Structures and Materials Commons^™

Advancing Sensing And Structural Health Monitoring Of Non-Conventional Space Structures, Scott Bender

Doctoral Dissertations and Master's Theses

Future lunar and deep-space missions will require new structural concepts that reduce mass while maintaining reliability. Two technologies that have received significant attention are inflatable habitats and additively manufactured structures; however, challenges remain in their characterization, validation, and long-term monitoring. This dissertation investigates methods to improve the testing and sensing of these non-conventional aerospace structures through the use of advanced photogrammetry and embedded distributed fiber-optic sensors. A color-filtering digital image correlation technique was developed to isolate orthogonal strain directions in woven inflatable structures, providing improved characterization of biaxially loaded softgoods. In addition, methods were developed to embed distributed fiber-optic sensors …

Made On Mars: Design And Manufacturing Of Structural Polymer-Regolith Composites, Pailey M. Vitale

Williams Honors College, Honors Research Projects

Human exploration of Mars is constrained by harsh environmental conditions and the prohibitive cost of transporting materials from Earth. Long-term sustainability requires the local production of mechanical and structural components using resources available on Mars, thereby minimizing payload mass. This project investigates polymer–regolith composites derived from atmospheric CO₂ and mineral-rich regolith as a pathway toward in-situ manufacturing. These composites, when compatible with additive manufacturing, could replace imported plastics, enable on-demand fabrication, and support closed-loop recycling systems. The objective is to design and evaluate polymer–regolith composites that maintain mechanical integrity and environmental resistance under Martian conditions, including extreme temperature swings, radiation …

Fused Filament Fabrication Additive Manufacturing Of 17-4 Ph Stainless Steel: Process–Structure–Property Relationships In Magnetic Materials, Maanav Patel

Theses and Dissertations

Additive manufacturing (AM) enables the fabrication of complex metallic components through layer-by-layer processing directly from digital models. Among AM techniques, material extrusion–based processes such as fused filament fabrication (FFF) provide an accessible method for producing metal parts using filament feedstocks composed of metal powders and polymer binders. When applied to precipitation-hardening stainless steels such as 17-4 PH, the processing route and heat treatments can influence the resulting microstructure and functional properties. This work investigates the magnetic behavior of 17-4 PH stainless steel fabricated using FFF and evaluates how heat treatment conditions influence measured magnetic properties. Samples were produced and analyzed …

Design For Additive Manufacturing: Simultaneous Optimization Of Structural Integrity And Minimal Support Structures, Naresh Ahuja

Doctoral Dissertations and Master's Theses

This dissertation addresses two core challenges limiting the widespread application of Topology Optimization (TO): the difficulty in fabricating its complex designs, especially for Additive Manufacturing (AM), and its significant computational costs. It develops a unified design framework that directly embeds AM constraints such as overhang angles and build direction into robust TO formulations. To enhance manufacturability, two distinct methodologies are proposed. Firstly, a Solid Isotropic Material with Penalization (SIMP) framework introduces a three-stage robust optimization algorithm. Secondly, the Geometric Projection Topology Optimization (GPTO) method inherently integrates overhang constraints by controlling individual geometric components and their inclined angles relative to a …

Embeddable Multi-Material Wireless Micro-Sensors Utilizing Additive Manufacturing And Enhanced Microstructure, Nicholas Reed

Doctoral Dissertations and Master's Theses

The development of embeddable, multi-material wireless microsensors offers transformative potential for structural health monitoring (SHM) in aerospace applications. This work integrates additive manufacturing (AM) techniques with advanced microstructural design to produce flexible, high-resolution sensors that can be directly embedded into polymer substrates. By utilizing the vat photopolymerization process, customized embedded sensors are seamlessly integrated into polymer AM structures. These sensors are then continuously refined, targeting increases in performance, both internal and external. Microstructural enhancements are explored to modify the rheological properties of the fabricated embedded sensing channels and enhance the adhesive bonding between the embedded sensor and the AM structure. …

