Dynamic Constitutive Model And Finite Element Analysis Of Steel-PVA Hybrid Fiber Concrete

Steel and PVA Hybrid Fiber Concrete can prevent the development of initial microcracks inside the concrete and control the speed of macroscopic crack, improving its strength, impact resistance and anti-cracking ability, toughness, etc. In some engineering field which is vulnerable to dynamic loads, such as impact and explosion load, the mechanical properties of Hybrid Fiber Concrete plays a more significant act. It has broad application prospects. As the steel fiber and PVA fiber are distributed disorderly in the concrete, the S-PHFC is a kind of extremely complex material and the research of mechanical properties has not yet completed. Studies in constitutive under dynamic loads are less.Firstly, the development,constitutive research and current situation of numerical simulation of Hybrid Fiber Concrete at home and abroad are briefly reviewed in this article. The article also describes six commonly used dynamic constitutive model of concrete material and makes a detailed analysis of each constitutive model. HJC model is a kind of concrete dynamic constitutive which is applied more and relatively more mature, but the original HJC constitutive can not be appropriate for Hybrid Fiber Concrete containing a volume fraction of steel and PVA fiber. Then based on the shock compression experiment of Steel and PVA Hybrid Fiber Concrete conducted by research team, considering the effect of fiber enhancement and the strain rate, a improved HJC dynamic constitutive model is put forward in this paper. After using finite element software LS-DYNA for numerical fitting, some results can be obtained:(1) The basic principles of enhancement, crack resistance and toughness effect of steel fiber and PVA fiber are described in this article. Considering the interaction of the two fibers and combining data of SHPB experiment, formula of fiber enhancement factor, toughness indicators and strain rate growth factor with different fiber content and different strain rates are obtained.(2) Steel and PVA Hybrid Fiber Concrete has a strain rate sensitivity as concrete. The relationship between dynamic enhancement coefficient and the logarithmic strain rate is a double broken line. When the logarithmic strain rate is less than a certain value, the dynamic enhancement coefficient DIF basically remain unchanged. When the logarithmic strain rate exceeds the threshold, DIF increases along with logarithmic strain rate. And DIF formula of this stage is matched.(3) The damage factor of Steel and PVA Hybrid Fiber Concrete, and fits the method of calculating damage factor are also discussed in this article.(4) Considering steel and PVA fiber enhancement effect and the strain rate effect, a improved HJC dynamic constitutive model is put forward. This lays a foundation for the numerical simulation of material.(5) Shock response finite element numerical simulation of Steel and PVA Hybrid Fiber Concrete is achieved in the paper. And the simulation results highly coincide with the experimental results. This states that the numerical simulation is reliable and verifies the improved the HJC dynamic constitutive is suitable for the experiment.