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
      NUMERICAL MATHEMATICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE