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Ruofan Dissertation (1).pdf (7.68 MB)

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A Novel Methodology for Durability Assessment of Rubber Materials

Liu, Ruofan
http://orcid.org/0000-0002-5340-8988
http://rave.ohiolink.edu/etdc/view?acc_num=akron1525784654741047

Abstract Details

2018, Doctor of Philosophy, University of Akron, Polymer Engineering.
Rubber materials are often used under fatigue loading conditions. Traditional methods for fatigue behavior evaluation, i.e. S-N curves and Miner’s rule, have limitations in assessing rubber materials. This research investigated the fatigue behavior of styrene butadiene rubber (SBR) compounds using integration of several methods to obtain a full picture of rubber material fatigue in compounded and tire composite forms. Mechanical properties, viscoelastic properties, adhesion strength between rubber compounds and steel cords/PET fibers, and development of cracks in the bulk rubber materials have been studied. Overall, the residual strength method is used to model fatigue behavior of carbon black filled and silica filled SBR compounds and their composites with reinforcing fibers. Samples are subjected to repeated fatigue loading (i.e., non-zero mean stress) using different strain amplitudes, and then subjected to uniaxial constant crosshead rate, relaxation and creep tests to assess their residual strength and viscoelastic behaviors respectively. The residual strength results are compared with typical S-N curves. Initial relaxation rates, initial creep rates, asymptotic relaxation values, and secondary creep rates are plotted as functions of fatigue cycles number to understand the viscoelastic behaviors of carbon black and silica filled SBR compounds as affected by fatigue processes. When the tensile stiffness behavior of fatigued specimens was evaluated, it was noted that the stiffness vs. strain behavior which exhibited a monotonic decreasing-increasing behavior with the pristine specimens changed to a “dual-stiffness” condition, where the specimens went through a first (low) turning point as with the pristine samples, but then dropped off of a peak to go through a second softening stage, similar to the first softening stage of the pristine material. Molecular slippage and bond ruptures are the main factors affecting the physical properties of carbon black-filled compounds, while breakage and recombination of the filler are the key mechanisms affecting the silica-filled compounds during the fatigue process. Micro X-ray CT-scan tests were performed on both pristine and fatigued samples. Filler aggregation as well as crack development and progression were investigated as a function of fatigue cycles by using micro X-ray CT-scan. Cracks were observed in directions both parallel (mode I) and perpendicular (mode II) to the applied uniaxial tensile fatigue loads.
Erol Sancaktar, Professor (Advisor)
Kevin Cavicchi, Professor (Committee Chair)
Jiahua Zhu, Professor (Committee Member)
Sadhan Jana, Professor (Committee Member)
Wieslaw Binienda, Professor (Committee Member)
234 p.
Engineering; Materials Science; Polymer Chemistry; Polymers

Recommended Citations

Citations

  • Liu, R. (2018). A Novel Methodology for Durability Assessment of Rubber Materials [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525784654741047

    APA Style (7th edition)

  • Liu, Ruofan. A Novel Methodology for Durability Assessment of Rubber Materials. 2018. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1525784654741047.

    MLA Style (8th edition)

  • Liu, Ruofan. "A Novel Methodology for Durability Assessment of Rubber Materials." Doctoral dissertation, University of Akron, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525784654741047

    Chicago Manual of Style (17th edition)

akron1525784654741047
501
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This open access ETD is published by University of Akron and OhioLINK.