Aerospace Engineering Commons^™

Predicting Mechanical Behavior Of 3d Printed Structures Using Mechanics Of Composites And Fracture, Megha Tangri

Mechanical and Aerospace Engineering Theses - Archive

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 …

Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli

Electronic Theses and Dissertations

Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of process-structure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the …

Case Study: Cooling Channels For Material Testing Applications Using Laser Powder Bed Fusion, Benjamin M. Doane, Ryan P. O'Hara, K. Liu, Carl R. Hartsfield

Faculty Publications

Additive Manufacturing continues to gain a reputation as a key technology that will have a major impact on all aspects of mechanical engineering. The United States Air Force’s (USAF) Air Force Institute of Technology (AFIT), based in Dayton, Ohio, has expanded its AM-focused education and R&D capabilities with the purchase of a Laser Powder Bed Fusion system from Germany’s Concept Laser.

Direct Metal Laser-Sintered Stainless Steel: Comparison Of Microstructure And Hardness Between Different Planes, M. Ghasri-Khouzani, H. Peng, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microstructural analysis and micro-hardness measurements were performed on different planes of 316L stainless steel fabricated by direct metal laser sintering (DMLS) technique. A fine cellular network was observed within the steel microstructure, where morphology of most cells changed from columnar on XZ-plane (vertical section) to equiaxed on XY-plane (horizontal section). Correspondingly, morphology of most grains was found to alter from columnar for the XZ-plane to equiaxed in the case of the XY-plane. Moreover, X-ray diffraction (XRD) analysis revealed a fully austenitic structure for both the planes. The average micro-hardness value for the XZ-plane and XY-plane was insignificantly (≈ 3%) different, …

Design And Testing Of An Additively Manufactured Cubesat Structural Bus, Karson A. Roberts

Theses and Dissertations

Recent innovations in additive manufacturing and design capabilities have opened the door for more opportunities to integrate multiple functions into a structural de- sign. Specifically, 3D printing through advanced laser powder bed fusion of metal powder allows for the development and integration of advanced structures that were previously unachievable. The demonstration of these techniques on a small satellite results in a structural bus consisting of various external and internal features, increasing its functionality and capabilities beyond simply providing structural support. 3D printing a multi-functional CubeSat bus with these integrated features such as internal lattices and wiring tabs demonstrates a new …

Effects Of Manufacturing Process Variables On Ultrasonic Testing In Electron Beam Melted Ti-6al-4v, Andrew D. Durkee

Theses and Dissertations

Further research on validating additive manufacturing production quality is required before the realization of direct print-to-fly application of critical components. This research examines the response of ultrasonic testing as a function of various manufacturing variables in electron beam melted samples of Ti-6Al-4V. Four dimensionally identical blocks with 6 spherical voids at varying depths were manufactured using different combinations of stock powder, edge treatments, and void melting. Scans were completed on two sides of each specimen with the transducer focused on the mid-plane. Additionally, one specimen was scanned 6 times, with the focal plane adjusted for each scan to match the …

Analysis Of Additively Manufactured Injectors For Rotating Detonation Engines, Michael C. Waters

Theses and Dissertations

This research represents an experimental and computational analysis of additively manufactured injectors for Rotating Detonation Engines (RDEs) for use in rocket propulsion. This research was based on the manufacture and testing of existing injector element designs using additive techniques. The designs were modeled from geometries gathered from Sutton and Biblarz Elements of Rocket Propulsion [23]. The goal of this research was to characterize the viscous losses of each design based on the discharge coefficient. The designs were computationally simulated to gain insight to the flow characteristics using multiple sets of conditions for surface roughness and inlet pressure. The results were …

Towards The Fabrication Of Bioresorbable Constructs With Customized Properties Using Additive Manufacturing, Prashanth Ravi

Mechanical and Aerospace Engineering Dissertations - Archive

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 …

A Design Methodology For Continuous Fiber Additive Manufacturing Using Advanced Computer Aided Engineering Techniques, Nicholas Venter

Mechanical and Aerospace Engineering Theses - Archive

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 …

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Disk-shaped 316L stainless steel parts with various diameters and heights were additively manufactured using a direct metal laser sintering (DMLS) technique. Neutron diffraction was used to profile the residual stresses in the samples before and after removal of the build plate and support structures. Moreover, distortion level of the parts before and after the removal was quantified using a coordinate measuring machine (CMM). Large tensile in-plane stresses (up to ≈ 400 MPa) were measured near the as-built disk top surfaces, where the stress magnitude decreased from the disk center to the edges. The stress gradient was steeper for the disks …

