Failure Localization and Correlation of High-Speed Tension and Impact Tests of Strain-Hardening Cement-Based Composites

Mechanical properties of strain-hardening cement-based composites (SHCC) subjected to impact and high-speed tensile loading were studied. The impact test setup was based on a free-fall drop weight on a three-point bending specimen. A servohydraulic high-speed tensile machine was used for tension tests. As the input impact energy increased from 6.7 to 67 J, absorbed energy increased from 0.7 to 3.6 J and remained constant at that level. Ultimate load and maximum deflection also increased with increasing input energy. Uniaxial tension tests on SHCC specimens were conducted at strain rates of 25, 50, and 100 s^-1. Increases in tensile strength and strain capacity were observed with increasing strain rate. Digital image correlation (DIC) method was used to measure the full-field deformation in addition to the nature of the localized strain and shear lag region near transverse cracks. An analytical model was used to correlate the tensile and flexural impact responses and address the effect of localized failure on the overall sample response. The results indicate that the two test methods of impact and high-speed tension can be correlated by using a constitutive material model and that the correlation of the material properties under increasing strain rate with an increase in input impact energy can be addressed through cracking and size of the localization zone.