Fiber Additive Manufacturing Using Advanced Computer Aided Engineering Techniques, Nicholas Venter
Mechanical and Aerospace Engineering Theses
A design methodology for Continuous Carbon Fiber Additive Manufacturing (CCFAM) developed using Computer Aided Engineering (CAE) techniques takes advantage of both the mechanical strength of composite materials and the Fused Filament Fabrication (FFF) method. By performing topology optimization and Finite Element Analysis (FEA) on a load-bearing part, engineers can design much lighter optimized parts that are just as strong as those produced using FFF. This weight reduction is achieved by relying on the mechanical strength of continuous carbon fibers printed alongside a traditional thermoplastic matrix. The FFF additive manufacturing method enables the production of complex shapes, which can match the …
Towards The Fabrication Of Bioresorbable Constructs With Customized Properties Using Additive Manufacturing, Prashanth Ravi
Towards The Fabrication Of Bioresorbable Constructs With Customized Properties Using Additive Manufacturing, Prashanth Ravi
Mechanical and Aerospace Engineering Dissertations
Additive Manufacturing (AM) has been employed to fabricate medical constructs for over two decades. This dissertation investigates the effects of AM process parameters on raster level geometric features and structural properties of bioresorbable constructs. The development of an open architecture custom multi-process 3D printer employed for fabricating bioscaffolds and test structures is discussed. Bioresorbable polymers including a newly synthesized radiopaque polymer, poly (glycerol sebacate fumarate) gadodiamide (Rylar) and medical grade poly-L-lactic acid (PLLA) were investigated. In the first part, the effects of process parameters on raster geometry were investigated to aid in the fabrication of structures with improved geometric features …
Development Of An Advanced Geometry Toolkit Framework For Fitting Complex Topology-Optimized Mesh Structures, Harshit Girishkumar Jani
Development Of An Advanced Geometry Toolkit Framework For Fitting Complex Topology-Optimized Mesh Structures, Harshit Girishkumar Jani
Mechanical and Aerospace Engineering Theses
Additive Manufacturing is playing a significant role in developing complex geometries which are not possible by conventional Manufacturing Processes. Topology optimization is playing key a role in deciding conceptual design for additive manufacturing. The output of topology optimization is rough and noisy surfaces. Fitting these surfaces poses challenging task to a designer as it is a tedious and a time-consuming process. The main aim of this research is to automate the process of smoothing noisy meshes. In this research work, I have developed algorithms in MATLAB to create NURBS (Non-Uniform B-Spline) surface patches from given a set of control points. …
Design Optimization Of Race Car Steering Knuckle For Additive Manufacturing, Yobani Martinez
Design Optimization Of Race Car Steering Knuckle For Additive Manufacturing, Yobani Martinez
Mechanical and Aerospace Engineering Theses
Additive manufacturing enables increased geometric complexity in structural configuration compared with conventional manufacturing methods. A Physics-first Computer Aided engineering (CAE) process beginning with structural topology optimization enables engineers to take advantage of this increased geometric design freedom. This work develops and demonstrates the steps and tools necessary to realize complex design configuration for additive manufactured. This report looks at the race car steering knuckle using the UTA FSAE upright as a case study. The stiffness driven upright component design is executed using topology optimization and NURBS based surface modeling tools. The topology optimization model is developed for 3 different load …
Manufacturing And Characterization Of A 3d-Printable, Antibacterial, Magnesium Oxide Nanoparticles Reinforced Abs Filament, Saket Thapliyal
Manufacturing And Characterization Of A 3d-Printable, Antibacterial, Magnesium Oxide Nanoparticles Reinforced Abs Filament, Saket Thapliyal
Mechanical and Aerospace Engineering Theses
This research work consists of two phases. In phase one it is intended to manufacture an antibacterial 3D printable filament by extruding a solid state mixture of (MgO) nanoparticles (NPs) and Acrylonitrile Butadiene Styrene (ABS) pellets. A single screw extruder was used to extrude ABS pellets containing 0, 0.5, 1, 2 and 4 wt. % MgO NP. This phase deals with manufacturing and testing the filament for mechanical properties, antibacterial properties and 3D printability. On one hand tensile strength, ductility and 3D-printabiliy were observed to decrease with increasing concentrations of MgO NP in ABS matrix, on the other hand the …
Slicing Algorithm For Complex Contour Generation From Coarse Meshed Iso-Surface Data, Divya Hareshkumar Shukla
Slicing Algorithm For Complex Contour Generation From Coarse Meshed Iso-Surface Data, Divya Hareshkumar Shukla
Mechanical and Aerospace Engineering Theses
Finite element based topology optimization is used to develop complex geometric configurations for additive manufacturing. Complex coarse-meshed Iso-surface data is extracted from topology optimization results and smooth mathematical geometry must be fit to that data in order to accomplish further design development. To accomplish this geometry fitting, cross-section data must be extracted at specific locations. The stereo lithography (STL) file format is a triangular mesh format which can be developed using 3D CAD Software and is widely used for additive layer manufacturing processes. The main aim of this research work is to generate cross-section contours using a nearest tail-to-head distance …
Effect Of Manufacturing-Induced Defects And Orientation On The Failure And Fracture Mechanism Of 3d Printed Structures, Amit Khatri
Mechanical and Aerospace Engineering Theses
Additive manufacturing is a rapidly growing cutting edge technology. Number of experimental studies have shown that strength of product manufactured by additive Fused Deposition Method (FDM) is influenced by different processing parameters involved during manufacturing. This thesis work presents experimental and theoretical investigation of mechanical behavior of ABS material fabricated with variation in some of process parameters such as Axis Orientations, Raster Orientation, Infill Percentage, Layer Height and Number of Shells. Different experiments were designed to understand the basics of 3D printing manufacturing and to characterize the mechanical behavior of 3D printed structures. This study helps to understand, how different …
Investigation Of Additive Manufacturing Using Industrial Robots, Matt Heuser
Investigation Of Additive Manufacturing Using Industrial Robots, Matt Heuser
Mechanical and Aerospace Engineering Theses
Conventional additive manufacturing platforms are controlled using G-code, a numerical control language used to define the process parameters and move- ment of the print head. First, a digital model of the desired shape is created using 3-D computer graphics software. Then the model is analyzed by software tools that generate the necessary G-code instructions to be used by a 3-D printer to produce the desired object. The goal of this research is to lay the foundation and develop the necessary tools to 3-D print custom objects based on the viscous extrusion process using industrial robots. The first task is to …
Additive Manufacturing Methodologies For Multi Process And Multi Material Scenarios, Tushar Saini
Additive Manufacturing Methodologies For Multi Process And Multi Material Scenarios, Tushar Saini
Mechanical and Aerospace Engineering Theses
Additive Manufacturing processes have been developing and continuously improving but are primarily constrained to single materials, albeit some commercial multi extrusion 3D printers do exist where by it is possible to print with multi-colored fluidic polymers or at most two filaments of the same type. 3D printing an object with volumetric varying properties requires manual modification of the G-Code, not a feasible option considering the average size of G-Code generated by the slicing software. This research focuses on developing a post processing methodology that modifies the large G-Code files generated by the slicing software according to user requirements. The proposed …