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Design, Fabrication, and Analysis of a Multi-Layer, Low-Density, Thermally-Invariant Smart Composite via Ultrasonic Additive Manufacturing

Pritchard, Joshua D
http://rave.ohiolink.edu/etdc/view?acc_num=osu1406284899

Abstract Details

2014, Master of Science, Ohio State University, Mechanical Engineering.
Smart materials are a class of materials that couple different regimes, such as thermal, mechanical, electrical, and magnetic. Shape memory alloys (SMAs) are classified as such due to their ability to couple the thermal and mechanical regimes. One particular type of SMA is nickel-titanium (NiTi), which can recover up to 8\% elastic strain. In this study, the large strain recovery of NiTi is used in the development of a metal matrix composite that exhibits low to near-zero coefficient of thermal expansion. This is done by utilizing the strain recovery of NiTi fibers to offset the expansion of the aluminum matrix in which they are embedded. The fabrication of this metal matrix composite is made possible through the use of ultrasonic additive manufacturing (UAM). Ultrasonic additive manufacturing combines ultrasonic welding with subtractive machining operations to create complex parts from dissimilar metals. The resulting parts can be made of similar or dissimilar materials. In UAM, 20kHz vibrations created by piezoelectric transducers are transferred to a textured steel horn, which presses a thin strip of metal to a substrate with a normal force in excess of 5000 Newtons. Under these conditions, the surface oxides and asperities are broken down, producing atomically clean faces on both pieces, allowing for pure metal-to-metal contact and instantaneous bonding to take place. Unique to UAM is its low-temperature, solid-state operation, which means no melting of the constituent materials takes place. This feature provides the unprecedented opportunity to embed materials that are thermally sensitive, such as SMAs. This study focuses on the fabrication and characterization of NiTi-Al UAM composites with an emphasis on developing a method of producing composite structures. Process parameters that were studied include securing the NiTi ribbons during fabrication, ensuring proper placement of the ribbons in the composite, and applying the necessary pre-stress to produce the appropriate recovery strain in the SMA. In addition, the weld parameters and the surface treatment of the NiTi ribbons were tested via fiber pull-out tests to quantify the bond strength between the fibers and matrix. Characterization of the composites was conducted to obtain experimental values for thermal diffusivity, electrical conductivity, and coefficient of thermal expansion (CTE). The CTE was measured in a thermal chamber by recording strain variations via strain gages over given temperature variations. The final focus of this study was an analysis between the experimental results from these methods and NiTi-Al composite characterization models.
Marcelo Dapino, PhD (Advisor)
Mark Walter, PhD (Committee Member)
156 p.
Engineering; Mechanical Engineering
ultrasonic additive manufacturing; UAM; shape memory alloys; SMA; metal matrix composite; MMC; smart material; coefficient of thermal expansion

Recommended Citations

Citations

  • Pritchard, J. D. (2014). Design, Fabrication, and Analysis of a Multi-Layer, Low-Density, Thermally-Invariant Smart Composite via Ultrasonic Additive Manufacturing [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406284899

    APA Style (7th edition)

  • Pritchard, Joshua. Design, Fabrication, and Analysis of a Multi-Layer, Low-Density, Thermally-Invariant Smart Composite via Ultrasonic Additive Manufacturing. 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1406284899.

    MLA Style (8th edition)

  • Pritchard, Joshua. "Design, Fabrication, and Analysis of a Multi-Layer, Low-Density, Thermally-Invariant Smart Composite via Ultrasonic Additive Manufacturing." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406284899

    Chicago Manual of Style (17th edition)

osu1406284899
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This open access ETD is published by The Ohio State University and OhioLINK.