ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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Experimental procedures and data analysis of orthotropic composites

Description
Composite materials are widely used in various structural applications, including within the automotive and aerospace industries. Unidirectional composite layups have replaced other materials such as metals due to composites’ high strength-to-weight ratio and durability. Finite-element (FE) models are actively being developed to model response of composite systems subjected to a…

Composite materials are widely used in various structural applications, including within the automotive and aerospace industries. Unidirectional composite layups have replaced other materials such as metals due to composites’ high strength-to-weight ratio and durability. Finite-element (FE) models are actively being developed to model response of composite systems subjected to a variety of loads including impact loads. These FE models rely on an array of measured material properties as input for accuracy. This work focuses on an orthotropic plasticity constitutive model that has three components – deformation, damage and failure. The model relies on the material properties of the composite such as Young’s modulus, Poisson’s ratio, stress-strain curves in the principal and off-axis material directions, etc. This thesis focuses on two areas important to the development of the FE model – tabbing of the test specimens and data processing of the tests used to generate the required stress-strain curves. A comparative study has been performed on three candidate adhesives using double lap-shear testing to determine their effectiveness in composite specimen tabbing. These tests determined the 3M DP460 epoxy performs best in shear. The Loctite Superglue with 80% the ultimate stress of the 3M DP460 epoxy is acceptable when test specimens have to be ready for testing within a few hours. JB KwikWeld is not suitable for tabbing. In addition, the Experimental Data Processing (EDP) program has been improved for use in post-processing raw data from composites test. EDP has improved to allow for complete processing with the implementation of new weighted least squares smoothing options, curve averaging techniques, and new functionality for data manipulation.
ContributorsSchmidt, Nathan William (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2016
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Effect of Fiber Morphology on Tensile Properties of Polypropylene Cement Composites

Description
The main objective of this study is to investigate the effect of polypropylene fiber morphology on the tensile response of cementitious composites. Two proprietary polypropylene fibers manufactured by BASF – MAC 2200CB, a crimped monofilament macro fiber and MF40, a bundled multi filament polypropylene made up of 500 filaments,40-micron diameter…

The main objective of this study is to investigate the effect of polypropylene fiber morphology on the tensile response of cementitious composites. Two proprietary polypropylene fibers manufactured by BASF – MAC 2200CB, a crimped monofilament macro fiber and MF40, a bundled multi filament polypropylene made up of 500 filaments,40-micron diameter each were compared. The stiff structure and crimped geometry of MAC 2200 CB was studied in comparison with the multifilament MF40, which provide a higher surface area and a bundled fiber effect. Uniaxial tensile tests were performed on individual fibers to study fiber strength and failure pattern at three different gage lengths. The interaction of these 2 fibers with cement matrix was studied under varying strain rate, embedded fiber length and matrix mixes by a series of quassi - static fiber pullout tests. Unidirectional filament wound composite laminates were manufactures with the two fibers and only MF40 woven textiles were used to manufacture MF40 textile reinforced composites. The mechanical behavior of polypropylene fiber and textile reinforced cementitious composites subjected to static tensile loading with the effects of fiber type and dosage, textile weave and dosage, matrix formulations, processing techniques etc. is studied. Evolution of distributed cracking mechanism and local strain fields was documented using digital image correlation (DIC) and correlated with the tensile response and stiffness degradation. VIC 3D-7, commercial software developed by Correlated Solutions, Inc. was used to run the DIC analysis for the tensile tests on laminates. The DIC technique was further used for automated determination of crack density, crack spacing, and characterizing damage evolution.
ContributorsMehere, Himai Ashok (Author) / Mobasher, Barzin (Thesis advisor) / Dharmarajan, Subramaniam (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2017