Accession Number : AD0635003

Title :   ELASTIC-PLASTIC MATERIAL RESPONSE TO SUBMICROSECOND UNIAXIAL STRESS.

Descriptive Note : Master's thesis.

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : Harris, Charles Edward

Report Date : MAR 1966

Pagination or Media Count : 289

Abstract : Flat samples of 6061-T6 aluminum were impulse loaded with 50 mil x-cut synthetic quartz fliers using a 2.5 inch air gun. An oscillograph record of shock pressure as a function of time was obtained from the rear of the sample using piezoelectric quartz pressure transducers. The fliers were laterally supported and their characteristic low acoustic impedance and high dynamic elastic limit relative to the target material provided square wave pressure loading on the impact surface of the target. The dynamic strain response of the material is calculated from the oscillogram after applying correction for tilt which includes modifications for determining the magnitude of the Bauschinger effect during the rare-faction process. The observed specific impulse from the oscillograms agree well with the input specific impulse measured from sabot velocity and peak calculated stress except where peak stresses were lost in sabot tilt. The magnitude of reverse yield stress in 6061-T6 Al was determined to be 1.3 times the dynamic elastic limit. The overtaking relaxation model proposed by Zubabakin is essentially verified by the unresolvability of peak stresses from sample thicknesses approaching 1 centimeter. This effect accounts for low apparent strain values during rarefaction on some shots. (Author)

Descriptors :   (*ALUMINUM ALLOYS, IMPACT TESTS), (*IMPACT SHOCK, ALUMINUM ALLOYS), SHOCK(MECHANICS), HYPERVELOCITY GUNS, STRESSES, ELASTIC PROPERTIES, PLASTIC PROPERTIES, MEASUREMENT, STRAIN(MECHANICS), QUARTZ, TARGETS, SHOCK WAVES, EXPERIMENTAL DATA, NUMERICAL ANALYSIS, SURFACE PROPERTIES

Subject Categories : Metallurgy and Metallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE