Design, testing, and utilization of a spherical shock-recovery system to investigate material response to ultrahigh pressure

Show full item record

Title: Design, testing, and utilization of a spherical shock-recovery system to investigate material response to ultrahigh pressure
Author: Wilson, James N
Abstract: The existing shock recovery systems can be classified as planar or convergent . Both systems are used extensively in the study of materials under high pressure . However , a three -dimensional system capable of substantially higher pressure with the capability of full sample recovery would add a new dimension to the analysis of materials exposed to ultra -high shock pressure . In this thesis , an explosive -based spherical shock -recovery system was designed , tested , and used to perform a series of three -dimensional shock -recovery experiments . A system was desired that would generate extremely high pressure in the sample while maintaining its structural integrity for post -shock analysis . The system consisted of a spherical metallic shell containing a sample of precursor materials at its center . The metallic shell was surrounded by a spherical layer of high explosive . Several detonators were placed at regular intervals around the outside of the explosive layer . To hold the detonators in place during assembly and transport , a spherical brass shell was placed around the explosive . The detonators were placed in holes drilled in the brass shell at the proper locations . To provide confinement for the explosive , this assembly was placed inside a short section of naval gun barrel . The remaining volume of the barrel was filled with sand to aid confinement . Several shock -recovery experiments were performed with the spherical system . Five experiments were performed with samples containing mixtures of nanograde nickel powder and buckeyballs . Two experiments were performed on solid spheres of steel with pearlitic (one inch diameter ) and martensitic (1 .5 inch diameter ) microstructures . The post -shock analysis of the samples consisting of a metallic shell surrounding precursor materials revealed that it is possible to use this system to synthesize materials that under normal conditions are difficult to make . The analysis of the solid spheres revealed that , due to shock loading , a hole was formed at the center of each sphere . In the pearlitic steel sphere numerous changes were made to the microstructure , some of which have not been previously observed . The martensitic sample did not undergo as drastic a change as the pearlitic sample , which by itself is an interesting observation that deserves more study . According to two -dimensional computer simulations performed with the CTH hydocode , this shock -recovery system is capable of producing ultrahigh pressure levels in both solid and powder materials . The simulations indicate that the pressure in the one inch diameter sphere increases from 50 GPa at the surface of the sphere to about 1 TPa at its center , 0 .5 inches away .
URI: http : / /hdl .handle .net /2346 /20035
Date: 2001-05

Citation

Design, testing, and utilization of a spherical shock-recovery system to investigate material response to ultrahigh pressure. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /20035 .

Files in this item

Files Size Format View
31295018169416.pdf 14.64Mb application/pdf View/Open

This item appears in the following Collection(s)

Show full item record

Search DSpace

Advanced Search

Browse