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

提出了一种表征材料高应变率响应的新型测试系统。这种新方法利用弹性棒中积累的内部应变能，将高速、高能脉冲传递到试样上。所提出的测试系统克服了传统冲击测试装置的综合限制，以可扩展、廉价、紧凑、快速和安全的方式实现高质量的冲击测试。另一个关键的优点是能够用较小的装置进行测试，相对较大的样品尺寸，这使得测试更真实地代表非同质建筑材料的行为。将进行基础研究以优化和探索所提出的系统的功能。开发的系统将用于研究高性能和超高性能纤维增强胶凝复合材料的速率依赖行为。已知这些材料在伪静态载荷下具有优异的强度、延展性和韧性，因此在快速载荷条件下具有高损伤容忍度和能量吸收材料的潜力。所提出的技术所承诺的冲击试验的改进将导致更快地开发出更好、更经济的耐冲击建筑材料。高应变率下材料响应的增强最终将导致国家物理基础设施系统更好地承受不可预见和极端载荷事件的能力的提高。这项工作还将对人力资源的发展产生重要影响。通过不同学生研究人员的参与，新一代的学生将被引入到使用计算结构模拟，高应变率测试和高性能结构材料。

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.