In-Situ Defect Detection In Selective Laser Melting Using Convolutional Neural Networks, Ethan Gaigalas

Master's Theses

This thesis develops and trains a convolutional neural network (CNN) to classify defects in metal parts produced by selective laser melting (SLM) using acoustic emission (AE) data. The model successfully identified porosity and standard build layers with high accuracy but consistently struggled to classify lack of fusion (LOF) defects, regardless of input type, normalization, or class count. These results suggest that while AE signals contain distinguishable features for certain defect types, LOF signals may be too subtle or inconsistent for reliable detection. The study addresses the ongoing challenge of in-situ quality monitoring in metal additive manufacturing, where defects like cracks, …

Exploring Metal Additive Manufacturing In Martian Atmospheric Environments, Zane Mebruer

Mechanical Engineering Undergraduate Honors Theses

On-surface manufacturing is key to the success of a planetary colonization, especially that of Mars. However, traditional subtractive manufacturing processes are equipment, energy, and material intensive, meaning novel additive manufacturing (AM) processes must be pursued for this end. Selective laser melting, one of the most effective and versatile AM methods, would be incredibly beneficial to a Martian mission but requires an artificial argon atmosphere to create effective parts. The purpose of this study was to examine if carbon dioxide, the gas that makes up over 95% of Mars’ surface atmosphere, would be a sufficient substitute for argon in SLM fabrication. …

The Effect Of Atomic Oxygen On Additively Manufactured Materials, Ryan Grogan

Master's Theses

Additive manufacturing (AM) is a rapidly developing manufacturing method utilized in fields such as the aerospace industry. In-space AM is a technology of interest for the future of spaceflight, including on-orbit manufacturing. However, AM materials are subject to defects that may impact their performance in space-based applications. How these defects change the material’s reaction to the space environment, specifically atomic oxygen (AO), has only recently been explored. AO is a highly corrosive, dominant constituent in low Earth orbit that causes continuous erosion of spacecraft surfaces. The effect of AO on various AM materials is investigated in this thesis. Stainless steel, …

A Comparison Of Beamforming Characteristics In Isotropic And Composite Plate Structures For Use In Structural Health Monitoring, Sarah Ketchersid

Doctoral Dissertations and Master's Theses

Structural health monitoring in plate-like simple structures using phased array beamsteering of guided Lamb waves is useful in damage detection and evaluation efforts. Lamb waves can be effectively used for beamsteering using a linear array. The experimentation primarily focuses on beamsteering in the aluminum panel, which involves developing a simulation based on extracted data to visualize the dispersion of waves across the panel. By evaluating parameters such as slowness, velocity, and amplitude direction and variation for a specific metallic plate, the wavefront generated by a single wave source can be represented as a function of propagation angle and distance from …

Short Strand Carbon Fiber Reinforced Polylactic Acid Filament For Additive Manufacturing, Dale Chenoweth, Lukas Seggi, Luke Phillips

Williams Honors College, Honors Research Projects

In this design project, the additive manufacturing filament of short strand carbon fiber (SSCF) reinforced polylactic acid (PLA) composite was developed. The micro-size, precision cut SSCFs were mixed with the PLA pellets through a melting homogenization process. Through this process the composite material block is cut and divided into pieces for ease of pelletizing. The material block pieces are then pelletized to be fed through the single screw extruder to develop the SSCF-PLA composite filament. The SSCF-PLA filaments were manufactured with a varying amount of SSCF ranging from 0.5% to 10% of the material block's weight. Development of a 1% …

Improving The Tensile Mechanical Properties Of Direct Energy Deposited (Ded) Inconel 718 Aircraft Components Using A Standard Heat Treatment, Spencer Vincent Flynn

Materials Engineering

This project aimed to improve the mechanical properties of as-printed additively manufactured Inconel 718 samples using a heat treatment usually used for cast and wrought Inconel 718. The mechanical properties sought to be optimized were yield strength, ultimate tensile strength, elongation, and reduction in area. The property goals were to match or exceed those of cast and heat treated Inconel 718. Wire-fed electron beam direct energy deposition (DED) was used to manufacture the samples, which were then heat treated using the AMS 5663 standard in an inert atmosphere. The samples were then tested in tension to obtain data on their …

