A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite

Bibliographic Details
Main Author:	Sunny, George Padayatil
Language:	English
Published:	Case Western Reserve University School of Graduate Studies / OhioLINK 2011
Subjects:	Materials Science Mechanical Engineering High strain-rate bulk metallic glass HTPB rubbery polymer SHPB
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=case1295634962

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-case12956349622021-08-03T05:33:51Z A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite Sunny, George Padayatil Materials Science Mechanical Engineering High strain-rate bulk metallic glass HTPB rubbery polymer SHPB <p>High strain-rate tests are performed on LM-1 using a Split-Hopkinson Pressure Bar (SHPB) to investigate effects of L/D ratio and annealing. An ultra high-speed camera was also employed to record the deformation and failure processes of LM-1. The amorphous specimens exhibit a reduction in peak stress with reduced L/D ratio and failure at the specimen-insert interface, indicative of stress concentrations due to the difference in the specimen and insert diameters, while the annealed specimens exhibited extensive fragmentation. The stress concentrations in the specimen motivated simulations using LS-DYNA to design new inserts. A tapered insert design was chosen to reduce stress concentrations on amorphous and annealed specimens. Strain gages were also attached to as-cast specimens to determine the elastic stress-strain response. As-cast and annealed specimens with tapered inserts exhibit failure in the gage section, and a comparison of the peak stresses from quasi-static and pressure-shear plate-impact experiments to those in the current study indicate a negligible strain-rate sensitivity of LM-1.</p><p>Additional experiments are carried out using a modified SHPB to investigate the loading-rate sensitivity of notched LM-1 specimens. An ultra high-speed camera is employed to provide images synchronized with load-displacement traces from a high-bandwidth oscilloscope. No loading-rate sensitivity on the fracture toughness was observed. Experiments are also conducted to induce damage into notched LM-1 specimens without causing catastrophic failure; a damage zone is present in the specimens and slip-line fields are created which are consistent with those expected in an elastic-perfectly plastic material. Finally, experiments conducted to load previously damaged LM-1 samples indicate an increase in the fracture toughness and energy required to induce catastrophic failure. </p><p>Finally, high strain-rate compression experiments are conducted on a hydroxy-terminated polybutadiene (HTPB) polymer and its composite using another modified SHPB for testing of soft materials. Results from the experiments on HTPB polymer indicate a transition in the polymer between low and high strain-rate sensitivity at 2100/s, along with axial splitting at strain-rates above 3000/s. On the other hand, reduced rate-sensitivity is observed in the HTPB composite, most likely due to the presence of numerous interfaces between the glass beads and the polymer binder.</p> 2011-03-15 English text Case Western Reserve University School of Graduate Studies / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=case1295634962 http://rave.ohiolink.edu/etdc/view?acc_num=case1295634962 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Materials Science Mechanical Engineering High strain-rate bulk metallic glass HTPB rubbery polymer SHPB
spellingShingle	Materials Science Mechanical Engineering High strain-rate bulk metallic glass HTPB rubbery polymer SHPB Sunny, George Padayatil A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
author	Sunny, George Padayatil
author_facet	Sunny, George Padayatil
author_sort	Sunny, George Padayatil
title	A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
title_short	A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
title_full	A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
title_fullStr	A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
title_full_unstemmed	A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite
title_sort	high strain-rate investigation of a zr-based bulk metallic glass and an htpb polymer composite
publisher	Case Western Reserve University School of Graduate Studies / OhioLINK
publishDate	2011
url	http://rave.ohiolink.edu/etdc/view?acc_num=case1295634962
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A High Strain-Rate Investigation of a Zr-based Bulk Metallic Glass and an HTPB Polymer Composite

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