A gravity-driven split Hopkinson tension bar for investigating quasi-ductile and strain-hardening cement-based composites under tensile impact loading

摘要

A gravitational split Hopkinson tension bar (SHTB) was developed with the goal of enabling an accurate characterization of the mechanical behavior of quasi-ductile cementitious composites in terms of force-deformation (stress-strain) curves under tensile impact loading. The design of the setup targeted additionally compact dimensions, simple operation, high adjustment flexibility, and low construction costs. The testing principle and the quality of the measurements were demonstrated by investigating a strain-hardening cement-based composite (SHCC) made with ultra-high molecular weight polyethylene (UHMWPE) fibers as well as its non-reinforced cementitious matrix at tensile strain rates of up to 200 s(-1). The tensile impact tests were accompanied by high-speed optical measurements for subsequent analysis by means of Digital Image Correlation (DIC). In this way the mechanical measurements were double-checked, and the fracture processes in the specimens were analyzed in detail.