Engineering Commons^™

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 …

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 …

Wireless Coupled Feed Structure For Additively Manufactured Conformal Antennas, Blake Roberts

Doctoral Dissertations and Master's Theses

Due to advancements in additive manufacturing, it is possible to create electromagnetic devices that can be conformally printed directly onto 3D surfaces using conductive inks and dielectric pastes. Instance, the traditional antenna radomes that had the purpose of protecting the antenna on its inside can now become the antenna itself. With the components on the surface of the structure, instead of inside if it, a direct feed line would require cutting through dielectric layers and creating a direct electrical connection, also called vertical interconnect access (VIA). Such interconnects are frequent sources of failures, especially in applications that are subject to …

A Design Flow For Additively Manufactured 3d Metasurface Antennas​, Justin Parkhurst

Doctoral Dissertations and Master's Theses

Metasurface (MTS) antennas are complex arrays consisting of hundreds or thousands of individual elements that each exert their own influence on the performance of the antenna. Due to this, the process of designing and developing a MTS antenna can be intensive in terms of both the time to understand the how these antennas operate and time running calculations that achieve optimal performance. Through the use of automation for geometry creation in ANSYS HFSS, the work involved in making a MTS antenna can be greatly simplified. The overall objective of this thesis is to reduce the burden of constructing a MTS …

Advanced Manufacturing And Dielectric Material Characterization Techniques For High-Temperature Mm-Wave Antennas, Seng Loong Yu

Doctoral Dissertations and Master's Theses

As traditional monitoring data sensors in high temperature environments such as gas turbine engines and aerospace applications are being replaced by wireless equivalents in recent years, there is a need for low-cost, low-time, and low-infrastructure alternatives to further push the state of the art. In this work, two aspects of high temperature materials in the above context are explored: (a) the development of advanced manufacturing techniques for high temperature materials that is lowcost, low-time, and low-infrastructure, and (b) the development of material characterization techniques that can be integrated with the manufacturing processes of high temperature materials. Additive manufacturing has been …

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 …