New Composite Protective Materials Of The Dynamic Static Mechanical Properties And Engineering Application

Research on new composite protective materials with high strength and good absorbing energy dissipation has important theoretical academic and engineering application values in protection engineering.In this study,the dynamic static mechanical test of a steel fiber reinforced concrete composite was conducted,and the quasi-static constitutive relation and nonlinear visco-plastic dynamic constitutive relation were proposed.Then,a new type of shell particle composite material was prepared,and the protective engineering distribution layer underwent an explosion test and numerical simulation and analysis.The shell particle composites of the three-dimensional Kelvin-Maxwell dual viscosity coefficient of the equivalent constitutive model was proposed,and the numerical simulation and experimental results of the stress-time history curve,peak stress,and stress pulse-width were compared,thus optimizing the material in the equivalent constitutive parameters.Meanwhile,the equivalent constitutive model was applied to the numerical calculation of the protective structure,and the dynamic response and damage effect of the protective structure were studied.The main contents and innovations of this study include the following.A quasi-static test of steel fiber concrete was performed,and the stress-strain relation curve of a material with low strain rate and different steel fiber contents was obtained through a rock tri-axial stress test machine.A clear physical concept and a convenient fitting process of the quasi-static constitutive relation-containing damage of a new sectional steel fiber reinforced concrete were proposed given the strain and steel fiber contents as the two independent factors from the test curve.The corresponding material parameters were obtained by a fitting of the concrete test curve of the different steel fiber contents.Results showed that the strength and deformation toughness of the steel fiber content on the concrete were evidently enhanced.These strengthening and toughening mechanisms were analyzed theoretically.The dynamic mechanical properties of the steel fiber reinforced concrete were studied by the SHPB technology,and the stress-strain curves of the different steel fiber contents and strain rates were obtained.The use of a type of steel fiber reinforced concrete,which is dependent on the strain and strain rate of the correlation function of the new nonlinear visco-plastic dynamic constitutive relation,was proposed to analyze the dynamic stress-strain curve characteristics of steel fiber reinforced concrete and review these characteristics on the basis of dynamic constitutive model theory through the test curve of three successive least squares optimization simulations.The material parameter was obtained by the numerical simulation method of the strain rate and the dependency relationship of the steel fiber content.The theoretical basis and the test scheme for the field explosion test were presented in detail,and a field explosion test of stratified civil engineering was conducted successfully.Under the condition of the same explosion test,the distribution layer of the shell particle composite material and the distribution layer of sand were constructed.The peak stress,stress pulse-width,and failure mode of the two layers were obtained.Results showed that the new type of shell building layer and the distribution of the particle composites of the explosion wave had strong attenuation and dispersion effect.Moreover,the peak stress reduced by 50%,the stress pulse-width increased by approximately 20%,and the range of the composite protective layer damage of the new type of shell particles decreased considerably and had the capability to withstand repeated blows.In a stratified type air-defense site blasting experiment,which was considered the foundation,a series of numerical calculations for the field blasting test was performed.However,given that the complexity of shell particle composites has a heterogeneous structure,conducting a direct numerical simulation was difficult or even impossible.An equivalent constitutive model of a new 3D Kelvin-Maxwell dual viscosity coefficient was proposed,and a new display constitutive computing module was embedded in the software LS-DYNA.The corresponding constitutive parameters were optimized by a comparison of the numerical simulation and experimental results in terms of the peak stress,the stress-time history curve,and stress pulse-width.The optimized parameters and numerical simulation results showed that the error of the equivalent constitutive model and the peak stress was within 10%,and the uniformity of the stress-time history curve and stress pulse-width has an important significance in engineering and academic practice.Finally,with the equivalent constitutive model of the new form of the viscosity coefficient,a numerical calculation of the corresponding protection structure was performed and the dynamic response characteristics and damage effect of the protective structure were studied.