Additively Manufactured Lenses For Modulating Guided Waves In Laminated Composites, Hajar Righi

Theses and Dissertations

Composite materials have increasingly been used as an alternative to metals and other isotropic materials for primary structural components in aerospace industries. Unlike traditional isotropic materials, composite materials are known to have complex internal microstructures. Therefore, it is essential to develop methods for the inspection, evaluation, and monitoring of composite materials. Ultrasonic-guided waves and, more precisely, Lamb waves have proven to be an efficient and accurate technique for the non-destructive testing. Since guided waves are dispersive and multimodal, it is important to develop a practical method to manipulate Lamb waves to achieve better structural health monitoring and non-destructive inspection results. …

Manufacturability And Analysis Of Topologically Optimized Continuous Fiber Reinforced Composites, Jesus A. Ferrand

Doctoral Dissertations and Master's Theses

Researchers are unlocking the potential of Continuous Fiber Reinforced Composites for producing components with greater strength-to-weight ratios than state of the art metal alloys and unidirectional composites. The key is the emerging technology of topology optimization and advances in additive manufacturing. Topology optimization can fine tune component geometry and fiber placement all while satisfying stress constraints. However, the technology cannot yet robustly guarantee manufacturability. For this reason, substantial post-processing of an optimized design consisting of manual fiber replacement and subsequent Finite Element Analysis (FEA) is still required.

To automate this post-processing in two dimensions, two (2) algorithms were developed. The …

In-Situ Monitoring Of Additive Manufacturing Using Digital Image Correlation, Martina Jani

Doctoral Dissertations and Master's Theses

Advances in additive manufacturing over the past decade have led to applications in multiple fields. In particular, additive manufacturing answers the need for high flexibility in designing complex structures, however, the rapid thermal fluctuations during processing lead to numerous defects and processing-induced residual stresses. In this research, an in-situ approach using Digital Image Correlation (DIC) is developed to monitor the deformation during the processing, and thereby analyze the formation of defects and residual stresses. DIC is a visual technique that compares the changes in speckle pattern in consecutive images of a specimen to determine the displacements and strains. This research …

Metallurgical And Thermal Processing Investigation Of Additively Manufactured Superalloys Jbk-75 And Nasa-Hr-1, Allyse Birken, Derek Noel

Materials Engineering

Aerojet Rocketdyne is investigating the use of directed energy deposition (DED), an additive manufacturing process, to reduce cost and lead time for manufacturing complex rocket engine components for their RS-25 engines. JBK-75 and NASA-HR-1, two Fe-Ni-base, age-hardenable (γ′) superalloys, are used for nozzle structural jackets and hot gas manifolds. Currently, these parts are produced using traditional forging or casting methods followed by intensive machining operations. Additionally, these alloys were designed for use in the wrought condition and require a different set of post-processing heat treatments when produced using DED due to their dendritic, segregated microstructure in the as-built condition. Homogenization …

Design, Validation, And Verification Of The Cal Poly Educational Cubesat Kit Structure, Nicholas B. Snyder

Master's Theses

In this thesis, the development of a structure for use in an educational CubeSat kit is explored. The potential uses of this kit include augmenting existing curricula with aspects of hands on learning, developing new ways of training students on proper space systems engineering practices, and overall contributing to academic capacity building at Cal Poly and its collaborators. The design improves on existing CubeSat kit structures by increasing accessibility to internal components by implementing a modular backplane system, as well as adding the ability to be environmentally tested. Manufacturing of the structure is completed with both additive (Fused Deposition Modeling …

Thermal Modeling Of Additive Manufacturing Using Graph Theory: Validation With Directed Energy Deposition, Jordan Severson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Metal additive manufacturing (AM/3D printing) offers unparalleled advantages over conventional manufacturing, including greater design freedom and a lower lead time. However, the use of AM parts in safety-critical industries, such as aerospace and biomedical, is limited by the tendency of the process to create flaws that can lead to sudden failure during use. The root cause of flaw formation in metal AM parts, such as porosity and deformation, is linked to the temperature inside the part during the process, called the thermal history. The thermal history is a function of the process parameters and part design.

