Numerical Simulation Of Dynamic Behavior Of Microcapsule Based Self-Healing Cementitious Composites Under Impact Loading

As an indispensable building material,concrete exhibits brittleness and low tensile strength.During the use of concrete,micro cracks and local damage will inevitably occur.If these cracks cannot be repaired effectively,it will seriously affect the performance and durability of the structure during normal use,and may develop into macro cracks or even cause some catastrophic consequences.Self-healing concrete is a civil engineering functional material developed in recent years.It can promote the self-healing of cracks without the need for major interventions on the structure,and can self-heal the cracks and damages.Compared with traditional methods,self-healing concrete technology is dedicated to improving the durability of engineering structures and extending service life.The self-healing system based on the microcapsule method is an important branch in the field of self-healing concrete research.Its repair effect on the mechanical properties of concrete under static load has been confirmed by relevant domestic and foreign experimental research institutes.However,at present,there is a lack of research on the mechanical properties and repair performance of microcapsule selfhealing concrete under dynamic load,and there is a lack of systematic research on the microscopic mechanisms that affect its macroscopic performance.Based on the current research status,this article studies the dynamic mechanical properties of microcapsule self-repairing concrete from the perspective of dynamics.Based on the Hopkinson bar experiment,the research is conducted through simulation technology.First,write the ABAQUS subroutine VUMAT,embed the HJC model into the finite element calculation,and implement the microcapsule concrete dynamics calculation in the ABAQUS software.The correctness of the subroutine is verified by two calculation examples.Secondly,the Hopkinson rod experimental model of microcapsule concrete was established to simulate the impact of microcapsule concrete with different contents to reveal the effect of microcapsule content on the dynamic mechanical properties of concrete.The dynamic compressive strength decreases,which is consistent with the experimental results.At the same time,the dynamic strength enhancement factor will increase as the strain rate increases.Finally,on this basis,the SHPB model of macro-capsule concrete was established.Impact experiments were performed on HIPS,ABS capsule materials,one and two macro capsules,the location of capsules in the sample,and samples with cracks of different lengths and depths.By comparing the simulation results,it can be seen that the macro-capsule concrete and the microcapsule concrete have similar dynamic mechanical properties,and the dynamic compressive strength of the concrete containing the macro-capsule is smaller than that of the original sample;The lower the compressive strength of the specimen;as the crack length and depth of the specimen increase,the compressive strength of the macro capsule concrete decreases.For samples with double capsules,the closer the center of the two capsules,the lower the compressive strength of the sample.By studying the dynamic mechanical properties of macrocapsule concrete,the dynamic mechanical properties of microcapsule concrete can be inferred.