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Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason Gerald Vogeler
Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason Gerald Vogeler
Department of Engineering Mechanics: Dissertations, Theses, and Student Research
Polycarbonate (PC) is a tough, transparent engineering thermoplastic. Its impact strength and ability undergo large plastic deformations without shatter make PC an ideal protective material for impact-resilient eyewear, aircraft windows and transparent armor. A good understanding of the response of this material to large deformations at high strain rates is critical for its utilization in these applications. To this end, a striker-less Kolsky bar device is employed in this work for the needed material characterization. The apparatus allow impulsive torsion and/or compression loadings with pulse durations sufficiently long for the plastic flow behavior to develop fully. Three new testing techniques …
Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason G. Vogeler
Kolsky Bar Experiment For High-Rate Large Deformations Of Polycarbonate, Jason G. Vogeler
Department of Engineering Mechanics: Dissertations, Theses, and Student Research
Polycarbonate (PC) is a tough, transparent engineering thermoplastic. Its impact strength and ability undergo large plastic deformations without shatter make PC an ideal protective material for impact-resilient eyewear, aircraft windows and transparent armor. A good understanding of the response of this material to large deformations at high strain rates is critical for its utilization in these applications. To this end, a striker-less Kolsky bar device is employed in this work for the needed material characterization. The apparatus allow impulsive torsion and/or compression loadings with pulse durations sufficiently long for the plastic flow behavior to develop fully. Three new testing techniques …
Anomalous Loss Of Toughness Of Work Toughened Polycarbonate, Shawn E. Meagher
Anomalous Loss Of Toughness Of Work Toughened Polycarbonate, Shawn E. Meagher
Department of Engineering Mechanics: Dissertations, Theses, and Student Research
Glassy polymers such as polycarbonate (PC) can be toughened through compressive plastic deformation. The increase in toughness is substantial, showing as much as a fifteen fold increase in the amount of dissipated energy during failure for samples compressed to 50% plastic strain. This toughness increase can be reversed through thermal aging at temperatures below the glass transition temperature (Tg = 147°C).
The combined effect of plastic compression and thermal aging has been studied using Charpy, Single Edge Notch Bending (SENB), and Compact Tension (CT) tests. The tests mapped the response of samples cut along different orientations relative to the …
Thermodynamically Consistent Large Deformation Constitutive Model For Glassy Polymers, Ashwani Kumar Goel
Thermodynamically Consistent Large Deformation Constitutive Model For Glassy Polymers, Ashwani Kumar Goel
Department of Engineering Mechanics: Dissertations, Theses, and Student Research
Polycarbonate(PC), like most glassy polymers when undergoing large deformations exhibits a very complex thermo-mechanical response. We look at PC as a model glassy polymer and examine its response to changes in loading rate, loading direction and temperature. We show that plastic flow in compression is accompanied by a change in the elastic response of PC from isotropic to anisotropic. This provides the necessity to introduce a new modeling method that can capture these changes. A finite deformation plasticity like thermodynamically consistent model is developed to capture this and the observed rate and temperature dependence. For this modeling method, we need …