Study On Structural Mechanical Response Of Rectangular Tube With Functionally Graded Negative Poisson’s Ratio

At present,a lot of research has been done on the sandwich structure,and there are many studies on the positive and negative Poisson’s ratio sandwich structure,but it mainly focuses on the mechanical response of single gradient sandwich structure,and the research on the mechanical properties of multi gradient sandwich structure is not very in-depth.Based on this background,a new type of negative poisson’s ratio sandwich structure is designed,and its static and dynamic mechanical properties and explosion resistance are studied.The main research contents are as follows:The model size of the gradient rectangular tube sandwich structure is designed.After exploring the manufacturing process of the model,the gradient rectangular tube sandwich structure is prepared by brazing,and the quasi-static flat compression experiment is carried out on the prepared gradient rectangular tube sandwich structure.It was found that the structure went through four stages:initial deformation phase,core contraction phase,core rotation phase,core compaction phase.According to the research on the rectangular tube sandwich structure with different gradients,the numerical simulation of the rectangular tube sandwich structure with different gradients under static compression conditions is carried out,and the elastic modulus E₁of the initial stage of the gradient rectangular tube sandwich structure with different gradients is obtained.The elastic modulus E₂in the compacting stage,the equivalent yield stressσ₁ in the shrinking stage of the core,the equivalent yield platform strain lengthε₁,the influence law of the core energy absorption and the core specific energy absorption,and the optimal gradient core configuration suitable for human body is obtained.The drop hammer impact experiment was carried out on the prepared gradient sandwich structure,and the experiments were carried out for the same drop hammer height,different drop hammer mass and different drop hammer height with the same drop hammer mass to explore the influence of drop hammer height and drop hammer head mass on the impact load.The rectangular tube sandwich structure with different gradients is studied,and the numerical simulation of the rectangular tube sandwich structure with different gradients under the drop hammer impact condition is carried out respectively.The elastic modulus E1 in the initial stage and the equivalent yield stress in the core shrinkage stage of the rectangular tube sandwich structure with different gradients are obtainedσ1.Equivalent yield platform strain lengthε1.Final equivalent strain of sandwich structureεz.According to the influence law of core energy absorption and core specific energy absorption,the optimal gradient core configuration in line with human body is obtained.The effects of different hammer head mass and different hammer head speed on the sandwich structure of the optimal gradient rectangular tube are studied,and the prediction fitting curves of energy velocity and energy quality are obtained.The dynamic response of the gradient rectangular tube sandwich structure under the impact load of gas explosion is carried out by numerical simulation,and the research objects such as the deflection of the sandwich structure backplane,the peak reaction force at the support of the backplane,and the energy absorption of the core are explored.The explosion resistance performance of different gradient sandwich structures is studied,and the optimal sandwich structure conforming to the human body is found.Analyze the backplane deflection,peak reaction force at the backplane support,and core energy absorption of the gradient rectangular tube sandwich structure of optimal configuration under different charge and burst distance,and use the origin software to simulate the relationship curve.Together,the backplane deflection and burst distance,core absorption energy and burst distance,support peak and burst distance,backplane deflection and charge,core absorption energy and charge,and support peak reaction force The empirical formula of drug quantity provides a theoretical reference for future gradient sandwich structure design and engineering application.