TITLE:
Occurrence of Dynamic Shear Bands in AISI 4340 Steel under Impact Loads
AUTHORS:
Gbadebo Owolabi, Daniel Odoh, Akindele Odeshi, Horace Whitworth
KEYWORDS:
Adiabatic Shear Band; Finite Element Model; Strain Hardening; Thermal Softening; Johnson-Cook Model; AISI 4340 Steel
JOURNAL NAME:
World Journal of Mechanics,
Vol.3 No.2,
April
30,
2013
ABSTRACT: In this study, occurrence
of adiabatic shear bands in AISI 4340 steel under high velocity impact loads is
investigated using finite element analysis and experimental tests. The
cylindrical steel specimen subjected to impact load was divided into different sections separated by
nodes using finite element method in ABAQUS environment with boundary
conditions specified. The material properties were assumed to be lower at the
section where the adiabatic shear bands are expected to initialize. The finite
element model was used to determine the maximum flow stress, the strain hardening,
the thermal softening, and the critical strain for the formation of adiabatic
shear bands. Experimental results show that deformed bands were formed at low
strain rates and there was a minimum strain rate required for formation of
transformed band in the alloy. The experimental results also show that cracks
were initiated and propagated along transformed bands leading to fragmentation
under the impact loading. The susceptibility of the adiabatic shear bands to
cracking was markedly influenced by strain-rates. The simulation results
obtained were compared with experimental results obtained for the AISI 4340
steel under high strain-rate loading in compression using split impact
Hopkinson bars. A good agreement between the experimental and simulation
results was obtained.