Research On Stress Wave Propagation And Attenuation Characteristics Of TC4 Laminated Structure Based On Different Intermediate Layer Material

The theory of stress wave propagation is the basis of analyzing the response and failure characteristics of structures and materials under impact loads,which is of great value in national defense and civil engineering.In recent years,due to the widespread use of armor-piercing projectile and armor-breaking projectile,the damage of stress wave to homogeneous armor material is becoming more and more obvious.TC4 laminated composite armor has the advantages of high strength,high hardness and low density at the same time.Moreover,due to the interface with different impedance,the stress wave propagation characteristics have certain complexity,so it has attracted wide attention and attention in the field of armor protection.However,the dynamic mechanical behavior of layered structures under uniaxial compression and the propagation characteristics of stress waves in layered structures have not been fully studied.Based on the above research background,this paper firstly conducts SHPB test and numerical simulation on the monomer component materials that make up the layered composite structure armor,analyzes the strain rate sensitivity and failure mode of the materials,and then designs three solid models of "sandwich" laminated composite structure with several common armor materials as the intermediate layer.The influences of material impedance,strain rate effect,plastic deformation and other factors on the propagation and attenuation characteristics of stress waves in layered structures were analyzed by numerical simulation.The main research contents are as follows:1.Using SHPB equipment,dynamic mechanical properties of monomeric component materials composed of layered composite structures were tested under different strain rates,and strain rate sensitivity and stress uniformity under SHPB experiments were discussed.Reasonable parameters of dynamic constitutive model are used to simulate several monomer components by SHPB finite element method to verify the validity of the selected constitutive model parameters.2.The characteristic line method is used to draw the incident stress wave in the input bar,and then the contact stiffness of penalty function in SHPB simulation is precisely selected by using vector finite element method,and the initial velocity is replaced by sinusoidal wave input at all nodes of the impact bar.The stress wave in the input bar and output bar is filtered,and the simulation results are greatly accurate.The correctness of the filtering method is verified.The wave differential equation and boundary condition expressions of the monolayers under the loading conditions of elastic wave and elastic-plastic wave were constructed by the force analysis of the monolayers in the laminated composite structure and the subsequent intersection of reflected wave and transmitted wave were simplified to a certain extent.The differential equation was solved analytically by the method of separation of variables.3.The finite element simulation method is used to study the influence of different initial velocities of the impact rod on the stress wave propagation characteristics of the sandwich laminated composite structure in the SHPB experiment.According to the simulation results,the change law of the stress field in the composite structure with time is studied.The effects of wave impedance,strain rate effect and plastic deformation on the stress distribution of laminated composite structures are analyzed.The results show that the increase of the wave impedance of the intermediate layer significantly reduces the impact resistance of the layered structure,and the strain rate effect also has a certain effect on the impact resistance.The plastic deformation of the intermediate layer material plays a homogenizing role in the internal stress field of the structure and is also an important standard to measure the attenuation characteristics of stress waves.To sum up,the dynamic mechanical response of monomer components of laminated composite armor was obtained through this study,and the stress wave propagation characteristics and stress field distribution law of "sandwich" laminated structure under different initial conditions and different interlayer materials were analyzed,which provided some reference for the design of more excellent armor structure.