Study On Dynamic Response Characteristics Of POZD Air Defense Door Structure Under Impact Load

As the mouth of the project,the blast door bears the important responsibility of protecting the safety of internal personnel and equipment,and has always been the key research content of underground civil air defense engineering.After in-depth analysis and research on the present situation and existing problems of civil air defense doors,applying new materials to composite structures is a new idea to improve the anti-explosion and anti-impact performance of structures.Polyurea has good physical and chemical properties and spraying technology,and has important application prospects in the field of safety protection.Polyisocyanateoxazodone（POZD）is a new polyurea elastomer material,which will be used as the research object in this paper.The influence law of POZD coating on the impact property of civil air defense door structure under impact load is studied,mainly including the following three aspects:（1）through the quasi static tensile,compression,hopkinson pressure bar experimental research,the relationship between the stress and strain of POZD,results show that the nonlinear POZD has obvious correlation with strain rate,under the condition of the same strain,with the increase of strain rate,POZD specimen needed to achieve the same strain stress increase,namely POZD specimen rigidity increases with the increase of strain rate.Based on the experimental results and the Mooney-Rivlin constitutive model,the parameters of the Mooney-Rivlin constitutive equation and the strain rate related parameters are fitted.（2）The impact resistance of steel plate coated with POZD was studied by numerical calculation and impact loading test.The results show that POZD can significantly improve the resistance of the target plate when the base material is 4mm and the surface density is3.524g/cm~3,the resistance of steel plate coated with POZD only on the opposite side is better.When the surface density is 3.72g/cm~3,POZD is coated on both sides with the same thickness and the coating thickness is 3-6mm,the resistance improvement effect of the steel plate is the best.In addition,the composite target plate is coated on both sides with the same thickness.When the thickness of POZD coating on the opposite side is greater than that on the front side,the resistance improvement effect of the target plate is better.When the thickness of front coating is increased by equal gradient,the strain peak of composite target increases first and then decreases.When the thickness of the reverse coating is increased by equal gradient,the strain peak of the composite plate decreases,but the resistance improvement effect of the target plate begins to show a downward trend.（3）POZD was studied by numerical calculation and impact load test for coating the shock resistance of the coating blast door,the results show that the POZD coating composite panel structure unit in the process of shock load,a significant number of shock wave energy and impulse can be converted into the energy for the deformation of the composite target plate unit,part of the energy absorbed by POZD layer dispersion and;Due to the different wave impedance matching,the POZD coating thickness must match the structure to improve the structural resistance.The designed new lightweight blast door structure can meet the resistance requirements.Compared with the original blast door,the mass of the new lightweight civil air defense door is reduced by 32.5%,and the total cost is not increased.