Effects of Impact Velocity and Stress Concentrators in Titanium on Failure by Adiabatic Shearing

摘要

This Interim Report covers the contract period from Nov. 18/2000 to Feb. 17/2001 (second period of three months). During this period a series of shear tests on fast servo-hydraulic testing frame with three specimen geometries have been completed. That is the following geometries of notches were applied: (1) U-geometry, (2) V-geometry, and (3) I-geometry. The standard geometry with a square notch was tested during the first interim period. The specimen geometries are specially design to increase the stress concentration before triggering an adiabatic shear band. The material tested was Ti-6A1-4V, delivered by the ARL- APG-AMSRL. This series of tests was limited to relatively low nominal strain rates, from 10E-3 1/s to 10E+3 1/s. Analysis of the oscillograms obtained with those tests are almost finished. The experimental setup for the direct impact loading has been improved and experiments are started and are continued. The range of the nominal strain rates covered by the direct impact technique is from 10E+3 1/s to 10E+5 1/s.