Experimental impact analysis on ultra-high performance concrete (UHPC) for achieving stress equilibrium (SE) and constant strain rate (CSR) in Split Hopkinson pressure bar (SHPB) using pulse shaping technique

This work emphasizes obtaining and validating experimental test results of ultra-high performance concrete (UHPC) under compressive impact loading at high strain rates (30-200 S-1). Cylindrical specimens of 9.2 mm in height and 23.8 mm in diameter were used for compression tests under dynamic and static conditions. Quality of stress equilibrium and constant strain rate were investigated using pulse shapers made of Copper and Aluminum with various geometries. Digital image correlation (DIC) was used to monitor the strains of some samples using a high speed camera at 186,000 frames per second and thus to compliment the calculated strain values obtained by the split Hopkinson pressure bar (SHBP) equations. The results showed that nearly constant strain rate and dynamic stress equilibrium over an effective duration of the test can be achieved for UHPC with a compressive strength of about 200 MPa. This validated the experimental test setup and allowed for the determination of the UHPC's dynamic impact factor based on the results obtained. (C) 2017 Elsevier Ltd. All rights reserved.