Efficient Design of Fiber Reinforced Cementitious Composites Through Interface Tailoring

点击翻译按钮获取中文摘要

The present work focuses on a new type of toughening mechanism -- extensive diffused damage surrounding in the main crack-tip. The proposed research is motivated by a recent discovery of a ductile fracture mode in strain hardening brittle cement matrix composites (SHBMC) reinforced with 1-4 % polyethylene fibers. Crack propagation is observed to be accompanied by extensive volumetric inelastic deformation surrounding the crack tip, in addition to conventional fiber bridging and pull-out in the crack wake. The off-crack-plane energy absorption is found to be even higher than the fiber bridging energy in some specimens we have tested so far, with total fracture energy reaching 34 kJ/m2. This represents roughly 3400 times the fracture energy of the virgin matrix without fibers. As reference, the fracture energy of aluminum alloys is between 8 - 30 kJ/m2. Experimental investigations on R-curve behavior, and on- and off-crack-plane fracture energy partitioning will be conducted based on the J-based fracture testing technique. Correlation between pseudo strain-hardening processes in uniaxial testing and the spatial evolution of damage during the ductile fracture process in notched specimens will be used to establish the detail micromechanisms of the ductile fracture mode.