Two-dimensional shear bands growing dynamically in plates: An investigation of transient deformation fields, temperature fields and shear band toughness
- California Institute of Technology, Pasadena, CA (United States)
The phenomenon of dynamic initiation and propagation of two-dimensional adiabatic shear bands is experimentally and numerically investigated. Prenotched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch-tip and propagate rapidly in a direction nearly parallel to the direction of impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high speed infrared detector system. The materials studied are C-300 (a maraging steel), HY-100 steel and Ti-6Al-4V. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 6000C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by HY-100 steel and Ti-6Al-4V. Deformation fields around the propagating shear band are recorded using high speed photography. Shear band speeds are found to strongly depend on impact velocity are as high as 1200 m/s for C-300 steel. Finite element simulations of the experiment are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high speed infrared detectors and high speed photography. Finally, the numerical calculations are used to investigate motions of shear band toughness. The shear band driving force is calculated as a function of shear band velocity and compared to the crack driving force versus velocity relations for mode-I, opening cracks in the same material.
- OSTI ID:
- 175094
- Report Number(s):
- CONF-950686--
- Country of Publication:
- United States
- Language:
- English
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