Accession Number : ADA428314
Title : Numerical Hopkinson Bar Analysis: Uni-Axial Stress and Planar Bar-Specimen Interface Conditions by Design
Descriptive Note : Final rept. Jan-Mar 2003
Corporate Author : DELAWARE UNIV NEWARK CENTER FOR COMPOSITE MATERIALS
Personal Author(s) : Gama, Bazle A. ; Gillespie, John W., Jr
Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA428314
Report Date : SEP 2004
Pagination or Media Count : 57
Abstract : High strain rate characterization of materials is usually performed using the Split Hopkinson Pressure Bar (SHPB) in the strain rate range 100 - <10,000. In the one-dimensional analysis of Hopkinson bar experiment it is assumed that the specimen deforms under uni-axial stress, the bar-specimen interfaces remain planar at all-time, and the stress equilibrium in the specimen is achieved in travel times. The first two assumptions are in general not true for acoustically hard specimens with diameter smaller than the bars. Explicit dynamic finite element analyses are used to investigate these assumptions. A new specimen design is suggested which satisfies the uni-axial stress condition in the specimen under the linear-elastic deformation phase of the specimen. A new Hopkinson bar experimental technique is presented to ensure that the bar-specimen interfaces remain planar at all time. Extensive numerical analyses are performed to quantify the accuracy of the proposed configurations.
Descriptors : *INTERFACES , *NUMERICAL ANALYSIS , *PRESSURE GAGES , *STRAIN RATE , *AXIAL LOADS , COMPRESSION , STRESSES , SIMULATION , INERTIA , DEFORMATION , STRAIN(MECHANICS) , THREE DIMENSIONAL , CYLINDRICAL BODIES , PLANAR STRUCTURES , FAILURE(MECHANICS) , FRICTION , TRANSMISSIONS(MECHANICAL).
Subject Categories : MECHANICS
LAMINATES AND COMPOSITE MATERIALS
Distribution Statement : APPROVED FOR PUBLIC RELEASE