Evaluation of the collapsing thick-walled cylinder technique for shear-band spacing

The thick-walled cylinder (TWC) technique was successfully used to investigate the shear-band patterning in AISI 304 stainless steel. Several factors that may influence the shear-band distribution and spacing in the TWC configuration were examined. The role of machining, annealing, and shrink fitting, as well as the variation of the shear-band distribution along the longitudinal axis of the cylindrical specimen were evaluated. Experimental results indicate that the machined surface at the internal boundary of the cylindrical specimen, where shear bands initiate, provides a strain-hardened layer that significantly changes the condition for their initiation. Specimens with such a layer have a higher density of bands with a smaller spacing, in comparison with those without a work-hardened layer. The nature of contact interface in the cylindrical specimen assembly, either causing a clearance that changes the initial loading conditions or introducing a pre-strained layer with shrink-fitting technique, does not influence the spacing of shear bands, but does affect the evolution and development of multiple shear bands at the initial stage. The distribution of shear bands along the cylinder has a constant spacing but the maximum lengths of bands are sensitive to the position. The collapse process of the cylindrical specimen was simulated by using the RAVEN hydrocode. The deformation, temperature, and velocity histories during the cylinder collapse were calculated. The calculated results are in good agreement with the previous experimental data.