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Shweta Gupta thesis.pdf (6.82 MB)

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The Constitutive Behavior of Copper at High Strain Rate as Determined by the Free Expansion Ring Test

Gupta, Shweta
http://rave.ohiolink.edu/etdc/view?acc_num=osu1366200117

Abstract Details

2013, Master of Science, Ohio State University, Mechanical Engineering.
Study of deformation of materials at high strain rate is important to many industries. Several techniques exist to characterize materials at high strain rates but all of them have their limitations. The ring expansion technique is explored in this thesis. This technique can augment the scope of research in this field. The introduction of Photonic Doppler Velocimetry (PDV) offered measurement of the velocity of the ring in this technique with higher temporal resolution, reliability and portability. But quantitative analysis of the data from the PDV was a problem, which has been addressed in this thesis. A MATLAB code is developed which analyzes the signal from PDV with minimum user intervention and generates stress-strain plots from the experiments and saves the required data automatically. Extraction of the signal frequency from the raw PDV data is done by taking discrete time short time fourier transform (STFT) of the data and then fitting a Gaussian curve to the power spectral density sub-matrix at each time step. Fitting of the velocity-time graph is necessary to calculate acceleration of the ring to obtain flow stress in the ring. Power law of second degree, linear fit, quadratic fit and cubic fit were tried and power law fit was finally used in the code. OFHC copper is tested using the ring expansion technique with aluminum wire and urethane as actuator. Results from the experiments are presented and it can be shown that stress increases with increasing strains. It can also be shown that high stresses are obtained if higher peak velocities are achieved. But it is difficult to comment about the strain rate sensitivity of the material at this stage. Johnson Cook and Zerilli Armstrong constitutive models are fitted to the experimental data and it can be concluded that one constitutive law is unable to describe the nature of the material in the conditions present in this technique.
Glenn Daehn (Advisor)
Anthony Luscher (Advisor)
117 p.
Engineering; Materials Science; Mechanical Engineering

Recommended Citations

Citations

  • Gupta, S. (2013). The Constitutive Behavior of Copper at High Strain Rate as Determined by the Free Expansion Ring Test [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366200117

    APA Style (7th edition)

  • Gupta, Shweta. The Constitutive Behavior of Copper at High Strain Rate as Determined by the Free Expansion Ring Test. 2013. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1366200117.

    MLA Style (8th edition)

  • Gupta, Shweta. "The Constitutive Behavior of Copper at High Strain Rate as Determined by the Free Expansion Ring Test." Master's thesis, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366200117

    Chicago Manual of Style (17th edition)

osu1366200117
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© 2013, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.