Accession Number : ADA261568


Title :   Experimental Investigation of Adiabatic Shear Banding at Different Impact Velocities


Descriptive Note : Final rept. Nov 1990-Jan 1993


Corporate Author : METZ UNIV (FRANCE) LAB OF PHYSICS AND MECHANICS OF MATERIALS


Personal Author(s) : Klepaczko, Janusz R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a261568.pdf


Report Date : Jan 1993


Pagination or Media Count : 87


Abstract : In order to expand shear testing to different nominal strain rates a new experimental technique has been developed. A modified specimen geometry of double shear has been designed (MDS specimen). The MDS specimen with flat faces is loaded directly by a bar projectile which can be accelerated to a desired impact velocity by a gas gun. Since the specimen is backed by a long tube which transmits the force imposed on the MDS specimen the shear stress history can be exactly recorded by the transmitted elastic longitudinal wave. The shear displacement of the MDS specimen is measured directly by an optical gage. The experimental setup which consists of the air gun, transmitter tube (Hopkinson tube) and optical displacement gage, permits for a wide variation of the nominal strain rates. There is no limitation of maximum shear strain. Evaluation of dispersive effects of elastic longitudinal waves in tubes has been studied. A closed-form solution has been obtained for a semi-infinite tube loaded at the end by the step pressure function p = p sub oH(t), where P sub o is the amplitude of pressure and H(t) is the Havyside function. Dispersion effects in the real configuration of the MDS specimen and Hopkinson tube have been analyzed for several idealized trapezoidal incident pulses using a dynamic FE code. Those calculations revealed characteristic features in dispersive changes of the transmitted pulses by the MDS specimen.


Descriptors :   *IMPACT STRENGTH , *SHEAR STRESSES , *ADIABATIC CONDITIONS , *LOW ALLOY STEELS , VELOCITY , STRESS STRAIN RELATIONS , COMPUTER PROGRAMS , MATHEMATICAL MODELS , MACHINING , PRESSURE , TORSION BARS , DRAWING(FORMING) , SHEAR STRENGTH , ELASTIC WAVES , ROLLING(METALLURGY) , FAILURE(MECHANICS) , IMPACT TESTS , DEFORMATION , DISPLACEMENT , STRENGTH(MECHANICS) , STEEL , STRAIN RATE


Subject Categories : Metallurgy and Metallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE