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Articles 1 - 8 of 8
Full-Text Articles in Structures and Materials
Advancing Sensing And Structural Health Monitoring Of Non-Conventional Space Structures, Scott Bender
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 …
Ti Nano Powder Speckle Pattern Creation And Use In Dic Of Zno Modified Single Carbon Fibers, James Matthew Harris
Ti Nano Powder Speckle Pattern Creation And Use In Dic Of Zno Modified Single Carbon Fibers, James Matthew Harris
Doctoral Dissertations and Master's Theses
As the use of composites continues to grow across aerospace, naval, automotive, construction, 3D printing, and other countless industries, so does the desire to continuously improve their mechanical properties. Improving the adherence of the fiber-matrix interface is one important step for amplifying the capabilities of composites. Work has been performed in modifying carbon fibers by growing zinc oxide (ZnO) nanorods in the fiber surface using a hydrothermal approach, increasing interfacial area and fiber-matrix friction. Macroscale evaluation has shown that the interfacial modification decreases the inter-ply movement and reduces the processing strains and residual stresses. To fully understand the mechanism taking …
Digital Image Correlation System Design, Verification And Analysis, Tyler Kraft, Matthew J. Riczo, Andrew Chong
Digital Image Correlation System Design, Verification And Analysis, Tyler Kraft, Matthew J. Riczo, Andrew Chong
Williams Honors College, Honors Research Projects
Two dimensional digital image correlation provides an accurate and effective way to capture strain data on test sections with unusual or oblique geometries. The system requires a camera to record video footage, alignment fixtures and software to convert the footage into strain values. The system works by capturing the video footage of a specific portion of the specimen and comparing the movement of selected pixels. This is all done in the software GOM Correlate and Tracker. This test document outlines the setup, procedure, and validation steps to fulfill this goal. The setup involves a camera, tripod, blue lighting, and laser …
In-Situ Monitoring Of Additive Manufacturing Using Digital Image Correlation, Martina Jani
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 …
Kinematics Of Inter-Ply Interfaces In Composite Manufacturing, Sandeep Chava
Kinematics Of Inter-Ply Interfaces In Composite Manufacturing, Sandeep Chava
Doctoral Dissertations and Master's Theses
The ubiquitous usage of polymer matrix composites in many applications demands a comprehensive understanding of composite interfaces and processing induced residual stresses, which critically affect both the manufacturing processes and the deformation mechanisms. Processing induced residual stresses are often responsible for causing warping, delamination, and dimensional instability in composite structures. This research includes new in-situ experimental approaches, cure cycle design, interface modification, and thermomechanical modeling for developing a fundamental understanding of the cure kinetics during composite manufacturing. Strains, ply-movement, and formation of defects are observed in-situ using digital image correlation (DIC) during the autoclave cure cycle for the first time. …
Using High Resolution Images To Investigate Fatigue Crack Initiation Of Alloys At The Microstructural Level, Michael P. Reinhold, Alberto Mello, Michael Sangid
Using High Resolution Images To Investigate Fatigue Crack Initiation Of Alloys At The Microstructural Level, Michael P. Reinhold, Alberto Mello, Michael Sangid
The Summer Undergraduate Research Fellowship (SURF) Symposium
Microstructural features within a material dictate the material’s mechanical behavior and lead to localized strains as the sample is deformed. In order to further understand structural failure, an improved understanding of how microstructural features influence failure is necessary. Fatigue is one common mode of failure for aerospace applications, and a better understanding of the conditions of crack initiation can provide information that ultimately may increase longevity of aerospace systems. This paper investigates the hypothesis that fatigue crack initiation for a cyclically loaded sample is correlated to areas of higher localized strain. The experiment was conducted using a Ti-6Al-4V sample subjected …
Identifying And Correcting Biases In Digital Image Correlation At Multiple Length Scales, Catalina Parada, Alberto W. Da Silva Mello, Michael D. Sangid, Hannah K. Woods, Samuel E. Otto
Identifying And Correcting Biases In Digital Image Correlation At Multiple Length Scales, Catalina Parada, Alberto W. Da Silva Mello, Michael D. Sangid, Hannah K. Woods, Samuel E. Otto
The Summer Undergraduate Research Fellowship (SURF) Symposium
Accurate strain measurement at grain and sub-grain levels is important to predict and understand crack initiation during fatigue of materials. During cyclic loading, low magnitude strain is accumulated in the material and any distortion in the images can lead to inaccurate strain measurements and false prediction of the material’s behavior. Digital Image Correlation (DIC) is a reliable tool used to measure strain localization by correlating images before, during, and after cyclic loading. DIC tracks the deformation of nano/micro-scale patterns placed on the surface of the specimens to determine strain fields. However, DIC software does not account for biases due to …
Set-Up Of Digital Image Correlation Apparatus, German A. Parada, Michael Sangid
Set-Up Of Digital Image Correlation Apparatus, German A. Parada, Michael Sangid
The Summer Undergraduate Research Fellowship (SURF) Symposium
Digital Image Correlation (DIC) is a valuable and customizable experimental technique employed to analyze localized strain regions on materials by tracking the displacement of points on the surface of the studied material under applied stress. To investigate materials behavior, it is vital to correctly set-up the DIC apparatus so work has been done to ready the equipment to start measurements on two distinct projects. On the first project, the fatigue crack behavior of a high-strength aluminum alloy will be studied by cyclic loading, testing necessary for the safe design of aircraft parts utilizing this novel alloy. DIC will be carried …