Characterizing High-Strain-Rate Response of Cementitious Composites Using a Novel Strain-Energy-Based Impact Test System

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A novel test system is proposed for characterizing the high-strain-rate response of materials. The new method exploits the internal strain energy accumulated in an elastic bar to impart a high speed, high energy pulse onto a specimen. The proposed test system overcomes the combined limitations of traditional impact test setups and enables high quality impact testing in a scalable, cheap, compact, fast and safe manner. Another critical advantage is the ability to test with a small set-up, relatively large size specimens, which permits tests that more truly represent the behavior of non-homogenous building materials. Fundamental research will be conducted to optimize and explore the capabilities of the proposed system. The developed system will then be used to investigate the rate dependent behavior of high performance and ultra high performance fiber reinforced cementitious composites. These materials are known to possess exceptional strength, ductility and toughness under pseudo-static loading and therefore have the potential to serve as highly damage tolerant and energy absorbing materials under rapid loading conditions. The improvements in impact testing promised by the proposed technology will lead to faster de-velopment of better and more economical impact-resisting building materials. Enhancement in material response under high strain rate will eventually result in improvements in the ability of the national physical infrastructure system to better withstand unforeseen and extreme loading events. The work will also have an important impact on the development of human resources. Through the involvement of a diverse set of student researchers, a new generation of students will be introduced to the use of computational structural simulation, high strain rate testing, and high-performance structural materials.