Fracture analysis of multifunctional fiber-reinforced concrete using phase-field method

In this paper, a numerical analysis has been conducted to predict the fracture response of a novel type of fiber reinforced concrete blocks, called "multi-functional fiber reinforced concretes"(MFRCs). In MFRCs, fibers have been coated with a shell. This will allow the structure to be used for multiple purposes, including concrete self-healing. This study is conducted utilizing phase-field fracture framework. The shell thickness and the ratio of fiber length to diameter are the geometrical parameters whose effects on the fracture resistance of the MFRCs have been analyzed. As choosing the right shell material is under investigation, in the next step of the study, in addition to the geometrical factors, different material mismatch cases for the critical energy release rate of the shell has been analyzed. Moreover, the application of two different fibers, polyester fiber and polypropylene fiber (with almost 10 times higher critical energy release rate), are looked into. All the structures undergo three loading conditions: tensile loading, compressive loading, and three-point bending. In order to judge what configuration performs best, the values of peak force and absorbed energy of each structure in each case study have been taken into consideration and compared with those of other structures. It was seen that the most favorable performance and configuration depend on the loading condition and also the material set. Under tension, MFRCs with the lowest fiber length to diameter ratio exhibit the highest peak force and absorbed energy in the case of polyester fiber. The same observation was made for all models and material sets under compressive loading. Under three-point bending loading condition, for the cases of polyester fiber, similar results were obtained as the lowest fiber length to diameter ratio showed the best mechanical response. Having said that, it must be mentioned that shell material had a dominant effect on the fracture response of the structure under this loading condition. Polypropylene fibers also managed to increase the peak forces in different loading conditions.