Additive Manufacturing Of High Solids Loading Hybrid Rocket Fuel Grains, Stephen P. Johnson, Michael Baier, Ibrahim E. Gunduz, Steven F. Son

The Summer Undergraduate Research Fellowship (SURF) Symposium

Hybrid rocket motors offer many of the benefits of both liquid and solid rocket systems. Like liquid engines, hybrid rocket motors are able to be throttled, can be stopped and restarted, and are safer than solid rocket motors since the fuel and oxidizer are in different physical states. Hybrid rocket motors are similar to solid motors in that they are relatively simple and have a high density-specific impulse. One of the major drawbacks of hybrid rocket motors is a slower burning rate than solid rocket motors. Complex port geometries provide greater burning surface area to compensate for lower burning rates …

Design Optimization Of Race Car Steering Knuckle For Additive Manufacturing, Yobani Martinez

Mechanical and Aerospace Engineering Theses - Archive

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 …

Development Of An Advanced Geometry Toolkit Framework For Fitting Complex Topology-Optimized Mesh Structures, Harshit Girishkumar Jani

Mechanical and Aerospace Engineering Theses - Archive

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. …

Manufacturing And Characterization Of A 3d-Printable, Antibacterial, Magnesium Oxide Nanoparticles Reinforced Abs Filament, Saket Thapliyal

Mechanical and Aerospace Engineering Theses - Archive

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 …

Analysis Of Additively Manufactured Lattice Structures Using Finite Element Methods, Christopher A. Box

Theses and Dissertations

Additive Manufacturing (AM) processes are well known for their ability to fabricate parts with complex geometries. Lattice structures leverage this ability to create parts with high strength-to-weight ratio and other desirable structural qualities. This research presents a parameterized modeling tool using common Finite Element Analysis (FEA) and scripting software with which aggregated lattice structures can be analyzed, given different geometric properties and loading conditions. A full factorial Design of Experiments is run to explore the effects of various parameters on the strength of lattice structures. Experimental compressive strength results from three FDM-produced PLA lattices are discussed and compared to predictions …

Slicing Algorithm For Complex Contour Generation From Coarse Meshed Iso-Surface Data, Divya Hareshkumar Shukla

Mechanical and Aerospace Engineering Theses - Archive

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 - Archive

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 …

Development Of The Compact Jet Engine Simulator From Concept To Useful Test Rig, Henry H. Haskin

Mechanical & Aerospace Engineering Theses & Dissertations

Two Compact Jet Engine Simulator (CJES) units were designed for integrated wind tunnel acoustic experiments involving a Hybrid Wing Body (HWB) vehicle. To meet the 5.8% scale of the HWB model, Ultra Compact Combustor technology from the Air Force Research Laboratory was used. The CJES units were built and integrated with a control system in the NASA Langley Low Speed Aero acoustic Wind Tunnel. The combustor liners, plug—vane and flow conditioner components were built in-house at Langley Research Center. The operation of the CJES units was mapped and fixes found for combustor instability tones and rig flow noise. The original …

Investigation Of Additive Manufacturing Using Industrial Robots, Matt Heuser

Mechanical and Aerospace Engineering Theses - Archive

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 …

Effects Of Additive Manufacturing Methods On The Dynamic Properties Of 15-5ph Stainless Steel, Allison A. Dempsey

Theses and Dissertations

Experimental research was conducted to determine the dynamic properties and characterize the microstructure of 15-5PH Stainless Steel manufactured through Direct Metal Laser Sintering (DMLS) additive manufacturing (AM) processes and heat treated using common heat treatment protocols. A thorough understanding of the material's properties is necessary before such parts are utilized in an operational capacity. Of the five builds, two deviated significantly from the specified composition of 15-5PH stainless steel. The remaining three builds, possessing the desired composition and crystalline structure, were tested in compression and tension at two strain rates. Tension tests using a reflected wave and a momentum trap …

Surface Roughness Of Electron Beam Melting Ti-6al-4v Effect On Ultrasonic Testing, Evan T. Hanks

Theses and Dissertations

Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of Electron Beam Melted (EBM) additively manufactured Ti-6Al-4V. Additive Manufacturing (AM) is a developing technology with many potential benefits, but certain challenges posed by its use require further research before AM parts are viable for widespread use in the aviation industry. Possible applications of this new technology include, Aircraft Battle Damage Repair (ABDR), small batch manufacturing to fill supply gaps, and replacement for obsolete parts. The research presented here assesses the effectiveness of ultrasonic inspection in detecting manufactured flaws in EBM manufactured Ti-6Al-4V. EBM products are …

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 …

Additive Manufacturing Methodologies For Multi Process And Multi Material Scenarios, Tushar Saini

Mechanical and Aerospace Engineering Theses - Archive

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 …

Characterizing Strain Accumulation, Residual Stress, And Microstructure Of Additive Manufactured Materials, Hannah K. Woods, Todd A. Book, Catalina Parada, Michael D. Sangid

The Summer Undergraduate Research Fellowship (SURF) Symposium

Additive Manufacturing (AM) is a rapidly evolving fabrication technology beneficial for its cost-saving potential to produce complex, low-volume shapes. However, AM materials are currently limited to nonstructural applications due to variability in their structural integrity, particularly their fatigue lives. IN718, Ti64, and Al10MgSi specimens manufactured by Direct Metal Laser Sintering (DMLS) were characterized based on variation of post-processing techniques and build direction. To understand the impact of each variable, surface roughness, hardness, residual stresses, microstructure, and strain accumulation in response to Low Cycle Fatigue (LCF) were studied. The use of Electron Backscatter Diffraction (EBSD) provided grain orientation and grain size …

Characterization Of Laser Deposited Ti-6al-4v To Nb Gradient Alloys, Clincy Cheung

Materials Engineering

An alloy was fabricated with Ti-6Al-4V and Nb powder using laser deposition (LD) to form a compositional gradient. The gradient was deposited, starting with Ti-6Al-4V powder, onto a forged Ti-6Al-4V substrate in an Argon environment. Niobium (Nb) composition increased by 4-at.% with each layer deposited until the composition reached 100-at.% Nb. This process yielded steep thermal gradients and affected the microstructure and mechanical properties across the compositional gradient. To observe the microstructural changes in the alloy, an etched gradient was viewed with optical microscopy at 1000x, where the grain structure was observed to be an acicular α phase at 100-at.% …

The Design For Manufacturing And Assembly Analysis And Redesign Of An Aircraft Refueling Door Hinge Utilizing Additive Manufacturing, Kurt A. Schwarz

Doctoral Dissertations and Master's Theses

In this thesis, an aircraft door hinge assembly provided by Gulfstream Aerospace was analyzed following an established process called DFMA. The hinge was then redesigned to be additively manufactured, which is uncommon currently in industry for load bearing components. It was shown that the Design for Manufacturing (DFM) guidelines were inadequate when applied to the new technology of additive manufacturing (AM). This was primarily due to AM's unique and unprecedented manufacturing capabilities.

A conservative redesign approach was followed due to a limitation in current AM material properties and time available for analysis. Despite this, a significant improvement in weight reduction …

Does Material Choice Drive Sustainability Of 3d Printing?, Jeremy Faludi, Zhongyin Hu, Shahd Alrashed, Christopher Braunholz, Suneesh Kaul, Leulekal Kassaye

Dartmouth Scholarship

Environmental impacts of six 3D printers using various materials were compared to determine if material choice drove sustainability, or if other factors such as machine type, machine size, or machine utilization dominate. Cradle-to-grave life-cycle assessments were performed, comparing a commercial-scale FDM machine printing in ABS plastic, a desktop FDM machine printing in ABS, a desktop FDM machine printing in PET and PLA plastics, a polyjet machine printing in its proprietary polymer, an SLA machine printing in its polymer, and an inkjet machine hacked to print in salt and dextrose. All scenarios were scored using ReCiPe Endpoint H methodology to combine …

Deposition Thickness Modeling And Parameter Identification For Spray Assisted Vacuum Filtration Process In Additive Manufacturing, August Mark

Electronic Theses and Dissertations

To enhance mechanical and/or electrical properties of composite materials used in additive manufacturing, nanoparticles are often time deposited to form nanocomposite layers. To customize the mechanical and/or electrical properties, the thickness of such nanocomposite layers must be precisely controlled. A thickness model of filter cakes created through a spray assisted vacuum filtration is presented in this paper, to enable the development of advanced thickness controllers. The mass transfer dynamics in the spray atomization and vacuum filtration are studied for the mass of solid particles and mass of water in differential areas, and then the thickness of a filter cake is …