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Constitutive Modeling of Poly(Ethylene Terephthalate)

Venkatasubramaniam, Shyam
http://rave.ohiolink.edu/etdc/view?acc_num=osu1417444300

Abstract Details

2014, Master of Science, Ohio State University, Mechanical Engineering.
The ability to accurately computationally predict the end properties of Poly(Ethylene Terephthalate) (PET) based components is of immense use to the packaging industry to reduce product development and lifecycle costs. One activity being undertaken prominently by the industry is the development of PET bottles to maximize the shelf life of beverage-filled bottles. This thesis deals with the development of a material model of PET for use in finite element simulation of blow molding. The mechanical behavior of PET is highly non-linear with temperature dependence, strain-rate dependence, molecular weight (Inherent Viscosity – IV) dependence, strain-state dependence and the tendency when induced by strain to crystallize. Uniaxial compression experiments were conducted on PET samples to characterize the temperature, strain-rate and IV dependence of stress-strain characteristics. The temperature range for the tests was 363K to 383K, the (true) strain rates used were 0.1/s and 1/s and the IVs of samples used were 0.80, 0.86, 0.92 and 0.98. The Dupaix-Boyce (DB) model (Dupaix, 2003) is a complex physically-based material model which can capture the viscoelastic, hyperelastic and plastic aspects of polymer mechanical behavior. This model was fit to the compression test results. Furthermore, uniaxial tension tests were conducted to check the predictive capability of the compression fit DB model in tension. The model under-predicted stress in tension and a different set of constants had to be used to fit the initial portion of the DB model stress strain results to the experimental curves. The temperature range for the tension tests was the same as for the compression tests while the strain rates used were 0.05/s, 0.1/s and 0.425/s engineering strain rate. The IVs used were 0.80, 0.92 and 0.98. A major observation from the uniaxial tension tests was the inability of the DB model to capture drastic strain hardening associated with strain-induced crystallization. This hardening occurred at very large strains in uniaxial tension and not compression. The onset of this hardening and the magnitude of stress increase were highly dependent on the temperature and strain-rate. An algebraic model to capture this strain hardening was developed to be used with the DB model. The results from the modified model were studied and discussed.
Rebecca Dupaix (Advisor)
Brain Harper (Committee Member)
343 p.
Mechanical Engineering; Polymers
Constitutive Modeling; Poly Ethylene Terephthalate; Uniaxial; Compression; Tension; Dupaix-Boyce; Model; Strain-Induced Crystallization;

Recommended Citations

Citations

  • Venkatasubramaniam, S. (2014). Constitutive Modeling of Poly(Ethylene Terephthalate) [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417444300

    APA Style (7th edition)

  • Venkatasubramaniam, Shyam. Constitutive Modeling of Poly(Ethylene Terephthalate). 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1417444300.

    MLA Style (8th edition)

  • Venkatasubramaniam, Shyam. "Constitutive Modeling of Poly(Ethylene Terephthalate)." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417444300

    Chicago Manual of Style (17th edition)

osu1417444300
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