Consequently, the first step …

Characterization Of Directed Energy Deposition Additively Manufactured Grcop-42 Alloy, Scott Landes

Electronic Theses and Dissertations

GRCop is an alloy family constructed of copper, chromium, and niobium and was developed by NASA for high heat flux applications. The first of its kind, GRCop-84, was specifically designed for the environments seen by channel cooled main combustion chamber liners. To further increase thermal conductivity while maintaining material strength characteristics, the percentage of alloying elements were cut in half and GRCop- 42 was developed. In recent years, NASA has successfully additively manufactured GRCop with comparable material characteristics to wrought GRCop using a Laser Powder Bed Fusion (L-PBF) process. Benefits of this process include fabrication of intricate cooling channels as …

Redesign Of Cubesat For Beam Charging, Kuba Preis

Industrial and Manufacturing Engineering

This paper is intended to be a study in the applications of the design freedom granted by additive manufacture in the design of a 1U CubeSat frame. The main loads experienced by a CubeSat are structural (during launch) and thermal (solar radiation). Beam charging is an emerging technology which involves charging a CubeSat using a laser beam. In this paper, a CubeSat frame was redesigned to account for the structural loads induced during launch and the thermal loads induced when beam charging. The thermal, weight, design, and structural requirements for a new CubeSat design were derived. The 1U CubeSat frame …

An Evaluation Of Ultrasonic Shot Peening And Abrasive Flow Machining As Surface Finishing Processes For Selective Laser Melted 316l, Rhys Gilmore

Master's Theses

Additive Manufacturing, and specifically powder bed fusion processes, have advanced rapidly in recent years. Selective Laser Melting in particular has been adopted in a variety of industries from biomedical to aerospace because of its capability to produce complex components with numerous alloys, including stainless steels, nickel superalloys, and titanium alloys. Post-processing is required to treat or solve metallurgical issues such as porosity, residual stresses, and surface roughness. Because of the geometric complexity of SLM produced parts, the reduction of surface roughness with conventional processing has proven especially challenging. In this Thesis, two processes, abrasive flow machining and ultrasonic shot peening, …

The Effects Of Varying Composition And Build Direction On Direct Metal Deposition Fabricated Inconel 718, Abigail P. Nilan, Jessica M. Fordham

Materials Engineering

Inconel 718 (IN718) is a popular wrought superalloy, and is currently being investigated for additive manufacturing (AM) applications in the aerospace industry. However, overaging and the presence of microcracks have caused a significant reduction in properties. The purpose of this study is to meet or exceed the mechanical properties of wrought IN718 by varying the composition and build direction of the AM alloy. Alternative compositions were selected with Oerlilon Metco’s Rapid Alloy Development (RAD) software, and differ in niobium content, which increases the fraction of the primary strengthening phase (γʺ). Direct metal deposition (DMD) was used to fabricate the samples, …

Investigation Of 2195 And 2219 Post Weld Heat Treatments For Additive Friction Stir Lap Welds, Matthew Champagne

LSU New Orleans Theses and Dissertations

To evaluate potential uses for friction stir welding in additive manufacturing, two separate parts were fabricated, one of 2195-T84 and the other 2219-T87, utilizing fixed pin techniques and additive lap welds. The parts were cut into samples, artificially aged and subjected to Rockwell hardness (HRB), Vickers hardness, micrographic photography, and metallographic imaging on both pre- and post- heat treatment. Additionally, tensile testing was performed on the heat-treated samples. A comparisons of test results showed a minimal increase in the yield strength of the 2195-T84 samples compared to as-welded tensile results obtained from a previous project. The ultimate tensile strength was …