Stress Concentrators and Rate Effects in Formation of Adiabatic Shear Bands (Revised Version).
Final technical rept. 1 Sep 95-1 Aug 96,
METZ UNIV (FRANCE) LAB OF PHYSICS AND MECHANICS OF MATERIALS
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The phenomenon of shear instability and flow localization is investigated in this Report. The ultrahigh strength steel VAR 4340, approx. 52 HRC was tested in shear at wide range of the imposed velocities, from quasi-static to 120 ms. A new experimental technique of direct impact on double shear specimen was used. Four specimen geometries were tested with different stress concentrators, from standard to a very sharp notch. At loading velocities higher than the threshold value a substantial drop of the failure strains and failure energies was observed. To study this effect a series of FE simulations was run for two notch geometries. An extended FE simulation program was performed on occurrence of the Critical Impact Velocity CIV in shear. The FE calculations confirmed experimental result, CIV for VAR 4340 steel approx. 52 HRC is approx. 130 ms. A substantial drop of the localization energy was found at impact velocities higher than the CIV 130 ms.
- Properties of Metals and Alloys